Honda 250-305 Super Hawk Restoration & Maintenance Guide 1961-1967 Honda CB72-77 Super Hawk Maintenance, Restoration & Repair Guide All-new 2004 edition! Bill “MrHonda” Silver Copyright, 01/2003 1 Honda 250-305 Super Hawk Restoration & Maintenance Guide TABLE OF CONTENTS Cover 1961 CB72 Page 2-3 Table of Contents Page 4 Forward Page 5 Highlights Page 6-10 Super Hawk History Page 11-13 Riding the Super Hawk Page 14-15 Identifying CBs by Year Page 15-17 Major Changes by Year Page 17 Interesting Tidbits Page 18-19 Finding a bike Page 20 Buying a CB? What to check Page 20-24 Tools Page 24-26 Engine Overview Page 26 Cylinder Head - Caution Page 27-31 Power vs. Force Page 31 Primary Chains & Oil Filter/Pump Page 32 Valve Train Page 33-35 Head Gaskets/O-ring & Swapping Parts Page 35 Kick Start Covers/Clutch Page 37 Clutch Page 37-38 Transmission Page 38-45 Carburetor - Float Gauge-Setting Guide Page 45 Engine Electrics- Starter Clutch Repair Page 46-48 Chassis Electrics Page 48-49 Chassis Overview Page 49-52 Basic Rehabilitation Page 52-54 Common Mistakes Page 55-56 Basic Troubleshooting Tips Page 57-58 Specifications Page 58-61 Tune-up Procedures-Idle Setting Page 62-63 Daily and Periodic Maintenance Page 63-64 Beginning at the beginning/Parts and Parts numbers/Product Codes Page 64 Interesting Variations - Non-OEM Parts Page 65-66 Disassembly - Engine Removal Page 66-68 Dismantle Chassis Page 68-71 Chassis Parts - Analysis/Front Forks Page 71-72 Front Fender/Fork Crown/Steering Damper Page 72-73 Steering Stem - Handlebars Page 73 CB77 factory photos Page 74-75 Cables – Fuel Tank/Emblems Page 76 Petcock Page 76-77 Frame Label – Side Grip – Side Stand – Steering Head Bearings Seats Page 77-78 Seat Straps & Bolts – Side Covers – Stands and Steps Page 79-80 Kickstarter Arm/Shift Lever - Footplates 2 Honda 250-305 Super Hawk Restoration & Maintenance Guide Page 79-82 Page 82-83 Page 84 Page 84-85 Page 85-86 Page 86-88 Page 88 Page 88-89 Page 89-92 Page 91 Page 92-94 Page 94-97 Page 97-106 Page 106-108 Page 108 Page 108-111 Page 112-121 Page 121-123 Page 123-129 Page 130-132 Page 132-134 Page 134 Page 135-142 Page 143 Page 144 Page 145 Page 146 Page 147 Page 148 Page 149 Page 150 Page 151 Page 152 Page 153-159 Page 159-162 Mufflers Air Filter – Toolbox – Tool Kit – Owner’s Manual Rear Fork Chain Guard – Rear Fender – Mudflaps – Rear Cushion Front Wheel – Rear Wheel Tires/Aftermarket Shocks – Headlight Case/Headlight Speedometers Tail Lights – Dimmer Switch/Starter Switch Mirrors – Wiring Harness/Points/Battery/Rectifier Wiring Wiring Chart Honda Charging Systems Race Kit Racers –YB Parts-WEBCO 350cc Kit Instructions Chassis Restoration Parts Gaskets Fasteners Parts Bulletins Change in Threaded Parts Honda Service Bulletins Troubleshooting-Factory Notes Resources Acknowledgements Set-up Manual Wiring Diagram Cylinder Head Torque Crankcase Torque Break-in Tag Sales Tag Pistons-Early & Late Cable joint – Primary Gear Splines – Oil Filter Cover Oil Screen – Oil Pumps – Tachometer Drives Tail light – 1962 – 1963-early 1967 Tappet covers – Hot Tips – Closing comments Details, Details, Details. Tips from Restorers 3 Honda 250-305 Super Hawk Restoration & Maintenance Guide FORWARD My introduction to Honda motorcycles began in 1967, when I bought the first motorcycle I ever owned: a 1967 CL90 Scrambler, which once carried me safely on a 3-day, 1,500mi adventure. At 100 mpg (U.S. gallons) and a 50-55 mph "cruising" speed (95% of available power) it was very economical, but only marginally safe enough to compete with the highway traffic of the day. The only problems encountered during the entire trip were (1. a failure of the low beam filament and (2. a fouled spark plug (at about 7,000 feet altitude, running slightly richer than standard jetting). It ran for 10-12 hours a day, at temperatures from 75ºF degrees during the day to 12ºF degrees at night (I learned a lot about wind-chill factors that trip). Even now, as I look back upon that adventure, I marvel at the remarkable reliability of that tiny engine. From that time onwards, I have always had a deep respect for the quality of Honda motorcycle products. Ironically, it has only been in the past 18 years that have I really become involved with the 250-305cc-series machines. Since 1985, I have owned and worked on all of the CA, CB, CL72/77 models and all of the information contained herein is a product of that experience, along with the advice and assistance of other members of the Vintage Japanese Motorcycle Club of North America. I have been a member of the US-based, VJMC of N.A. organization since 1981 and its sister club in Great Britain since 1987. This worldwide network has been instrumental in the recognition and promotion of all Japanese motorcycles, but primarily Hondas, due to their worldwide distribution and acceptance. I highly recommend that all Honda enthusiasts investigate membership in the club. The versatile CB72/77-series models really established Honda as a major force in the world motorcycle market, way back in 1961. While they got their initial foothold with the Cub 50 models, the 250-305cc dry-sump twins (built from 1960-onwards) have shown the world that a mass-produced, high-rpm 250-305cc motorcycle could hold its own with many other bikes (often double its size in displacement) and maintain that level of performance without premature failure. Features like electric-starting, reliable lighting, oil-tight engines capable of 9,500rpm engine speeds, delivered at a competitive price, was what put Honda on the path of becoming the world's premier motorcycle manufacturer. The CB72/77 is a milestone motorcycle, both in styling and performance. Here is the history of this model's evolutionary journey and all of the details of restoration and maintenance that I can find to share with the Super Hawk enthusiasts around the world. The 305cc Super Hawk is one of my all-time favorite machines and more than 72,000 models were sold in the US alone. It is my intention to bring forth all the available information possible in this book, for the benefit of anyone who owns or is considering the purchase, repair or restoration of one of these fine machines. 4 Bill “MrHonda” Silver Honda 250-305 Super Hawk Restoration & Maintenance Guide NOTE: This book is a companion publication to my previous 250-305cc Engine Repair Guide (and an eventual replacement for the combination CB/CL72-77 restoration reference book). The overview of this machine is similar to what I have presented previously and you will notice inclusion of some of the older material. Appropriate notations, offered mostly in the same sequence as the illustrated parts manuals pages, will support those illustrations shown in the Honda parts books. You will find an expansion of the previous Super Hawk information here, as well as new material that I have collected for the past 10 years, concerning this classic machine. As always, I encourage you to evaluate all that you read here and give any constructive feedback necessary to correct and/or upgrade the information offered. Highlights of this book include: * History of the model. * Changes made during each model year. * What to look for or expect when buying a Super Hawk. * Engineering changes that were made to components during the production run. * Differences between the CB and CA/CL engine components. * Unusual variations of this model, as sold in other countries, including CP77s (both Police and non-Police versions). * Accessories and aftermarket parts, past and present. * Tune-up procedures * Trouble shooting the charging system. * Carburetor rebuilding tips. * Maintenance checks and recommended service intervals. * Recommended modifications for performance and reliability. * Restoration tips * Disassembly and reassembly tips and procedures. * Honda technical information (Service Letters) applicable to this model. * “Techknuckle Pages,” taken from my columns, written for the VJMC newsletter. * Photos of discussed items that bear illustration. * Part numbers of restoration parts and fasteners. * Trouble shooting information from the factory service manual. * Sources and Suppliers of parts/information. 5 Honda 250-305 Super Hawk Restoration & Maintenance Guide Honda Hawk/Super Hawk History (1961-67) The CB72 Hawk (250cc) and CB77 Super Hawk (305cc) machines were launched in the US and Europe, beginning in 1961. Note: Honda’s Collection Hall Museum released a CB72 clock, with an image of the bike at the top, using a likeness of the speedometer & tachometer needles as humidity/temp readings at the bottom. The caption under the image of the bike reads: “1960 Honda Dream CB72 Super Sport”. I have discovered that Honda began production of the CB72-77s in November 1960, thus the date mentioned. All the CB72-77 serial numbers I have found in parts and service books reflect a 1961 production year, however. There were 1960 yearmodel wet-sump Dreams sold in Japan and elsewhere that carried 1960 serial numbers sequences. The above photo is of a prototype dry-sump CB72, circa 1959-60. After 10 years of making only single-cylinder motorcycles (1947-57), the first of Honda’s 250-305cc 2-valve, SOHC parallel twins were released in 1957, as a “dry-sump” design (employing a separate oil tank). Beginning with the 1960 250-305cc Dream-series machines, the engine was reconfigured to a “wet-sump” design, holding approximately 1.6qts (U.S.) of motor oil. In 1961, the CB72-77s became the first of Honda’s newly designed “Super Sport” machines, with 18” rims/tires, a tubular “spine” type frame and large 8” DLS (double-leading shoe) brakes on both wheels. Push-button, electric starting was standard equipment and the 3-phase, ACgenerator supplied reliable electrical energy to the starting and lighting systems. Twin carburetors were featured, in either 22mm (250cc) or 26mm (305cc) sizes. The factory-recommended redline for this engine was 9,500 rpm and a well-tuned CB77 would usually reach 100 mph. This kind of performance was a revelation in the motorcycle world of the 1960s and the machine became a 6 Honda 250-305 Super Hawk Restoration & Maintenance Guide milestone in both design and performance, placing Honda in the mainstream of “real” motorcycle makers. Then, as now, most Japanese motorcycle manufacturers loved to prove their machines in racing events of various types. From the beginning, Honda supplied factory-designed “YB accessory” race-kit parts for CB72-77s to convert standard street bikes into production road racers. A lengthy list of modified items included a close-ratio 4 or 5-speed transmission, clip-on handlebars, racing seat, rear-set footrests, hydraulic steering damper, megaphone exhaust, number plate brackets, alloy fenders and special camshafts and valve springs, to name a few of the items. Please see the YB race-kit racing section for more information on these parts. On the other side of the coin, Honda outfitted the CB chassis with a host of options that were meant for the law-enforcement agencies. These models were never imported into the US, however. The all-white CYP77 machines boasted cable-driven sirens, special speedometers for registering and holding indicated vehicle speeds, dual patrol lights (red or blue), heel-toe shifters, crash bars, solo seats with rear luggage racks, which held the ticket boxes or 2-way radios; plus 17” wheels/tires on the later (1963-on) versions. Few of these CYP77s have survived, though. As Super Hawk sales soared in the US, aftermarket suppliers offered saddlebags, handlebar fairings, replacement fuel tanks in fiberglass, extended cable sets for high handlebar options, replacement mufflers and even replacement seat covers in metal-flake colors. Big-bore piston kits created engines up to 350cc, without having to do machine work on the upper cases. Numerous camshaft companies reground the camshaft halves from hot street to all-out roadracing profiles, requiring special springs, retainers and other complementary engine modifications. Honda Super Hawks were available in Scarlet Red, Royal Blue, Black and White paint colors, with either black or blue (on blue bikes) seats. See following chart concerning paint and vinyl color codes, both old and new. All Police models were white, but not all white bikes were Police bikes. Some bikes designated as CP77 were not Police bikes, either. The only way to be sure that a bike is a genuine Police bike is to check the serial numbers, which have a unique numbering system. Nothing, other than “normal” CB72-77s, were imported into the U.S. by American Honda Motor Corporation, but numerous examples of non-Police CP77s have been located within this country, often imported by servicemen returning from Asia or other Pacific Rim assignments. Only two genuine CYP77 Police bikes are known to exist in the US, presently. 7 Honda 250-305 Super Hawk Restoration & Maintenance Guide 8 Honda 250-305 Super Hawk Restoration & Maintenance Guide Shown above: A rare 1961 CM72 version of the CB72. Note: round single speedometer, high handlebars, split seat, side stand and turn signals (single carburetor, 360° firing crankshaft engine). ************************************************************************ PAINT COLOR CODE TABLE VINYL LEATHER CODE (Seats) Code No. /Color Old Code Code No. Color Old Code A White NH-0 A Black NH-1L B Black NH-1 B Blue B-2L C Scarlet R-2 E Royal Blue PB-5 S Dark Silver NH-10M T Metallic Silver NH-2M XJ Candy Red R-3C Z Non-Sanding RT (primer gray) ****************************************************************************** In general, the Super Hawks fell into two different series: the 1961-65 machines featured “flat” bars; “flat” seats; chassis-colored, internal-spring “Type 1” steel front fork cases and “reverse-needle” speedo-tachometer gauge sets (until early 1965). By 1966, the bikes were delivered with “Western” riser-type handlebars, new external-spring “Type 2” alloy fork cases (painted silver), and dual seats with a rise at the front edge and concentric operating meters (introduced in the early 1965 production). Silver painted fenders were standard for all but the late 1967 models (chromed), which also gained an oval-shaped tail light assembly in the process. There were a myriad of small detail changes of both the engine and chassis parts during the 7-year production run and these will all be addressed, as you read this book. Pay close attention to this information, as it will be most beneficial in your hunt for the right bike or the 9 Honda 250-305 Super Hawk Restoration & Maintenance Guide right parts for your bike, whether you attempt either restoration or repair of the machine. A copy of the factory parts books is indispensable for the identification of the correct parts for your particular machine. Always reference your machine’s engine and serial numbers when ordering a part and/or be aware of the difference between the variations, if you are seeking items from a private party, salvage yard or a parts bike you might find in your travels. This knowledge will minimize expenditures of time and money spent for incorrect parts as you repair, maintain or restore your bike. They may all look alike at a glance, but they are NOT all alike, so pay attention to the details here. In today’s market, you are apt to find CB72-77s in any type of condition and configuration. Even when new, they were often modified with higher handlebars, somewhat like those seen on the Elvis Presley movie entitled “Roustabout.” That bike was a standard, red, CB77 fitted with CL-type high “crossbar” handlebars and some rear side racks, which held his guitar and road gear. Handlebar swaps were the most commonly departure from the original for many riders, as the “café-racer” look was still about 10 years off in the future. The handlebar changes required a complete set of new, extended cables and switch wiring extensions. Back in the 60s and 70s, when chrome plating was relatively inexpensive, many riders had the headlight shells, side covers, chain guards and sometimes both fenders plated to give their mounts a more “custom” look. From there, the sky was the limit, as Super Hawks were stripped for drag racing or road racing; while others were made into small-scale “choppers,” equipped with pull-back handlebars, rigid-strut rear suspension, 16” rear wheels, extended fork tubes and shorty mufflers, along with the obligatory “peanut” gas tank and solo seat combination (and don’t forget those 3-foot tall “sissy bars”!) Do keep in mind that there were a limited production of genuine, factory-built, all-chromed CB77s, built somewhere in the 1963-64 year range. “VALUE” CB72/77 motorcycles have a value which ranges from $0 ("free") to $5,000-plus, recently asked, for a "new one." In the U.S., the 250cc CB72 models are quite rare, due to a combination of factors. First, the price differential between the CB72 and CB77 models was negligible, but the power differential was substantial. Second, there were no licensing restrictions that concerned engine displacement in this country. Consequently, most buyers opted for the more powerful CB77, which was far better suited for the "wide-open spaces" in America. Thus, the sales of CB72's were small and their general availability is very limited. Average prices for a complete running motorcycle are $500-$1,600. Restored models usually average $2,000-4,500. There were fewer of the early models, but the later models had most of the "bugs" worked out, so take your pick! And to truly enjoy this fine Honda milestone model, ride it often! 10 Honda 250-305 Super Hawk Restoration & Maintenance Guide With over 75,000 CB72/77-series machines sold in the US, there are still many more out there than you might think, so don’t give up on your search for the right bike for your budget and interests. I often hear from owners who have kept their original machines from the ‘60s and either want to get them going again or get them out of mothball storage after 30 years and sell them to an appreciative Super Hawk fan. My suggestion to those who have limited mechanical experience is to buy the very best bike they can find in the beginning, rather than attempt to resurrect a “bare bones” rolling chassis that they found for “free.” You will probably wind up with the same money invested, no matter which path you travel and one will get you on the road a lot faster than the other. Still, for those who truly enjoy the process of restoration, I would suggest that you find a complete machine to begin with, in order to minimize the expenses of replacing missing parts in order to complete the project. Honda is not going to be making any more parts for these machines and there is minimal support for most Vintage Japanese machines from the aftermarket suppliers, due to the diversity of models and current tooling/manufacturing costs. My personal process was to find the best bike I could afford, then repair as necessary and ride it until I found a better one. I probably have bought and sold about 20 Super Hawks, ranging from “parts bikes” to one that had 800 original miles on it. Sometimes, it is just a matter of finding the right bike that feels/looks right for you. Although they were all mass-produced, there is a definite difference in “feel” between some of the different series of engines, transmissions and chassis combinations. Some are rough, cranky and cantankerous, while some are smooth, sweet natured and a real joy to ride out on the road. How they have been treated and how they are tuned and maintained makes a world of difference in the quality of your own experience with the legendary 250-305 Super Hawk line. Riding the Super Hawk I have had the pleasure of owning some nice, original CB77s, plus a CB72 or two (even a CBM72 and a CYP77), and have developed a pretty good feel for when they are “really good” and when they are struggling and tired. Apart from a somewhat noisy 2nd gear in my most recent machine (a 1963 CB77), that bike was pretty typical of a “good” bike, that hasn’t been crashed or abused. Here’s my “take” on going for a ride on that black beauty, few years ago. “Every time I pull off the blanket and see the gleam of shiny black paint, flashes of chrome and cast alloy engine casings, I always take a moment to appreciate what an amazing machine this is, especially for something that was designed over 40 years ago. I check the tire pressures, chain adjustment and oil level (just dip the stick in, don’t screw it back in to check the level) and then roll it out for a little “exercise”. Petcock ON (after I checked the fuel level) and 11 Honda 250-305 Super Hawk Restoration & Maintenance Guide pull the choke lever up to aid in the initial firing-up of this cold-blooded machine. The addition of the PROBE electronic ignition made a substantial improvement in the starting and cold running ability of this particular machine. If the battery is up to full charge, I will just thumb the starter button with the choke full ON and pull it back down about 20%, as soon as it begins to run evenly. When properly jetted, they will be a bit cantankerous when cold, but Super Hawks should warm up in a minute or two, enough to be able to roll down the driveway and begin to move under its own power. I always tell people, that if the bike will start and run WITHOUT any choke, then it is not jetted or tuned properly. As soon as it takes the throttle in low gear, I consider putting the choke to the OFF position altogether. There is a mild clatter of valves and pistons, gears and chains, as it moves off down the road, but after a few blocks of running, it is begins to become comfortable and move off smartly through the gears. Coming to a stop sign, I am conscious about the footpegs. They can catch on your pant legs and fold themselves upwards, staying in the upright position, because there are no return springs on the pegs. It is annoying and unnerving to find nothing where a foot peg was a moment before. Also, as a self-defense for my shins, I removed the non-folding rear passenger pegs, to protect my shins from the inevitable collisions that occur when you are just moving the bike around the shop. I finally moved the driver pegs to the center position, using the optional YB shift link rod (one of three kinds) and that keeps my pant leg away from the kickstarter pedal, which also can be a problem sometimes. Coming to a stop reacquaints you with the double-leading shoe brake’s power to slow the machine down from a good clip without too much drama. Never as accurate or as powerful as modern disc brakes, they are nonetheless pretty good binders, as long as you are going forward. The double leading shoe system was designed to bring the bike to a halt quickly and safely on the street (and even on the track), but the brakes only work well in ONE direction. Trying to hold the bike on an uphill position becomes quite a feat, after awhile, as there is little braking force when the machine is moving in the reverse direction. Going through the gears requires some attention in making a clean shift with your foot, as these transmissions can be prone to sticking in between gears, on occasion. In my earlier writings, I cautioned against leaving the fine wire retainer rings in the clutch pack, which were rumored to be prone to breakage and then the parts could be ingested into the oil pump. Comparing two 1963 CB77s that I have owned, the one with the wires still installed does definitely shift better, as well as allow for engagement of neutral, when at rest. So, now I must retract my earlier statements about the wires and recommend that people keep them installed for street riding, if they are in good condition. 12 Honda 250-305 Super Hawk Restoration & Maintenance Guide I have always enjoyed the flat bars of the CB77, and feel that they look best when so equipped. They allow a nice “forward lean” into the wind and help keep just enough weight on the bars for good control, without causing wrist pain for long rides. I’m 5’9”, though, so your body may or may not respond in similar ways to the flat bars of the early models. A healthy engine, properly tuned will run past the 9,000 rpm redline with little effort, although the few dyno charts I have seen, show that the stock cams are pretty much done feeding the power curve at about 8,500 rpm, so the rest is just over-run room to overcome the gaps in the wide-ratio transmission. Doing the “X” job on the transmission closes up the 1-2 gear spacing at the expense of increasing it on the 3-4 shift, so the choice is up to you. With 15/30 standard gearing, the bikes are usually traveling at 6,000 for a 60-65 mph indicated speed. My experience with two different 1963 CB77s was that the speedometer needle is generally reading about 10mph greater than actual speed, but the odometer is spot-on. The differential gets greater as speed increases and at a true 75 mph, you might be seeing 90+ on the needle position. For whatever reason, the later meters seem to be a little more realistic and closer to correct speed indications. As mentioned elsewhere in this book, I always remove the stock rear shocks and replace them with RED WING shock assemblies (now discontinued), which give a much-improved ride and control over bumps than the OEM units. Adding some slightly thicker oil to the front forks will increase their damping abilities, too, resulting in a nicely balanced feel to the handling and comfort. DO consider finding something other than the OEM units if you are going to ride your bike regularly. Progressive Suspension and Works Performance can build something suitable. Out on the highways and twisties, the CB77 can hold its own with most cars and bikes in normal traffic situations. Because the power really doesn’t kick in strongly until about 6,000 rpm, you have to give it a good handful of throttle to make up for the lack of overall power from such a small power plant. Unsuspecting riders of more modern machinery are surprised and impressed with the bike’s ability to accelerate and go around corners, ridden within “normal” limits. I always have to be mindful in high-speed left turns, as the optional sidestand on my bike drags readily and will pick the bike up and scoot it over a foot or two, if you don’t pay attention. Overall, I find riding a nice running Super Hawk for an hour or so to be very exhilarating; feeding your whole body with sounds, feelings and smells of a finely engineered machine doing its job in a joyful manner. In my opinion, owning and riding a CB77 is one of a motorcyclist’s most cherished experiences. If you have ever had the experience, I’m sure that you will agree!” 13 Honda 250-305 Super Hawk Restoration & Maintenance Guide MODEL YEAR IDENTIFICATION The CB72/77-series (Known as either 250cc Hawks or 305cc Super Hawks) were numbered as follows: In 1961-63, the first digit in frame or engine number after “CB72” or “CB77” (i.e. frame #CB72 (7)-XXXXX and engine #CB72 (7) E-XXXXXX) designated the year of manufacture. The frames had five digits in '61-62 and six digits in '63. In 1964, frames and engines both started with CB72(7)-100001(both 6 digits), plus there was a series of bikes that began with CB72/77-400001. The 1965 models started with 1000001 (seven digit frame and engine numbers) and continued in that fashion. Generally, the frame and engine numbers are within 150 numbers of each other or less, if they are the factory-matched set. Frame and Engine No. history ‘61 Type CB72E - 110001 - 113443 CB72 - 10001 - 13443 CB72E - 150001 - 151657 CB72 - 50001 - 51657 CB77E - 110001 - 111249 CB77 - 10001 - 11249 CB77E - 150001 - 150480 CB77 - 50001 - 50480 CP77E - 110001 - 110080 CP77 - 10001 - 10080 ‘62 Type CB72E - 210001 - 211880 CB72 - 20001 - 21881 CB72E - 260001 - 263469 CB72 - 60001 - 63444 CB77E - 210001 - 210900 CB77 - 20001 - 20902 CB77E - 260001 - 260395 CB77 - 60001 - 60395 CP77E - 210001 - 210228 CP77 - 20001 - 20228 ‘63 Type CB72E - 310001 - 315446 CB72 - 310001 - 315446 CB77E - 310001 - 319222 CB77 - 310001 - 319222 CB77E - 340001 - 340015 CB77 - 340001 - 340015 CP77E - 310001 - 311094 CP77 - 310001 - 311094 CP77E - 340001 - 342015 CP77 - 340001 - 342015 CP77E - 3100001- 3100100 CP77 - 3100001 - 3100100 ‘64 Type (1) CB72E - 100001 - 104165 CB72 - 100001 - 104165 CB77E - 100001 - 109755 CB77 - 100001 - 109755 CP77E - 1100001- 1100803 CP77 - 1100001 - 1100803 ‘64 Type (2) CB72E - 400001- 402754 CB72 - 400001 - 402707 CB77E - 400001- 403838 CB77 - 400001 - 403841 CP77E - 400000l - 4001260 CP77 - 4000001 - 4001103 CP77E - 4900001 -4901223 CP77 - 4900001 - 4900641 ’65-67 “The machines which were discontinued the year of manufacture are as follows:” CB72E -1000001 - 1006342 CB72-1000001 - 1010918 CB77E -1000001 - 1056494 CB77-1000001 - 1056432 CP77E -1000001 - 1002015 CP77 -1000001 - 1001966 CP77E -1900001 - 1901540 CP77 -1900001 - 1901535 (Figures taken from Honda parts manual, which may contain errors. Not all versions shown (i.e. CBM72, CM72, etc.). For CB models, there are several model variations, other than the "regular" Hawk/Super Hawk versions. Apparently, some (but not all) '64 models with 400001 serial numbers may be found with Type 2 (360 degree crank) engines or they may have been models destined for the German market (modified to meet special noise restrictions). The rest of the 100001-on ('64) series bikes all seem to be normal Type 1 (180 degree crank) engine versions, however. You may also find the odd CP77- stamped frame/engine, which may or may not be a real "Police version," 14 Honda 250-305 Super Hawk Restoration & Maintenance Guide (which is usually called a CYP77, but also stamped with CP77 serial numbers), as well as a CBM72, which has high bars, turn signals and a Type 2 (360 degree) crankshaft, so don’t be surprised if you see something other than “normal” serial numbers, during your search. There are also "domestic" versions of CB77s with Type 2 (360 degree) engines. Deviations from the "normal" numbering sequence, usually denotes models for specific countries or special applications. Genuine CYP77 “Police” bikes, mentioned previously, are all white and have a single, round speedometer, rather than the oval, dual speedo-tachometer gauges of the other models. The late-model Police models, built after 1963 had 17" wheels, front and rear. Actual “Police” versions have crash bars, turn signals, solo seats, a rear rack or rear bumper-rack combo, special lever brackets for the siren controls, patrol lights and a cable-driven siren (driven off the rear wheel). From 1965-on, there is no definitive break between years 1965, 1966 and 1967. However, CB77s with Type 2 alloy front forks began at CB77-1030130 and seem to be the mid1966 models, offered here in the U.S. The chrome-fender CB models, with the "oval" taillight, were introduced from frame number CB77-1056084 and onwards, which was at the end of the production run in 1967 (CB77-1056432 was the last machine). There are three different crankshafts, three transmissions, two series of pistons, three series of camshafts, five different mph speedometers (running in two different directions), two types of Type 1 (steel) and one Type 2 (alloy) fork assemblies, three different fork crowns, etc. for the CB-series bikes. This is why you must always check your engine and frame numbers before ordering parts! Sometimes, you might find that the original CB engines have been swapped with different CB or even CL engines. CL engines are not equipped with electric starters, but can be retrofitted with CB or CA starter motors and starter clutches, for CB installations. Again, check those numbers carefully, if you are ordering parts or doing a "correct" ground-up restoration! MAJOR FEATURES FROM YEAR TO YEAR 1961 Serial numbers: CB72(77)-1XXXX (5 digits), CB72(77)E-11XXXX (6 digits). These early bikes had SLS (single-leading shoe) front brakes (changed to DLS at CB72-11549 & CB77-10281) and alloy front fenders, rear brake stays and rear shock covers. The rear swing arms had an extra lug near the shock mount for passenger pegs. The taillights were unique (CP type /__\ shape) to 1961 models only. The rear of frame was crimped and slotted for seat mounts (1” shorter than later bikes). The speedometer unit was mounted in special fork bridge with circular mounting ring and retained with a spring inside the headlight shell. 9.5:1 compression pistons 15 Honda 250-305 Super Hawk Restoration & Maintenance Guide were used through 1964. The engines lacked primary chain tensioners until 1963. Multi-tapered large 37mm fork tubes and triple clamps were featured. The speedometers lacked Hi-Beam indicator lights (at least until 1964 in the US). “Diamond-pattern” handgrips, like those of the C110 were used in 1961-63, mounted on OEM “flat” handlebars. Use of the original “round bowl”-shaped carburetors continued until 1964. Heavy, flywheel-type, cam sprocket assemblies were used in 1961 only. All of the brake linkage arms were retained with self-locking nuts, until 1963. DREAM 250 or DREAM 300 tank badges were featured until mid-1963. Most cables (other than throttle) had grease fittings installed. Early bikes had black rear brake, tachometer and speedometer cables. The horn had “hook connectors” from the harness and was painted black. The speedo drive unit did not use sealed flange-to-hub design. Rear upper engine hanger bolt increased from 6mm to 8mm diameter. Mufflers used sleeve-type seals at header pipe inlets. Thick alloy rear brake stay changed to thin steel unit. Oil filter covers (small hole design) were blank on the outside. The only thing that said HONDA was the back of the seat and the tank badges. 1962 Serial numbers: Frame CB72 (77)-2XXXXX(5 digit), Engine CB72(77)E-21XXXX(6 digit). The “rear breather” engine case was superseded to cylinder head breather design, requiring a new top case, in addition to a revised top cylinder head cover and breather plate/gasket, which took over the crankcase ventilation chores. Spark plugs were switched to 12mm D8HA spark plugs from 10mm C10HA versions, used previously. New, lighter, smaller cam-sprockets used with L/H thread locking nuts. The transmission was upgraded from “CB71” (258 code) to CB72 (268 code) designed parts. Transmission cover changed from rear breather type to new style. Engine crankcase & cylinders changed to relocate oil passage. “Short” –268-810 tail light lenses, new fork bridge and speedometer mounting design, along with new headlight shell, steel front fender and steel rear brake stay, steel shock covers were implemented. The foot peg lug was deleted on the swing arm and the frame had separate welded fittings for rear seat mount. Seat frame brackets lengthened 1” to match change in frame. Speedometer drive sealed to front hub with flange. 1963 Serial numbers Frame: CB72(77)-31XXXX(6 digit), Engine: CB72 (77)E-31XXXX(6 digit). Longer “standard” 268-680-taillight assembly added; primary chain tensioner added; and “pinchbolt” brake arms implemented. New fork cover sets, including chrome rib, cushions, along with new, more slender fork tubes and revised lower fork cases. New steering damper parts design. Fuel tank emblems changed from “ Honda Dream 250” and “Honda Dream 300” to “ Honda 250” and “Honda 300” (CB72-311905 & CB77-312293). Stainless steel mufflers introduced with new 16 Honda 250-305 Super Hawk Restoration & Maintenance Guide O-ring seals. Oil filter cover now labeled “HONDA.” The 205-code (CB92) “waffle pattern” grips superseded the original 268-code diamond patterned versions. 1964 Serial numbers: CB72 (77)-10XXXX(6 digit), CB72(77)E-10XXXX(6 digit). High beam indicator lights were standard equipment. New, “square bowl” carburetors now used on both models, with bowl drain screws. Oil filters now stamped “HONDA” and “Made in Japan” 1965 Serial numbers CB72 (77)-1XXXXXX(7 digit), CB72(77)E-1XXXXXX (7 digit) New pistons lowered engine compression to 8.5:1 from 9.5:1, previously used. Rear swing-arm design changed from cast lug to flat-plate design. Seat strap ends attached under seat pans, Western bars introduced (requiring longer cable sets) and “concentric” meters introduced. Kick starter cover modified with 1” more forward clutch cable placement. Rear brake cable was lengthened ¾,” along with a longer rear brake arm. 1966 New Type 2, (silver-painted alloy) fork design, introduced mid-1966. This change required a new front fender, steering stem, upper fork bridge, fork covers, fork assemblies, fork springs (external) and seals and hardware. Seat has rise in the front, partially covering the back of the fuel tank. 1967 Frames had lugs for turn signals (not installed on U.S. machines), chromed fenders with ovalshaped taillights, plus metallic red paint on the last few bikes produced. Crankshaft, primary drive sprocket, camshaft and transmission updated with shallow-spline modifications. Crankshaft main bearing knock pin modification. Narrow 32mm wide cam chain tensioner and die-cast cylinder block introduced (CB72E-1007137 & CB77E-1050999). Semi-domed valve caps were used, but no new part number for them was revealed. The metal horns were replaced with a plastic copy. TOTAL U.S. SALES OF CB72-CB77 MACHINES CB72 (1961-66) 3,479 units. CB77 (1961-69) 72,396 units. Production ceased in 1967) INTERESTING TIDBITS WHAT’S MY NAME? The first 1961-62 oil filter covers had no markings on them at all. Then, in 1963 they were just marked HONDA. About 1964, they were stamped HONDA in the middle, plus “Made in Japan” on the bottom edge. WHAT’S MY NUMBER? There is no part number listed for the tachometer cable bracket that mounts under the horn. So, don’t lose the bracket because you can’t order a new one. I have heard that they came with a replacement frame, however. Also, there is no part number listed for the blue and white tail light/brake light wiring harness, which goes from the main harness to the 17 Honda 250-305 Super Hawk Restoration & Maintenance Guide taillight assembly, running inside the left channel of the rear fender. It actually does come with a new tail light socket assembly, though. WHAT’S MY COLOR? Original 1961 cable sets were black on the bottom set (tachometer, rear brake and speedometer) while the upper cables (clutch, front brake and throttle) were silver (gray). The 1961 Horns were black, instead of painted silver, as well. WHAT’S MY LINE? The 24tooth, 2nd gear (23430-258-000), located on the transmission main shaft, was the only transmission gear not modified during entire production run. One gear fits all! All of the shift drum/forks and kick-starter spindle shaft parts were unchanged, as well. FINDING A BIKE TO RIDE OR RESTORE After almost 40 years, any bike you find for sale, in less than running and restored condition, will require some skilled labor and at least a few new parts to get it back into a fullfunctioning state. Even when stored in ideal conditions, parts will continue to deteriorate with time and exposure to chemicals and atmosphere. Each machine is a case-by-case scenario, but the following are some generalizations of what you might expect to find when you are out tracking down a bike for yourself. “Best-case scenario:” This bike is running, licensed and either fully-restored or is a mint, original example. Buy it, drive it, maintain it and enjoy it, you lucky person! “Next-best case scenario” For a bike that was serviced and stored correctly. Install a new battery; change the oil, clean carburetor and fuel tank. Inspect or replace the petcock seals and fuel lines. Change spark plugs (NGK-D8HA or equivalents), clean ignition points and check static timing. Air up the tires, lube and adjust the drive chain. Check all controls for correct function. Start the engine with kick-starter, warm to operating temperature; check ignition timing with timing light, while running. Go riding! “Usual ‘good’ scenario:” For a bike that was not serviced and stored correctly, but kept out of the weather. Install a new battery. Adjust valves and camchain tension. Replace tappet cover O-rings. Check compression in both cylinders. Remove camchain tensioner and inspect roller for damage. Remove clutch cover, pry the clutch pack apart and replace damaged parts. Replace clutch springs. Clean oil filter/cover and replace O-rings. Replace primary drive chain. Inspect clutch inner and outer parts for wear on splines. Replace clutch cover seal (shift shaft) and gasket. Replace clutch lifter and thread set. Replace cables as necessary. Grease swing arm bushings, control levers and pedals and replace brake shoes. Remove and overhaul carburetor (file flanges flat), replace O-rings on carburetor bodies and at insulators. Overhaul petcock, replace all seals and screen, and file the backside of petcock 18 Honda 250-305 Super Hawk Restoration & Maintenance Guide fuel lever flat for smooth sealing surface. Flush out fuel tank, treat surface rust and replace crossover fuel hose. Replace ignition points/condenser (check for leaking point shaft seal), install new spark plugs. Set static timing. Replace inner tubes/tires as necessary. Replace drive chain/sprockets as necessary. Repair cracked chain guard and repair broken tabs on swing arm. Locate and reinstall muffler diffusers. Replace shifter linkage pins, clevis and lever arm. “Barn fresh’ scenario:” Requires all of above, after you have removed the “stuck” engine, which probably has a damaged stator and cracked kick-starter cover. Cut camchain in half to release the cylinder head assy (Actually you can get around that part. Read further!). Use steering wheel-puller tool to push out seized pistons (See Techknuckle story). Rebore cylinders to .75mm or 1.00mm oversize. Hone small ends of rods (and new piston pin bores) out for oversized wrist pins. Find a new camchain and tensioner (one of two widths) and center guide roller/pin. Split cases and replace low gear bushing, kick starter pawl (see below), kick starter shaft and roller bearings, primary chain and tensioner, transmission shaft bushings and bearings, oil filter chain, starter chain, 2nd gear set, all engine seals and gaskets. Replace oil pump and filter screen. Locate and install new stator, starter clutch hub parts, starter motor drive chain, neutral switch, kick starter cover with new gears and clutch pushrod. Disassemble cylinder head and replace valve guides, valves, camshaft bearings. Replace or weld up cam sprocket and replace return springs. Replace camshafts (matched to the correct cam sprocket) and rocker arms (268-305 parts with oil hole in the center of the contact pad). Inspect or replace rocker pins, as necessary. Disassemble chassis and replace swing arm bushings and shaft and seals. Replace steering head bearings and races. Paint or powder coat chassis parts after repairing damaged battery box area of frame. Replace fork seals, bent fork tubes, fork covers; rechrome seal holders or covers (alloy forks). Repair fenders and side covers for repaint. Replate the rims and replace the spokes and tires. Replace wheel bearings and polish the hubs and brake backing plates. Replate the brake linkage arms and shafts. Replace rotted out fuel tank and rusty side covers. Buy new tank badges and knee pads. Find a new toolbox that has both ears on it, and then try to find the tool kit to go with it. Next, buy new wiring harness and ignition switch assy; plus replace brake light switch, rectifier, starter solenoid, horn and headlight/tail light assembly. Replace speedometer-tachometer assembly and/or meter packing. Replace handlebars, all cables, switches, lever brackets, along with levers and cable adjusters. Now you have a perfectly restored CB77! Wasn’t that easy? 19 Honda 250-305 Super Hawk Restoration & Maintenance Guide Here is a guide to use, when checking out your potential new project bike. OVERALL VISUAL CHECK: Remove the seat and fuel tank. Inspect the inside of the fuel tank for rust and the seat pan for rot, if the seat cover shows damage. Remove the carburetor and petcock float bowls and inspect for corrosion, damaged, or missing parts. Fuel left to sit in the tank and carburetors for 1 to 20-plus years can do irreparable harm to all affected components. Inspect the wiring harness for breaks, damage and "modifications." The original harness will have a small white tag on the outer cover (located under the fuel tank area, close to the ignition coils), which shows the date (year) of manufacture and the part number. Check all the electrical connections for corrosion or damage. Sight down the backbone of the frame and look for frame damage from accidents. Inspect motor mount connections for vibration damage or missing fasteners. Check condition of air filter mounting hardware and the filters themselves. Inspect battery box area for battery acid damage and cracks. Check forward frame mounts (at rear of battery tray area), which hold the rear fender, for damage, as well as the fender itself. Look at the foot peg plates and muffler brackets on the frame for damage from a fall. Inspect center stand and mounting points for wear/damage. Check the relationship of the handlebars to the direction of the front wheel (should be 90 degrees from each other). Check the headlight mounting brackets for damage. Look to see if the forks are parallel to each other and lower fork sliders are not nicked or dented deeply. Look for oil leaks at the head gasket, right side cover area (there are 6 oil seals under that cover), at the clutch cover, around the oil pump and at the front fork seals/rear shocks. Inspect the rubber chassis seals and grommets for deterioration. Spin the wheels to check for roundness and note the position of the brake cable adjusters, as an indicator of brake shoe wear. Ask for any receipts or service records to obtain as much history as possible, of the bike. Check the serial numbers for a match to the title and a close match for the engine/chassis numbers (usually within 150 numbers). Don't take anything for granted! See it to believe it! Avoid bikes with altered serial numbers and be careful of CB's with CL engines, 250 engines with 305 top ends, etc. LET’S TALK TOOLS! TOOL KITS Owning a motorcycle and not owning tools is a “non sequitur” -it does not follow! Vintage motorcycles, particularly, need adjustments and regular maintenance. Unless you are a corporate CEO and can just pull out the plastic money and have someone else do it for you, it is required that you make use of some kind of tools to keep your vintage motorcycle happily going on down the road. 20 Honda 250-305 Super Hawk Restoration & Maintenance Guide Honda announced in 1998 that they had built their 100 MILLIONTH motorcycle and every one of them had a tool kit, for maintenance and minor repairs. WHERE ARE THEY NOW??? As more and more enthusiasts restore their vintage bikes, there is a growing demand for original tool kits, to complete their "as-original" restorations. For vintage Hondas, "tool kits" can come in two different classifications.... tools in a small pouch, usually found in the tool kit holder area or under the seat, in many models...OR, the factory workshop tools (Special Tools), which came in a metal box and were specifically created to facilitate the repair and overhaul of those particular models. Examples were workshop tool kits for the C100-110s, the 125-150 twins and 250-305 twins. Workshop tool kits usually possessed items like valve spring compressors, valve seat cutters, bearing pullers, rotor removal tools, piston ring compressors, piston rests for cylinder installation, special sockets and removal tools for shocks and other chassis disassembly. Honda part numbers for Special Tools kits begin with 07000-XXXXX. The kit for the 250-305 is a 07000-25901. The tool kits for the motorcycles generally came in a rollout bag, in the early days. Early 250 Scramblers had green, canvas tool bags, which cushioned the tools and the toolbox from some of the vibration, which is so prominent in the Scrambler-series bikes. Most early model Super Hawk, Benly and Dream models had blue or black vinyl, rollout, tool pouches. In later years, Honda replaced the rollout bags with simple rectangular pouches, closed at one end with a single button snap. As years have passed, the replacement kits were downsized by the elimination of a few items that were originally offered back in the '60s (like scissors). Recently, the demand for these small kits has grown so much that the few NOS kits that come to the surface are being offered for $100 each! For reference, Honda's retail price for these, a few years ago was about $20. Tool kit part numbers are generally 89010-XXX-000 or -010, etc. In an original 1961 CB77 parts manual, the tool kit was shown to have the following items: Tool bag (C90 part number), tappet wrench, Axle wrench (double ended for front and rear sizes, 24x26mm), three screwdriver tips (#2, #3 Phillips and one straight slot), screwdriver grip handle (plastic), a "lever" (metal T-handle for the screwdriver tips), pliers, two tire levers, spark plug wrench, 37mm pin spanner (shock adjusting tool), scissors (part number for the scissors is 89243-253-000) and tire patch kit, 10x14mm open ended wrench, 19x17mm open ended wrench, and a tappet gauge (.002"). Later kits deleted the scissors, patch kit and tire irons. CB72/77 tool kits were 89010-268-000, later superseded to -010 (earliest ones had plug wrench for 10mm "Cseries" plugs rather than the usual 12mm "D-series" NGK spark plugs). Many of the tool kit parts are "generic" items, found in most all kits. The screwdriver tips are 99003-1000, -2000 and –3000 numbers. The "lever" is a 99003-4000 and the plastic grip is a 21 Honda 250-305 Super Hawk Restoration & Maintenance Guide 99003-5000 number. The pliers carry a 99002-15000 designation. The tappet wrench is either a 89201-268-010 or 259-000. The tappet gauge is a .002" 89231-001-000, 200-000 or 216-000 for most models, except the larger four-cylinder bikes. Spark plug sockets are 99004-16170 for the DH8A 12mm spark plugs. For the open-end wrenches, 99001-10140 and 99001-17190 for the 10x14 and 17x19. Often salvage yards have boxes of old, loose, tool-kit tools that just need some careful sorting in order for you to create a fairly complete kit for your bike. Check with your local dealers to see if they have any leftover kits, from discontinued models, as well as pouches or tools from Honda power products. With a little diligence and patience, you can come up with a good set of applicable tools that won't cost $100+, like you see on the Internet auction sites. When you are hunting down those parts for your restoration, don't forget to ask your contacts if they know where you can find some Honda tools. Look for either the "Hm" logo or "Honda" written on the larger pieces, like axle and combination wrenches. When you've gathered them up, send them down to the plater, when you are doing a batch of bright zinc or cad plating and they will look like new! REPAIR TOOLS Less damage occurs when you have the right tools for the job of disassembly and reassembly, so toss the $12.95 Universal Tool kit from the local auto parts store and buy some nice sockets and wrenches. In most cases, a set of 6-point sockets will minimize the damage to bolt heads and can fit into most locations easily. Much of the small hardware can be removed with a good quality set of ¼” 6-point drive sockets (covers 4mm to 14mm generally), but a 3/8” drive set (from 8mm to 19mm) is most useful for other larger jobs requiring larger socket sizes. My favorite wrench sets are from MAC or SNAP-ON and are the combination open end and flip-socket metric wrenches. Most of the sizes are 6-point configuration and apply plenty of torque to the nuts and bolts on the bike. You will want to have a backup set of regular combination wrenches, as some sizes are used on both ends of a fastener. The only real “special tools” are the rotor puller tool, available from Honda (p/n 0701121601) or m/c shops that carry aftermarket tools (like K&L or Kowa) and an adjustable pin spanner for the fork seal housings, which unscrew from the tops of the fork cases on the Type 1 fork assemblies. An internal and external snap ring pliers set is required. A 15/16” box end wrench will come in handy for a few locations. The top fork nuts and rear axle nuts are 25-26mm, just a little too big for a 1” wrench and too small for a one and one eighth-inch tool for a snug fit. Try to find either the correct metric wrench or an inch and one-sixteenth” box end item. It is easy to round off the edges of these items, so be careful. The other oddball tool required is a one and three eighths-inch box end wrench for the steering stem nut, which supports the steering damper 22 Honda 250-305 Super Hawk Restoration & Maintenance Guide knob and rod. If you have a lot of bikes in your garage, I would suggest getting a Honda shock absorber spring tool from either Honda or Kowa, as it eases the disassembly of the rear shock assemblies considerably. You MUST HAVE a good impact driver with short and long bits, especially Phillips #2 & #3 tips. Use the long tips to loosen corroded Phillips head screws, by pounding on them with a good-sized ball-peen hammer (like you are hitting them with a center punch), before you place the tool bit back in the impact driver for final loosening and removal. This procedure will shock the threads and break the corrosion bond between the steel screws and the aluminum parts into which most screws are threaded. Failure to do this step will probably result in rounding out the head of the screws, as they will give way before the screw threads break loose, in a high percentage of cases. While on the subject of screws and threads, invest in a good set of metric taps and dies, so you can clean up all of the threads before assembly. NOTE: Read the tech service bulletin concerning the changeover from JIS to ISO thread screws. This bulletin is listed with the other applicable service bulletins. Be sure not to damage or lose any JIS thread fasteners, which are nominally 5mm on most cases. They are extremely difficult to replace. Honda does not stock any early JIS-thread fasteners. Do get a good quality set of nice sharp flat blade and Phillips tip screwdrivers and use them as they were recommended, not as impact drivers or pry bars. A set of long and short steel punches is useful for driving out bushings and bearings and a good brass drift is a handy thing to have when you need to minimize metal damage while applying some force to loosen something. A couple of different sized gasket scrapers will be necessary, plus an EXACTO knife or singleedged razor blade for scraping that stubborn gasket material from the engine surfaces. REMEMBER: Most all of the engine gaskets are made from ASBESTOS, which is very toxic! Be careful not to blow the debris around the garage and always dispose of it in a responsible manner. Same thing applies for old waste oil from the engine and the forks, as well as stale gasoline from the fuel tank. Suggested (pretty much required) tools: 3.5mm (tappet) wrench, 5.5mm(points) wrench, 8mm, 9mm, 10mm, 12mm, 14mm, 17mm, 19mm, 21mm, 23mm (15/16"), 26mm (1-1/16"), 35mm (1-3/8") wrenches and sockets, nylon strap wrench or adjustable pin spanner (early front forks), “216” rotor puller (07011-21601 or equivalent)) Valve spring compressor, rocker pin tool (6mm threads), impact driver with long/short #2 & #3 Phillips tips, #2 & #3 Phillips screwdrivers, gasket scraper(s), torque wrench, large flat files, plastic mallets, ball peen hammer, feeler gauges (.002"-.028"), internal & external snap ring pliers, wire brushes, points file, etc. 23 Honda 250-305 Super Hawk Restoration & Maintenance Guide Other Honda Special Tools (most numbers are discontinued) 07034-26801 fork puller (seal holder), 07013-25002 Rocker arm pin puller, 07021-25901 Camshaft holder, 07022-25901 Drive sprocket holder, 07024-25001 Clutch Outer Holder0703125001 Valve Lifter, 07032-25001(25101) Piston Ring Compressor, 07033-25001 Piston Base, 07035-26801 Rear cushion tool, 07047-25901 Valve Guide Remover, 07048-25901 Bearing driver, 07054-26801 Front Fork Oil Seal Driver Guide, 07054-27391(27302) Fork Seal Driving Assembly, 07071-25001 Main Switch Spanner, 07072-25901 40mm Pin spanner (shocks), 07075-25001 Rear Damper Nut Pin Spanner, 07077-25901 Camshaft Pin Spanner, 07080-26802 35mm Front Fork Bolt Wrench, 07081-25901 Tappet Adjusting Socket Wrench, 07083-25001 Steering Top Cone Race Box Wrench, 07085-25901 10mm Socket Wrench, 07084-25001 10mm T-Handle Long Socket Wrench, 07086-25901 34mm Crankshaft Lock Nut Wrench, 07144-99920 Float Gauge, 07777-99921 10mm (99922 12mm) T-Handle Universal Joint Spark Plug Socket Wrench, Float Level Gauge 07144-99998, Stock up on a good supply of penetrating oils, of one kind or another, as well as some quality degreasing chemicals, before you begin. Kroil, WD-40, Tri-Flo, etc. are all good quality products and should be used wherever you are attempting to loosen corroded fasteners. I recommend use of some kind of gloves to protect your skin from unnecessary petroleum product contacts, as well as small abrasions and cuts. Keep a few rolls of paper towels or shop rags handy to clean up parts, tools and your hands, even when gloved. Some metal drain pans will be necessary for draining fork assemblies and engines, prior to overhaul. Always dispose of all used fluids and old batteries in a responsible manner. CB72-77 HISTORY ENGINE OVERVIEW The CB72/77 engine, as mentioned, has its origins in the 1957-59 SOHC 250-305 dry-sump engines, used in the CE-71, C71-76 models. The CB72/77 engine was designed into a more compact, wet-sump configuration in 1960. Most of the early-style original castings were of a sand-cast design and show the grain of the molds. These original early parts are generally heavier and less well finished, than the smoother, late-model, die-cast parts. The design changes are as follows: The ‘61 engine cases are very easy to identify, primarily due to the “hump” on the rear of the upper crankcase, which housed the crankcase breather, through CB72E-113068, CB77E1l1030 (“010” & “020” cases). These early models, used oil from the breather system to lube the drive chain, via a “breather valve.” When the “rear breather” was deleted, the upper crankcase 24 Honda 250-305 Super Hawk Restoration & Maintenance Guide and cover were both redesigned. The next upper crankcase change at CB72E-113069 ran through CB72E-211881, CB77E-111031 to CB77E-210900 (“325”) for the change in the oil passage, followed by CB72E-311734-later, CB77E-210901 through CB77E-318072 (“040” superseded to “050”) for cylinder stud upgrades and a transmission redesign. The lower crankcase was changed at CB72E-211581 thru 311306, CB77E-21070l thru 311978, to incorporate the oil receiver and matching oil pump strainer. These parts were modified again at CB72E-311306-on/CB77E3l1979-on. Crankshaft changes occurred at CB72E-112069, CB77E-110281 (“020” change in main bearing), CB72-not identified, CB77E-1052505 (“030” larger spline root from 21mm to 23 mm). The left crankshaft main bearings were changed at CB72E-112068, CB77E-110280 (6206Z); CB72E-113068, CB77E-11103l (6306). Right side main bearings were changed before CB72E112069, CB77E-110281 and again after CB77E-1052524 (knock pin). CB72/77 crankshafts differ from the CL-series parts at the right side crankshaft seal surface. There is a lubrication hole (for the starter sprocket) on the CB’s, which is not used on CL’s. The crankshaft’s primary chain drive sprocket changed at CB77E-1052505, in conjunction with the crankshaft spline root modification. CB72 models were probably no longer in production at that time (late ‘67). The cylinder block and gasket was changed at CB72E-211881, CB77E-210900 (change in oil passage location). The cam chain tensioner design was changed three times (two bolt patterns (32mm or 41mm across) and adjuster bolt moved from left side (000) to the right (010) side. The change in widths occurred at CB72E-1007137, CB77E-1050999 (020). There was a piston and ring design change with CB72E-110667 (lower compression from 10:1 to 9.5:1), CB72E-104082, CB77E-1007661 (lower compression 9.5:1 to 8.5:1). The chrome piston rings were added at CB72E-113304, CB77E-111181 and modified at CB77E-210604. Oversize wrist pins (.004”) are available to repair worn small ends of the connecting rods. CYLINDER HEAD Moving up to the cylinder head, we find that the ‘61 models and early-’62 model castings featured 10mm C9H spark plugs, through CB72E-210301, CB77E-210201 (changed to 12mm NGK D8HA plugs, thereafter). The final change was at CB77-1050497 (vent fittings deleted). The cylinder head cover changed at CB72E-111369, CB77E-110152 (mount bolt hole size increased to 8mm), and again at CB72E-113069, CB77E-111031 (institution of the crankcase breather feature in the top cylinder head cover, when the “rear breather” was eliminated). A late version in 1967 relocated the breather fitting to the rear edge of the top cover. The left cylinder head cover was changed along with the tach drive and gear at CB77E-311504. CB72-312177. 25 Honda 250-305 Super Hawk Restoration & Maintenance Guide The cam sprocket was changed along with the special locking nut at CB72E-213801 CB77E-212261 (right hand threads), then again at CB77E-1052547 (change in spline diameter, reduced from 17.5mm to 17mm). Left camshafts were changed at CB77E-1052547 (splines). Right camshafts were changed twice, once at CB72E-402706, CB77E-1000794 (different point shaft) and again at CB77E-1052547 (change of splines). The “000” and “010” point shafts are not interchangeable, due to difference in shaft diameters. These cylinder heads have the cast-in steel “skull,” which incorporates the combustion chamber and the spark plug threads. The castings are similar for both the CB72 and CB77; however, the edges of the combustion chamber are machined with a chamfer on the CB77, to allow clearance for the larger bore of the 305 pistons. Valve sizes are the same for both engines. ITEMS NEEDING SPECIAL ATTENTION! At approximately 115 pounds, the engine is a robust collection of cast and machined steel and aluminum. However, there are a few "genetic" weaknesses in the design, which I will discuss: The OHC cam chain system is an interesting and relatively simple design, incorporating a guide roller, mounted on the upper crankcase between the cylinders and a camchain tensioner situated at the rear of the cylinders. However, the camshaft sprocket assembly is a part that can be the source of several problems. This assembly incorporates the spark advance system into the design. This part often becomes a problem, when the mileage goes beyond 12-15,000 miles. The advancer springs (governor springs) often stretch out or sometimes break, causing the spark advance system to be partially or fully advanced, even at idle speeds. The springs are available separately, but the engine must be removed and the top engine cover removed for access. Second, the sprocket assembly is riveted together and the rivets will loosen with age and vibration, causing the cam and ignition timing to be late and inaccurate, as well as creating a distinctive "rattling" sound. “Tack welding” with a heli-arc (TIG) welder is recommended in four locations (both sides), to prevent/repair this problem. The second area of concern is the camchain guide roller and tensioner. These parts are made of neoprene rubber, which are transformed, through the elements of age, heat, and chemical assault, into a brittle plastic, which begins to chip off when contacted by the camchain. Replace these parts when they lose their elasticity. Vintage racers used a CB450 or Kawasaki 900 top idler sprockets, in place of the rear tensioner roller, to ensure positive control of the camchain, but these idlers are getting scarce now. This conversion would require some assistance from your local machine shop. Les Barker, at VINTAGE ADVANTAGE (formerly called Little Engine Service) in WA, is remanufacturing Honda cam chain tensioners using a new roller material and some delicate grinding and welding on the roller pins in order to accomplish the changeover. 26 Honda 250-305 Super Hawk Restoration & Maintenance Guide Mark McGrew’s M3 Racing has a new single-piece slipper-type tensioner assembly available, as of 2002. Otherwise, you must purchase a new assembly from HONDA, if you can. CAUTION! Remember, there are two tensioner bolt patterns ("narrow" 32mm and "wide" 41mm). The camchain will stretch with normal usage and especially so, if they have been allowed to flop around, when the tension has not been properly maintained and adjusted. Replace the camchain master link, along with the chain. For real peace of mind, use a CB450 master link, which requires the ends to be "staked or peened" like a rivet. If the engine is "stuck" (won't turn over with the starter or a wrench on the end of the crankshaft) BEWARE! The pistons will seize in the cylinder bores, usually due to moisture entering through spark plug holes or open intake/exhaust valves. This moisture migration can happen through the mufflers, air filters or sometimes when water (or old gas) has come from the fuel tank (condensation), filling up the carburetor float bowl (float valve stuck open), entering the intake port and then the cylinder, through an open intake valve. The damage can be variable, depending upon the length of time of exposure, the position of the piston in the cylinder and the type of corrosion (fuel or water). Trying to disassemble a "stuck" engine can be quite challenging, but can be done! Once the top cover has been removed, the camchain link must be located and separated. If it is somewhere under the crankshaft, then access to the link can be found by removal of the oil pump assembly. Soaking the pistons with penetrating oil or solvents, for a few days, can sometimes be of value (Kroil from Kano Labs is a great product for this application), when trying to move/remove the pistons. If the pistons are seized from old fuel/oil deposits, use some carburetor cleaner to loosen the chemical bonds. Occasionally, the use of a propane torch, to heat up the pistons, will break up the corrosion bond between the parts. Try to rock the crankshaft back and forth to start some movement. Use a block of hardwood and a mallet to encourage some motion, but it is best to avoid hammering on the pistons. The shock loads will be transmitted down to the connecting rod needle bearings and damage the surfaces of the rod, creating the probability of a future crankshaft failure. Even in the best situations, expect to invest in a set of top end gaskets, pistons, rings and probably a re-bore, to clean up the cylinder walls. The following “TECHKNUCKLE STORY” (from past VJMC newsletters), features my idea of using a steering wheel puller to dislodge stuck pistons in the 250-305s. Power vs. Force - The easy way to remove stuck pistons! Sometimes, you have to learn the same lesson several times before it dawns on you that there must be a BETTER WAY! So it has been for me, at least, in finding ways to remove stuck pistons from 250-305s. I’ve done physical damage to my body and to the parts in the process of 27 Honda 250-305 Super Hawk Restoration & Maintenance Guide disassembly, while soaking the pistons with penetrating oils and acids; pounding on them with blocks of wood and mallets; drilling holes in the crown; heating them with propane torches and other methods, usually with less than satisfactory results. I receive the VJMC Internet mailing list, in digest form a few times a day and several innovative ideas have been put forth by both professional mechanics and home-enthusiasts, in this regard. Some have suggested replacing the spark plug with a modified one, incorporating a grease-fitting; then pumping in grease under high pressure until the piston begins to move. This method could be quite useful as long as the valves weren’t open. Some have used either phosphoric or muratic acid to melt away the rust and corrosion, but acids, especially the latter one are quite dangerous to handle. I found myself presented with two different CB77 engines that appeared to be “terminally-seized.” One engine had standing water/muck on top of the pistons for probably 5 years or more. Water can cause the rings to rust solidly to the cylinder bores, as well as create some level of electrolysis due to the presence of dissimilar metals being joined by the water molecules. Plus, the presence of water on raw aluminum is never a good thing and causes that white corrosion that we are all so familiar with. I donned some rubber gloves, safety glasses and went to work with a sense of dread. As I began the disassembly, I had an inspired thought, which involved a tool that had been waiting in my toolbox for years... see below for details! Of course, before you can get to the pistons, you have to remove the cylinder head and to do that you have to unhook the cam chain at the master link. If the link is down deep in between the cam and crankshaft and you can’t reach the link, you have the option of (ONE) cutting the chain in half, which usually gets metal fragments inside or (TWO) drive out the cams and then lift out the cam sprocket, after you work the cam chain past it. This is not a pretty task and usually involves some damage to the cam bearings, as you will find few places to catch with a pointed drift or other driver-type tool. Position of the pistons and thus the cams can affect the ease of removal, as the cam lobes can hang up on the rocker arms as you drive them out, when found in certain crankshaft positions. The procedure follows below: The first thing to do, after removal of the top cover and two nuts under the spark plugs that hold the head to the cylinder block, is to loosen the external cam sprocket lock nut, as well as remove the valve tappet adjusting screws/nuts (keep them in order, so they can go back to the same tappet and valve stem set). Next, you have to loosen the nut on the end of the left camshaft and tap on the end of the camshaft-locking bolt to release the internal tension on the camshaft to the sprocket. You just have to loosen it and not drive it out any distance. Be careful not to damage the threads of the locking bolt. I usually leave the nut on loosely with a small gap between the nut 28 Honda 250-305 Super Hawk Restoration & Maintenance Guide and the shoulder of the camshaft and then give it a sharp rap with a steel hammer. As soon as it can be wiggled with your fingers, you are done there. Once the camshafts have been released, then you can take a small narrow chisel or punch and find a safe place to drive the camshaft halves out of the sprocket. The bearings may or may not come with the camshafts, but the focus is to get the cams clear of the cam sprocket so it can drop down enough to release the chain from the sprocket teeth. You have to wiggle the camshaft sprocket around within the confines of the narrow passageway, in order to get the chain past it; then you can withdraw the sprocket and let the cam chain fall down on the guide roller. Now, you can lift the cylinder head free of the rest of the engine and determine what you are going to do next. In the case of the freestanding water/muck engine, I used paper towels to sop up the excess moisture, cleaned the area with some WD40-type solvent and degreaser while I scraped the edges of the pistons, to get down towards clean metal again. I then decided to try some household “CLR” (Calcium-Lime-Rust) remover to see if it would affect the rust and corrosion there. I poured some on the tops of the pistons and let it set overnight to do some magic. Next day, it didn’t look a great deal different than when I began, so I used more paper towels to suck up the CLR and pondered about what to do next….. Then, it dawned on me! Press the pistons out with a threaded tool of some kind! What did I have in the toolbox? A large steering wheel puller set, that was probably bought from Harbor Freight or someone like that (you can probably rent one from an auto parts store) about 8-10 years before and used about 4 times to pull steering wheels from some cars I used to own. I pulled out the set and lay the central portion of the tool over the studs of the engine. It fit perfectly over the bolt pattern! Of course, only three of the four studs were being used, due to the arrowhead shape of the puller plate, but it was close enough to the other stud so that I was able to cobble up a steadying hold on the edge of the tool with a 3/8” drive 27mm socket, cocked sideways enough to grab the edge of the tool for a solid 4point hold. SEE PHOTO FOR DETAILS I grabbed a handful of 3/8”drive, deep sockets and stacked them on the studs, until I could just get a cylinder head nut on the end of each stud to hold the stack in place. I had to adjust the central puller bolt position to get everything even. I fitted the center bolt with a revolving flat-headed tip from the kit. Juggling the position of the bolt around in conjunction with the sockets gave me a place to start to begin the pushing process. I began to crank down on the central bolt with a 14mm wrench and it immediately began to dislodge the stuck piston, giving off audible groans and creaks and squeals, as the corroded parts began the separation process. If both pistons are seized, as these were, then as one goes down, SOMETHING has to move on the opposite side. In this 29 Honda 250-305 Super Hawk Restoration & Maintenance Guide case the cylinders began to rise up on one end. You don’t want to overdo the process here and bend a rod, so I kept a lot of oil/penetrating fluids around the tops of the pistons to allow them to flow downwards as much as possible, during the pressing process. After the right side piston began to move down about ¼”, I removed the tool and socket setup and transferred it to the left side to release that piston, too. After I transferred the tool back and forth about two or three times, the cylinders were getting free of the pistons and the cylinder block. I blocked up the bottom of the cylinder block with tools or wedges as I proceeded, to encourage the block to come up evenly off of both of the pistons. Once the tool was installed the first time, the whole process probably only took about 1015 minutes to release the pistons completely from the cylinders. No muss, no fuss, no pounding, no cussing, no heating, no acids, etc. just a nice clean release of two rusted/corroded pistons from the cylinder block. If you happen to have two sets of steering wheel pullers, the process will be expedited, as you won’t have to move the setup back and forth to free up both pistons. If the pistons were still in STD or .25 sizes, you can usually bore the rust out of the cylinder liners and install some .75 or 1.00 pistons, saving the cylinder block from a re-sleeving or the metal scrap yard. I repeated the process, the next day, with another engine and with the same results, so I am confident that it will work in a vast majority of cases of stuck pistons, whether the issue is due to rust or varnishing. Now that my arm has healed up from the previous pounding attempts, I know that I will never be forced to resort to brute force again, in order to dismantle a 250-305 engine. It is interesting that the book I have been reading lately is called “Power vs. Force”! True power will win out over brute force, when applied with focused attention, every time. Try it and see for yourself! See photo of the original set-up on the following page. 30 Honda 250-305 Super Hawk Restoration & Maintenance Guide PRIMARY CHAINS An ever-worsening dilemma faces 250-305 engine owners in the form of the need for new primary chains. There is supposed to be only a maximum of ¾” slack in the chains, but most exceed this figure rather quickly. All engines use the same chain, so there are still many hundreds of engines out there that all need chains while the supply has virtually dried up. Honda did supersede the original 259/266 chains with a 268 version, which may have been a little sturdier, but any will fit the engines. Check the upper inside of the clutch cover for any shiny spots that have been worn there from loose primary chains. If you see the telltale signs, go hunting for a chain that is better than the one you have now! The primary chain tensioner was not introduced until CB72E-211581, CB77E-210701. OIL FILTER/PUMP These engines do not have an appreciable amount of oil pressure. Its parts rely on a constant bath of clean lubrication for the many roller, needle and ball bearings. Infrequent oil changes, being operated with missing or damaged air filters or low oil levels will cause wear and failure in many areas. Inspect the centrifugal oil filter, for signs of metal flakes, indicating possible component damage and clean thoroughly before reassembly, using a new O-ring between the cover and the rotor body. The two small oil pumps gears are the first targets for any kind of foreign matter to enter the lubrication stream. They are often found damaged because of their vulnerable location. The 31 Honda 250-305 Super Hawk Restoration & Maintenance Guide pump gears are no longer available, so you will have to dress the parts up as well as possible and look for spare oil pumps to rebuild for future needs. The gasket for the side plate is very thin material. If you make your own gasket don’t use anything thicker or you will lose some oil pressure/volume because of excessive side play in the gears. Don’t over-tighten the drain plug on the pump body or the threads will crack. Be sure to use a new aluminum, sealing washer on the drain bolt. The oil pump gear was changed at CB72E-210300, CB77E-210200 (brass gear to steel) and the entire pump was superseded to a CL72 unit (15110-273-000), which has a cast-in boss for the lower CL engine mount bolt. The oil receiver was deleted and strainer changed at CB72E311306, CB77E-311979. See photos at end of book. The oil filter housing (plain, instead of the cast-in HONDA, until 1963) was changed at CB72E-103955, CB77E-105233 (different diameters), as was the clutch cover. The oil filter rotor was changed at CB72E-213081, CB77E-211921 (change from flat snap ring to wire-type retainer ring). VALVE TRAIN The intake valves of the ‘61 CB72 were changed at CB72E-110666 (increased diameter from 30mm to 32mm, increased stem length from 89.28mm to 89.97 mm). The “YB” 14751(61)– 268-810 (inner & outer) valve springs are recommended for top performance. Note that the tips of the inlet rocker arm shafts are .5mm (.020”) larger diameter than the exhaust shafts (11.5mm vs. 11.0mm). There have been four different valve cap designs, but only two different part numbers! The early ones were “domed” (268), the domed with a small flat edge, superseded by a more flattened-shaped one (259). The forth, half-domed shaped cap’s part number, usually seen in the 1967 models, hasn’t been identified as being different than the others. Scoring of the cam followers and the cam lobes is common, especially in high-mileage bikes. Bikes that have been operated without air filters tend to have worn guides and valves due to ingestion of dirty air. The cam followers have been redesigned in the later models (268-305 code part), to provide oil supply directly on the contact pad of the cam followers. Use this latest design, whenever replacement is necessary. If the head is disassembled, inspect valve adjuster screws for "flattening" and the ends of the valve stems for damage. Check valve guides for wear, particularly the exhaust guides. Valve guide clearances are .01-.03mm (.0004-0012") for the intake and .03-.05mm (.0012-.002") for new parts. The air vent fittings, installed on the back of the cylinder heads, are to provide a vent for the intake valve guides. The intake guides are drilled with small holes, which breaks up the "suction effect" of the oil film on the valve stem moving in the guide. The idea was to prevent excess oil from being drawn down the guide and into the 32 Honda 250-305 Super Hawk Restoration & Maintenance Guide intake port. If the passages are plugged or restricted, exhaust smoke and increased oil consumption can occur. There are no valve stem seals installed in these engines. Ironically, Honda deleted the whole air vent system on the last of the models in 1967. HEAD GASKETS/O-RINGS Head gaskets often leak around the cylinder studs, which carry the oil passages. When replacing the gasket, smear a small amount of silicone sealer into the inside edges of the gasket holes, to prevent oil migration laterally through the gasket. Be sure to replace the O-rings that seal around the outside knock pins. Check head and cylinder surfaces for flat and parallel surfaces. There are some reports of aftermarket head gaskets suffering from oil leaks due to an overly thick combustion chamber fire ring, which holds the cylinder head up off of the outside O-rings. Check all parts carefully before installation. Compressed head gaskets are generally about 1mm thick (.040”). SWAPPING ENGINE PARTS FROM OTHER 250cc-305cc ENGINES The differences between the 250cc and 305cc Super Hawk engines are: cylinder heads (beveled edges on 305 combustion chambers); cylinders (54mm vs. 60mm); pistons (54-55mm vs. 60-61mm), piston pins (length is different, diameter is the same) and rings (54-55mm vs. 6061mm); head gaskets (55mm vs. 61mm); carburetor (22mm vs. 26mm; crankshafts (smaller balance holes on 250's). If you think that you can indiscriminately swap CB engine parts with Scramblers and Dreams, please read the following: Here is what differs between the three different models. Crankshaft: All are different. 250s are balanced differently than the 305s (3/4” vs. 1” holes). The CB/Dream versions both have extra oil feed holes for the starter clutch, but CB/CL crankshaft timing is 180 degrees, while Dreams have 360 degree crankshaft firing. CL crankshafts will interchange with CBs (just use the CL crank seal) for racing purposes, but do not have the extra oil feed hole for electric-starting purposes. Early Dreams use ball bearing mains on the ends, until 1962, while CB/CLs have roller bearing mains on the rotor end of the crankshaft. Cylinder heads: CL and CB are the same, featuring dual-port castings. (250s and 305s have different machining in the combustion chambers, however). All Dream cylinder heads have single intake ports and smaller diameter valve seats than the CB/CLs. Pistons: CB/CLs share the same piston sets, but earlier (pre-1965) CBs had higher compression pistons. Dream piston crowns have a wider, machined band around the combustion chamber area, which drops the compression by about two tenths of a percent. Dream pistons use the thinner CB/CL rings in the later editions. CB pistons superseded the CA77 Dream pistons, however. Valves/springs/retainers: CB and CL are the same in both 250 and 305s; Dreams have smaller 33 Honda 250-305 Super Hawk Restoration & Maintenance Guide valve heads and more dished valve spring retainers. CB/CLs share the same valve spring sets, while the Dreams have lighter pressure spring sets. Left cylinder head covers: Dream and Scrambler are the same; CB has tach drive (2 versions) Right cylinder head covers: all the same, except for some early/late changes. Top cylinder head covers: all different. CB has tach drive relief on left; CL looks similar to Dream, but Dreams mount their condenser on the top (mounting holes provided). CLs have a rubber mount pressed into the top cover for vibration control. Carburetors: CB77 and CL77 are the same except the jet needle; CB72 carb is power-jet (4 jet) style, CL72 is a conventional 2 jet (main and idle jets). Dream carbs are all 22mm (both 250 and 305). Remember that there are “square bowl” and “round bowl” types of CA/CB carbs, but not the CLs. SEE CARB SECTION FOR MORE DETAILS. Carburetor insulators: CB and CL77s share 26-28mm, while CB and CL72s share 22-24mm; Dreams are different with a chamber placed below carburetor. Note the tapered inlet in them! Points & Condenser: CB/CL72-77s share same dual points/condenser components. Dreams have single points (ND or Hitachi, which do not interchange) and condenser is mounted on cylinder head cover vs. coil mount on the CB/CLs. Points cover: CB/CLs with 180-degree cranks share “TYPE 1” marked covers. Dreams have either blank or TYPE 2 stamped cover. Kick-starter covers: All different, plus there are early and late versions of them all (clutch cables relocated ¾” forward on 1965-later ones). Transmissions: CB/CLs share same ratios, with mods done to bushings, shafts and gears over the years. Dream transmission ratios are different than CB/CL, using lower first gear and different gear spreads. 34 Honda 250-305 Super Hawk Restoration & Maintenance Guide Oil pump: CB and Dream share the same pump. Part number for CB/Dream superseded to the CL pump, which has an extra cast in mount for an extra lower engine mount bolt. Camshafts: CB/CL share same cam timing, but several changes were made to camshaft splines and cam sprockets, so that all parts are not interchangeable. Dreams have “shorter” cam timing for improved mid-range power/torque. All cams have the same valve lift figures. The right side cams have two different inside diameters to match the two different point shaft outside diameters. Cam sprockets: CB/CL cam sprockets are similar to each other (when you match the cams to the cam sprockets), but Dream cam sprockets have longer advancer weights than the CB/CLs, which speeds up the advance curve (2,500 rpm vs. 3,300 rpm). There is less spark advance for Dreams. The change in cam timing for the Type 2 engines was accomplished by turning the cams 90 degrees, using a relocated “master spline”. Advancer shafts: The CB/CLs share the same single-lobe advancer shafts, while Dreams have a double-ended points cam lobe, so they can fire the points every crankshaft revolution. There are two different diameters on the shoulder behind the oil slinger portion. Stator/Rotor: CB/CLs share the same stator/rotor components, but early CBs had high-output generator sets vs. the low-output (marked L on rotor face) variety. Dreams have similar components, but the rotors are only marked for one set of timing marks on the rotor. There are Kokusan and Nippon-Denso parts, which have different part number suffixes. Shift Drum/Forks/Selector: Shift drum and shift forks are the same for all models, except for "rotary" shift Dream models. There was a change on the shift shafts lengths, however. Engine Cases: For the most part, the upper and lower engine cases, from 1963-on, are pretty much the same for all models. Earlier engines, thru 1962, did not have primary chain tensioner mounting bosses in the lower case, thus no primary chain tensioner. CB72-77 KICKSTARTER COVERS Right side engine (kick starter) covers will often crack and break, if the clutch release mechanism and kickstarter parts are not kept well lubricated (see service bulletin). Insure that all of the cover screws are installed and kept tightened. The kickstarter gear bushing is made of a fiber material, which wears and works loose in the outer case housing. This part is not replaceable from Honda; however, brass or bronze bushings could be fitted by a machine shop. Be sure, that a provision for lubrication is made in the replacement bushing. If repairs are not feasible, a new cover will have to be purchased. There are two versions of the cover, with the later one having a relocated clutch cable joint closer to the forward support screw area. There is a different clutch cable joint and return spring for each design. Note that there are two sets of punch marks on the k/s gears for 35 Honda 250-305 Super Hawk Restoration & Maintenance Guide installation. There is a single punch mark and a round “O” punch mark stamped on each gear. One set is for initial gear alignment. When the other set is aligned, after winding the return spring, the cover can be installed on the k/s shaft splines. Be sure that the k/s arm is positioned correctly, to prevent interference with operation of the brake pedal. Wear in the clutch lifter threads will create a heavy clutch lever pull and contributes to clutch drag. Also, check the clutch lever return spring for wear, at both ends of the spring. Finally, when reinstalling the clutch adjuster thread in the side case, note that the index marks on the case and on the edge of the clutch adjuster MUST align at a 1 o’clock position (o’). The clutch adjuster thread CAN be installed upside down and still function, but the holes for the grease nipple will be blocked, preventing proper lubrication of the clutch release parts. 36 Honda 250-305 Super Hawk Restoration & Maintenance Guide CLUTCH The clutch assembly will give good service, if it is checked and adjusted periodically. The clutch springs should be replaced with "810" springs, current upgraded parts from Honda or Barnett Kevlar plates and spring kits. Check for worn friction plates and warped steel plates. The inner clutch hub can become "notched" from wear and prevent a smooth release of the plates, causing excessive "clutch drag." Discard the wire stopper rings for racing applications. However, I DO recommend that you leave them in for street use, as they do ease clutch release (especially for finding neutral at a stop sign) and breakage is rather rare. There are a couple of different clutch center hubs and two different spline configurations for each. The clutch plates and hubs cannot be interchanged, in those cases. The early 6 plate clutch friction plates are all fiber material, whereas the later 020 plates for the 5 plate clutch had a metal backing with friction material bonded onto the surface. Early models (thru ‘64) used 6 friction discs (010), while later models (CB72E-1010287, CB77E-1012460-on) used 5 discs (020) and a different (thicker) Plate “A.” Currently, new clutch kits are available from Barnett Tool & Engineering dealers, located across the US. Four different clutch centers were used: CB72E-210001-213081, CB77E-110001-211440 used the C72 (“259”) parts, including the clutch plate stopper ring. The later 5-disc model was superseded from a (030) to a (040) part, when the splines were changed. Clutch springs were superseded from (-268-000 or 275-000) to the “YB”-spec (810) parts for all applications (either “268” or “275”). There are two different clutch outers; one with a cush drive and the originals without. The clutch outer was changed only once at CB72E-1002395, CB77E-1007035 (cush drive installed). Always check the drive sprocket on the rear of the outer hub for looseness. Either the rivets are loose and the clutch hub is coming apart OR the original rubber drive cushions are shrunken and hard, allowing some movement inside. All of the clutch outers will interchange on all engines. TRANSMISSION The transmission and gear selection components are rather trouble-prone. Rounded-off engagement "dogs" and insufficient dog engagement (see service bulletin section) are generally the causes of transmissions jumping out of gear (usually second gear). Worn shift forks, shift drums and low gear bushings all contribute to gear selection problems. Transmission parts can cost upwards of $100-200 (and often much more) each, so evaluate your transmission components carefully. Worn low gear bushings can also contribute to problems of the kickstart ratchet mechanism. Watch for worn kickstart shaft pawls and transmission bushings, too. Check the gearshift and kickstart spindles for worn, damaged, or twisted splines. 37 Honda 250-305 Super Hawk Restoration & Maintenance Guide Transmission parts were redesigned at CB72E-211881, CB77E-211021 (“258” CB71 parts changed to “268” CB72 design), then again with a modification at CB72E-1005909, CB77E-104304l on the 34T low gear, when the 14mm bushing was changed. Another major redesign occurred at CB72E-1008204, CB77E-1052457 (change in spline root diameter from 25.5mm to 28mm on both shafts, 2nd c/s gear, 3rd in/s gear, top gear, c/s sprocket & plate, and clutch center). The gear selection parts were virtually unchanged throughout the life of the model, except for the addition of a stopper arm distance collar at CB72E-210301, CB77E-210201. CARBURETORS The carburetors used on the CB72's are 22mm, while CB77 models are 26mm units. The CB72 carburetors are of the "power jet" design. At high speeds, these circuits added extra fuel, drawn through a brass tube from the float bowl. This fuel was metered and mixed with air, which was drawn from the air filters, through small rubber tubes. CB72 "power jet" carburetors had #35 slow jets and #95-100 main jets, #160 power jets and #90 air jets. The CB77 carburetors use #42 slow jets and #135 main jets. Slow jets are available from #35-45 and main jets from #90-145. CAUTION: The thread pitch for early model carburetor jets is J.I.S., while later models are I.S.O. (marked with a grooved ring). Part numbers for slow jets begin with 99134-XXX04 and main jets 99102-XXX04. The XXX numbers determine the jet sizes (i.e. 035 or 135). Float levels were 22.5mm for 26mm carburetors and 26.5mm for 22mm carburetors. There were two styles of carburetor bodies, float bowls and floats. The early ('61-64) "253" floats, float bowls and gaskets were "round bowl" design, while the later (64-on) "268"-series parts were for "square bowl" configurations. Round float part numbers were superseded to –312- (SL350K1) parts, in the past few years. Overflow hoses were not used on the float bowl tubes. The "square bowl" shape refers to the sharper 90-degree corners of the float bowl and flat outer sides of the float. Float bowls on the '61-63 models did not have drain screws. 38 Honda 250-305 Super Hawk Restoration & Maintenance Guide Carburetors for the CB77 and CL77 are interchangeable, with the only difference being the taper of the "Jet Needle." The difference between the CL72 and CB72 is a different needle, a 3.0mm slide and the power jet circuit, featured on the CB72s only. The part # for the CB77 needle is 16151-275-004 vs. 16151-278-004 for the CL77. The model applications are generally stamped either on the upper edge of the carburetor-mounting flange and/or sometimes on the choke lever arms. The CB77 needles are stamped K24231; CL needles K24304; CA needles K22401; and CB72 needles K22402. Most of the major parts of the carburetor are not available separately, but the "banjo" fittings for the fuel lines are similar to the 17625-250-000 Joint; 90168-250-010 Bolt; and 17791-250-000 Gasket (4) from the C70 fuel petcock. The carburetor insulator spacers are specifically designed for each application. The CB77 insulators are generally marked 25-26 (mm) on top. CB72 insulators are marked 22-24mm. The holes are tapered to maintain air velocity through the intake system. Be sure to use only the correct sized O-rings when you are replacing them, as oversized (in thickness) O-rings will often swell up with today’s fuels and break through the thin outer edge of the insulator, resulting in an unwanted air leak. The insulators for CBs and CLs are the same. CARBURETOR OVERHAUL/REPAIR Repairing/restoring carburetor is becoming increasingly more difficult, due to lack of replacement parts and wear/abuse by previous owners. Years of evaporating fuel residues can cause insurmountable problems, in extreme cases. Many are found with float bowls full of water or mineral deposits from evaporated water left in the float bowls. Other maladies are damaged floats, embedded pilot jets and warped carburetor bodies, which cause the throttles to stick open. Dropping the carburetor bodies in a bucket of caustic carburetor cleaners is often the first line of attack, in clearing out the varnish and fuel deposits. This will generally clean the petrochemical deposits out, any rusty parts, like the choke linkages will not be restored at all. Most carburetor cleaners will not dissolve the mineral deposits, either. Some household cleaners like CLR (Calcium-Lime-Rust) cleaner will neutralize those problems, after the varnish has been removed. Use of a bead blaster can be effective, if a small nozzle and very low pressure is used to de-scale the parts. Because of the nature of the glass beads breaking into tiny pieces during the blasting process, a very thorough cleaning of all parts must be done afterwards (try baking soda or a fine plastic media instead). All air and fuel passages must be blown out with compressed air to verify that they are not restricted. The float bowl vent passages at the top of the float chamber in the carburetor body must be clear and unrestricted. The external tubes on the side of the carburetor body are the source for atmospheric pressure equalization for the float bowl. If these passages are blocked, the carburetor will flood immediately. 39 Honda 250-305 Super Hawk Restoration & Maintenance Guide Once the parts are cleaned up, they must be inspected and replaced, as necessary. Worn float valves, slides, needle jets and jet needles must be replaced to ensure that proper fuel metering takes place. You can check the fit of the needle jet on the needle once it has been removed from the carburetor body. Be sure that the jets are correctly sized for a standard application, so you have a baseline to work from. Check the floats for any pinholes, to prevent “sinking” once the float chamber is full. Almost all used carburetor bodies will have warped mounting flanges. A large flat file will flatten the flange area out, if used carefully. If new O-rings are installed, the carburetor mounting nuts must be just lightly tightened, otherwise more bending of the flanges will occur. After the flanges are straightened, the slides can be tested in the bores for a smooth fit. When possible, use the later anodized, silver-gray, alloy slides, rather than the original chromed brass units, as they have a different heat expansion rate and are less likely to than the brass items. Run the slide up and down inside the bores and feel for any tendency to stick anywhere inside. You may have to sand off some high spots with some 400 grit paper until you get a smooth fit. Try the carburetor bodies on the cylinder head and see if the slides are still moving smoothly after they have been tightened down on the studs. Not only do sticking slides cause the engine to race uncontrolled, but it can cause engine damage due to one cylinder trying to pull the rest of the bike along in opposition to the side that is not opened. If this happens on the road, the sticking side will usually cause piston seizure, rather quickly, so don’t dismiss the potential severity of this problem. Once you have everything cleaned up and ready for assembly, be sure to check and adjust the float levels. The 22mm carburetors have a 26.5mm setting, while the 26mm mixers get a 22.5mm level adjustment. See photos of the float setting information and actual float setting tools shown in this book. If you set the float levels accurately and there is a problem with fuel leaks at the overflow tubes or bowl gasket areas, consider the possibility that your float valves are leaking (be sure to put the paper gasket under the seat when you screw it in) due to worn needle/seat contact area or a float is sinking. Other problems occur when the old bowl gasket is left in after cleaning and it has gotten a little melted, causing interference with the float in the closed position. Even new aftermarket gaskets can cause this problem, so check float clearance very carefully. In rare cases, the float bowl overflow tubes become cracked and will leak fuel through the sides of the tube. Use of aftermarket carburetor “overhaul kits” can cause numerous running problems, when installed in place of OEM repair parts. The jets are often poorly calibrated, causing richness at idle (Hint: If the bike starts with NO CHOKE, it has a problem!). The gaskets are not 40 Honda 250-305 Super Hawk Restoration & Maintenance Guide accurately cut and need trimming to fit the carburetor body on top and the float bowl. About all you can generally use are the float valve and some O-rings, perhaps. As of the time of this writing, Honda still supplies some gaskets and O-ring seals for vintage Honda carburetors and petcocks. Once you are ready to install the carburetor, be sure that your throttle cable is serviceable and lubricated with a little light oil. When you are installing the carburetor tops and slides, be sure that the needle clip position is the 4th from the top (CB77- at sea level and about 60 degrees), which raises the needle in the jet holder slightly. This is the recommended setting for a stock engine with stock air filters and mufflers installed. Any changes from the OEM installedequipment or differences in altitude or temperature will create a need for some adjustments to the standard carburetor settings. High altitude settings will require replacing the stock #42 & #135 jet sizes with something more like a #38 & #120-125 combinations. Install the carburetor and connect the choke links and be sure that both choke plates are closing together at the same time. Be sure to install both carburetor slides with the cutaways facing the air cleaners. Install the carburetor tops on the right and left sides (L&R). Correctly positioned, the carburetor tops should locate the cables inwards towards the frame. Once everything is bolted (gently) in place, take a moment and remove the float bowls and main jet holders carefully. This allows you to watch the tips of the needles, as they extend downwards into the jet holders. With the idle screws backed out enough to allow the slides to bottom in the carburetor bodies, carefully watch the two needle tips, as you gently open and close the throttle. Use the cable adjusters on the tops of the carburetor to change the amount of cable slack on each side, until they both go up and down at the same moment. Looking through the open choke plates into the throttle bores, watch the slides go up and down and note if there is any tendency to stick in a partially-opened position. If this occurs, you must remove that carburetor and repair the problem before attempting to start the engine. Once you are satisfied that the carburetor slides are synchronized and are opening and closing smoothly, reinstall the main jet holders and float bowls. Set the idle mixture screws to about three-quarters to one turn out and turn the idle speed screws in until they just begin to raise the slides, then add about one-eighth to one quarter more turns in to give the engine an opportunity to idle, once it is started for the first time. Use 5mm or 5.5mm metric-sized fuel hose, if possible, to connect the carburetor to the fuel petcock and for the crossover tube. I generally use a very long piece of tubing for the crossover and loop it over the frame, instead of under it. This negates the function of the 41 Honda 250-305 Super Hawk Restoration & Maintenance Guide crossover tube, but allows for easy removal of the fuel tank, without all of the fuel spillage problems that occur with trying to pinch off the crossover tube and seal the ends, before removing the fuel tank. As noted elsewhere, Honda deleted the crossover tube and fitting on the petcock towards the end of production, anyway. Once you have the engine running properly, (meaning AFTER you have set the ignition timing with a timing light), then you can fine-tune the carburetor for mixture and idle speeds. If you don’t have an inductive tachometer or gas analyzer machine, you will have to listen and adjust in small increments, until you hear a smooth exhaust note from both sides at idle. Some experts will ground one of the spark plug wires and adjust each side at a time. If the engine is timed correctly and has good compression, it will run on one cylinder for a few minutes, as you maximize the carburetor settings. I generally just listen to each side, turning the mixture screw in until the engine begins to falter, then out about ¼ to ½ turns Keep readjusting the idle speed screws until you have a smooth idle and good throttle response, when you open the throttle for acceleration. An intermittent popping in the exhaust generally indicates an air leak (lean condition) in the intake side and/or an exhaust leak from the header pipe joint or muffler joint. Exhaust leaks will draw cold air into the exhaust system, which collides with the outgoing exhaust charge that usually contains some flammable vapors. This will cause a small explosion in the exhaust system, which is heard as a popping, backfire sound. Check all exhaust gaskets before you begin to adjust the carburetors for this condition. If the exhaust is tight, then you have a lean condition in the intake tract: lean idle mix adjustment, low float level, bad O-rings, warped flange, partially blocked carburetor jet, wrong carburetor slide or needle position, worn carburetor body, etc. 42 Honda 250-305 Super Hawk Restoration & Maintenance Guide FULL SIZED IMAGES OF FLOAT SETTING GAUGE SETTINGS FOR 305 (TOP) AND 250 (BELOW) ENGINES Copy and paste onto a piece of cardboard for use as a float tool. 43 Honda 250-305 Super Hawk Restoration & Maintenance Guide =============HONDA CARBURETOR SETTING GUIDE========== This is an abridged copy of information published in Cycle and Moped Trade Journal, Dec. 1965 and reprinted in the October 1997 issue of Classic Japanese Motorcycle Club newsletter. “The carburetor settings from the Honda factories have been made, based on the atmospheric pressure at sea level and air-temperature of 15Cº (49Fº). Therefore, when these products are used in cold, tropical or mountainous areas where the atmospheric pressure and temperature are different from that used in the carburetor pre-setting, it is necessary to adjust the setting by referring to the tables.” The following main jet sizes are available from Honda: 55, 58, 60, 62, 70, 72, 75, 78, 80, 82, 85, 88, 90, 95, 98, 100, 105, 110, 115, 120, 125, 1310, 135, 140, 145 Setting: A= Size number of main jet B= Location of clip attached to needle C= Air screw (Pilot Screw) turns (t) from full closed (plus or minus ¼ turn). Model Venturi dia 15Cº (49Fº) Setting: CB72 22mm .87" 2000m (6560ft) Sea Level 40Cº (104Fº) 0Cº (32Fº) 40Cº (104Fº) A B C A B C A B C A B C 100 -2- 1.125t 95 -2- 1.125t 85 -1- 2.0t 90 -1- 2.0t 115 -2- 1.75t 120 -2- 1.75t CB-CP77 26mm 1.02" 135 -4- 1.25t 130 -4- 1.25t 44 Honda 250-305 Super Hawk Restoration & Maintenance Guide ENGINE ELECTRICS REPAIRING THE STARTER CLUTCH The starter clutch, which mounts to the rear of the rotor, can be a source of problems. Moisture, dirt and vibration can cause the plungers to stick in their bores. Usually the plunger springs break or lose tension and sometimes the screws loosen and the entire assembly separates from the rotor. You have to get one of the special rotor puller tools from Honda or from accessory shops, in order to remove the rotor and access the backside of the starter clutch for spring/cap/roller replacement. This is a description of the rotor puller tool and the applications: 16mm x 1.5 Special bolt: fits late-model CB600 R series, 700 NIGHTHAWK, ATC 90K, ATC11O, CB160-175, CA/CB/CL72/77 (250-305), CB 350, CB350-400F, CB360, CB500550-650 SC, CM185- 200T, CM(X)25O, CM450, CM250, CT9O, SL175, SL350, early-model CR125M and CR25OM (mid 1970's). Replaces Honda #216 tool. It is not necessary to remove the whole kick-starter side case, if you are careful. With the dyno cover removed, you have to loosen and remove the central rotor bolt with a 14mm wrench/socket. You might put the bike in gear to keep the rotor from spinning so freely. Use a long 14mm wrench or breaker bar on the bolt head and then hit the wrench/breaker bar sharply with a hammer in the counterclockwise direction. Usually a sharp jolt will break it loose. Take out the bolt and insert the rotor puller tool. Snug it down and then smack that tool, similarly with a hammer in the clockwise direction to jolt the rotor from the end of the crankshaft taper. It should pop off and then you will see the end of the crankshaft with the woodruff key sticking out. Remove the woodruff key and keep it safely stored until you need to reinstall it. The backside of the rotor contains the rollers/springs/caps and outer clutch hub parts. Clean everything out and install the new parts. Replace the key and be sure that it is snug in the groove, so it doesn't slip during rotor installation. You have to line up the keyway on the rotor with the key on the crankshaft and turn the whole thing at the same time. This procedure is easier if you are installing the rotor with a Honda T-handle tool (preferred), so you can support the rotor a little while you are pushing/turning it slightly. Sometimes you can tap the starter button lightly, while you are pushing in on the rotor. The rollers have to retract ever so slightly, so they can raise over the edge of the starter clutch hub, allowing the rotor to snug down against the taper again. You will feel it drop in and the rotor will go almost flush with the outside of the k/s cover opening. Once it has all lined up, install the rotor bolt (14mm head) and tighten it down in the opposite order that you loosened it. Leaking crankshaft seals can cause damage to both the starter clutch and the stator winding insulation. When the insulation is soaked with oil, it begins to loosen and fall off. This 45 Honda 250-305 Super Hawk Restoration & Maintenance Guide allows the windings to move around on the mounting posts and eventually grounds them out, degrading the charging system output. The charging system is really a "battery maintenance system," capable of only a 1 to 2.8 ampere output. When everything is functioning normally, the system will maintain a fullycharged battery. Loose wire connectors, dirty/corroded switch contacts, stator grounding, and rectifier damage will diminish the output to the point where it cannot keep up with the electrical loads of the starter, ignition and lighting systems. Remember that running the engine, with a dead or low battery (or no battery), will instantly damage the rectifier. Read charging system info section, further on. The starter motors are generally very reliable. The brushes can be replaced. It is a good idea to repack the gear reduction set with fresh grease. CA and CB starters are interchangeable. As noted earlier, there were two suppliers for ignition points and condensers: Denso and Kokusan. Due to different parts designs, neither will interchange with the other. Only an entire point plate and contact assemblies should be installed. See other notes about worn points cams affecting the ignition timing. Ignition coils were superseded from the original metal-cased units to a plastic/epoxy case coil with molded-in spark plug leads. Original spark plug caps had a HM Honda logo embossed in the outer surface. These caps have NO resistors inside, unlike replacement plug caps on the market today. Some versions had metal caps, designed to help suppress radio interference signals, but they tended to short out, so Honda recommended removal of the outer metal jackets. CHASSIS ELECTRICS The chassis electrics consist of: the ignition switch, the wiring harnesses A & B, the handlebar switches, the starter solenoid, the brake light switch, the headlight switch, the head and tail light assemblies, the horn, the battery and the rectifier. -The ignition switch: Ignition switches usually have problems in the key/tumbler area due to the location and vibration of the engine. Keys are either broken off inside the switch from hitting them with your leg or the keys fall out due to worn tumblers that fail to retain the key in the ON position. Switch contacts can become damaged or corroded and careful disassembly CAN bring them back to life. The Bakelite contact bases get very brittle eventually and can chip easily when trying to reassemble the switch. Early model ignition switches, with NA or NB key codes, are difficult to have keys made for, due to the configuration of the key blank, which is not available. 46 Honda 250-305 Super Hawk Restoration & Maintenance Guide -The wiring harnesses come in two sections: the main section “B” feeds the majority of the power to the chassis, whereas the “A” harness is for the fuse and feeds the coils. Original USspec wiring harnesses have no provision for turn signal wiring. Later replacement harnesses, with a –305 suffix on the part number did come with “winker” wiring installed, however. -The handlebar switches control switches have numerous places to have difficulties. If the switches rotate on the handlebars during an accident, they often shear the wiring where it runs into the wiring holes in the bars. This condition can cause blown fuses or just an open circuit to whatever you are trying to operate. -The left dimmer switch knob is replaceable, as is the spring and button for the horn. If the wires are sheared, the headlight will not function in one or both positions. If the wire(s) is/are grounded, the fuse will blow out when the headlight switch is turned ON. -The early dimmer switches had an “off” position between high and low beam which allowed riders to turn the headlight switch ON in order to more fully charge the battery. This feature was eliminated (SEE SERVICE BULLETIN) and if you put the later switch in an “inbetween” position both beams will come on, draining the battery rather than charging it. The handlebar switches for many of the Honda models from the mid-60s were all the same except for length of the harness or sometimes just the color of the loom sheath. If you need a dimmer switch for a CB77 and can only find a switch from a CB160, by all means use it! -The right side starter switch has only a single wire, which grounds the starter solenoid primary windings to activate the starter motor. If the wire is sheared off, then the starter will not operate. If the wire is pinched, then it will run the starter motor continuously, burning it up in a short time. The button and return springs were offered separately for repairs. - The starter solenoids can suffer from dirty or worn contacts, which can often be cleaned and repaired. If the starter switch wiring is grounded anywhere between the solenoid and the starter button, the solenoid will be activated, engaging the starter motor. Watch for pinched, sheared or shorted wires at the handlebar switches, especially, if the bike has been down and the switches have rotated on the handlebars. -The brake light switch is the same unit as that for the 250-305 Dreams, but has a unique activation spring and attachment loop. The switch is normally-open and the contacts are closed as the plunger is pulled out via the spring/loop connection to the backside of the rear brake pedal. -The headlight switch is the same part for both the CB and CL (Scrambler) models. The switch provides a means to connect the two legs of the stator together to boost the current to the battery during nighttime operation. The other function is to provide power to the headlight 47 Honda 250-305 Super Hawk Restoration & Maintenance Guide dimmer switch, which then connects with either filament (HI-LO) in the headlamp, plus feed power back to the tail light assembly and the instrument lights in the ON position. Most US-spec bikes have only a 2-position switch, but you might find some out there with 3 positions, one being a source for the Domestic/Euro front parking lamps. -The headlight bulb is a sealed beam bulb/reflector unit for the US editions. Other countries featured reflectors that housed replaceable headlamps and parking lamps. The headlight bulbs must be grounded to the headlight rim through the GREEN wire with a WHITE TRACER connector to the speedometer ground), which then must be connected to the headlight shell for proper operation. The RED wire is for the LOW BEAM filament, while the BLUE wire connects to the HIGH BEAM and the high beam indicator lamp, if equipped. Late style units (1967) have adjustable left-right headlight assemblies, which required new headlight shells, rims and bulbs. -The taillight came in various shapes in the first three years. As noted elsewhere, the 1961 machines carried a unique /__\ shaped lens with a circular reflector at the top. In 1962 the taillight changed to more of the type seen on most 60s Honda models, except that the lens was shorter than the 1962 editions. The light assembly remained the same until 1967 when the ovalshaped taillights appeared. The WHITE wire from the harness and ignition switch feed the tail light lamp. The brake light power came from the brake light switch feed on the BLUE wire. -The horn was pretty much the same through the years except the first ones were black and had “hook” terminals, rather than the more commonly-seen bullet connector wiring. In 1967, the metal horns were replaced with plastic ones. -The battery remained the same, throughout the production run: a YUASA-brand 12N93A. Use of any other battery (like 12N9-3B) will necessitate the need to create battery cable adaptors, at the very least. -The rectifier is a multi-section, selenium design item, which converted AC volts from the stator into a fairly steady DC voltage, which is strong enough to keep the lights running brightly and build up the reserve in the battery for some electric-starting duties. The last of the rectifiers made available from Honda were of the silicon diode variety, rather than the original selenium versions. CHASSIS OVERVIEW Engine vibration will take its toll in several areas of the chassis. The battery box is one such area. When the battery is not properly secured, it will dance around in response to various engine vibration periods. This will: loosen the connections; cause damage to the battery plates; or loosen the filler plugs, which allows battery acid to drip onto the frame. The acid corrosion attacks the battery box welds and the rear fender mounting tabs, which are often broken just from 48 Honda 250-305 Super Hawk Restoration & Maintenance Guide vibration. Chain guards are often missing because the two tabs on the swing arm break off, due to a combination of vibration and the rubbing forces of the chain guard against the inner and outer crankcase covers. Foot peg brackets are usually bent from the impact of the solid passenger foot pegs hitting the ground, during either a "tip over" or crash of almost any force. Early-model (‘61‘62) driver foot pegs were also a solid, one-piece type, but were replaced by the folding design (268-810 part). When the foot peg brackets are bent, the upper muffler brackets are forced into misalignment, causing problems with removal/assembly and can aggravate muffler vibration cracking and general chassis vibration. Early-style mufflers are prone to cracking in the area behind the upper mounting bracket. Late-style replacement mufflers were modified to alleviate this tendency, with separate muffler adapter plates. If the bike shows damage on the mufflers from a crash, often the inner muffler mounts, which are welded to the frame, are often bent out of position. Steering head bearings are usually ready for replacement after as little as 10,000 miles. They can be upgraded with aftermarket, tapered roller bearings. The swing arm bushings are of a "bakelite" construction with a center collar which, if not lubricated, can become corroded and bind to the rear fork pivot bolt. Rear fenders are subject to vibration-cracking at their forward attachment points and also at the taillight brackets. The taillight bulbs and ground wires in the bulb socket are particularly vulnerable. The tabs on the toolboxes also tend to crack and break off due to vibration. Speedometers are subject to vibration-related problems. Be sure that the speedometer cushion is in good condition and mounted securely. Vibration will cause odometer indicator failures and will often loosen the internal assembly screws. Spinning odometer numbers, broken or stuck indicator needles and/or "jerky" speedometer or tachometer action are signs of either bad cables or internal meter damage. Brake shoe wear will use up the brake cable adjustments rather quickly. The cables will experience a certain amount of "stretch" and are vulnerable to inner cable corrosion and cable strand breakage. Wheel bearings should be inspected for wear and moisture contamination. Check wheel rims for out of round or dented conditions and spoke tension. Bright Zinc coatings or chrome plating can renew spokes. A more permanent solution is to replace the chrome spokes with stainless steel spokes. BASIC REHABILITATION Service Quick Tips: Plan on cleaning out the entire fuel system (and rebuilding the petcock and carbs); an oil change (with filter service); replacing all of the bike's cables and fuel lines; and installing a new battery 49 Honda 250-305 Super Hawk Restoration & Maintenance Guide (12N9-3A) before attempting to operate the machine. Avoid fuels with alcohol added to them! The alcohol will cause the petcock seals/carburetor gaskets and O-rings to swell up beyond original dimensions. If a bike has been sitting for an extended period, the carburetors will often accumulate varying degrees of varnish/sludge in the float bowls. It is not unusual to find the float bowls and carburetor slides "glued" in place by old, partially-evaporated fuel deposits. DO NOT PRY ON THE SLIDES, until you have applied carburetor cleaner to all available surfaces of the slide. Generally, the carburetor cleaner will partially dissolve the gummy deposits enough to allow the slides to begin to move. Submerging the entire carburetor (with the cables, if necessary), for a few minutes in a can of cleaner, will accomplish the same effect. Clean all parts thoroughly and carefully. Check floats for signs of damage or pinholes, which will cause them to sink. The holes in the pilot (idle) jets are approximately .012-016" in diameter, so clean and inspect them carefully. Be sure that all air passages are clear including the bowl vent fitting. Plan on removing the clutch cover (after you remove the foot peg, shift linkage and left exhaust system), when servicing the oil filter; and always replace the gasket. The thrust washer for the oil filter goes on the outside of the oil filter cap, against the oil filter stopper pin. In the past, there has been some confusion about whether the washer should go on the inside or outside of the filter assembly. So, look for it in either of those two locations. When you pull the oil filter cover, usually the shaft will stay in the filter cover. Once the shaft has been withdrawn from the crankcase, the thrust washer will fall behind the primary chain tensioner, if it had been placed on the inside of the filter, next to the crankcases. Later model clutch cover/oil filter covers are larger diameter (from CB72E-103955 CB77E-105234) and allow service work without removing the entire clutch cover, but reinstalling the oil filter chain on the filter can be difficult, using this method. Always be sure to account for the whereabouts of the thrust washer and reinstall it properly, before installing the oil filter cover. Inspect or replace both the clutch cover and oil filter "O-rings". Before installing the oil filter cover, note the location of the small locating pin in the end of the shaft. It must correspond to the small slot in the outer filter cover, in an 11 to 12 o'clock position. If the cover will not fit flush using hand pressure, check for misalignment. DO NOT FORCE THE COVER INTO POSITION WITH TOOLS (like hammers, etc.). When removing/replacing the engine assembly, use a hydraulic floor jack and install engine in a vertical motion. The engine will not install by inserting the rear lower motor mount bolts and "tilting" it up into place. Install all mount bolts loosely, before tightening any of them. Re-torque the cylinder head nuts once more before installing the engine. Use a special fork seal holder removal tool, nylon/fabric "strap wrench" or "pin spanner" 50 Honda 250-305 Super Hawk Restoration & Maintenance Guide to loosen the chrome fork seal holders (early steel forks), before you remove the forks from the bike. Tighten them after they are installed. Avoid using a metal punch, pliers or pipe wrenches to loosen/tighten the holders, if possible. Because of the "O-ring," design, these parts do not require exceptional amounts of tightening, to prevent the fork oil from leaking. Honda painted their parts directly, without a prime coat. This finish was easily damaged and moisture would find its way under the paint, resulting in a "spiderweb" paint surface. All CB72/77's are basically “Cloud (dark) Silver” (try Mazda's Sunbeam Silver "DuPont Centauri 45040A" or Duplicolor #1615 Silver Wheel paint ) on both fenders, side covers, horn, crankcase cover and starter motor with the rest of the chassis: frame, fork sliders (steel ones), fork ears, headlight shell, lift handle (side grip), lower fork, steering stem, shock covers, chain guard, swing arm, toolbox, fuel tank and rear fuel tank mount all color-matched. All U.S. center stands and taillight brackets (except white models) were painted black. The colors (codes) to choose from are: Scarlet R-2 (try Ford's Sunset or Vibrant Red or Ditzler DPL71654K or Pepsi-Cola Red), Black NH-1, Royal Blue PB-5 (check early 80's Toyota truck colors and Future Farmer’s of America Blue 63203UH.) and White NH-0. There was a batch (perhaps 10 to 50) of all-chrome models made at one time, but they are exceedingly rare. Also, the last few hundred CB72/77 models produced (CB77-1056084-on) featured "Candy Red" (XJ code suffix) paint on the tank, chain guard, headlight shell, fork ears, shock and side covers on black frames, along with chrome fenders and large oval taillights. Noted Honda restorer, Ed Moore, suggests: RED 6543UM, BLACK 99U, BLUE 63203UH and SILVER 5040U IMRON paint codes. Red is also known as PEPSI COLA RED. Blue is also known as FUTURE FARMER’S OF AMERICA BLUE. Mazda SUNBEAM SILVER is an option for the side covers and fenders, along with Duplicolor Silver Wheel paint for steel wheels. If the engine outer cases are badly scratched or corroded, either a soaking in carburetor cleaner can strip them or lightly "bead blasted" to a smooth finish. "Krylon" paint is available in a finish called "Dull Aluminum" which nearly duplicates the factory finish. Only a few parts like the brake backing plates/hubs, dyno (generator) cover, fork crown (bridge), levers, lever brackets, handlebar switch assemblies and the point cover were clearcoated polished alloy. Powder coating, where available, is another finish solution, which should be considered. It is available in many colors, which are close to factory finishes and can be custom color matched, if required. Powder coat is a fuel and acid-resistant coating which is electro-statically applied and baked in an oven at about 400 degrees. When properly applied with a spray gun, it is drawn into many nooks and crannies, which are not accessible with a normal paint gun. The fuzzy 51 Honda 250-305 Super Hawk Restoration & Maintenance Guide powder melts onto the sandblasted metal in the oven and glazes the parts into a shiny, durable finish. Powdercoated parts can even be sanded and painted over, if necessary, in the future. While this does not duplicate the factory finish, it is a quicker, easier and less toxic task than using paint strippers and attempting to sand all of the welds and crevices by hand. The main disadvantage of powder coating is that you cannot use plastic fillers or lead to repair dents and nicks. Those materials will melt and cause the powder coating to bubble from underneath. Also, rubber swing arm or shock bushings, which are pressed into the swing arm or chassis will need to be removed, as they will be damaged from the 400 degree oven. NOTE: It is necessary to remove powder coat or paint from certain areas of the frame for proper grounding of the electrical system. These areas include: 1) under one of the engine mounting bolts, preferably next to the battery ground connection; 2) the area where the ignition coils mount, in order to ground the condensers properly; 3) the top of the upper fork covers, where they contact the top fork bridge. Otherwise the headlight case will not have a sufficient ground contact and the lights will not work correctly; 4) tail light bracket and rear fender mounting. Without a good ground the tail light bulb will not work, but the brake light will. Any time that you experience unusual electrical symptoms, check first for sufficient voltage, and then connect a jumper lead from the battery ground to a point where the component is normally grounded, to verify that the problems are ground-related. Ungrounded components will often find a ground path through the wiring to another component, which IS grounded, interfering with that unit’s operation. Common mistakes made by new Super Hawk owners *Jump starting a bike with a dead battery, then letting it run off of the charging system. The battery, when fully charged, provides an electrical load for the generator and dampens the output of the AC generator to the rectifier. Above 3,600 rpm, the system can produce 40 volts unregulated and will blow out all of the light bulbs that happen to be illuminated at the time. A loose or bad ground cable will do the same thing. * Installing the battery backwards! The correct 12N9-3A Yuasa battery has two horizontal posts which extend from the battery about 1/2” or so. Some aftermarket replacement batteries, using the same battery number, only have two vertical posts, which requires modifying the battery cable ends to match or use of some copper strips as extenders. REMEMBER: The battery ground (-) is towards the front of the bike, along with the battery vent tubes. The battery CAN be inserted into the battery box in reversed position, with the cables stretched to fit the terminals by creative hands. Connecting the battery cables in reversed polarity will destroy the rectifier! * Failing to check the rectifier for proper function after installing a new battery. If the rectifier is shorted internally, the battery will discharge overnight. 52 Honda 250-305 Super Hawk Restoration & Maintenance Guide * Putting the slides in backwards in the carburetors. Carburetor slides are LEFT and RIGHTsided with cutaways facing the air cleaners, when properly installed. If slides are installed in a reverse position, extreme richness will occur and plug fouling will quickly follow. NOTE: The carburetor tops are also left and right sided, with cable adjusters being correctly located inboards, towards the frame to avoid contact with the bottom of the fuel tank. * Setting ignition timing statically with a 12v test light and not verifying the settings with a dynamic timing light with engine running. Failing to take wear and slop into the equation, ignition timing will usually change drastically once the engine is running. A loose points cam (sideways motion) changes point opening and closing settings. If ignition timing is allowed to exceed the maximum advance marks on the stator, piston seizure is a probable outcome. * Putting the thrust washer on the wrong side of the oil filter. This is a rather common problem, as Honda’s service and parts books don’t clearly show the sequence of the oil filter parts for reassembly. When you assemble the oil filter parts, the shaft must go through the filter thrust washer FIRST, then into the filter cap/rotor itself before installation into the crankcase hole. IF the washer is installed on the inside of the filter, next to the crankcase (seems logical somehow!) then there will be a small misalignment between the drive sprocket on the crankshaft and the sprocket on the back side of the oil filter rotor. Eventually this will wear the oil filter drive chain excessively and the two sprockets will show wear on the sides of the sprocket teeth. * Over-tightening the valve covers (tappet covers). The covers need only to be snugged down gently, as the O-rings are the source of sealing the surfaces, not the threads. Over-tightening the caps to solve an oil leak will only cause the threads to deform; then the covers become very difficult to remove. Also, using anything but the proper-sized 6 point wrench will round off the edges of the hex-shapes leaving visibly scarred, damaged and unsightly parts. * Over-tightening the drain plug. Be sure that a fresh aluminum washer is used to seal the drain plug and don’t overdo the tightening process here, either. Too much muscle on the drain bolt will crack the oil pump’s drain plug threads, requiring repair or replacement of the pump assembly. * Use of D6HA spark plugs (used in Dreams), rather than the correct D8HA plugs, which are two heat ranges cooler. This can lead to overheating, detonation and piston seizure. High speed running requires going up to D9H plugs to prevent overheating. Add just a drop of oil to the spark plug threads, prior to installation, to aid in the prevention of stripped sparkplug holes in the cylinder head. When installing new plugs, tighten down just ¾ turn after the gasket seats. Used plugs only require about one eighth to one quarter of a turn to secure. * Leaving out or losing the large ball bearing that lives inside the clutch lifter thread, which operates against the end of the clutch pushrod. Watch for the whereabouts of the large ball 53 Honda 250-305 Super Hawk Restoration & Maintenance Guide bearing that lodges in the clutch lifter. Usually they stay in due to the grease, but if they have not been serviced, they can fall out and roll away. It is hard to adjust the clutch when this part is missing and the small ones from the steering head will NOT work! * Leaving out the diffusers in the mufflers. Lack of exhaust backpressure will cause the carburetor jet settings to be altered. The same goes for removal of the air filters and connector tubes. Changing to different camshaft grinds and big-bore piston kits always require carburetor jetting adjustments. * Installing oversized tires/wrong shocks. Even though they look so skinny, the stock tires are just fine for street riding. Installing oversized tires will change the chassis geometry and will often prevent the use of the center stand, due to the change in height of the wheels/tires. Use of CB350-type shocks will also cause center stand clearance problems because they are 12 3/4” long, instead of the correct 12.50” length. * Installing longer bolts in the Type 1 steel fork legs. Longer bolts bottom out in the fork cases, deforming the metal case, which causes the forks to bind and stick, during normal fork travel. *Installing the wrong head gasket. Sounds unlikely, but is not that uncommon when reassembling a big-bore (S8-S12-S16) engine and someone mistakenly installs a standard bore (61mm) 305-sized cylinder head gasket. Generally, you’ll have a clue as the squish band on the edge of the piston will contact the metal fire ring of the gasket and the engine will stop rotation. In some cases, where the interference is small, turning the engine over further will compress the ring somewhat and there will be less resistance on the following revolutions. If this “feeling” is disregarded as camshaft/valve spring resistance factors, then the engines will be installed and will, in fact, start up and run. There will be some audible noise, but the fire rings will conform to the edge of the pistons and allow the pistons to continue their motion. Generally, the fire rings become overheated at the exposed areas and begin to burn away. Once the ring has burned through, the combustion gases continue to burn through the head gasket material (asbestos) until it gets to hole, which usually is a cylinder stud hole. Once this happens, there is direct communication between the high-pressure combustion gases and the crankcase cavity. The standard crankcase breather line is barely large enough to vent the gases under normal circumstances, so when the combustion gases arrive, there is a LOT of smoke and oil leaks wherever the pressure can push through. This often a seal or gasket and certainly the breather tube will be spewing considerable amounts of smoke. On the intake stroke, the piston will draw in both an intake charge from the carburetor, plus fumes from the crankcase creating a smoky cloud that sends a strong message…. “SOMETHING IS VERY WRONG HERE”! Bottom line: Be sure that the edge of the gasket is flush or slightly back from the 54 Honda 250-305 Super Hawk Restoration & Maintenance Guide edge of the cylinder when you reassemble the top end. There are sources of oversized head gaskets for big bore applications and/or you can make one out of a sheet of .040” copper sheet, if necessary, using the old gasket for a template and increasing the bore size to suit. * Installing the top cylinder head cover breather plate and/or gasket upside down. There are two drain holes for the plate and gasket that must be placed in the DOWN position when installing the cylinder head top cover. The two holes allow oil solids to be drained back into the crankcase, while the design of the labyrinth design of the cover separates the oil fumes from the oil solids. If the plate is installed upside down (there is usually a big ARROW stamped on one side of the plate, pointing down or forwards) then the oil solids cannot drain back to the crankcase. Thus, they become trapped and expelled with the crankcase fumes out of the crankcase breather tube, causing considerable oil loss, especially at high engine speeds. Basic Troubleshooting Tips * Engine won’t start: No fuel. Dead battery. Bad Condenser. Dirty or misadjusted ignition points. Weak coil. Loose wiring connections. Low Compression (damaged rings or valves). Fouled (oil or fuel) spark plugs. Carburetor jets, fuel cap vent hole or petcock passages are clogged. Carburetor needle valve clogged or stuck closed. Plugged carburetor passages or exhaust system. * Engine doesn’t turn over with electric starter: Dead battery. Starter button on handlebar switch is damaged or wire is broken. Starter solenoid is damaged or has loose connections. Starter motor is damaged. Starter clutch components are damaged (roller springs are often damaged/broken). *Battery loses charge: Bad battery. Loose wiring connections. Defective rectifier. Defective (grounded) stator windings. Defective headlight switch. Demagnetized rotor *Engine runs very rich and fouls spark plugs quickly: Carburetor slides installed in a reversed position. See mistakes note above. High float levels (sinking floats), Blocked air vent passages in the carb body, loose jets or sticking float valves can also cause rich running at idle *Engine seizes during operation under load. Restricted or incorrect jetting (mains or needle position incorrect), incorrect spark timing at full advance, lack of oil, oil pump failure, carburetor slide sticking on one side, incorrect spark plugs (heat range). Mechanical failures: (broken primary chain, crankshaft primary gear nut loosens, transmission snap ring failure, transmission gear damage, valve/valve spring damage, piston failure). Also, excessive engine lugging will overheat engine… keep the revs up! * Engine lacks power or runs rough. Low compression, incorrect camshaft/spark timing, incorrect spark plugs, plugged carburetor jets or petcock passages, carburetor not synchronized or 55 Honda 250-305 Super Hawk Restoration & Maintenance Guide calibrated properly, fuel tank cap vent hole plugged, loose camshaft sprocket rivets, camshaft/ignition timing incorrect, restricted intake or exhaust systems, vacuum leaks in intake tract, air cleaner modifications or removal, exhaust leaks or incorrect mufflers, low battery voltage to coils, damaged coils/condensers, loose wiring connections, damaged/loose spark plug caps/wires, loose ignition condenser (ungrounded), worn/damaged ignition points, worn advancer shaft or points cam lobe, ignition points grounding on points cover. * Engine noises. The subject of noises can cover a lot of ground, including: excessive piston clearances, excessive piston pin clearance in rod, damaged rod bearings, damaged crankshaft main bearings, loose/stretched primary chain or damaged primary chain tensioner. Damaged camchain tensioner/guide roller, damaged rocker arms, damaged camshafts/bearings, loose valve guides, rocker arm wear/side play, loose camshaft sprocket locknut/bolt, camshaft sprocket rivets loosened, incorrect spline match-up with cam sprocket and camshafts. Loose/worn camchain. Piston noises, usually a ringing/slapping sound noticeable at idle Piston pin noises, usually under load, then reducing on part throttle Big end noises are usually load related, rpm related Connecting rod noises usually show up as part throttle clatter, if side clearances are excessive. Main bearings are usually a rumbling noise in the crankcases Camchain sprocket damage is a rattling (loose nut/retainer bolt or from loose rivets, broken return spring). You can verify this condition with a dynamic timing light (or by watching a valve open and close while rocking the engine back and forth at the crankshaft-there is a delay between the crankshaft motion and the valve motion). Transmission bearings usually growl or rumble under load Bad low gear bushing can cause incomplete k/s selection and increasing noise in 1st gear under load. Worn gears usually make noise in just that selected gear. Bad k/s shaft surface/rollers cause motion at the k/s pedal, under load. Bad camshaft bearings are constant noises, rpm related in the top end. Clutch basket rattles are evident at idle, under the left cover. Worn rockers will show very little remaining threads left on the adjuster screws and make a clattering sound. Some rockers will be noisy because of a combination of excessive sideplay and incorrect machining that causes the rocker to move laterally, as it opens the valve. Worn primary chains will rub against the upper part of the clutch cover on “coast down.” Worn/damaged rollers in the k/s shaft will generate vibration and motion in the k/s lever. 56 Honda 250-305 Super Hawk Restoration & Maintenance Guide There are a lot of moving parts inside, so isolation of each possible cause requires a good ear, ability to focus on particular area of the noise source and then operating the engine under idling, acceleration, load conditions and in/out of gear. Engine oil leaks. Damaged gaskets, seals, O-rings. Excessive crankcase pressure due to blocked breather tube/passages or worn pistons/rings. Oil breather plate reversed in cylinder head. Damaged crankcase mating surfaces or not properly sealed at assembly. Excessive wear on sealing surfaces of starter sprocket, crankshaft journal, clutch pushrod, output shaft, kickstart shaft, shift shaft. Blown cylinder head or cylinder base gasket. Loose side cover screws on cylinder head or clutch cover. Damaged gasket on camchain tensioner. See more trouble shooting tips from the Honda Service Manual at the end of the book. SPECIFICATIONS: HONDA MODEL 250/300 CB72/77 ENGINE-Total cylinder capacity: CB72: 247cc Bore x Stroke: 54mm x 54mm 2.1259” x 2.1259” Comp. ratio: CB77: 305cc 60mm x 54mm 2.3622” x 2.1259” 10:1 (1961 250) or 9.5:1(1961-63) or 8.5:1(1964-on) approx.160-175psi Max. Horsepower:(early): 25.2 or 24 hp 28.5 hp @ 9,000 rpm 22 hp 26.5 hp @ 9,000 rpm Max. Horsepower:(late): Max. Torque: 2.06 kg-m @ 7,500 rpm 2.5 kg-m @ 7,500rpm Ignition: Battery and dual coil (dual points-Type 1/single points Type 2) Spark plug: NGK D8/9H or C7/C10H ('61 w/10mm plugs) @ .6mm (.024") gap Condenser Capacity: .21-.27 MFD. Ignition point gap: .3-.4mm (.012-014”) Carburetor: 250cc PW22 (22mm) 305cc PW26 (26mm) #35 idle #100 main jets #42 idle #135 main jets 26.5mm float level 22.5mm float level Lubrication: Wet sump w/ gear-type oil pump; chain-driven, centrifugal oil filter Clutch: Wet-type, Multi-plate (6 plate-early or 5 plate-late) Transmission: 4-speed constant-mesh, foot shift Ratios: 2.788 (1), 1.661 (2), 1.171 (3), 1.00 (4) Starting: Electric & kick starting Crankcase capacity: 1.2L (.46 US gal.) or “1.6” quarts of 10W-30/40 motorcycle oil FRAME Tire size: 2.75x18 4 ply (front) 3.00x18 4 ply (rear) Tire pressure: 1.8-2.0kg/cm (25.6-28.4 psi.) front_2.0-2.3kg/cm (28.4-32.7 psi) rear Caster: 60-62 degrees 57 Honda 250-305 Super Hawk Restoration & Maintenance Guide Fuel tank capacity: 14L. (3.64 US gallons) Overall length: 2,025mm (79.7") Overall width: 615mm (24.2") Overall height: 950mm (37.4") Ground clearance: 140mm (5.5") Dry weight: 153 kg (72) 336 lbs. 159 kg (77) 350 lbs. PERFORMANCE Maximum speed: (72) 155 km/hr (96 mph) (77) 160 km/hr (99 mph) Fuel consumption: 445 km/lit @ 40 km/hr (109 mpg @ 24mph) Stopping distance: 16m (52.5 ft.) from 50 km/hr (31 mph) SERVICE SPECIFICATIONS: Cam lift: IN 5.69mm(.222) EX 4.56mm(.178") Valve clearance: 1.0mm (.0039") COLD (intake and exhaust) Valve timing: STD cam: (IN) 5 BTDC/30 ABDC (EX) 35 BBDC/10 ATDC Valve timing: YB RACE cam: (IN) 20 BTDC/40 ABDC (EX) 40BBDC/20ATDC Valve timing check clearance: 1.1mm (.0429”) lift Valve spring pressure: (STD) 53.5-54.8kg (RACE) 55-58.5kg Valve spring length: 37.54mm(1.464") inner, 43.36mm( 1.691") outer Camchain length: 94L 723-723.8mm (28.46-28.49") limit 728mm(28.66") Wrist pin clearance: .016-.049mm(.0006-.0019”) limit .08(.0031”) Brake shoe thickness: 2.5-5mm (.098-.196") Spark Advance: 40-43 degrees maximum, plus 5 initial. Limit = 45-48 degrees total Ring gap: top/second .15-.35mm(.006-.013") limit .6mm(.023") oil.1-.3mm (.004-.012") limit: .8mm(.031") Ring clearance: top .045-.07mm(.00175"-.0028) limit: 15mm(.005") Second/oil .01-.04mm(.0004-.0015") limit .1mm(.004") Piston diameter: (250cc) 53.98-54mm (2.125-6") limit 53.9mm(2.1021") (305cc) 59.98-60mm (2.361-2") limit 59.9mm(2.3361") Cylinder diameter: (250cc) 54.00-.01mm(2.106-.1064") limit 54.10mm(2.110") (305cc) 60.00-.01mm(2.362-.3625") limit 60.10mm(2.366") Piston clearance: .01mm-.03 (.0004"-.0012) limit .1mm(.0039") Valve seat width: 1.0mm (.039") limit 2.0mm(.078") Clutch disc: 2.9 - 3.0mm(.113"-.117") limit 2.5mm(.0975") (6-plate disc clutch) 2.5mm (5-plate) Cylinder head nut torque: 2.1m-kg (15.19 ft-lb.) 58 Honda 250-305 Super Hawk Restoration & Maintenance Guide Fork oil capacity: 200/225cc (aluminum/steel fork-dry assembly) Rear drive chain length/size (CB77 15t & 30t sprockets): 94 links #530 pitch drive chain CB72-77 TUNE-UP PROCEDURE 1. Remove seat. Remove 10mm nut on rear fuel tank mount. Lift up tank (do not remove unless you want to deal with the crossover hose or you have blocked off the crossover fittings) and prop up high enough to be able to remove the carburetor slides. Be careful not to damage the paint at the front of the fuel tank, where it can contact the fork bridge. Remove carburetor tops and remove slides. NOTE that there are “left” and “right” sides for the tops and the slides. The carb tops must be installed so that the throttle cables are positioned inboards toward the frame. The carb slides must be installed so the cutaway is facing the REAR (air cleaner side) of the engine. 2. Remove jet needle from slide and install clip on second notch from the bottom (#4 of 5 notches on CB77. On CB72s leave needle clips in the center position). Make certain that the clip and needle are securely fastened in the slide before installation. 3. Remove float bowls. Clean bowls, all jets and set float levels carefully to 26.5mm for 22mm carburetors and 22.5mm for 26mm carburetors. (See float gauge photos) Idle jet sizes are #42 for stock CB77s. CB72s will probably have #35-38 idle jets. Main jet sizes are #135 for CB77 and #100 for CB72s 4. With main jet holders removed, observe the tips of the needles for synchronized movement, when throttle is opened. Adjust cables as necessary. Reassemble carburetors carefully and completely. Be sure that both slides close simultaneously and do not stick in their bores. Reinstall fuel tank hardware and seat. 5. Change spark plugs to C9H (10mm) or D8HA (12mm). Use colder plugs for high-speed operation. 6. Remove the alternator cover and observe the "T" "F" "LT" and "LF" marks. "T" marks are for TDC (top dead center) and the "F" marks are the "firing" marks (at idle). "T" and "F" marks are for right cylinder and "LT" and "LF" marks are for the left cylinder. 7. Use the 14mm bolt to rotate the engine to TDC (compression stroke). Remove valve cover caps and adjust valves to .004" (intake and exhaust) when engine is on compression stroke (both valves loose). Rotate crankshaft to "LT" marks (compression stroke) and adjust valves on that cylinder. When engine is on "T" mark (compression stroke), loosen the lock nut and lock bolt for the camchain tensioner. Press lightly on the end of the tensioner shaft and ensure that it is not "stuck". It should feel a little "spongy." Retighten the lock bolt and lock nut. 8. Remove ignition point cover. Clean ignition points thoroughly and set gap to .012" to .014". 59 Honda 250-305 Super Hawk Restoration & Maintenance Guide Lubricate point cam and put a few drops of oil in the felt wick. 9. Turn idle mixture screws in lightly to stop, then open them back out about 1 to 1 1/4 turns. 10. Start engine and warm up for a few minutes. Set idle speed to 1,100-1,200 R.P.M. adjusting both carburetors equally. Install timing light on right side cylinder and adjust mounting plate until the "F" mark lines up with the pointer. This sets the ignition timing for the right cylinder. 11. * Install timing light on the left cylinder and adjust the point gap until the "LF" mark lines up with the pointer. This sets the left cylinder timing. 12. CHECK THE TIMING OF BOTH SIDES, TO ENSURE THAT NEITHER EXCEEDS THE "FULL ADVANCE" MARKS (45-48°° MAXIMUM). THESE SMALL DOUBLE MARKS ( ll ) ARE LOCATED 40°° TO THE RIGHT OF THE "F" AND "LF" MARKS. THIS ALIGNMENT WILL OCCUR ABOVE 3,300 rpm. IF EITHER SIDE EXCEEDS THE ADVANCE MARKS, RE-ADJUST (RETARD) THE IGNITION TIMING TOWARDS THE "T" AND "LT" MARKS, UNTIL "ADVANCE" MARKS ARE ALIGNED WITH THE POINTER. THIS MAY RESULT IN INITIAL TIMING BEING SET AT CLOSER TO "TDC" ("T" & "LT" marks or somewhere in-between) AT IDLE, INSTEAD OF THE "F" & "LF" MARKS. FAILURE TO HEED THIS WARNING CAN RESULT IN PISTON SEIZURE AT HIGH ENGINE SPEEDS/LOADS. 91-PLUS OCTANE IS RECOMMENDED. THESE ENGINES ARE VERY OCTANE SENSITIVE, BUT NOT LEAD SENSITIVE! AVOID FUELS CONTAINING ALCOHOL. *For best results, use a separate battery to power the timing light. 13. Reinstall the generator and point covers. Readjust idle speed to 1,100-1,200 R.P.M., if necessary. 14. Check throttle response. If, after the engine is warmed up, there is a hesitation or "spit back", when the throttle is opened, turn mixture screws (air screws) in one eighth of a turn at a time, until response improves. 15. Persistent low-speed "rich" fuel mixtures can often be traced to plugged air bleed passages for idle or main jet circuits, high float levels (mis-adjusted or sinking floats); leaking float valves, or worn needle jets/ worn jet needles (or both). Idle adjustment & part-throttle response – The Bigger Picture Getting the engine to idle at the 1,200 (or so) rpm specification requires very specific adjustments in order to achieve this goal. Starting with the basics: compression and valve timing, the foundation of good carburetion performance and operation must come from a sound engine assembly. The compression ratings of 175 psi, should not deviate more than 10-15% from side to side. This figure is measured with a cold engine and the throttle held wide open, while cranking 60 Honda 250-305 Super Hawk Restoration & Maintenance Guide the engine over with the electric or kick-starter. If there are significant variations from those specifications, then the valves can be checked for proper clearance to see if that has an effect on the readings. Honda used hardened valves and seats, so there is not a problem about running them on unleaded fuels, unlike many of the other manufacturer’s machines of the era. If the valve clearances are correct and compression figures are normalized, then you can move on to other items on the list. If the compression does not improve after a valve adjustment, then there is a mechanical reason for the disparity (i.e. burned/worn valves, worn/broken pistons rings or worn/seized cylinder walls. If these items are not corrected, then you will never achieve satisfactory engine performance, even if everything else is rebuilt and set to factory specifications. Once you have solved the compression issues, you can work on the ignition timing adjustments. As noted elsewhere, the ignition points cam runs inside the right side camshaft and they have a tendency to wear causing excessive side clearance between the two parts. This side clearance affects the point gap directly, which then creates ignition-timing errors. Other than the E-ignition, which is not affected by the point cam sideplay, you must correct the sloppy fit between the camshaft and the points cam shaft. If new parts cannot be found, you can bore the camshaft and rebush it carefully. The pointcam shaft is hardened and not easily machined. It could be ground down slightly, hard chromed again, followed by grinding back down to correct size. This would be rather costly and time-consuming, but within the realm of possibility if no new parts could be located. Once the ignition timing is set properly (engine running, using an automotive timing light) then you can finally turn your attention to the carburetors for fine-tuning. The carburetors have three main metering circuits which can be adjusted: idle jet (pilot jet) for idle mixture and part throttle transition; jet needle (inside the carburetor slide) for one eighth to three quarter throttle positions) and main jet for three quarters to full open throttle operation. If you encounter problems when using the stock settings, then adjustments for altitude, temperature and changes to the intake/exhaust system can be made through changes to the above circuits. If you experience hesitation in performance, use the choke to help identify whether the problem worsens or improves, by application of varying degrees of the choke lever. The choke shuts down the amount of air going into the engine, thus causing a temporary “enriching” condition. If the engine responds favorably to a little application of choke, then you need to richen up the needle (raising its position in the slide, by lowering the clip position) or changing to a larger main jet. Because of the overlap of the metering systems, you will have to make one small change, verify its effect and then either undo the change or make 61 Honda 250-305 Super Hawk Restoration & Maintenance Guide further changes, as required. Learning to “read” the spark plugs for signs of lean or over-rich conditions is very beneficial. Take careful notes about each change and you will learn a lot about the cause and effects of making adjustments of any kind to the overall performance of the machine. NOTE: Any attempts to adjust the carburetors BEFORE you verify and properly set the ignition timing will be a futile waste of time! Trying to compensate for uneven compression or incorrect valve (camshaft) timing is a similar self-defeating effort. Don’t forget to start with a fully-charged battery and a fresh set of spark plugs (NGK D-8HA in most cases). ================================================================ AMERICAN HONDA MOTOR CO., INC. SERVICE BULLETIN GM #101 CUB-BENLY-DREAM Rev. 1/11/63 GENERAL SERVICE BULLETIN SUBJECT: Correct Fuel/Air Mixture and Spark Plugs The carburetors on all Honda machines are jetted to develop maximum horsepower. This mixture is somewhat leaner and hotter than that used on other machines. It is most important, therefore, to use the correct heat range of spark plug as follows: Break-in & Moderate & Town Driving Freeway 10mm 12mm CB-72 & CB-77, C7HW 10mm 12mm D8H C10HA D9H-D10H Extreme 10mm 12mm C12H D12H ALWAYS USE HIGH QUALITY PREMIUM GASOLINE! All Honda engines are high compression and require 100 Octane gasolines. Recent tests performed by independent testing agencies show that the differences in MAJOR BRANDS of premium gasoline are slight. All major brand premiums performed well. DO NOT USE OFF-BRAND cut-rate fuels, as their performance is questionable. Remember: If plugs are burning, the wrong heat range is being used, the mixture is too lean, and/or a cheap gasoline is being used. AMERICAN HONDA MOTOR CO., INC. Service Director ******************************************************************************* Daily Maintenance-Pre-Ride Checks Check Oil level. Level should be between the two marks on dipstick-NOT screwed in. Check Head, tail and stop light operation Check clutch, front & rear brake cable free play set to (3/4”-1 ¼ “) Check fuel level/petcock position (ON-OFF-RESERVE) Are tire pressures correct? Front 26-29psi. Rear 28-33 psi Check horn operation 62 Honda 250-305 Super Hawk Restoration & Maintenance Guide Is drive chain lubricated and adjusted to ¾” minimum slack with chain at the tightest point? Periodic Maintenance *Clean & adjust points and ignition timing every 1500 miles (.012-014” gap. Check timing with automotive timing light, engine running. Timing not to exceed full advance marks at 45 degrees). *Adjust valve clearance (.004”) every 1500 miles *Adjust and oil drive chain every 1500 miles *Adjust front brake every 1500 miles *Adjust throttle cable play and synchronization every 3000 miles *Adjust rear brake every 1500 miles *Adjust cam chain every 1500 miles (at TDC, on right side compression stroke) *Adjust carburetors every 1500 miles *De-carbonize muffler every 3000 miles *Clean air filter every 3000 miles *Clean oil filter every 3000 miles *Clean fuel strainer every 3000 miles *Clean spark plugs every 3000 miles (adjust gap to .024”) *Change engine oil every 1000 miles (300 miles in severe conditions) 1.5 US Quarts of 10W-30 or 10W-40 motorcycle oil. *Check battery level every 600 miles or once a month *Grease chassis every 3000 miles *Check bolts/nuts for tightness every 3000 miles. BEFORE YOU BEGIN THE RESTORATION…. Whether you are starting with a low-miles beauty or a rust-bucket parts bike, the restoration process begins with disassembly of the machine, hopefully in an orderly fashion. Before you grab the wrenches, sockets, screwdrivers and impact driver tools, take a moment to check the components as they are, noting obvious items to be repaired before the refinishing process begins. There are many ways to organize the process of stripping a bike, including a photographic record, video, notebooks and the “plastic baggie” system. If you are not familiar with the machine, obtain parts manuals and any service information pertinent to this bike and review it all to get an idea of your plan of attack. Some people have the ability to throw all the loose parts in a box and sort them out once they are ready for reassembly. Others will buy a couple of sizes of ZIP-LOCK bags to sort the parts by type, so they are reminded by how they came apart when it comes time to reassemble it all again. There are over 1045 different part numbers listed, just to assemble one 63 Honda 250-305 Super Hawk Restoration & Maintenance Guide CB72-77 machine. Some of those part numbers are represented by quantities of 1 to 36, used in the building of one machine. That is a lot to keep track of in your head. Take time to organize the parts as you disassemble, so your reassembly process is smooth and easy. You’ll be glad you did! PARTS/PART NUMBERS Honda’s original part number system used the model number as the beginning reference, usually followed by and additional 4-5 numbers which designated the type of part. In 1965, a new system was instituted called the NPS (new part number system), which consists of 5 digits, which identify the type of part, followed by a 3-digit product code (model type) and then 3 more digits (some exceptions) to identify the series (-000, -010, 020, etc). Thus, a NPS part number 50100268-050Z equates to a frame for a CB72, with 5th generation modifications, in primer (Z code). In this case, the original number was CB724101E-RT. With few exceptions, the majority of the parts found in a CB72-77 will be sourced from the following product codes. Here is a list of the models associated with those codes. 250 254 258 262 266 270 275 281 C70 251 C75 252 CA70 253 CS71 255 CA71 256 CAS71 257 CB71 259 C72 260 C(A)76 261 CA72 263 CII72 264 CS(II)72 265 C(S)77 267 CA(S)77 268 CB72 269 CM72 271 CIII72 272 CIIIA72 273 CB77 276 CIIB77 279 C78 280 C(2)P77 282 C2P77 Some interesting variations of the CB72-77 series bikes are: C71 CE71 C(A)S76 CR71 CIIB(M)72 CL72 CA78 CM72: a single-carburetor, Type 2 engine-powered 250cc machine that had a single speedometer (no tachometer), solo seat with luggage rack (optional passenger seat pad attaches to rack) and full turn signals. I have never seen a real one, but did include a photo earlier in the book. CBM72: another Type 2 engine 250cc machine, with twin carbs, turn signals and western-type handlebars. CP77: Non-Police bike series, fitted with normal instrumentation, early-style taillight, nonfolding pegs, turn signals, Type 2 forks in 1965, western-style handlebars. CP77 Police Bikes: Factory-equipped with single speedometer, patrol lights, solo-seat with rear rack that holds a radio and/or ticket box, cable-driven siren and crash bars. There were two series of Police bikes, the latest equipped with 17” wheels/tires and oversized fenders. None of these bikes were ever sold/imported directly to the U.S., however a few did find their way into Canada. NON-OEM PARTS For the most part, I recommend using genuine Honda parts to repair or restore the Super Hawks. There are instances, however, where the OEM replacement parts were vastly inferior to the originals that came on the machine, when it was first produced. The worst of the offenders were 64 Honda 250-305 Super Hawk Restoration & Maintenance Guide the last of the replacement header pipes, which no longer had a nice continuous curve from the exhaust port to the muffler. The angle of the bends and the lack of precision in the bending process causes a noticeable mismatch in the muffler junction and often the header pipe come close to contacting the starter motor. Other replacement parts in the final years were similarly ill finished or executed, as if an off-site fabrication house was making them. There were, however, sources of aftermarket replacement parts for Super Hawks that came from other Japanese suppliers. Accurate copies of mufflers/diffusers, cables, fuel tank side covers, front fenders, points/condensers/rectifiers, carburetor repair kits, tail light assemblies, headlight bulbs and headlight rims and other items are still out there and waiting to be discovered. Be aware that the quality of the parts is less than OEM, but in a pinch you might have to use them anyway. Check for some reproduction CB72-77 items being made at Ohio Cycle (www.ohiocycle.com). DISASSEMBLY-WE BEGIN AT THE BEGINNING-Finally! First, if you are planning a complete teardown of the entire machine, be sure to drain the engine oil, fuel tank, carburetor bowls and forks, before you remove those components. Remove the battery and store (or dispose of) properly. Take a look at all of the fasteners on the bike and note which ones are corroded. Spray all of the fasteners with penetrating oils and use the extended Phillips bits to loosen the screw thread corrosion bonds, using a few sharp blows from a hammer. The bike weighs about 350 pounds, so it has a lot of mass just sitting still. Take advantage of this situation to loosen as many fasteners as possible, before removing the components for disassembly. Once the components are off the bike, it is more difficult to hold them without damage, in order to remove various fastened parts that you could have loosened earlier, when it was together. The fork seal holders on the early Type 1 steel forks should definitely be loosened before the forks are removed. Taking a little extra time to break the initial corrosion bonds, on as many available fasteners as possible, will save you a lot of extra disassembly time later. This is especially important as you begin to take the engine apart, where so many fasteners are threaded into aluminum. Don’t say I didn’t warn you! TAKING IT DOWN-ENGINE ASSEMBLY REMOVAL. *Remove the seat, using 14mm wrench on rear seat bolts *Remove the rear fuel tank mount nut/washers, using 10mm wrench. *Remove fuel petcock lines (carburetor and crossover) and remove fuel tank from the bike. To prevent fuel spillage, drain fuel tank prior to removal. The easiest way to do this is to remove one fuel line from the petcock and attach a 3 ft piece of ¼” fuel line to the fitting. Allow the fuel tank 65 Honda 250-305 Super Hawk Restoration & Maintenance Guide to drain out through this hose. Be sure that the container is big enough to hold the fuel load in the tank. *Remove left side shift linkage and foot peg assy, using 10 and 14mm tools. *Remove left side muffler mounting hardware and muffler/header pipe, using 10 and 14mm tools. *Remove tachometer cable from cylinder head using 17mm wrench. *Remove top rear engine mount bolt, using 14mm socket and wrenches. *Remove left side carburetor top and slide assembly. Remove left side air filter brackets and filter/tube, using 10mm tools. *Remove right side brake pedal/foot peg assy using 14mm socket. *Remove right side muffler mounting hardware and muffler/header pipe, using 10 and 14mm tools. *Remove right side dynamo cover (three 5mm JIS Phillips screws). *Remove right side kick-starter cover screws, starting with the inner drive sprocket cover, using a #3 Phillips screwdriver. Strike screw heads with a hammer, using Phillips head extension, before attempting removal with impact driver. Hold k/s arm steady when removing the kick-starter cover- IT IS SPRING-LOADED! *Remove clutch cable holder from case and unhook the cable from clutch thread. Remember to watch for the large steel ball nestled inside the clutch lifter thread and don’t lose it! *Remove drive chain at the master link, using a set of pliers. *Remove right side carburetor top and slide assy, as well as the air filter tube and brackets using a 10mm socket. *Disconnect all engine wiring at generator harness junctions, spark plug wires attachments. *Remove ignition points cover and points plate assembly with #2 Phillips screwdriver. *Support engine assembly with floor jack. LAST CHANCE TO LOOSEN ANY EXTERNAL ENGINE BOLTS/SCREWS! *Remove upper engine bolts with 14 and 17mm wrenches/sockets. *Remove remaining four engine bolts with two 17mm wrenches. After removal of bolts, lower engine assembly and remove, taking care not to contact the front fender. INSPECT ALL FASTENERS FOR DAMAGE. DISMANTLE CHASSIS *Remove rear brake cable, using 14mm wrench to loosen cable slack at pedal end, then remove cable at rear brake plate. DOES CABLE NEED REPLACEMENT? 66 Honda 250-305 Super Hawk Restoration & Maintenance Guide *Remove rear brake stay cotter pin and bolt, using pliers and 14mm wrench. REPLACE COTTER PIN WITH NEW ITEM. *Remove rear axle cotter pin and nut, using pliers and 1 1/16” (26mm) wrench. REPLACE COTTER PIN WITH NEW. INSPECT NUT FOR DAMAGE. *Remove axle shaft, using soft mallet to start movement, then remove rear wheel assembly. Inspect brake shoes, brake drum surface and wheel bearings for wear. *Remove rear chain case, using 10mm socket wrench. CHECK FOR CRACKS. *Remove L&R rear shock assemblies, using 17mm sockets and wrenches. DISASSEMBLE FOR RECHROME/PAINT ON COVERS *Remove L&R footplate brackets, using 17mm sockets. CHECK FOR CRACKS, DAMAGE OR BENDING, DUE TO CRASHES. *Remove rear fork pivot bolt self-locking nut, using 23mm and 19mm sockets. Withdraw pivot bolt and remove rear fork and footplate bracket assemblies. CHECK PIVOT BOLT, BUSHINGS, SEALS FOR DAMAGE. REINSTALL WITH LOTS OF LUBRICATION! *Remove rear fender/taillight assembly, using 10 and 14mm sockets, after disconnecting the wiring leads to taillight. CHECK FENDER FOR CRACKS AT MOUNTING HOLES. *Remove two Phillips screws from headlight rim. Disconnect headlight wiring from headlight unit. Disconnect speedometer and tachometer cables from the meter. *Remove two, meter-packing mount screws and remove meter after disconnecting wiring for instrument lights/high beam indicator and ground wire connection. Disconnect wiring connections inside headlight shell. Remove two 14mm headlight case mount bolts and remove headlight case. CHECK ALL CABLES AND BULBS FOR CONDITION. *Remove front brake cable, using 14mm wrench on front brake backing plate. *Remove front brake stay, by first un-staking the locking tab for the mount bolt, then removing the bolts. REPLACE LOCK TABS WITH NEW ITEMS. *Remove speedometer cable from hub drive unit, using pliers to loosen the nut. *Remove front axle cotter pin and nut, using pliers and 23mm wrench. REPLACE COTTER PIN WITH NEW ITEM. INSPECT NUT FOR DAMAGE. *On Type 1 forks, loosen front axle pinch bolts on left fork case and withdraw axle. On Type 2 forks, remove axle clamp nuts/washers. Withdraw wheel assembly from front fork. Inspect the brake linings and brake drum, as well as the wheel bearings. *Remove front fender fasteners, using 10 and 14mm wrenches. BE SURE TO INSTALL THE CORRECT INNER FENDER STAY BOLTS. IF THEY ARE TOO LONG, THEY WILL DAMAGE THE FORK CASE TUBING ON TYPE 1 FORKS. 67 Honda 250-305 Super Hawk Restoration & Maintenance Guide *Remove handlebar switch screws and remove throttle cable from right side switch housing. LUBE THROTTLE DRUM BEFORE REASSEMBLY. *Remove clutch and front brake cables from lever brackets. *Remove horn assembly and tachometer cable retainer bracket, using 10mm sockets. *Remove wire clip from bottom of steering damper rod. Unscrew damper rod and remove all of steering damper parts from bottom of steering stem. INSPECT ALL DAMPER PARTS FOR WEAR, CORROSION AND DAMAGE. *Remove four 14mm head bolts from handlebar clamps and remove all parts. *Loosen the fork seal holders on Type 1 forks PRIOR to removing the fork assemblies. *Remove fork bolts and stem nut, using 25mm and 35mm wrenches. *Remove top fork bridge and upper fork covers. *Remove steering stem thread with adjustable hook spanner, and lower fork assembly downwards. Place a piece of paper or cloth under front of frame to retain the falling steering head ball bearings. Remove stem and fork assemblies complete. *Remove fork assemblies, fork lock and covers from steering stem. INSPECT STEM BEARING RACES FOR DIMPLES, CRACKS, SCORING, ETC. REPLACE WITH NEW ITEMS OR CONSIDER REPLACING ALL STEM BEARINGS WITH TAPERED ROLLERS. *Remove toolbox, rectifier, ignition switch assembly, chassis wiring and harness ties. CHECK TOOLBOX EARS FOR CRACKS. INSPECT WIRING HARNESS FOR CRACKS, BROKEN WIRES OR DAMAGED INSULATION. *Clean and inspect frame for cracks, corrosion damage, bent or dented sections and general alignment. Drive out the steering races with a long drift or punch and clean steering head and bearing races carefully, inspecting them for any damage or wear. You are now finished with the disassembly process. See my Honda 250-305 Engine Repair Guides, containing step-by-step instructions for disassembly, inspection, overhaul and reassembly of the engine & transmission unit. * Reassemble chassis in reverse order, taking note of the following: * If chassis parts were painted, be sure to provide a good ground path (bare metal) at the tail light bracket, rear fender, rectifier, headlight case, condenser, etc. to insure proper operation of electrical units. * If the chassis was powdercoated, clean out all threaded holes with a suitable tap and die set. Assemble chassis on a soft pad or thick blanket to minimize any scratches/dents while 68 Honda 250-305 Super Hawk Restoration & Maintenance Guide reassembling the parts. As above, be sure that there are areas of bare metal for electrical grounding of required components. * Assemble all threaded or moving parts with appropriate oils or greases. CHASSIS PARTS FRONT FORK ANALYSIS The front forks of the CB72-77 were the most changed items of the whole chassis. There are two different styles of forks, Type 1 (steel cases) and Type 2 (alloy cases); at least 4 different types of fork tubes; 3 types of lower fork cases, 2 different fork seal sizes, two different fork spring sets, different fork bushings, damper rings, snap rings, O-rings and other assorted hardware. There are also 3 sets of lower fork covers and two different trim rings. There are different capacities of fork oil between the Type 1 and Type 2 fork styles. TYPE 1 FORKS The 1961-62 “Type 1” (steel fork cases) forks were 33mm at the seals, then bulged out to about 37mm at the steering stem clamps, then thinned down a little only to widen out at the upper fork bridge again. The lower fork cases were steel and the damper rod/ spring stand was located about ½ way down inside the fork case. A few rivets, rather than a snap ring retain the lower fork bushing. The fork bushing must be removed, in order to change the fork seals. Heavy, but sturdy, these forks were replaced in early 1963 (#1005 CB72 and #1502 CB77) with the next series, which featured lower bushings retained with snap rings and fork cases with the damper rod/spring stand located slightly above the top. The fork tubes were 33mm at the seal surfaces and then tapered down slightly as they approached the fork bridge. The fork seals are 33x46x10mm and were used for both Type 1 forks. The fork seal holders were the same for both of these fork styles, as well, The four fork covers changed, when the fork assemblies were revised, as did the chromed fork rib and cover cushions. Type 1 forks held the front axle in a leading position, with a pinch bolt on the left side and the axle nut locking in on the right. The chromed fork trim ring, (also called a rib, front fork 15608-268-020), as well as the front fork cover cushion 15622-268-020 were both changed in early 1963 (CB77-31503CB72-311005). When the fork seal holders are unscrewed from the fork cases, the seals can be replaced after removal of the snap rings above the seal. Driving the seals out from the bottom requires some care, so as not to damage the seal holder. Lubricate the seal lips with some light oil or grease prior to reassembly. Replacement of the seals and lower fork parts do not require removal of the complete fork leg assemblies. 69 Honda 250-305 Super Hawk Restoration & Maintenance Guide NOTE: “Type 1” fork cases are easily damaged, when the wrong length bolts are installed in the center fender stay holes. The steel cases are deformed when the bolts bottom out in the blind holes. This condition will damage the lower fork bushings and damper ring and cause difficulty in disassembling the forks. As the fork tubes are withdrawn, the deformed areas will bind on the bushings and cause them to stick at the point where they are damaged. Unless an extra long bolt has been inserted and over tightened, the fork tubes can usually be dismantled with some force applied. The damaged parts must be replaced prior to reassembly. FORK OIL CAPACITY: 215-225cc (7.3-7.6 oz) “dry fork” or 200-210cc (6.8-7.1 oz) on refill TYPE 2 FORKS These forks seemed to have arrived in the U.S in about mid-1966. (CB72F-1005228, CB77F1030130). Other than the alloy fork cases and double 2-stud axle clamps, they don’t look too much different, at first glance. When you take the 3rd generation lower fork covers off (larger diameter to house the external fork springs and spring seat) and you will find external fork springs, straight 33mm fork tubes, 33x43x9 fork seals, chromed sleeves mounted on the machined edges of the fork cases, rather than the screw-on fork seal holders of the past, plus other miscellaneous hardware changes. The alloy fork cases brought the axle back under the center of the axle assemblies; so new steering stems and fork bridges were made to make up for the lack of axle offset. The alloy cases use cast-in bosses for the fender stays, requiring a repositioning of the central fender mounting stay in the fender. The axle clamps, fork piston and piston rings were all pirated from the CB450K0 machines, but other internals were CB72-77 specific for the alloy forks. Fork seal 70 Honda 250-305 Super Hawk Restoration & Maintenance Guide removal is performed by draining the fork case and removing the fork assembly from the triple clamps. Remove the slip-on chrome sleeve using a soft mallet to tap around the edges of the sleeve at the fork case. The sleeve is just tapped onto the edge of the fork case, but is often found to be firmly attached due to corrosion caused by moisture draining down inside the cases. Liberal doses of penetrating oils and sometimes some low heat are required to work the sleeves free from the fork cases. Remove the snap ring above the seal and slide out the fork tube from the lower case. The lip of the upper fork bushing will contact the bottom of the fork seal and act as a seal driver to remove the seal from the case. Reinstall in reverse order, but a proper-sized seal driver tool will be needed to install the seal in the fork case. Installation of the Type 2 fork assembly in the steering stem and upper fork crown is more difficult than the Type 1 forks, due to the external fork springs. To ease installation, it is recommended that a 12” piece of metric-threaded rod be inserted into the top of the fork tubes and the forks be drawn upwards, through the fork covers and steering stem. An old fork nut can be welded onto a piece of rod stock to act as a tool for this purpose, after the head of the nut is removed. SEE SERVICE BULLETIN ON PROPER WHEEL & AXLE INSTALLATION FORK OIL CAPACITY: 200cc (6.8 oz) “dry fork,” 185cc (6.3 oz) on refill FRONT FENDER The first CB72 fenders were alloy construction, as were the YB racing fenders. After that, they were all painted steel, except for the last chrome-plated versions. As mentioned earlier, the center fender stay was changed to match the Type 2 fork assembly in 1966 (CB72F-1005228, CB77F1030130). In a pinch, you can drill out the rivets and install the early mount in a later fender assembly. Chrome fenders (front and rear) were installed on the last 438 bikes made, along with the oval-shaped tail light assemblies for the rears. Fenders can be repainted with Krylon Dull Aluminum spray paint with a clear coat applied over that or try Duplicolor-brand paint, who makes a steel wheel finish that has a minimum of silver granules in it. FORK CROWNS The 1961-62 fork crowns (fork bridge) incorporated a loop, which held the speedo-tachometer unit. When the speedometers received a “2-screw packing” for the meter unit, allowing the meter to be mounted on the top of the headlight case, both items were modified accordingly. The first meter units were mounted on a thin, rubber, gasket packing (no screws), mounted on the top of the fork crown, and were held in place with a spring that hooked to the bottom of the headlight case and bottom of the meter unit. Fork crowns were changed in early-1962, when the meter case loop was discontinued and again when the Type 2 forks were introduced at CB72F-1005228, 71 Honda 250-305 Super Hawk Restoration & Maintenance Guide CB77F-1030130 (different fork offset). The YB racing fork crown, which has no castings to mount handlebars, fits all the Type 1 fork styles only. STEERING DAMPER The steering damper parts were redesigned when the forks were changed from the large tubes to the smaller ones. The steering damper friction parts were redesigned at CB72F-311006, CB77F311503 with the new damper disc bolt. The Damper Plate, Plate A, Damper Spring, Spring Lock Nut, Friction Disc were all modified at this changeover. There is a special “short” steering damper knob, which is used in conjunction with the YB fork bridge, if the friction damper is retained. The YB hydraulic steering damper can be used, if the matching special steering damper mount bolts are installed. The upper one is used in place of the standard motor mount bolt, while the small double-ended damper mount bolt screws into the bottom of the steering stem. These parts were factory-installed on CP77 chassis, both Police and non-Police versions. The steering lock cover was changed at CB77F-1052627, but the ‘61 models had no cover. Originally, they were all-chrome steel, now replaced by plastic parts. Take a moment to clean and lubricate the threads on the end of the steering damper knob, especially before you attempt to remove it from the bike. The threads are exposed at the base of the steering stem and often become corroded. If you try to unwind the knob from the knob shaft, it can snap off the knob or at the threads below. STEERING STEM There were 4 steering stems and three different fork bridges (not counting the YB racing fork bridge, which doesn’t fit the Type 2 fork setup). The first steering stems for 1961-62 models didn’t have fork locks and were machined for the big, multi-tapered fork tubes. The 1963-65 stems had smaller clamps for the 33mm tubes and included fork lock receptacles. The Type 2 fork change required a different offset and had a matching fork bridge. Four different steering stems were used, which changed at CB72F-311006, CB77F-311503 (smaller fork tubes, steering damper parts change), again at CB72F-402338, CB77F-403441 (steering damper spring lock nut) and finally at CB72F-1005228, CB77F-1030130, with the “Type 2” fork. The fork geometry was altered with the “Type 2” fork and the earlier fork crowns (including the “810” racing upper fork bridge) will not interchange. HANDLEBARS Only two types of street handlebars were installed on U.S.-market CB72/77s. Flat bars were OEM items from the first bike until CB77-1028216 (CB72-1004689), when the higher-rise, “Western bars” were introduced, to suit the needs of the American market. The U.S. marketplace 72 Honda 250-305 Super Hawk Restoration & Maintenance Guide was 10 years away from embracing the “café racer” look, so Honda went with handlebars that would better accommodate a more “sit-up” riding position. Finding an original CB72-77 that still has the flat bars is somewhat unusual, as they seemed to be a component that was readily changed. CL-type handlebars were often employed as alternatives and extended cables were readily available in those days. The Elvis Presley movie called “Roustabout” featured Elvis riding a fully equipped, red, CB77, complete with Scrambler-type handlebars, luggage racks and crash bars. The bike gets run off the road and crashes through a fence in one scene, but is repaired and delivered back to him towards the end of the film. The actual fate of that particular motorcycle is unknown at this time. There were two sets of racing clip-on handlebars, from the YB race kit list, available for CB72-77s. The 268–810 set is for the large diameter forks, but requires a special 1mm thick insert, in order to fit properly. The 268–811 set fits the later Type 1 33mm and all Type 2 fork tubes. Shorter 268–810 throttle, clutch and front brake cables were available to install the clip-ons properly. Aftermarket “drag bars” are close copies to the original CB bar sets, but are generally a couple of inches too wide, requiring some shortening and drilling of wiring access holes, if you are to maintain the “original” look. For most restorers and enthusiasts, the look of a restored Super Hawk isn’t quite right, unless it is fitted with the correct “flat” bars and cables. Check with RETROBIKES in Port Angeles, WA (www.olypen.com/retro) for reproduction “flat bars” and cables. Most people agree that a “flat bar” Super Hawk really captures the essence of the design. Don’t you agree? 73 Honda 250-305 Super Hawk Restoration & Maintenance Guide CABLES Other than the previously mentioned YB cable sets, the OEM handlebars required two sets of cables for either flat or riser bars. There is an extra clutch cable part number due to the fact that Honda relocated the clutch cable joint further forward by about 1”, in early 1965. The change in angularity of the cable joint to the clutch lifter thread required a modified kickstarter cover, reangled cable joint and new clutch lifter spring. If your '65 bike has a serial number below CB77-1028216, CB72-1004688, it should have flat bars, with 17910-268-000 or a carefully routed -810 (YB racing) throttle cable, 22870268-010 clutch cable and 45450-268-010 front brake cables. TIP: USE ACETONE or other cleaner to brighten up gray cables. Cable measurements: "810" throttle cables (for factory clip-ons) are 24" housings with 30 1/2" cable, while "000" versions are 26 1/4" and 32 3/4" (cable 2 5/8" longer than housing on top and 2 5/8" on carburetor ends). The "010" flat-bar front brake cables are 38 1/2" housings and 44 3/4" overall length (cable 5 7/8" longer than housing). Clutch cables are: "000"=32 3/4" & 38"1/8", "810"= 29 1/8" & 34 1/2", while the "821" (high bars) are 33 7/8" & 39 1/2 (inner cable 3 7/8" longer than housing). The rear brake cables came in two different lengths, so you have to be sure to obtain the correct one, based on your bike’s serial number. Those changed at CB77-1029375, CB721004893 and the cables are about 3/4” longer, which matched the lengthened brake arm to 74 Honda 250-305 Super Hawk Restoration & Maintenance Guide increase the rear brake’s power. Tachometer cables were black in early 1961, then gray for the rest of production. The last of Honda’s replacement cables were again manufactured in black sleeve material. FUEL TANK/CAP/EMBLEMS The fuel tanks on CBs pretty much stayed the same, unlike the Dreams and Scramblers. CBs always had a seam down the middle and the filler hole to the right side. Apparently there were some wider tanks made in the early years, but I haven’t verified the dimensions. The early fuel tanks used a formed section around the petcock mounting threads in order to raise the petcock up from the base of the fuel tank to avoid picking up water/debris. Unfortunately, this process weakened the metal and cause cracks and leaks at that location. Late replacement fuel tanks have no crossover tubes on the bottom and the matching petcock is blanked off there, as well. 17500268-040XJ is the part number for the Candy Red fuel tank that was installed at CB77-1056084, CB72-1010083. All others are Scarlet Red, Blue, White and Black or Z-code (sandable primer) parts. The fuel caps have been superseded from the original stainless steel versions to a chromed steel type (402 code) that seems to be less prone to leaking. The fragile, plastic tank badges have been replaced with stamped metal –230-000 replacements. Fortunately, a couple of enterprising people have tooled up for reproduction “250” and “300” tank badges in the US and the UK. The earlier “Dream 250” and “Dream 300” versions (before CB77-312293, CB72-311905), featured on 1961-63 bikes are not being remade, however. The 3x8mm tank badge screws are only available in ISO threads, not the original JIS pitch, so you have to re-tap the holes in the tank panels to use the ISO screws now and perhaps use some thread sealer to insure retention of the screws. 75 Honda 250-305 Super Hawk Restoration & Maintenance Guide PETCOCKS The fuel petcock lever, packing, spring, and lever setting plate had some minor changes in 1962, but that was about it. Honda has continued to supply replacement rubber parts for the rubber packings, but the “hard” parts are getting scarce. As noted above, the late replacement petcocks (CB77-1052488-on) do not have fittings for the crossover tubes that connected both sides of the fuel tank together. Unless you are cruising the interstates, there is sufficient sloshing going on inside to equalize the fuel distribution, during normal riding, without the crossover tubes in place. When rebuilding the petcock, be sure to flatten the reverse side of the fuel lever arm with a file or emery paper. That surface becomes etched from old fuel deposits and a little warped, to boot, after 30 years and sometimes continue to cause a leak, even though you have replaced all of the rubber seals. FRAME The major frame change was from 1961 to 1962, when the tail end of the frame rails was changed to a couple of welded-on, slotted fittings, rather than the previous squashed and slotted tube sections. When the frame fittings were added, the spacing of the seat mountings increased by about 1”. Thus, CB seats fall into two original classifications: Short and Long, to match the frame dimensions. The center-to-center distance for the mounts is either 13” or 14.” For the most part, the frames were not greatly changed, as far as geometry is concerned. The frame originally had a vibration-prone rectifier bracket, which was later thickened and reinforced for strength. The frames can be damaged underneath, where the muffler brackets are welded to the lower section. Any crash landings, on the mufflers, pushes the muffler brackets out of position causing the exhaust system to bind and fit poorly when remounted or when a new system is mounted up. Check the two muffler mounts for position before installing a new exhaust system or refinishing the frame for restoration. Early ‘61 bikes had a smaller rear upper engine mount bolt, so the hole in the frame was reduced in size, as well. When the bolt size was upgraded, the frame number changed to reflect this change. Some of the 1967 frames had a loop at the back end of the frame, welded in place, for the addition of turn signals. LABEL Some bikes had a frame sticker (HONDA- Made in Japan) on the right side of the steering head. SIDE GRIP The handy “side grip” lifting handle was an option after 1964 and bolts to any CB chassis. They were generally painted to match the frame color. TIP: The “packing” is made from gasket paper. 76 Honda 250-305 Super Hawk Restoration & Maintenance Guide SIDE STAND An optional, OEM side stand bracket could be attached to the frame, requiring some changes to the motor mount and centerstand pivot bolt hardware. See section on “Steps and Stands,” further on, for details on the side stand installation. STEERING HEAD BEARINGS The steering head bearing races are all the same for all editions and fork styles. Inspect the races for “notching” or cracks, especially after a crash. Aftermarket tapered bearing sets can be fitted, in place of the ball bearing types, however. SEATS As mentioned above in the Frame section, there are two different mounting lengths for the CB7277 seats. The 1961s (and a very few early 1962s) had shorter mounting dimensions than all of the later ones. The early 1961 seat mounts actually bolted onto the seat pan, but this was changed to a hefty, welded-mount system that is difficult to remove and relocate. As new seats become ever more difficult to find, some of the early seats have been used on later bikes, by drilling out the spot welds on the rear mount and moving the mount about 1” further back. If you find a new early-style seat you can also just remove the cover, strap and chrome trim pieces and remount them on a later seat pan. The other change to the seats, starting in 1966 (CB72-1005603, CB77-1034092) was a seat that rises up the back of the fuel tank, giving a little protection to the tender parts of the rider’s lower torso. In 1967, a silver-colored seat piping was used, instead of black. OEM seats were available in either black or blue cover material. Other variations on stock seats were the European “violin case” seats, which were somewhat “figure 8”-shaped, when viewed from above (very comfy, though) and the rare YB racing seats, which had a little kick-up to the back end. YB seats were also offered in both mounting lengths. HONDA was always stenciled on the back of the street bike seats, generally in GOLD/SILVER letters. SEAT STRAPS & MOUNTING BOLTS The seat strap, whose ends had been mounted on external fittings from 1961 to early 1965, was changed and the strap ends then anchored on two studs beneath the seat pan. The original seat bolts were of a long-head design, machined in the center for lightness and appearance. The tips of the threaded sections were cross-drilled for use of a safety clip or safety wire, to minimize the loss of the bolts during riding, should they loosen. Later replacement editions just had long straight sides, without benefit of the extra machining steps. Example: )_( early vs. [_] late. 77 Honda 250-305 Super Hawk Restoration & Maintenance Guide SIDE COVERS Not much to say about them. They were always painted steel from the factory and both sides used the same length latch knob. The threaded sections of the knobs were machined to have a relief, so a 6mm nut could be threaded over the end and the fall into an unthreaded section. This allowed the latch knob to be retained in the cover and minimized its chances of being lost. Side cover mounting failures occur when the rubber bumpers are missing or squashed flat from use and age. The covers anchor to the bike on the tabs of the toolbox. The toolbox tabs have a tendency to crack/break due to the combination of tension applied to them; because of the weight and leverage of the side covers pulling on them; plus they are vulnerable to vibration cracking, because of engine/chassis harmonics. It is not unusual to find them chrome-plated instead of painted. This was a common customizing touch, but the covers were never offered from Honda as chrome-plated parts. In most cases, they were only painted in Cloud Silver. 17231-2680120XJ/17331-268-020XJ are the part numbers for the Candy Red side covers. STANDS AND STEPS In 1961-62, the bikes had solid, non-folding footpegs, both front and rear. The fronts were superseded by a set of folding –810 part number items. Although they now fold, they were not spring-loaded; so if they are up, they stay up. It is easy to brush them with your legs while rolling to a stop and then when you want to put your feet down on a peg, you will find them standing straight up! If only they had made the rears folding, as well! The rears will bash your shins every time you move the bike around in your garage, so it is best to leave them off, unless you are regularly carrying a passenger. The original finish was cad-plating. The footpeg rubbers are unique to the CB line; they come as lefts and rights for the front driver pegs. Rubbers for the original solid pegs are somewhat different than the ones for the fold-up versions. The rear peg rubbers are different from the fronts (plain, round holes), but are the same on both sides. CBs come with a center stand (painted black in the US), as original equipment, and have the option of the side stand assembly, which bolts up to the base of the frame on the left side. Installation of the side stand requires removal of the left muffler, the step arm with shift linkage and the left side footplate. The sidestand mounting bracket is about 1/8” thick, so longer bolts have to be installed on the motor mount, as well as a specially machined centerstand pivot bolt. The side stands came as a 268–810 part for the CB77, then were superseded to a 282-000 option, which was for the CP77. The side stand spring is a 268-810 part, but the pivot bolt is a 259 Dream part. An additional 6x16mm bolt (with lock washer and nut) is required to help anchor the bracket to the frame. All of the holes are present and it is a straight bolt-on installation, but you will have to wrestle with the side stand spring, as well as the center stand spring, when 78 Honda 250-305 Super Hawk Restoration & Maintenance Guide installing the pivot bolts for both stands. A rubber donut slips over the end of the side stand tip and insulates the stand from metal-to-metal contact with the bottom of the muffler, when retracted. There is a tradeoff for the sidestand installation, though. The stand makes it easier to park the bike on uneven terrain, but the problem is that it DRAGS on the ground in left hand turns of any real consequence. Perhaps, taking the side stand tip rubber and flattening one side of it will gain some clearance, but there is not much room for error there and little more clearance to be gained, without having to jack up the rear suspension any further, in order to achieve some additional clearance on the left side. If it is too bothersome, you can always leave the bracket on and remove the side stand arm and hardware, temporarily. KICKSTARTER ARM/SHIFT LEVER The original kickstarter pedals came with a rubber with the name HONDA embossed in the middle. Reproduction rubbers are similar, but the material is prone to splitting after installation and/or actual use. The shift levers came in two types: early style with a formed 90-degree tip for the rubber and one that had a welded on tip. The rubber is a 268 code specific part with a ribbed pattern. Later model machines have been seen with a cleated pattern rubber, which may or may not have been factory original. FOOTPLATES The cast alloy footplates, which cleverly allow repositioning of the driver pegs in one of three locations, also mount the rear passenger pegs, when the driver pegs are located in the most forward position. The footplates are vulnerable to bending/breaking because of the solid attachments of the non-folding passenger pegs, which transmit high forces to the plates when the bike tips over or crashes on either side. The rear mounting tabs for the mufflers can also break off in a crash or from the holes being misaligned when mufflers are mounted. Forcing bolts into misaligned holes will cause stress on the plate mountings, eventually breaking the mounting tabs. The plates are somewhat difficult to straighten out without some heat and a press, although some mallet blows to the passenger pegs in the opposite direction of the initial bend can bring them back to the original position, if you are careful. MUFFLERS With few exceptions, standard-equipment Honda motorcycles are very quiet, during normal operation. The Super Hawk (CB 72/77), often had their mufflers left intact (unless damaged), unlike the owner’s of CL72-77s, who usually tossed the muffler (if it had one), as well as the baffles on their machines. It isn’t difficult to remove the CBs "diffusers"(baffles) though, which are held in with at single 6mm bolt. Most Super Hawks APPEAR to have used the same mufflers 79 Honda 250-305 Super Hawk Restoration & Maintenance Guide from beginning to end, but that is hardly the case. As with almost all Honda models, there were modifications and product improvements, throughout the production run, on all of them. It is important to know this information when restoring your bike. The original Super Hawk mufflers, from '61-63, used a "sleeve-type" sealing gasket between the header pipe and muffler, which had a lip securing it to the sharp edge of the inlet side. The engineering upgrade for this design was the O-ring-type gasket, commonly seen on most "two-piece" (separate header pipes) mufflers originally installed at CB72-311506 and CB77-312192. These new O-ring-sealed mufflers were initially made from stainless steel for about two years. The Super Hawk models had a tendency to develop a vibration-induced fracture, just behind the top rear bracket. Eventually, the muffler would break in half at that point. Condensation would also cause rot to develop at the bottom seam, as well. Blocked drain holes contributed greatly to the process. In the period of 1963-64, as mentioned, many Super Hawks were found with stainless steel mufflers, which carried their own unique part number. These were substantially lighter than the chrome-steel versions and were generally corrosion-proof. The appearance was a bit duller than chrome, but a good polishing job would narrow the difference to next-to-nothing. The stainless mufflers mounted to the chassis the same way as the chrome-plated versions and often had the same types of vibration failures. Honda's response to this problem was to redesign the mufflers to have an internal stiffener plate with two studs extending towards mid-line of the bike. Special thick flat-steel plates were attached to these studs, which were formed to adapt to the two original rear-mounting points on the chassis. Most replacement 2-piece mufflers were supplied in this style, but the brackets were usually offered separately, under the part numbers 18353-268000 and 18354-268-000. And for some unknown reason, one side was usually more expensive than the other, despite the fact that they are “mirror images” of each other. Sometimes the brackets were zinc-plated, sometimes chromed. In the quest to maintain peace and quiet, Honda created the "1-piece muffler” systems, incorporating the header pipe into the muffler, as a unit. The forward muffler flanges were modified to make an outward flare and the inside diameter was reduced to a snug fit. A collar was welded to the header pipe, adjacent to the muffler connection and malleable, steel "donut" was swaged over the connection of the two pieces. Originally, the header flange (exhaust pipe joint) was slipped over the outlet end of the header pipe; the hole being slightly larger diameter than the pipe. Two straight-sided (half circle) collars were used to retain the header pipe flange into the cylinder head. 80 Honda 250-305 Super Hawk Restoration & Maintenance Guide With the new "one-piece" system, the original –259-000 pipe joints were too small to fit over the header pipe inlet flange, so new joints were cast, with a larger inside diameter hole, to facilitate slipping over the header flange. This meant that the collars had to have a 90-degree flare at one end to make up the difference in size. Originally, both the Dream and Super Hawk used a 259-000 “Dream” pipe joint and collar. With the changes, the pipe joints acquired a –268-000 part number (apparently Super Hawks got the change first) and then both used the standard, -273000 (250 Scrambler) 90 degree, flared collars. The exhaust studs usually have to be changed for the next longer length, when converting from 2-piece to 1-piece systems on either model. The part numbers changed, of course, to an 18300 (right) and 18400 (left) prefix, for the one-piece units vs. the 18130 and 18330 (right and left) for the two-piece designs. Early onepiece CB designs used the original continuous-curved shaped headers, attached to the new mufflers (suffix -670). Inexplicably, Honda began to build Dream and Super Hawk replacement header pipes with a "double-bend" shape, (crude example= __7 vs. __), which is the best I can do here) which was often incompatible with the bike's chassis and often fouled the starter motor, because of the poorly-formed shape. Later CB one-piece systems used the same late header design and included the EPA/DOT noise warnings stamped into the surface of the muffler or on an attached plate. These "last of the run" Super Hawk muffler systems had a -677 designation suffix attached on the part number, vs. the -670 non-EPA/DOT models. Generally, the 670-series suffix numbers are for "US-market" parts, but the EPA/DOT-stamped, two-piece CB units carried a -325 number. Here are some sequences of the part number changes for each model: 2-piece design: RT/(LT) 18310(330)-268-010 = 2-piece, steel with sharp-edged inlet (sleeve gasket) 18310(330)-268-020 = 2-piece, steel with O-ring holder inlet (O-ring gasket) 18310(330)-268-315 = 2-piece, stainless steel. 18310(330)-268-325-(EPA) = 2-piece steel, with two studs and adapter mounting plate. 18310(330)-268-610 (restricted German-market) = 2-piece steel, requires special diffuser. 1-piece design: RT/(LT) 18300(400)-268-670 or –677. The –670 mufflers had correctly bent header pipes, but generally came without hardware. The –677 mufflers had double-bend header pipes and generally came with all mounting hardware. NOTE: 1-piece mufflers require new exhaust pipe joints (18231-268-000) and new exhaust collars (18233-273-000) to complete the installation. Honda recommends that the exhaust studs be lengthened by 5mm (to 6x 40mm), as well. FYI: RT/(LT) 18310(330)-268-810 megaphones (round) or 18310(330)-269-810 (D-shaped), which were factory Super Hawk "YB" racing parts. 81 Honda 250-305 Super Hawk Restoration & Maintenance Guide As of the time if this writing (early 2003), the remaining options for muffler sets are some OEM copies (100 sets) made in Japan for Honda ($800 pair), newly-made steel units from a NZ source (available from Ohio Cycle in the US or David Silver Spares in the UK) at $400 pair; and a limited production of stainless steel copies, produced in Australia ($500 pair). AIR FILTER The original air filters were fitted with two additional inlet connections, which were used to supply clean air to the carburetor power-jet fittings on the CB72s. CB77s did not use that fuel delivery system, thus the fittings require caps to prevent unfiltered air from entering the inlet tract system. Air filter tubes used wire clamps on the 1961 machines, but those were superseded to a long coil spring type, with the ends connected. All the air cleaner mounting brackets remained the same, throughout production. Small rubber cushions, which insert into the outside faces of the brackets, provide some shock-proofing for the air cleaner side covers. German-market bikes used an extra cover over the air filters to dampen intake noise, so the filters are slightly smaller than normal, but still fit the standard mounting brackets. All filters are now out of production and rare. TOOLBOX The toolbox is suspended from two frame ears, below the battery box area. The toolbox provides storage for the tool kit and anchors the two air cleaner side covers to the machine. Because of the direct mounting of the toolbox to the frame, the adjacent engine provides a fair amount of highfrequency vibration, which can aggravate the connection point of the air cleaner covers to the toolbox mounting tabs. Between the engine vibration and the physical stress load on the toolbox tabs because of the rubber-vibration dampers pushing on the side covers. The most common failure here is the toolbox mounting tabs for the side covers. The tabs are spot-welded on and the combination of constant strain and vibration causes the metal to tear around spot-welds. Any TIG welding and addition of some strengthening material is a benefit here, during repairs. TOOL KIT The tool kit part number changed in 1962, when the 10mm C-series NGK spark plugs were replaced by the 12mm D-series units, requiring a different spark plug removal tool. The original tool bags were generally a large flat, roll-up blue vinyl items, with heat-stamped embossed HM logo and pockets for the individual tools. Some bikes have been seen with stitched canvas tool bags, too. Early tool kits came with tire irons, tire patch kits and scissors included. These items were deleted after the first year or so and eventually the roll-up tool bags were replaced with a simple, single pouch, closed with a single snap fastener. 82 Honda 250-305 Super Hawk Restoration & Maintenance Guide OWNER’S MANUAL I have seen at least 4 different types of owner’s manuals printed for these bikes. You can look at some of the photo details in the early versions to see what they used at what point in time. The first 1961 editions show the front brake adjustment on a SLS front brake and the rear footpegs back by the rear axle. The 1961 owner’s manuals were printed in a blue-colored print and have some extra pages that show the two main assembly plants and what was produced at each. Manuals were revised in late 1965 to reflect the changes in the speedometers, handlebars and again in 1966 for the Type 2 forks. All owner’s manuals have a wiring diagram in the back. PLEASE NOTE: I have discovered the same error, repeated in every wiring factory diagram (including Clymer’s books): The battery lead (dotted line) is mistakenly shown connecting with the GREEN (HL- headlight) wire from the ignition switch, instead of correctly connecting to the WHITE/RED (CH- charging) wire that joins to the RED lead of the rectifier output. The CH post has no internal contacts in the switch; rather it is just a connecting post. If the bike is wired like the diagram, the charging system WILL NOT function and the battery will probably run flat overnight. REAR FORK The rear fork (often called the rear swing arm) on the 1961 bikes had some extra lugs cast in, just forward of the shock mounts, apparently as footrests for the passengers. The first 380 CB77s had an alloy rear brake stay, which was thicker than the replacement steel units, so the attaching brackets reflected those needs. From CB77-10381 onwards, the swing arm part number remained constant, although the method of manufacturing it changed significantly. Until early 1965, the rear axles were located in a pair of left and right side steel castings that were slipped over the ends of the swing arm tubing and welded in place. Beginning in early 1965, the rear swing arm tubes were slotted and thick steel plates were inserted and welded in place. The flat plates located the rear axle shaft and carried mountings for the rear shock bushings. These plates could be used on either side of the swing arm, with only the marks for the chain adjuster alignment being different from side to side. Interestingly, despite the obvious difference in appearance, the part number was not changed. This is an example of Honda’s continuous changes to streamline the manufacturing process and reduce material costs and construction time. The rest of the remaining parts that make up the rear suspension were all unchanged during the production run. Honda’s use of a bakelite-type of bushing material for the pivot was sufficient for street-going pursuits, but those who were serious about racing the machines 83 Honda 250-305 Super Hawk Restoration & Maintenance Guide generally made up some brass or bronze replacements to minimize the flex and wear at this critical area. The most common problem with the rear fork is that the bushings are not lubricated properly and the bushings and swing arm bolts will seize to each other. The other problem stems from the forward chain guard mounting tabs getting broken off regularly. A combination of loose drive chains, tight fitting chain guards and vibration often contribute to their demise. CHAIN GUARD There is only one version of the chain guard for the standard Super Hawks and two things generally happen to them. First, they tend to crack at the rear, mounting bracket, just inside the shock absorber area. Second, they break the mounting ears off the front of the swing arm. Generally, the bolts will stay with the parts, so you have something to weld back on again. Reproduction chain guards have been available from a source in the UK. There was a special CYP77 Police bike chain guard (similar to a CL unit), with an extended and curved rear section for improved cleanliness of the rider and machine. Chain guards are always color matched to the frame’s color; except for the 40510-268-030XJ “Candy Red” chain guard. REAR FENDER The rear fenders were all silver-painted steel, other than the last of the chrome replacements and the rare alloy YB race-kit items, which were still painted silver. Chrome fenders were installed at CB77-1056084. Considering that the last serial number was CB77-1056432, the chrome-fender machines are rare, indeed, numbering a total of 398 units. All of the chrome fenders used the latestyle “oval” taillight assemblies, with matching tail light brackets. The bolt pattern for these brackets is inverted to that of the previous models, so that early taillights/brackets will not bolt right up to a chrome fender, without re-drilling the mounting hole pattern. See front fender note about paint color, if restoring. There was a special rear fender for the early 17” rear wheel versions of the CYP77, which was contoured to fit the smaller diameter of the wheels. MUDFLAPS The rear mudflaps are a soft rubber material that tends to droop down and get brittle after extended exposure to heat and weather. The part numbers for the mudflap and brackets all have an –010 behind them, indicating that some changes were made from the original design, but that is what they started with in 1961, according to the original parts lists. REAR CUSHION The rear cushions (shock absorbers) were available in Black, White, Red and Blue colors, with either steel or plastic upper cases offered. The 1961 and first 200 of the 1962 machines had alloy upper and lower cushion covers, which were easily dented and damaged, so they were replaced 84 Honda 250-305 Super Hawk Restoration & Maintenance Guide with steel units (painted on the top and chromed on the bottoms). The damper cases, shock springs and lower cases were all changed at this point and continued in the new design, thereafter. Use of a Honda shock spring removal tool will ease the disassembly process of the shock assemblies for restoration/replacement of the covers. Some of the early dampers had a removable damper rod/seal assembly, but the later ones were crimped over and cannot be disassembled. 52523-268-315XJ is the part number for Candy Red shock covers. FRONT WHEEL The first 280 CB77s and 1149 CB72s were delivered with an 8” single-leading shoe (SLS) front brake assembly, which was replaced with a double-leading shoe (DLS), matching the DLS rear that came on all units. The changeover to DLS front required new brake shoes (from longer –000 to shorter length -020) and new backing plate, brake cams, brake arms and return springs. Brake shoes were shortened, when the double-leading shoe brake was introduced, then both the shoes and brake springs were redesigned again at CB72F-23972, CB77F-22752. The 1961 thru-mid ‘63 brake arms (changed at CB72F-312196, CB77F-312673) were retained by self-locking nuts on flat, stamped-steel, brake arms. A similarly splined “doubler ring” was spot-welded on the backside of the brake arm for strength. The ends of the brake cams were threaded just beyond the splined sections, to utilize the locking nuts. Hard usage would cause the spot welds to brake and the narrow brake arms would cause excess wear on the brake cam splines, leading to less-thanefficient braking performance. The answer to this problem was a new set of single-piece, caststeel brake arms, utilizing a pinch bolt design to clamp the brake cams securely. The front brake stopper arm was changed at CB72F-402120, CB77F-402651. The front hub and front wheel bearing retainer were redesigned at CB72F-23082, CB77F-21492, when the speedometer drive gearbox was changed for improved weather protection. Rim size is 1.60 x 18.” NOTE: Removal of the wheel bearings often requires a long slender punch or steel rod to catch the inside edges of the bearings. In some cases, heating of the hub is required to allow the bearings to drop out of the machined recesses. REAR WHEEL All rear wheels for CBs were of the double-leading shoe design, with the same changeovers on the brake arm hardware as the fronts, in early 1963. At CB77-1029375, the rear brake cable and brake arm were lengthened about 3/4” for increased braking power. The rear brake shoes are the same as the fronts, after the change to DLS front shoes. The hub and brake panels were redesigned at CB72F-20302, CB77F-20201. The brake shoes and springs changed at CB7223972, CB77-22752. The brake cams changed at CB72-22627, CB77F-21228 and again at CB72312196, CB77-312673 (pinch bolt-style brake arms). Early model cams had grease fittings in the 85 Honda 250-305 Super Hawk Restoration & Maintenance Guide ends of the shafts. The rear brake panel spacer was machined for lightness originally, but later machines had a straight-sided solid steel spacer. Rear sprockets for the CB72 had 32 teeth, while CB77 models were equipped with 30 teeth. Racing sprockets were also available (28-66 teeth). Rim size is 1.85x18.” See above notes about wheel bearing removal. Be sure to lubricate the brake cams, where they turn in the backing plates. TIRES/AFTERMARKET SHOCKS Stock tire sizes for the CB72-77 are 2.75x18” ribbed front and 3.00x18” universal tread rear. Use of tires in sizes other than what are recommended can cause handling difficulties and clearance problems, when placing the bike on the centerstand. Use of longer than stock shocks can also cause the same types of difficulties. Because of the poor quality of the standard shocks, owners often installed CB350 shocks, which are about ¼” longer than the original units. I have seen many bikes with the original shocks, but with the upper covers removed and the lower chrome covers put on as a new top cover. This exposes the unplated rear spring to moisture and rust. My choice for a number of years has been RED WING shocks, made by Marubeni, back in the 1970’s. The all-chrome 12 5/8” RW shock is a bolt-on for CBs and came with a relatively soft 60/90 wt spring. Because of the larger spring diameter, the stock Honda shock covers do not fit over the exposed spring of the RW units. There is a small interference where the shock contacts the chain guard, so a longer rear mount bolt with a couple of lock washers stacked between the chain guard and the swing arm is required for clearance. You can’t get too carried away with this modification due to clearance problems with the chain and sprocket bolts. About one eighth of an inch is all that is needed. While changing out the OEM shocks to RW units, you must utilize the stock lower bolts from the stock dampers to mount the new RED WINGS. Honda mounted the shock bolts from the inside and then placed a thin nut on the outside to insure safety. I use the stock bolts, but add a lock washer under the bolt heads, then insert them from the outside. If you don’t add the spacer, the ends of the shock bolts can interfere with the turning rear hub sprocket bolts. Unfortunately, the RW shocks are pretty much gone from inventories now, so other avenues must be explored. The RW shocks have a much larger damper rod and are rebuildable, so if you can find a set, DO give them a try. Recently, the HAGON shocks, from the UK are a viable source and come with a full set of enclosed covers, much like the originals. Shocks of a greater than OEM quality make a huge difference in the handling and ride qualities of a Super Hawk. HEADLIGHT CASE/HEADLIGHT The headlight cases were changed several times; Some of the first models used a single-screw headlight retainer rim, so the case had only one anchor point, so the second series used the 86 Honda 250-305 Super Hawk Restoration & Maintenance Guide commonly seen 2-screw rims and attachments. Next, coinciding with the change in the upper fork bridge at CB77-21363, CB72-22842, an additional change to the headlight shells came when the lower grommet hole was increased from 21 to 25mm. A matching, larger grommet was installed at this time to better protect the wiring harness. A third version used the two-screw meter packing, but the ears were longer and set down lower in the edge of the headlight shell (CB77-20321 to 21361, CB72-20321 to 22841). The fourth edition, at CB77-21363, CB72-22842, used the –020 packing, which is now the hardest part to find, due to demand. New meters come with new packing glued to the meter, but Honda made the meter packing available separately, to replace damaged parts. All U.S.-spec headlights were sealed-beam units, rather than the separate, replaceable bulbs used in Europe and Japan. At serial number CB77-1051692, the headlight assembly was changed to a type that allowed for lateral adjustment. The light assembly is from the CB450K0 and a fifth headlight case, with a –670 suffix, was required to make the changeover. NEUTRAL LIGHT The neutral light assembly changed from a –259-000 part number to a –272-000 at CB77106221. You will find different colored lenses (red on black or blue bikes and blue on red machines) and types of fittings on the neutral lights of that era. The early versions used metal lens holders, where the later ones were all plastic construction. The rubber boot, which holds the bulb to the lens base, is prone to rot and damage from heat and age. Unfortunately, the individual parts were not available separately. The headlight switches come in two varieties: two or three-position. The two-position is most commonly seen in the US and is also used on the CL72-77s. The three-position switch can be used with bikes that have a front parking lamp, which is built into the headlight bulb reflector. SPEEDOMETERS At least 5 versions of speedometer-tachometer meters were seen on US models. The first four of the series were the “reverse needle” meter style, where the needles were opposed at the bottom of the meter and rose towards the top, as the respective engine and machine speeds increased. The first was for the 1961 machines and had a loop on the bottom to secure the retaining spring, which connected to the loop at the bottom of the headlight case. This spring loop was deleted when the fork bridge and headlight cases were changed in early 1962. The second set mounted in the headlight case, but lacked the high beam indicator feature. A brief, third version mounted in the headlight case, but the ears were longer and set down lower in the edge of the headlight shell (CB77-20321 to 21361, CB72-22842). 87 Honda 250-305 Super Hawk Restoration & Maintenance Guide At CB77-102261/400001, CB72-103257, the fourth set of meters incorporated a highbeam indicator at the top of the meter. Finally, the fifth, “concentric” meter (both meter needles moved in a clockwise rotation) set was introduced at CB77-1001731, CB72-1003907 and required a new speedometer drive unit, as well as a new speedometer cable for the changeover. These days, if you can’t find a new speedometer-tachometer unit, try some local automotive speedometer repair shops for repair assistance. Most cannot refurbish the faces, but they can often repair the mechanisms and calibrate the units for you. A final note about speedometer storage: Honda recommends that speedometers always be stored FACE UP, as damping fluids can leak and damage the face or cause meter failure due to lack of lubrication TAIL LIGHTS The 1961 and early 1962 machines featured a CP77-type tail light assembly, which was changed at CB77-21362, which seemed to be a magic number for engineering changes. The CP lens is wider at the bottom /___\ , than the commonly seen “generic” 268 light assembly used on so many 60’s Honda models. The mounting bracket and all trim parts were different, as well, for this early tail light assembly. The second tail light version was the “short lens,” –268-810 style, seen on 1962 bikes only. From 1963 to early 1967, the standard “long lens” –268-680 tail light lens is found on all U.S.-spec machines. See photos at the end of the book. The final changeover was when the new oval taillight was installed, along with the chrome fenders in 1967. The taillight brackets were prone to vibration-related failures of the license plate holder extensions. Brackets were generally painted Silver or Black (B code in part number). The taillight, itself, was noted for breakage at the braided ground wire connection, which creates a dimming of the bulb elements, as each filament tries to find a ground source through the other. Proper grounding of the tail light bracket to the fender is essential for correct lamp operation. DIMMER SWITCH/STARTER SWITCH The handlebar switches use internal wiring harnesses on both sides, instead of external wiring as seen on the CL72-77 series machines. Other than a change to the starter switch at CB77-1028216, CB72-1004689 for the high bar installation, the same switches were used on all machines. The early dimmer switches had an extra detent between HI and LOW for the purpose of allowing a faster charge of the battery, by bypassing both switch positions when the headlight switch was still on. See the Honda service bulletins about the deletion notice for this type of switch. As these parts become harder to find, the switches from other models can be used in their place. Usually the difference between the CB72-77 and CB160 parts, for instance, is just the length of the harnesses to accommodate the difference in handlebar heights. If you have a 88 Honda 250-305 Super Hawk Restoration & Maintenance Guide domestic or other non-US model, the turn signal switch is mounted on the right side handlebar switch, just above the horn button. MIRRORS The original 200-000/810 square mirror sets, which were universal for many 60s Honda twins were superseded to an 18110/18120-041-000/810-811 set, which has a different angle to the stem. In some handlebar installations, the mirrors see nothing but sky, so some careful bending of the stems must be done, in order to make the mirrors useful. WIRING HARNESS/POINTS/BATTERY/RECTIFIER *Original US-spec wiring harnesses do not have provisions for turn signal wiring. Most wiring original harnesses have a white tag attached to the harness sleeve under the fuel tank, which is dated (date of the harness). This date often is an indicator of the year of the bike, but when there is a crossover from one year to the next, the harness date is sometimes behind the chassis date (i.e. 1965 chassis with 1964 harness date). The part number for the main harness (Harness B) changed in 1962, at CB77-22753, CB72-23872, when the connector terminal ends for the horn were changed from hooks to male-female push connectors. Later replacement harnesses from Honda have a –305-suffix code, which do include turn signal wiring within the harness, making it more universal for multiple applications throughout the world. The Harness A, which connects to the ignition switch, carries the fuse holder and positive battery power to the coils was changed at CB77-10021, CB72-10967 for reasons not known at this time, but do coincide with a second change on the Harness B. *The ignition points are the same for CL and CB engines, sourced from Nippon-Denso (N-D). There are aftermarket points that are supposed to be interchangeable with the OEM N-D parts, but they are best used on the matching aftermarket point plate. Most aftermarket points have slightly different geometry, often causing a problem with limited adjustment when used on a stock N-D point plate. IF you choose to stay with standard ignition points, then use the correct ND points to avoid difficulties. There was a change in the point plate, point cover and right side engine cover in early 1962, but after that everything stayed the same. The condenser part number superseded to a -273-code Scrambler part in late 1965, but they all fit and function the same. The lead wires on the 273 are a bit longer than those of the 268 versions. While the standard ignition parts are generally suitable for non-racing purposes, there are problems with the advancer shaft that can cause inaccurate ignition timing from one cylinder to the other. There is a great deal of slop and movement in the spark advancer mechanism, which is part of the central camshaft sprocket, even in new condition. The loose fit between the tongue of the advancer shaft and the hole in the tang inside of the cam sprocket creates some looseness 89 Honda 250-305 Super Hawk Restoration & Maintenance Guide initially. The advancer shaft runs inside the right side camshaft, which is subject to harmonic vibrations, due to its job of opening and closing the valves rapidly and repeatedly. The advancer shaft is turning inside the hole in the camshaft and is subject to the lateral force of the two ignition points pushing against it at 90-degree angles from each other. Even the new parts have about .001” clearance and that increases rather rapidly, it seems. On average, most shafts have about .003-.006” side play, which corresponds to a like amount on the point gaps. Any change in point gap means a change in the ignition timing, so what happens is that the ignition timing varies both with engine speed (causing the points cam to both advance and to center itself somewhat) and varies between the left and right sides, both at idle and at full advance. What is most critical on these engines is the amount of spark advance above 3,000 rpm. The total advance must not exceed 45-degrees before top dead center (BTDC) on both sides to prevent overheating and piston seizure. Because of the variations in the timing, due to all the sloppiness in the mechanism, what often occurs is that when the full advance spark timing is set the same on both sides, the spark timing at idle is inconsistent between the left and right hand cylinders. One side might still be at the desired “F” mark on the stator, while the opposite cylinder might be firing at the “T” mark, instead. This irregularity makes for a hard-starting and lumpy-idling engine. Acceleration is also affected as the two cylinders fight each other, before they achieve full-advance status again. The other consideration here is that the springs in the spark advancer portion of the cam sprocket become stretched and/or break an end off, causing the spark to advance almost immediately after the engine begins to fire. Trying to set the carburetor and ignition timing, when the advancer has already gone part way out at idle, is a futile task to sat the least. Any changes in ignition timing affect the manifold vacuum in the intake tract, which changes the amount of suction on the idle and needle jets. The engine wants to run beyond the 1,000-1,200 rpm idle speed no matter how you try to adjust the carburetor or ignition timing. The only solution is to remove the engine and repair or replace the cam sprocket, advancer shaft and/or the advancer springs. The cam sprocket is also prone to loosening up where it is riveted together. This situation creates even more problems for both valve and ignition timing. Be aware that the cam sprockets on the CB/CL and CA-Dreams look similar, but differ in the types of advancer weights and return spring tension rates. When you look at the two sprocket assemblies, you will notice that the advancer weights on the Dreams extend out to a point, just beyond the stopper posts, whereas the CB/CL units are rounded off just beyond the posts. The tension springs are a little lighter on the Dream units, as well, offering a quicker spark advance curve than that of the Super Hawks and Scramblers. 90 Honda 250-305 Super Hawk Restoration & Maintenance Guide Thus far, the best solution is to install a custom-designed electronic ignition kit, made by Probe Electronics, in Capistrano Beach, California (contact the author). This system does away with the standard ignition contact points breaker plate and condenser, replacing both with a specially-created PC board and unique “hat” adapter that slides over the end of the points cam and is attached with some adhesive and a clamp. The “hat” contains sets of NORTH and SOUTH magnets and as they pass by the transistors embedded in the PC board, they generate a timing signal, which is then sent to a small control module. The control module switches the ignition coils ON and OFF creating the high-voltage discharge at the coils. The magnets are designed to sweep past the transistors at a precise point and are unaffected by those side-play variations of the advancer shaft. Sufficient coil saturation is assured up to 12,000 rpm according to the designer, Mark Whitebook. The installation is virtually invisible and maintenance-free, using the standard Honda ignition coils and wiring. *The correct battery is a 12N9-3A, which have horizontally-extended terminals to attach the ground and battery/harness wiring. Use of any other battery will result in the need to make up adapters to connect the vertical terminals to the wiring. *The Orange/Red selenium rectifiers handle both the voltage regulation and conversion of 40vAC to 30vDC, which is dampened down by the battery, when it is fully charged. Rectifiers can either short the voltage signals to ground or go to an open circuit status. *Other electrical parts updates came when the individual, metal-cased ignition coils were replaced with molded plastic-cased units, featuring integral plug wires and mounting brackets, similar to those seen on the CB350-450s, from 1968-onwards. Note: Some early ignition coil wires carry the date of manufacture stamped on them. *Original spark plug caps had an HM logo on the outside and were of a non-resistor type. *The rectifiers and starter solenoids carried along virtually unchanged, although Honda replaced the original selenium rectifiers with silicon diode replacements, in the later years. *Early ignition switches had NA and NB key codes, which are difficult to find either the original keys or even correct key blanks that will fit the locks. Later T-series keys are easier to obtain and to get blanks for copies. WIRING Honda used a nearly universal wiring color code for most of their models of that era. The notable exception is the 12 volt Green wire, which comes from the ignition switch HL terminal and supplies power to the lighting switch ML terminal and to the instrument lights. In almost all other applications, Honda generally uses Green wires as ground connections, but not on these 250-305cc models. There is also a Green w/white marker wire, which is used to ground the 91 Honda 250-305 Super Hawk Restoration & Maintenance Guide speedometer to the headlight rim. Obviously, incorrect wiring connections will put 12 volts directly to ground, blowing the fuse. Red and Red w/white is generally a “hot” wire, usually for the battery and charging system (rectifier). Black wires are usually main power feed sources. The Pink/Yellow/Brown wires come from the stator windings. The Pink one winds up at the lighting switch, while the Yellow & Brown go to the rectifier. Blue wires go to the brake light and to the “high beam” circuits. The Yellow w/Red stripe wire is the ground connection to energize the starter solenoid, while Black w/Red stripe is the power feed. The Light Green w/Red stripe wire is for the neutral light switch ground circuit, while a Black w/white wire from the ignition switch, which also feeds the Lighting Switch, supplies the 12-volt power to the bulb. The White wire is for the taillight power and for the small, front parking light, if so equipped. The Red headlight wire is for “low beam” circuit. A single 15amp fuse is used for circuit protection. See accompanying chart for more details about the electrical system and wiring color codes. COLOR *Black* Honda CB72/77 wiring chart_______________ USE From a. Brake Light a. Ign. Switch b. Ignition c. Neutral Light d. Horn To Brake Switch Coils (sub harness) Neutral Light Lamp Horn + Horn – to button e. Electric Starter Starter solenoid+ *Black/Bk w/White Switched Hot: Neutral Light Ign.Sw. Neut. Lt+/Lighting Switch *Black/Red Switched Hot: Starter Solenoid Ign.Sw. StarterSol/Sw-CB *Blue Switched Hot: HI Dimmer Switch Headlight *Blue Switched Hot: Brake Brake Switch Brake Switch Lamp *Brown Switched Hot: Taillight Brown/White Brown Wire *Brown Charging System Stator Rectifier *Gray Hot Turn Signal Flasher Relay Turn Signal Sw. *Green Switched: Headlight Feed Ignition Switch Meter/Light Sw *Green w/White Lighting Ground Speedometer Head Light Rim *Light Green/Red Neutral Circuit Bulb Neutral Switch *Pink (or Purple) Charging System Stator Rectifier *Orange (Lt) & Lt Blue (Rt) Switched Hot: Turn Sig. Turn Signal Sw. Turn Signal Bulb *Red Fused Hot: Battery Rectifier *Red/White Charging Lead Combo Switch Battery *White Switched Hot: LO Dimmer Switch Headlight *Yellow Charging System Stator Rectifier *Yellow/Red Starter Circuit Starter Switch Starter Button Ignition (Combination) Switch Terminals: BA=Battery=Red wire CH=Charge=Red or Red/White wire IG=Ignition=Black or Black w/White wire ST=Starter=Black/Red wire TL=Taillight=White wire HL=Headlight=Green wire Lighting Switch Terminals: DY=Day (no lights)=Purple or Pink wire IG=Ignition=Black or Black w/White wire HL=Headlight=Brown wire ML=Meter Light=Green wire SE=Selenium rectifier=Yellow wire 92 Honda 250-305 Super Hawk Restoration & Maintenance Guide System: IG (Ignition) IG terminal on CB combination switch=Black wire to coils (+). Feeds to Brake Switch. Feeds black/red wire to CB Starter Solenoid primary winding. Feeds to Horn female connector. Feeds Black/White 4-way connector in Headlight shell, splits to Neutral light and connects to IG terminal at Lighting Switch (Black w/White Spiral). System: BA (Battery) BA terminal on CB combination switch=Red wire to Fuse to Battery System: CH (Charging) CH connector terminal on CB combination switch= Red wire to Rectifier output terminal. Both run separate White/Red Spiral wire over to Battery post from CH terminal. This post does NOT contact internal switch contacts. System HL (Headlight) HL terminal on CB= Brown wire to 4-way connector in Headlight shell. Feeds instrument light bulb(s) and ML terminal on Lighting Switch. System TL (Tail light) TL terminal on CB =White wire to taillight bulb (Parking light, if equipped) System ML (Meter Lights) ML terminal on CB=Green wire connects to 4-way connector in Headlight shell. Feeds Meter Lights and returns to Combination Switch at HL terminal. System DY (Day operation-no lights) DY terminal on CB=Purple (Pink wire) to Stator winding for daytime use without lights. System SE (Selenium Rectifier) SE terminal on CB=Yellow wire connects to Stator windings and Rectifier terminal through the headlight switch. Neutral Light circuit grounds at Neutral Switch under right kickstarter case, near hole in upper engine case for stator wires. Neutral light grounding wire is Light Green w/Red Spiral. GROUND: Green w/White ground wires are found in the headlight shell to ground the headlight bulb to the instruments on CB. WARNING! DO NOT confuse the Green GROUND (which have a White collar or Spiral on them) wires with the HOT Green (solid color) wires feeding the instrument lights and headlight switch. Circuits requiring grounding are Head, Tail, Brake and Winker lights, Ignition Condensers, Neutral & Meter Lights, Horn, Starter Solenoid (Yellow w/Red Spiral), Battery and Selenium Rectifier. Dimmer Switch: Dimmer Switch is fed by the Brown wire from the Lighting Switch. Power is then sent to either the LO (Red wire) or HIGH (Blue wire) beams. Horn button ground wire is Black wire Starter Switch: Starter Switch on US versions has a single Yellow w/Red Spiral wire to ground the primary side of the Starter Solenoid to the handlebars, when the spring-loaded button is pushed. If equipped with "Winkers" (turn signals), the Starter switch is fed by the Gray wire coming from the Winker Relay. The Orange wires feed the left Winkers and Right Winkers are fed by the Light Blue wires, when the L-R sliding switch is moved to select that set of lights. All winker lamps are grounded through the mounting sockets to the handlebars and the rear frame brackets/mounts. Winker Relay The winker relay is located near the battery box and is fed by a Black 12v switched power lead. The Gray wire coming out feeds the winker switch on the handlebars. Ignition Breaker Points Ignition Points Breaker Plate grounds the Right (Green) and Left (Yellow) ignition coil primary wires coming from the Coil/Condenser assy. junctions. The condenser is grounded at the ignition coil with the ground strap that attaches to the forward engine mount bolt. 93 Honda 250-305 Super Hawk Restoration & Maintenance Guide Selenium Rectifier Selenium Rectifier grounds through the end posts where they mount to the frame. RED terminal is output to Battery. YELLOW terminal is for voltage from Stator for charging system and also connects to the SE terminal on the Lighting Switch. BROWN terminal is for voltage from Stator windings. When HEADLIGHTS ON are selected from Lighting Switch, the contacts inside are connected to the Purple (Pink) wires from the third leg of the Stator for additional voltage to offset the load of the Head, Tail and Meter lights in HL position. Horn Horn coil windings are fed from the Black wires from IG terminals. Power runs through the windings and is grounded through the left handlebar switch, when horn button is pushed. Brake Switch Extending the plunger on CB models activates the Brake Light Switch. Switch connects the 12v switched Black wire to the Blue wires feeding the Stop Light bulb filament. Starter Motor Starter Motor receives power through the contacts in the Starter Solenoid, via heavy-gauge cables. Starter Solenoid is connected to the Battery Positive Cable. Ignition Switch connections: COMBINATION 1st ON position =BAT-IG connected. HL-TL connected. 2nd ON position BAT-TL only. Lighting Switch: OFF is middle position on early 3-position switches. Later switches are OFF to left on 2-position switches. First position (early switch): Twilight position=IG-ML gives meters, running light and taillight only. Second position (early switch) Night position=IG-ML-HL and SE-DY gives meter/head/tail lights, plus increases charging system output. Change in LIGHTING SWITCH (2 vs.3 positions) coincides with introduction of LOW OUTPUT generator (1.0 vs. 1.8 amp output). Battery: Battery output rating CB72-77 (12N9-3A) is 9 Amp Hr. HONDA CHARGING SYSTEMS The most frequent complaints, concerning the Honda 250-305 models, is that the charging systems are either a.) Draining the batteries while sitting or b.) Won't keep them charged while riding. If you review the chart below, you will see that there isn't much reserve power designed into the system. It is really a battery maintenance system and not a true battery “charging system.” Here's a quick look at the mysteries of the permanent magnet charging system of these models, and some tips on how to troubleshoot it effectively. All you need to begin are a fully charged battery, a Volt/Ohm/Amp meter (digital or analog), 12v test light, screwdrivers, pliers and some fine sandpaper/small wire brush/contact cleaner etc. Let's get started! HONDA CB72/77 GENERATOR CHARGING RATES* ENGINE RPM 1,000 1,500 2,000 3,000 5,000 Charging ratelights off (Amp.) +- .0 +.5 +.9 +1.6 +1.6 -2.2 +-.0 +.7 +1.8 +1.8 Charging ratelights on (Amp.) "Low output models" charge starts below 2,800 rpm, charges 1.0 ± .5 amps @ 4,000 rpm * Figures provided from American Honda TL #9 6/1/66 These figures apply to a system with a fully-charged battery (approx. 12.6-12.8v). If you are trying to charge your dead battery, by riding around town, you can see that you will be stranded in no time! Your light bulbs will also be in jeopardy, because the charging system (fully 94 Honda 250-305 Super Hawk Restoration & Maintenance Guide functioning) will be delivering upwards of 30vDC to your 12v bulbs. The "flickering" impulses are trying to turn them into "flash bulbs." A fully-charged battery acts as a storage reservoir and dampens those voltage fluctuations. Let's look at the components of the charging system. The AC generator system starts with a stator made of copper windings mounted on the right side of the crankcase and a permanent- magnet rotor on the end of the crankshaft. The rotor sweeps lines of electromagnetic force across the windings of the stator, inducing an alternating current (AC) voltage. The pink, yellow and brown wires from the stator are carrying these AC voltages back to the selenium rectifier, which converts the positive half of the AC sine wave to DC voltage. The negative half is grounded through the diodes of the rectifier. This DC voltage is used to maintain the battery charge and to offset the current draw of the ignition system and the lights. STATOR With the engine off and the stator wires disconnected, use a continuity tester or ohmmeter to test for continuity between the three wires. They should be all connected together electrically, but should be isolated (insulated) from the grounded frame of the stator. With the engine running and the wires disconnected from the harness connectors, you should find nearly identical voltages on the yellow and brown wires, when measured from these wires to the engine cases (ground). The pink wire will show higher readings. Problems occur here when a.) the rotor loses its magnetism or b.) the stator windings lose their insulation wrappings (usually from bad crank seals soaking the insulation, causing the insulation to fall off). The coils then begin to bounce around on their mountings, shorting themselves out to the grounded stator frame). Stator lead wires can also work loose and rub against the rotor or frame. Leaving the stator connectors and going to the red/orange-colored, finned, selenium rectifier, (found under seat, behind the battery box), you will find that one of the wires has vanished! The pink wire is connected directly to the lighting switch, which is the DY terminal. There is an additional wiretap off of the yellow wire, also attached to the lighting switch on, which is connected to the terminal. When the headlight switch position is switched to "ON", the output from the yellow wire is connected to the pink wire, through the switch contacts. This connection adds extra current to the charging system immediately, when the lights are turned on, maintaining an electrical balance within the system. Now that you have found the selenium rectifier, check the voltages at the wire terminals (engine running). Those yellow and brown wires, attached to the rectifier, should have matching voltages (around 6vDC, checked to ground) on each wire (engine idling, lights off). If not, recheck the wiring connections from the stator back to the rectifier. Then, briefly, remove each 95 Honda 250-305 Super Hawk Restoration & Maintenance Guide wire from the rectifier individually, and check the voltage on the wire, while it is disconnected. If the voltage is the same on both wires (up to 15v!), but the red wire output is still low, the rectifier is shorting out the voltage to ground. Replace the rectifier. Operating the charging system either without a battery or with a “dead” battery will damage rectifiers. They also deteriorate with heat and age, as well. Damaged rectifiers can also bleed off battery voltage, through the diodes, while sitting in storage. If the voltages into the rectifier are both the same and at a normal level (6-7.5 volts or so), check the output lead from the rectifier (the red one, probably with a white stripe, sometimes white with a red stripe!) and measure the voltage. Again, using a fully charged battery, you should see 13-14.5v DC at the output (over 3,000 rpm), which goes straight to the battery. If you see something like 22 volts (or more!) at the output and the battery is still losing voltage, then check for an open wire connection to the ignition switch. The CH terminal on the ignition switch is a connection post, not an internal switch contact. The red/white wire, going to the battery from the sub-harness, and the output wire from the rectifier, must both be attached to this terminal. Be sure that the system maintains the voltage when the lights are "ON" and the engine is running over 3,800 RPM. If the voltages begin to drop much below 13.0v, check the voltage at the yellow and pink wire on the ignition or lighting switch. Sometimes the switch contacts burn out and the additional voltage (current) is not being carried back into the circuit. Remember, that the voltage (current) of the pink wire is being added to the yellow wire circuit, when the light switch is switched "ON". You should see an increase in the input voltage at the rectifier terminal (yellow wire). This input increase will be reflected in an increased output from the red/white terminal, which leads to the battery. Clean and check all the ground connections for the rectifier (at the mount bolts) and at all lights. Be sure that the chassis is well grounded to the engine. Early CB72/77 models had a rectifier frame mount that often failed from vibration. Later models had a redesigned mount for improved durability. The rectifier must be securely grounded to the frame! For best results, check all electrical connectors for clean, tight connections and correct color match. A final check is to insert an ammeter in series with the ground cable and start (kick start, don't electric start) the engine to observe the current readings. Use the above chart, to see if readings are up to specs. If you don't have an ammeter, a running system voltage output of over 13.5 volts DC (above 3,800 RPM with the lights "OFF") is an indication of a system that is close to specs! If you still don't get a proper output, the last remaining possibility is that the rotor has lost its magnetism. This can happen if the rotor has been dropped, hit with a hammer or sometimes just with old age and use. This is a difficult thing to measure. I usually compare a 96 Honda 250-305 Super Hawk Restoration & Maintenance Guide couple of rotors with a piece of steel or a wrench to determine if the magnetic strength is similar. I have observed an increase of .75a and .5v, just by replacing the rotor on a CA77. You may want to think twice, before using an impact driver on the starter clutch screws. The shock may cause the rotor to lose some field strength. This is not a common problem, but if everything else checks out okay, replace the rotor and test the output again. Rusty rotors will reduce the output too, so clean up the laminations with a wire brush or sandpaper. There is always a reason for low output! Find it and fix it. Then, you can enjoy the safety and satisfaction of a reliable charging system. See the following for basic diagram: BASIC DIAGRAM: AC GENERATOR STATOR: --yellow wire(AC)----- to: H/L Switch(CB-CL)"SE" terminal---------------I I and is also connected directly to the RECTIFIER (Lighting Switch) I --brown wire (AC)-----Directly to the RECTIFIER I I --pink wire (AC)--------to: H/L Switch (CB-CL) "DY" terminal-------------I 12.5-14vDC output from RECTIFIER --red/white wire --to--BAT. (+) terminal Resistance check through rectifier: (5-40 OHM one direction & >10K OHM the opposite direction to ground and to output terminal) When headlight switch contacts are closed (ON), the extra voltage and current from the pink wire is connected, through the switch contacts, to the yellow wire feeding the rectifier. This offsets the additional electrical load. Also, when checking output voltages from stator, pink wire output will be higher (2x) than yellow/brown wires. NOTE: "Low output" systems have an "L" stamped next to the rotor designation, often seen as "CB72 (L)." Quick-check: Use a 12v DC test light to check yellow, brown and pink stator wires, when engine is idling. Pink wire connector should be much brighter than the other two. DO NOT rev up engine with light connected, as the voltage rise WILL blow out test light bulb! Remember that there is a potential 40vAC (30vDC) capability, available within this system. Your test light will turn into one of those "flash bulbs," mentioned earlier! ----------------------------------Honda's "Race-kit" YB Racers-------------------------------When Honda produced its CB72/77 250-305cc twins in 1961, they were just coming off their successes at the Isle of Man. Honda was very serious about establishing a name for their products, both in the racing world and in the showroom. They even had their CR71/76 production racers approved by the AMA in 1960. However, there weren't enough of these rare models to fill the need for aspiring racers, so with the release of the CB72 in 1961, there was a selection of "YB 97 Honda 250-305 Super Hawk Restoration & Maintenance Guide race-kit" parts made available to convert those high-revving street bikes into serious productionbased road racers. During the 60's, the "YB" parts designation (usually with an "-810" part number suffix) generally meant that those parts were optional "accessory high performance racing parts." Because these models were too new for the "aftermarket" to be able to supply accessory parts, Honda designed and sold these parts, individually and in complete kits, through their dealer network to convert their street bikes into "modified production racers." There were also parts to convert Super Hawks into "Scramblers," prior to the CL72's release. Honda claimed that the "24 H.P." 250cc CB72 would reach 96MPH in standard form, which was performance unheard of for a 350lb four-stroke twin in those days. Although redlined at 9,500 rpm, poor-quality valve springs prevented many of the engines from revving up to or past their 9,000-rpm power peak. So, some of the first parts to be installed in the head were a set of the "YB" racing valve springs. Although the racing springs only had an extra 8-9 lbs pressure, a fresh set would allow the engine to turn up to 10,000 rpm's with stock camshaft profiles and to 12,000 rpm with YB racing cams. Yes, there were factory-designed "YB" camshafts, which featured stock valve lift, but offered 20 degrees more intake duration and 15 degrees more exhaust duration on their lobes. The rest of the engine treatment consisted of a special clutch basket, with an alloy sprocket attached and an altered primary chain sprocket ratio. There were some "YB" clutch springs to help clamp the clutch assembly together at elevated engine speeds. Two close-ratio "racing-only" transmission gear sets were offered briefly, as well. A close-ratio 4-speed or a close-ratio 5-speed transmission helped keep the engines up on the power band on the track, but they were useless on the street, because of extremely tall first-gear ratios. The low-budget trick for the stock transmission was to "X" (cross) the center gears on the transmission shafts, altering the ratios slightly. Otherwise, Honda was content to use the stock crankshaft, pistons, valves and cylinder head for maximum reliability. Some "racing carburetors" were listed as available, but they were simply re-jetted standard parts. Some photos have been seen, showing a set of magnesium Keihin CR carburetors attached to a CB72/77 engine, but they were probably units from the DOHC CR72/77 models. Something that DID seem to make a significant difference was a pair of long, curved, cast-aluminum air horns (air funnels), which clamped on the end of the stock carburetor mouths. When the cams, springs, air funnels and optional bolt-on megaphones were all working together, the increase in power (and noise) was substantial. Honda data sheets claim 32HP at the transmission, with a fully modified CB72 engine at 10,500 RPM. The 600mm long megaphones were made in two forms, the most common being the conventional round, tapered, and reversecone megaphone. But for the "European Racing Rules" there were special "D-shaped (or flat- 98 Honda 250-305 Super Hawk Restoration & Maintenance Guide sided) megaphones, which offered more ground clearance, when the machine was heeled way over. The product code for the D-shaped megaphones is 269, not 268. Most of the "YB" parts were designed to modify the already-nimble chassis even further. First, the riding position, which was pretty "racy" with the standard flat handlebars, was lowered even more with the installation of "clip-on" handlebars. These were available in two sizes to match the different sizes of fork tubes offered on this model. To install the clip-ons, the upper fork covers (headlight fork ears) had to be removed. This left the speedometer, normally mounted in the headlight shell, nowhere to go, so Honda created a racing upper fork crown (fork bridge), which actually replicated the original '61 design, which held the speedometer in a oval ring, cast as a part of the fork bridge. The handlebar mounts of the standard '61 part were eliminated, however. This fork bridge allowed the use of the stock meters, while eliminating the headlight assembly altogether. The lower fork covers, formerly held in place by the upper fork covers, were then held in place by small circular clamps that slipped down over the fork tubes and were secured by a pinch-bolt arrangement. Above these clamps, the optional front racing number plate bracket could be installed. A small bolt-on stop plate stopped the clip-ons from banging into the tank at full lock. Then, if desired, the speedometer cable could be removed and a special dust cap installed over the end of the speedometer drive connector, leaving only the tachometer to function. The stock location of the tachometer was somewhat difficult to see during racing conditions, so some racers used to mount CB92 or CR71 racing tachometers higher up in the line of sight. CB92 tachs read to 14,000 RPM, while the wild CR71 meters read up to 18,000! A full set of appropriate length cables were available to accommodate the "clip-on" handlebars reach. Although the frames and forks of all CB72/77 models were equipped with a friction-type steering damper, there were special fasteners created to mount a hydraulic steering damper from the upper engine mount bolt to a special fork-stem mounting bolt. This system was also used on the CP77 Police models. The upper engine mount bolt is a particularly unique machined part. Here is what you need to create and install the hydraulic steering damper: Honda CYB77 steering damper installation parts for Police or Racing application. Ref No. 1 2 3 4 5 6 7 8 9 10 Part No. 12441-268-810 12445-258-810 50371-268-810/820 90105-268-821/831 90521-268-810 53703-268-810 53702-268-810 90519-268-810 53731-268-810 53700-268-810 Description Req’d. Qty CAP, Tachometer for CYP77 1 PACKING, Tachometer for CYP77 1 PLATE, handle stopper 1 BOLT, Engine Hanger 1 WASHER, Plain 6mm 1 BUSH, Damper Rod End 2 BUSH, Rubber 2 WASHER, 11mm 1 RUBBER, Damper joint 2 DAMPER COMP, steering 1 99 Honda 250-305 Super Hawk Restoration & Maintenance Guide 11 12 13 14 15 16 17 53204-268-811/812 92300-06008 94001-06000 94001-08000 94101-08000 94201-12150 94201-20180 PIN, steering damper BOLT, hex 6mm NUT, Castle 6mm NUT, Castle 8mm WASHER, plain 8mm PIN, cotter 1.2x15 PIN, cotter 2.0x18 1 1 1 1 1 1 1 There was a set of racing alloy fenders offered. The front was probably the same as the original alloy front fender from the early 1961 editions, while the rear one was a racing-only piece that was "bobbed" (shortened) and fitted with a "wraparound" racing number plate bracket. Further enhancements to handling came in the form of a set of “DID” deep-shouldered, alloy, wheel rims of standard width, which could be fitted with a "racing rim lock." A distinctive solo "racing seat," featuring a noticeable hump in the rear and covered with a suede-like vinyl upholstery, was made available in lengths to fit both the '61 and the '62-later models. In order to be comfortable in that racing seat, there were two different sets of optional rear-set foot pegs and mount bolts, which would accommodate a wide variety of racing positions. There were three different-length shift rods to reconnect either the stock or "racing" shift levers back to the engine's shift shaft arm. One of the shift levers was similar to a CL72 lever turned around backwards, which reversed the standard shift pattern. A special "racing" rear brake pedal was also used in conjunction with one of the "racing" foot peg sets, to align the rear brake cable end properly. Rear sprockets from 28-37t (steel or alloy) & front sprockets of 12-15t could be used. 100 Honda 250-305 Super Hawk Restoration & Maintenance Guide Front fork action could be improved with a change to heavier fork oil and a set of optional "YB" fork springs. At the rear, installation of some aftermarket rear shocks, like "Red Wing" (Japanese), Girling - Hagon (from the UK) and others were substantial improvements over the OEM "spring hangers," that came as standard equipment. There was a set of "YB racing" rear shocks, but they were probably just standard shocks with the available stiffer rear "YB racing" shock spring. The multi-piece "bakelite" swing arm bushings should be replaced with machined bronze units. The charging system could be eliminated, too, with the use of the optional timing index wheel and timing piece (pointer plate), replacing the standard rotor and stator. This left the ignition dependent upon a total-loss system, which was generally suitable for brief racing sessions. The standard stator could also be rewired into an E.T magneto, with use of A.C. ignition coils, as a self-powered ignition system. In the mid-60's, Joe Hunt Magnetos, known for automotive racing magnetos, designed a crankshaft-mounted magneto for the CB72/CB77 engines. A few "YB" engine bolts were used, either to mount the special chassis parts and/or were drilled for safety-wire, to meet racing regulations. To save weight, the electric starter, solenoid and wiring was often removed and the starter hole covered up with the "YB" Sub cover, which was the stock "CL72/77" Sub cover, although some early parts were made of aluminum, instead of the later stamped-steel items. The “classic” 305 hop-up kit consisted of the WEBCO 350cc bore kit, which featured unique L-shaped “Dykes” top compression piston rings encircling the 64mm Forgedtrue Pistons that were part of the package. WEBCO offered valve and clutch spring kits, as well as the famous Harmon-Collins roller rocker camshaft kits, plus lightweight exhaust systems and other racing accessories. For the modern vintage racing enthusiast, there are a few remaining options for creating a competitive racer. Mega-Cycle Cams is still grinding several different high performance cam profiles and can supply valve springs, too. Powroll Products, in Oregon, used cast "Jahns" pistons in 64mm (and matching 65mm head gaskets) to bring the displacement out to 350cc, but these are now extinct. Honda CB350 & XL175 pistons can be made to work, as well as Kawasaki KZ650 parts, with some judicious modifications. Italian-made racing pistons utilize standard CB350 ring sets and are available in the UK. Les Barker at the Vintage Advantage offers titanium oversized valves and new materials for cam chain tensioners and guide rollers, among other racing products and services. Mark McGrew at M3 racing has slipper-style tensioners available. 101 Honda 250-305 Super Hawk Restoration & Maintenance Guide Bore x stroke possible combinations for the CB77 60 x 54 = 305.3 61 x 54 = 316 62 x 54 = 327 63 x 54 = 336.6 64 x 54 = 347.4 65 x 54 = 358.37 66 x 54 = 369.5 70 x 54 = 415.6 71 x 54 = 423.7 Several engines have been stretched out to 500cc, but this requires tremendously skilled machine work and creativity. Automotive breaker-less ignition systems can be adapted to run off of the crankshaft or we have the option of the new battery-powered PROBE-Engineering magnetically-triggered system, which eliminates the standard points and condenser. Alloy/fiberglass tanks and seats are made in the US, England and Japan. NOVA makes reproduction YB 5-speed transmissions in the UK. Endless heavy-duty camchains can be used from the early CB350-CB750s, which share the 219-94 link camchain dimensions. Numerous racing shops, nationwide, specialize in valve and port work and can rework the cylinder head breathing capabilities to maximize the power potential of these engines. Falicon Crankshafts, in Florida, can lighten and rebalance the crankshafts for racing purposes. "Aircone" in Las Vegas, NV can roll up megaphones in any size. Early-style CB750 individual carburetors seem to be very effective at feeding a 350cc version of the CB77. A specialty company in Japan, called Honda Revival is remaking many CB72/77 racing parts including: stainless megaphones, piston kits, fuel tanks/seats/fairings and even magnesium DLS and 4LS brake kits! Tony Milk, in the UK makes scooped brake backing plates and a host of other racing bits. With today's technology (and a lot of money), you can still create the racing Super Hawk of your dreams! Whether you choose to restore your bike to original specifications or build a full-bore racer, you'll find that your bike will receive an amazing amount of attention and comments from the "40-50 something crowd," who grew up with these legendary bikes, as their "first bike." The Honda CB72/77 models were an outstanding engineering achievement in the 60's and the enthusiasm for them continues to grow, even today. A few of these racing parts are still floating around in Honda's vast inventory system or are in the hands of enthusiasts. Most part numbers have been discontinued and/or the supplies have been exhausted. A race-kitted CB72/CB77 is a sight to behold and a number are being actively campaigned in vintage roadracing clubs around the world. The sight and sounds of these unique production-based bikes are unmatched anywhere. Honda has never supplied these kinds of parts for any of their street bikes, since the CB72/CB77 series. Sadly, with the advent of product liability lawsuits, skyrocketing costs and a declining interest in this form of racing, these kinds of parts will be not offered again. 102 Honda 250-305 Super Hawk Restoration & Maintenance Guide (CYB Accessory Racing Parts) Sub Cover 11381-273-000 (CL) Pri. Dr. Spkt. 14t 13611-268-810 Camshaft 14111(121)-268-810 Rt & Lft Valve Spring, outer 14751-268-810 (4) Valve Spring, inner 14761-268-810 (4) Carburetor 16100(102)-268-810 22mm Air Funnel 17261-268-810 Air Funnel Clamp 17265-268-810 Throttle Cable 17910-268-810 Stay, A Ex. 18236-268-810(CL ex)** Stay, B Ex. 18237-268-810(CL ex)** Cover, Lt. Ex 18240-268-810 Band, Cover 18242-268-810 Cover, Ex. Pipe 18260-268-810 Megaphone Rt/Lt 18310(330)-268-810 Band, Diffuser 18311-268-810 (2) Round, tapered, reverse-cone *600mm Pri, Drvn. Spkt. 41t 22104-268-810 Megaphone Rt/Lt 18310(330)-269-810 Clutch Outer 22100-268-810 "D" shaped (flat-sided) 600mm* Clutch Center 22212-268-810 Clutch Friction Disc 22201-268-810(5) Clutch Spring 22401-268(275)-810(4) Clutch Cable 22870-268-810 Primary Chain 23121-268-811 Shift Pedal 24701-268-810 Shift Pedal 24702-268-820 Shift Rod A 24730-268-820 270mm Shift Rod B 24732-268-811 147mm Shift Rod C 24733-268-811 210mm Index Timing 30901-268-810 Timing Piece 30907-268-810 AC Dyn Assy 31100-268-810# AC Rotor 31101-268-810 (#) Cover, Lt. Ex pipe 32110-268-810 (CL)** Harness, wiring 32102-268-810 (CP) Tachometer (CB92) 37250-205-810 Tachometer (CR71) 37250-265-000 Rim Rear 42701-268-830 Tire Rr 42711-268-830 Rim Lock 42715-268-810 Rim Frt. 44701-268-830 Tire Frt 44711-268-830 Brake Cable 45450-268-810 Brake Pedal 46500-268-810 Stay, Rear # Plate 50365-268-810 Plate Handle 50371-268-810early Plate Handle 50371-268-820 late Bar, Sidestand 50530-268-810 Spring, Sidestand 50542-268-810 Rubber, Sidestand 50543-268-810 Rt Step Arm 50630-268-820 Rt Step Arm 50630-268-830 Lt Step Arm 50640-268-820 Lt Step Arm 50640-268-830 Rt Step Rubber 50661-268-810 Rt Step Rubber 50661-268-820 Lt Step Rubber 50662-268-810 Lt Step Rubber 50662-268-820 Ft Cushion Spring 51401-268-810 "early" Ft Cushion Spring 51401-268-830 "late" Ring, Cover 51619-268-810 "early" Ring, Cover 51619-268-811 "late" Rear Cushion 52400-268-810 Rr Cushion Spring 52401-268-810 103 Honda 250-305 Super Hawk Restoration & Maintenance Guide Rt Handlebar 53100-268-810 early Rt Handlebar 53100-268-811 late Lt Handlebar 53120-268-810 early Lt Handlebar 53120-268-811 late Collar, Handlebar 53136-268-810 Bolt, Cable Adjust 53192-268-810 (1mm insert in early-style bars) Pin Damper 53204-268-812 Fork Bridge 53230-268-810 Bush Rubber 53702-268-810 (2) Bush Damper Rod 53703-268-810 (2) Rubber, Damper 53731-268-810 (2) Damper, Steering 53700-268-810 or Knob Damper 53740-268-810 Damper, Steering 53700-273-000 or Fender, Front 61100-268-810 Damper, Steering 53700-310-000 Stay, Frt # Plate 64231-268-810 Early Stay, Frt # Plate 64231-268-811 Late Racing Seat 77100-268-600A '61 Racing Seat 77100-268-601A (506A)'62-on Fender Rear 80100-268-810 Bolt Dyno Cvr 90081-268-810 (3) Bolt Eng Mount 90105-268-821/831 Bolt Sidestand 90108-259-000 (use with CL steering damper) Bolt, Left Main Stand 90146-268-810, Bolt Step Arm 90152-268-810/820 (2) (use with sidestand brkt) Washer 11mm 90519-268-810 Washer 6mm 90521-268-810 Note: Early: 37-8mm forks before CB72F-311006/CB77F-311503 Late: 33mm forks from the above frame numbers and later. *CR72/77 megaphones are 760mm long. # "Low-output" model **(CL ex) CL pipes mounted on CB chassis ****************************************************************************** WEBCO 350cc KIT INSTALLATION INSTRUCTIONS WEBCO 350 KIT SERVICE BULLETIN While our 350cc conversion kit has given completely satisfactory results for the vast majority of our customers, the fact that we now have so many kits in service has brought to light a few problems. The majority of these problems can be traced directly to insufficient lubrication, and as a result of studies made, we have incorporated some minor changes in the latest version of the 350 kit. These make the pistons less sensitive to marginal lubrication, and insure that there is some oil in the bores at all times. The new pistons have oil-holding grooves in their skirts; and oil feed holes have now been provided in the cylinder sleeves to apply oil directly to the pistons. Basically, the service difficulties with the 350 kit stem from the fact that the Honda engine’s oil pump delivers a very limited amount of oil. This is because all of the engine’s crankshaft bearings need only a trickle of oil. Indeed, too much oil is not good for this type of bearing, and that is the reason for the limited pump output. Unfortunately, this results in relatively 104 Honda 250-305 Super Hawk Restoration & Maintenance Guide little oil being thrown from the crankshaft up into the cylinders, and in the Honda engine the bores tend to run a trifle dry. In the stock engine this is relatively unimportant; there is enough oil, and that is all that matters. However the increase in power provided, by the installation of the 350 kit, reduces the margin of safety and unless the pump is working at maximum capacity, the margin may be entirely overstepped. There are measures you may take to prevent this from happening. Before installing the 350 kit, remove and disassemble the engine’s oil pump. If there are signs of scoring or wear, replace the affected parts before going farther. Moreover, even if the pump looks good, check the clearances between the pump gears and the case. There should be no more than .004” between the tips of the pump gears and the pump housing, and no more than that between the sides of the gears and the pump body side plate. It is preferred that the side clearance be no more than .0025” (minimum is given in the Honda Maintenance Manual as .0015”). Also inspect the pump gear spindles for wear, and make very sure that there is no place where the pump could be pulling in air instead of oil. When the 350 kit is being installed in an engine that has been in service a longtime, or one that has suffered some kind of mechanical disaster, very carefully flush out all of the oil passages. Bits of metal and/or hard carbon floating around in an engine’s oil supply will do terrible things to the Honda oil pump, which has a soft aluminum body. The oil filter should be cleaned, too, and this cleaning must be repeated regularly when the engine is back in service. (See the owner’s manual for this.) Honda’s recommendations for oils are marked on the engine’s crankcase by the filler opening. For ambient temperatures, below 60 F., they recommend 20W; above that, 30W. We would go further and ask that 40W oil be used in the warm summer months, when ambient temperatures may be above 90 F. When running the 40W oil, give it time to warm and begin circulating in the cool mornings before you ride off under full throttle. Finally do not neglect changing oil at the intervals specified in your owner’s manual, and check the oil level regularly. Should the oil level fall too low, the pump will pull a whirlpool in the oil and change to pumping air. While a good blast of air is just what we need outside the engine, the pump will not move enough air to cool the engine appreciably inside, and the air will be an exceedingly poor lubricant. Note: Dealers and Mechanics: When re-sleeved, the cylinder block is refaced in order to square the cylinder with the block. This refacing process shortens the cylinder, causing too high compression, thus a rough running engine 105 Honda 250-305 Super Hawk Restoration & Maintenance Guide and shorter engine life. Or the piston will possibly bang against the head. In order to compensate for this shortened condition, an additional gasket is possibly required. Stated simply: 1. Cylinder Height: If under 3.275 inches you should use two (2) cylinder base gaskets. 2. Compression Pressure: This should be checked very accurately. The cranking pressure with the throttle open should be 140 lbs min. to 160 lbs. max., regardless of the type cam used. Consideration of these two factors will lessen the possibilities of breakdown and will prove highly beneficial in the wear and tear of your engine. CHASSIS RESTORATION RUBBER PARTS (Not including Engine Oil Seals, O-Rings or Carburetor parts) 15761-259-000 Tube, Breather 16230-268-000 Tube, Air Vent (2) thru CB77E 110380 16230-268-010 Tube, Air Vent (2) 16234-268-000 Pipe, Power Jet (2) thru CB77E 110382 16234-268-010 Pipe, Power Jet (2) 16955-268-020 Packing A, Cock Valve 16958-268-010 Packing, Fuel Strainer Cup 17212-275-000 Plug, Air Filter 17253-268-030 Tube, Right A/C Filter 17353-268-030 Tube, Left A/C Filter 17257-268-000 Rubber, A/C Case Shock Proof (4) 17611-268-000 Cushion, Frt. Fuel Tank (2) 17613-268-030 Cushion, Rear Fuel Tank 17613-242-020 Packing Fuel Cock Joint Nut 17631-329-003 Packing, Fuel Filler Cap 17661-268-010 Rubber. Right Knee Grip 17662-268-010 Rubber, Left Knee Grip 18391-259-000 Packing, Muffler (2) Sleeve 18391-254-000 Packing, Muffler (2) O-ring 24781-268-000 Rubber, Change Pedal 28218-268-000 Plug, Kick Joint Sealing 28307-254-000 Rubber, Kick Starter 31468-253-000 Cover, Battery Terminal 32162-268-000 Band B, Wire Harness 32163-268-000 Band C, Wire Harness 32983-268-000 Band A, Wire Harness 33709-268-000 Packing, Taillight Lens '61-'62 33709-268-810 Packing, Taillight Lens '62-on 33709-041-000 Packing, Taillight Lens CB77 1056084-on 37242-268-000 Packing, Speedometer thru CB77 20320 37242-268-010 Packing, Speedometer thru CB77 21361 37242-268-020 Packing, Speedometer 50524-268-000 Rubber, Main Stand Stopper 50543-268-810 Rubber, Side Stand Stopper 50661-268-810 Rubber, Step, Right 50661-268-000 Rubber, Step, Rear (2) 50662-268-810 Rubber, Step, Left 51622-268-020 Cushion, Frt. Fork Cover (2) thru CB77 311503 51622-268-030 Cushion, Frt. Fork Cover (2) 52145-268-000 Rubber, Rear Fork Dust Cap (2) 52484-268-000 Bushing, Rear Cushion (4) 53124-250-000 Seal, Dust, Steering Head 106 Honda 250-305 Super Hawk Restoration & Maintenance Guide 53165-205-000 Rubber, Grip, Right thru CB77 1043574 53165-283-000 Rubber, Grip, Right 53166-205-000 Rubber, Grip, Left thru CB77 1043574 53166-283-000 Rubber, Grip, Left 61302-268-010 Grommet 21mm Headlight Case thru CB77 21362 61302-268-020 Grommet 25mm, Headlight Case (2) 80121-268-010 Mudguard, Rear Fender 83634-268-000 Rubber, Battery Band 90755-268-000 Oil Seal, Front Fork (2) Type 1 90755-268-010 Oil Seal, Front Fork (2) Type 2 91304-107-000 O-Ring, Bolt Frt Fork (2) 95001-50140 Tube, Fuel 5x140mm 95001-50168 Tube, Fuel Reserve 5x168mm 95001-50190 Tube, Fuel 5x190mm ENGINE/CARBURETOR/FORK O-RINGS, SEALS & RUBBER PARTS 90000-259-000 Oil seal kit, complete 91201-259-000 Oil seal, right crankshaft 32x65x7.5mm 91202-250-000 Oil seal, shift shaft 14x25x7mm (same as below) 91202-250-000 Oil seal, kickstart shaft 14x25x7mm (same as above) 91203-259-000 Oil seal, countershaft 30x62x8mm 91204-200-000 Oil seal, shift drum (neutral switch) 22x54x5mm 91204-259-000 Oil seal, point shaft 16x28x7mm 91205-200-000 Oil seal, clutch adjuster 22x26x29x8mm 91205-259-000 Oil seal, clutch pushrod 8x21x6mm 91208-259-000 Oil seal, starting sprocket 20x30x5mm 91301-250-000 O-ring, oil gauge 22mm 91301-259-000 O-ring, oil filter cover 57x3mm (2)-early 91301-253-000 O-ring, insulator to head 28.5mm CB77 (2) 91301-268-000 O-ring, tach drive 14mm 91302-250-010 O-ring, valve cap 47mm (4) 91302-259-000 O-ring, oil filter cover, 79.5x3mm (1)-late 91302-PFO-003 O-ring, insulator to head 26.9x2.4mm CB72 (2) 91303-259-000 O-ring, cyl stud knock pin 11x2.0mm (2) 91304-259-010 O-ring, oil filter 48.6x16 91305-250-000 O-ring, transmission mainshaft 12.8x2.2mm 91309-700-010 O-ring, oil filter cover 74.5x8 (1)-late 14500-268-010 Tensioner, cam chain thru CB77E-1050998 (41mm) 14500-268-020 Tensioner, cam chain CB77E-1050998-on (32mm) 14611-250-310 Roller, cam chain guide 15198-259-020 Receiver, oil thru CB77E-311978 16129-268-004 Washer, float chamber (square) 16171-250-004 Washer, carburetor top CB72 early 16171-259-004 Washer, carburetor top CB72 late 16171-275-004 Gasket, carburetor top (2) 16172-253-004 Washer, float chamber (round) 16173-253-004 O-ring, carburetor to insulator 27x2.4mm CB72 (2) 16173-260-004 O-ring, carburetor to insulator 29x2.4mm CB77 (2) 16175-260-004 O-ring, air screw 2.8mm (2) 23170-259-000 Tensioner, primary chain 28218-268-000 Plug, kick starter joint sealing 28307-254-000 Rubber, kick starter 32951-250-000 Grommet, low tension cord (starter cable) 33714-268-000 Grommet, tail light cord 51521-268-010 O-ring, front fork bolt 12.4x2.4mm (2) 51522-268-000 O-ring, front fork 40.5x3mm thru CB77F-1030129 (2) " " " " " " " " " CB72F-1005227 107 Honda 250-305 Super Hawk Restoration & Maintenance Guide GASKETS 06110-268-000 Top end set thru CB72E-211811 06110-268-010/030 Top end set CB72 06110-275-000 Top end set thru CB77E-210900 06110-275-010/030 Top end set CB77 06111-259-000 Lower end set 11395-259-000 Clutch cover gasket 12251-268-000 Cylinder head gasket CB72 12251-275-000 Cylinder head gasket CB77 12191-259-000 Cylinder gasket thru CB77E-210900/CB72E-211810 12191-259-010 Cylinder gasket 12391-258-000 Gasket, cylinder head side cover (2) 12391-259-000 Gasket, cylinder head cover 14591-258-000 Gasket, cam chain tensioner 15759-259-000 Gasket, breather shield plate FASTENERS 31203-253-003 Circlip, starter motor sprocket Kokusan (1) 31203-253-004 Circlip, starter motor sprocket Nippon Denso (1) 33102-200-000 Screw, 3mm, headlight ground wire (1) 35152-268-000 Nut, Light switch (1) 35153-268-000 Washer, Light switch setting (1) 35154-268-000 Bolt, Light switch (1) 61321-268-010 Spring, Speedometer (1) 1961 only 90008-268-010 Bolt, camshaft locking, (1) 90026-259-000 Bolt, Dynamo rotor (1) 90028-259-000 Bolt, kickstarter stopper (1) 90029-250-000 Bolt, kick spring clamp (1) 90031-259-010 Stud, A cylinder (2) thru CB72E-311733/77E-318672 90031-259-020 Stud, A cylinder (2) after " " 90031-268-010 Stud, C cylinder (4) thru CB72E-110426/77E-110426 90031-268-020 Stud, C cylinder (4) after " " 90034-268-000 Stud, D cylinder, thru CB72E-311733/77E-318672 90062-259-000 Stud, 8x116mm, (5) crankcase 90063-259-000 Stud, 8x128mm, (1), crankcase 90081-253-000 Bolt, Knock 6mm, (2), camchain roller guide pin 90105-268-000 Bolt, Engine Hanger (1) thru CB72F-11370/77F-10151 90105-268-020 Bolt, Engine Hanger (1) after CB72F-11370/77F-10151 90107-268-000 Bolt, Bottom rear shock (2) 90114-268-020 Bolt, Handle pivot (2) 90118-268-000 Bolt, Steer damper disc (1) thru CB72F-311005/77F-311502 90119-205-000 Bolt, Chain adjusting (2) 90121-268-010 Bolt, Rear Fork pivot (1) 90123-268-020 Bolt, Front Fork (2) 90124-268-000 Screw, Throttle grip adjusting 90126-268-000 Bolt, Front brake stopper (2) (Type 1) 90126-268-010 Bolt, Front brake stopper (1) (Type 2) 90127-268-000 Bolt, Rear brake panel (1) thru CB72F-12468/77F-10380 90127-268-010 Bolt, Rear brake panel (1) after CB72F-12468/77F-10380 90131-268-010 Bolt, Damper lock spring setting (1) 90133-268-000 Bolt, Rear brake stopper (1) thru CB72F-12468/77F-10380 90133-268-010 Bolt, Rear brake stopper (1) after CB72F-12468/77F-10380 90146-268-810 Bolt, Side stand setting (1) 90152-268-000 Bolt, Step arm fixing (2) 90154-268-000 Bolt, Headlight case setting (2) 90157-268-000 Bolt, Muffler fixing (2) 90205-259-000 Nut, Camshaft locking (1), thru CB72-213800/77E212680 108 Honda 250-305 Super Hawk Restoration & Maintenance Guide 90205-259-010 Nut, Camshaft locking (1), after " " 90206-250-000 Nut, Tappet adj. (4) 90231-259-010 Nut, Lock 20mm, (1) crankshaft 90241-259-000 Nut, Sealing 6mm, (1) 90281-259-000 Nut, Cap 8mm, (8) Cyl head 90303-268-000 Nut, Joint (1) petcock 90304-268-010 Nut, Steering head stem (1) 90305-268-000 Nut, Front Axle (1) 90307-205-000 Nut, Anchor Pin (1) thru CB72F-11548/77-10280 90314-200-000 Nut, Mirror locking (2) 90316-205-000 Nut, Anchor Pin setting (2) 90319-268-000 Nut, Steering Damper lock (1) 90321-268-000 Nut, Fixing (2) cable adjuster 90349-205-000 Nut, Lock 6mm, (1) RH thread 90349-268-000 Nut, Lock 6mm, (1) LH thread 90351-268-000 Nut, Self lock 10mm, (5) Brake cam thru CB72F-312195/77F-312672, upper motor mount 90354-268-000 Nut, Self lock 14mm, (1) swing arm pivot bolt 90356-205-000 Nut, Castle 8mm, (1) brake stopper bolt 90407-259(231)-000 Washer, 12mm, Drain cock packing 90416-250-000 Washer, (2) shift fork pin lock 90418-253-000 Washer, (2) shift arm spring 90423-250-000 Washer, (2) kick starter spring 90431-259-010 Washer, Lock 20mm, (1) crankshaft 90432-259-000 Washer, Lock (1) 6mm, pri. chain tensioner distance pc. 90441-259-000 Washer, Sealing, 8mm, (8) Cyl head (4) after CB77E-1005894 90451-258-010 Washer, Thrust, 7.5mm, (2) Tach gear 90451-268-000 Washer, Thrust, (1) k/s gear from CB72E-112091/77E-110381 90481-250-000 Washer, 6.5mm, (1) for 90241-259-000 90482-259-000 Washer, 8mm, (4) Cyl head after CB77E-1005894 90483-259-000 Washer, 14mm, (1) primary chain tensioner spring 90485-259-000 Washer, 9.5mm, (1) oil pump drive gear 90526-268-000 Washer, rear fork pivot (2) 90527-200-000 Washer, 10.3mm, (2) rear shock mount 90532-268-000 Washer, tongue 8.2mm, (2) front brake stopper 90537-268-020 Washer, front fork bolt (1) 90543-273-000 Washer, 6mm, fork drain (2) 90601-259-000 Set-ring, 11mm, (1) point shaft 90654-700-000 Ring, Snap 9mm, (1) oil pump gear 90672-268-000 Clip, 6mm, (2) brake stopper bolts 90741-253-000 Key, Woodruff 4mm, crankshaft (1) 91101-268-000 Roller, 4x10mm, (10) crank from CB72E-112069/77E-110281 91103-259-000 Roller, 10.2x11.5mm, (3) starter clutch 92000-06008 Bolt, Hex 6x8mm, (5) tank panel, exhaust diffusor, chain guard 92000-06010 Bolt, Hex 6x10mm, (9) fork drain (Type 2), A/C mount, chain guard, 92000-06012 Bolt, Hex 6x12mm, (26) primary tensioner spring seat, c/s spkt, shift drum stopper guide, oil separator, fork drain (Type 1), front fender (Type 1), A/C to mount, rear fender, coil mount, rectifier, solenoid, battery band 92000-06016 Bolt, Hex 6x16mm, (6) starting sprocket stopper, front fender (Type 2), side stand bracket 92000-06020 Bolt, Hex 6x20mm, (10) gear change arm, oil pump, starter motor, horn mount 92000-06022 Bolt, Hex 6x22mm, (4) brake arms w/pinch bolt 92000-06025 Bolt, Hex 6x25mm, (9) camchain tensioner, clutch springs 92000-0602502 Bolt, Hex 6x25mm, (2) handle lever bracket 92000-06030 Bolt, Hex 6x30mm, (1) pri tensioner distance piece 92000-06035 Bolt, Hex 6x35mm, (2) oil pump 92000-06040 Bolt, Hex 6x40mm, (1) crankcase 92000-06045 Bolt, Hex 6x45mm, (1) clutch adj. Piece 109 Honda 250-305 Super Hawk Restoration & Maintenance Guide 92000-06050 Bolt, Hex 6x50mm, (2) crankcase 92000-06070 Bolt, Hex 6x70mm, (2) crankcase, starter motor 92000-06075 Bolt, Hex 6x75mm, (1) crankcase 92000-08012 Bolt, Hex 8x12mm, (4) front fender (Type 1), rear fender 92000-08016 Bolt, Hex 8x16mm, (4) front fender (Type 2), side grip 92000-08022 Bolt, Hex 8x22mm, (2) upper muffler mount 92000-08028 Bolt, Hex 8x26mm, (1) kickstart arm 92000-0803002 Bolt, Hex 8x30mm, (5) handlebar holder, axle clamp 92000-08032 Bolt, Hex 8x32mm, (2) fork stem (Type 1) 92000-08038 Bolt, Hex 8x38mm, (2) fork stem (Type 2) 92000-08045 Bolt, Hex 8x45mm, (1) motor mount 92000-08075 Bolt, Hex 8x75mm, (2) muffler mount 92000-10018 Bolt, Hex 10x18mm, (2) step bracket 92000-10048 Bolt, Hex 10x48mm, (4) motor mount 92000-10055 Bolt, Hex 10x55mm (1) side stand bracket 92000-12038 Bolt, Hex 12x38mm, (2) pillion step 92700-06035 Stud, 6x35mm, (6), exhaust & cyl studs 92700-06040 Stud, 6x40mm, (4), carburetor & exhaust studs 92700-06103 Stud, 6x103mm, (3), crankcase 92700-06120 Stud, 6x120mm, (1) crankcase 92700-084930 Stud, Bolt 3x49mm, (4) axle holder (Type 2) 92700-0809630 Stud, 8x96mm, (2), crankcase 92700-0826735 Stud, 8x267mm, (2) cyl after CB72E-311733/77-318672 92700-0827335 Stud, C cyl 8x273mm, (2) after CB72E-311733/77-318672 92700-0828635 Stud, D cyl 8x286mm, (2) after CB72E-311733/77E-318672 92800-12000 Bolt, Draincock (1) 12mm 93500-03006 Screw, Cross 3x6mm, (2) starter motor brush 93500-0301002 Screw, Cross 3x10mm, (4) emblem after CB72F-311905/77F-312292 93500-04010 Screw, Cross 4x10mm, (2) tail light plate 93500-04020 Screw, Cross 4x20mm, (1) commutator cover 93500-04006 Screw, Cross 4x6mm, (2) Speedo packing 93500-05014 Screw, Cross 5x14mm, (1) Right switch 93500-0501602 Screw, Cross 5x16mm, (2) Left switch 93500-05012 Screw, Cross 5x12mm, (4) starter motor cover, point plate 93500-0502202 Screw, Cross 5x22mm, (1) Right switch 93500-06008 Screw, Cross 6x8mm, (2) rear fender mudguard 93500-06012 Screw, Cross 6x12mm, (3) neutral switch, starter cable clamp 93500-06016 Screw, Cross 6x16mm, (7) clutch cover, oil pump cover 93500-06020 Screw, Cross 6x20mm, (8) starter sprocket cover, rt. cyl head cover 93500-06025 Screw, Cross 6x25mm, (7) clutch cover, shift drum plate, starter clutch 93500-06030 Screw, Cross 6x30mm, (4) tach drive housing 93500-06035 Screw, Cross 6x35mm, (5) clutch cover 93500-06045 Screw, Cross 6x45mm, (1) clutch cover 93500-06060 Screw, Cross 6x60mm, (1) clutch cover 93500-06075 Screw, Cross 6x75mm, (1) clutch cover 93500-06115 Screw, Cross 6x115mm, (1) clutch cover 93600-06016 Screw, Cross 6x16mm, (7) wheel bearing retainer 93700-0306002 Screw, Cross 3x60mm (2) tail light lens 93700-0300802 Screw, Cross 3x8mm, (2) petcock plate 93700-0301002 Screw, Cross 3x10mm, (4) tank emblem thru CB72F-311905/77F-312292 93700-0501002 Screw, Cross 5x10mm, (2) headlight rim 93700-05016 Screw, Cross 5x16mm, (3) dyno cover 93700-05030 Screw, Cross 5x30mm, (2) point cover 93700-06020 Screw, Cross 6x20mm, (1) drive sprocket cover 93700-06025 Screw, Cross 6x25mm, (1) " " " 93700-06030 Screw, Cross 6x30mm, (3) right crankcase cover 110 Honda 250-305 Super Hawk Restoration & Maintenance Guide 93700-06040 Screw, Cross 6x40mm, (3) right crankcase cover 94001-03020 Nut, Hex 3mm (1) headlight ground wire screw 94001-05000 Nut, Hex 5mm (3) throttle grip screw, solenoid 94001-06000 Nut, Hex 6mm, (30) carburetor studs, cyl studs, camchain tensioner lock bolt, camshaft locking bolt, crankcase studs, rear fuel tank mount, brake pedal stopper bolt, side stand bracket, rear fender, chain guard, rear fender mudguard, brake rod, taillight bracket mount, rectifier, coil mount 94001-08000 Nut, Hex 8mm, (22) crankcase studs, stopper plate, lever bolts, axle holder (Type 2), motor mount bolt, muffler mount 94001-10000 Nut, Hex 10mm, (8) motor mount bolt, side stand, step mount, tool box 94002-06000 Nut, Thin 6mm, (2) air cleaner latch retainer 94002-10000 Nut, Thin 10mm, (2) rear shock bolt 94021-10020 Nut, Blind 10mm, (2) rear shock mount 94101-05000 Washer, Flat 5mm, (2) point plate 94101-06000 Washer, Flat 6mm, (10) kick spring clamp bolt, lever bolts, rear fender bolt, chain guard, rear fender mudguard 94101-08000 Washer, Flat 8mm, (16) axle holder (Type 2), side grip, seat bolt, muffler mount bolt, rear fender bolts, rear brake stopper bolts 94101-10000 Washer, Flat 10mm, (2) headlight mount bolt 94111-03000 Washer, Spring 3mm, (3) starter motor brush, headlight ground wire screw 94111-04000 Washer, Spring 4mm, (1) commutator cover 94111-05000 Washer, Spring 5mm, (2) solenoid 94111-06000 Washer, Spring 6mm, (29) camshaft locking bolt, camchain roller guide pin bolts, oil separator bolts, starter sprocket, stopper bolt, side stand mount bolt, air cleaner mounts, taillight mount, coil mount, rectifier mount, horn mount 94111-08000 Washer, Spring 8mm, (15) axle holder (Type 2), motor mount bolt, seat bolt, muffler mount bolt, brake stopper bolt 94111-10000 Washer, Spring 10mm, (11) motor mount bolt, step bracket, headlight mount bolt 95002-50000 Clip, Fuel tube (4) 96201-30000 Nipple, Grease 4.5mm, (6) step arm bolts, rear fork pivot, kickstart gear, clutch release 96211-08000 Ball, Steel 1/4" (38) steering head bearing 96211-10000 Ball, Steel 5/16" (1) clutch pushrod Note: Fasteners with -02 suffix on their part numbers have polished chrome finish. Otherwise, parts are usually finished with bright zinc plating. ==================================================================== 111 Honda 250-305 Super Hawk Restoration & Maintenance Guide 112 Honda 250-305 Super Hawk Restoration & Maintenance Guide 113 Honda 250-305 Super Hawk Restoration & Maintenance Guide 114 Honda 250-305 Super Hawk Restoration & Maintenance Guide 115 Honda 250-305 Super Hawk Restoration & Maintenance Guide 116 Honda 250-305 Super Hawk Restoration & Maintenance Guide 117 Honda 250-305 Super Hawk Restoration & Maintenance Guide 118 Honda 250-305 Super Hawk Restoration & Maintenance Guide 119 Honda 250-305 Super Hawk Restoration & Maintenance Guide 120 Honda 250-305 Super Hawk Restoration & Maintenance Guide CHANGE OF THREADED PARTS In an effort to obtain more universal uniformity of threaded parts, the JIS (Japan Industrial Standards) threaded parts standards have been modified to conform with those established by ISO (International Standards Organization). All Japanese industry, including Honda Motor Co., is cooperating in this change. Although the modifications of the present JIS system are not 121 Honda 250-305 Super Hawk Restoration & Maintenance Guide extensive, this change will require some new tools, different tool applications, and will introduce the possibility of non-interchangeability of similar parts. This changeover will be effective from the start of production of all new motorcycle models first produced after the beginning of 1967. In all other models, those previously in production, the changeover will be made gradually and on no set schedule. The following will describe the modifications and the effect they will have at the dealer level: 1. Changes in Thread Form The minor diameter of internal threads will be decreased slightly in all sizes. This change is very minor and will not affect interchangeability in any way. 2. Height of Bolt Heads There will be minor changes to the height (thickness) of bolt heads in several sizes. These changes will not affect interchangeability. 3. Thickness of Nuts The thickness of both common and thin nuts will be reduced in sizes 8mm and smaller. These changes will not affect interchangeability. 4. Width Across Flats of Bolts and Nuts The width across the flats of the hex (the wrench size) is changed for all nuts and bolts except 6mm. NOMINAL DIAMETER WIDTH ACROSS FLATS (WRENCH SIZE) (SIZE OF BOLT OR NUT) PRESENT JIS MODIFIED JIS (ISO) 3 mm 6 mm 5.5 mm 4 mm 8 mm 7 mm 5 mm 9 mm 8 mm 6mm 10mm 10mm 8 mm 14 mm 12 mm 10mm 17mm 14mm 12mm 19mm 17mm 14mm 21mm 19mm 16mm 23mm 22mm 18mm 26mm 24mm 20 mm 29 mm 27 mm New wrenches in the 5.5 mm, 7 mm, 12 mm, 22 mm, 24 mm and 27 mm sizes will be required for the modified bolts and nuts. All other sizes are currently in use. This change in hex size affects only the wrench sizes; interchangeability of bolts and nuts is not affected. 5. Changes in Thread Pitch The standard thread pitches for all bolts, nuts, and screws in the 3 mm, 4 mm, 5 mm and 12 mm sizes are changed as indicated below: NOMINAL DIAMETER THREAD PITCH (SIZE OF BOLT OR NUT) PRESENT JIS MODIFIED JIS (ISO) 3mm 0.6 0.5 4mm 0.75 0.7 5mm 0.9 0.8 12mm 1.5 1.25 These changes will affect the interchangeability of threaded parts in these sizes. Care must be taken to use the correct pitch to avoid stripping. These changes will also require new taps and dies. New tools, where required, will be available through parts department. To help avoid 122 Honda 250-305 Super Hawk Restoration & Maintenance Guide confusion in the 3 mm, 4 mm, 5 mm and 12 mm size, wherein the thread pitch has been changed, the modified JIS (ISO) threaded parts used by Honda will be marked such that they can be readily identified. The marks used are as follows: PART TYPE Standard Hex Bolt DESCRIPTION OF MARKING A number, indicating the strength of the bolt, will be embossed on the top of the bolt head. This mark will appear on modified JIS (ISO) bolts of all sizes; but as explained above, all sizes except 4 mm, 5 mm, and 12 mm (there are no 3 mm hex bolts) will interchange with the present JIS parts. Slotted Hex Bolt There will be a hemispherical embossment (bump) on the top of the bolt head in the 4 mm and 5 mm sizes (3 mm and 12 mm slotted hex bolts are not in use). Cap Bolt There will be a hemispherical dimple on the side of the bolt head in the 4 mm, 5 mm and 12 mm sizes (3 mm not in use). Stud Bolt There will be a hemispherical dimple or embossment on the nut end in the 5 mm and 12 mm sizes (3 mm and 4 mm studs are not in use). All Cross Screws Recess (Phillips) There will be a hemispherical embossment on the top of the screw head in the 3 mm, 4 mm and 5mm sizes (12 mm not used). All Nuts There will be a hemispherical dimple on either the top or side of the nut in all sizes with changed pitch. This will also apply to nuts that are permanently welded to other parts. All mechanics and parts department personnel should read and understand this bulletin, to avoid confusion and damage to threaded parts when the changeover occurs. Additional information relative to these changes (part numbers, tool numbers, etc.) will be published by the parts department. AMERICAN HONDA MOTOR CO., INC. MOTORCYCLE SERVICE DEPARTMENT Source: Honda Service Letter #74 6/8/67 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ CB77 #1 6/7/66 HONDA MOTORCYCLE SERVICE BULLETIN (Annotated) FUEL CAP VENTING BULLETIN To prevent fuel starvation and damage to the engine, due to lean fuel/air mixture, drill a second vent hole (1/16") opposite the existing vent hole, as near to the edge of the rim as possible. Check the cork gasket, by sliding it around, to ensure that one of the holes is open at all times. Note: Honda has replacement gaskets made from neoprene rubber. The replacement –402- code fuel caps are chromed steel and slightly thicker, but seem to be less prone to fuel leakage. =============================================================== 123 Honda 250-305 Super Hawk Restoration & Maintenance Guide CB77 #4 6/7/66 HONDA MOTORCYCLE SERVICE BULLETINS BREAKAGE OF THE RIGHT-HAND CRANKCASE COVER The possibility of breakage of the right-hand crankcase cover is lessened if the kickstart bushing and kickstart pinion bushing are lubricated on a regular basis. The grease fitting feeds the kickstart gear bushing. The pinion bushing can be lubricated by removing the rubber plug and applying a few drops of oil to the slot in the shaft. See Honda service bulletin #SL71 further on in this book for details of installing and adjusting the clutch adjuster thread correctly. ==================================================================== CA77 #1 6/12/67 HONDA MOTORCYCLE SERVICE BULLETINS "DREAMS" EXPERIENCING SECOND GEAR JUMPING To prevent the disengagement of the mainshaft second gear while driving, a special offset cotter has been designed to increase contact of the gear dogs. There are two types with different offsets as follows: Part No. Offset 702323-ASI 0.5mm (0.020") 23941-259-305 Offset 702323-AS2 1.0mm (0.040") 23943-259-305 In CA72/77 and CB72/77 engines, second gear jumping can usually be traced to damage of the shift drum or related parts. Please ascertain that no damage has been sustained by these parts, before installing the special cotters. Dog engagement should be at least 40%, when all backlash is taken up in the direction of disengagement. CA77 #1 6/7/66 HONDA MOTORCYCLE SERVICE BULLETINS MODIFIED DIMMER SWITCHES In order to comply with the legal requirements of several states, Honda Motor Co., LTD., is modifying the dimmer switches of all models to eliminate the "center-off" position. New switches will have instead a center position wherein both headlight beams are on at once. We wish to stress that this "double-center-on" position is necessitated by the design of the switch; the motorcycle should never be operated with the new type dimmer switch in the center position. If you have been instructing new riders in the use of the "center-off" position as an "emergency start" or "quick charge" position, please do not continue this practice. The new type switches will give the effect of a "quick discharge". Some of the owner's manuals make reference to the "emergency start" feature, and unfortunately these manuals cannot be rewritten for the USA only. We feel, therefore, that it is wise to specifically advise each Honda purchaser against any use of the dimmer switch center position. The possibility that a rider has been placing his dimmer switch in the center is also a good point to check on any machine with "dead battery" complaints. ===================================================================== 124 Honda 250-305 Super Hawk Restoration & Maintenance Guide SL #65 6/1/66 HONDA MOTORCYCLE SERVICE BULLETINS OIL SEEPAGE NEAR SPARK PLUGS IN ENGINES WITH ALUMINUM CYLINDER HEADS American Honda receives occasional complaints of the tendency for certain models with aluminum cylinder heads to seep a small quantity of oil near the spark plugs. In some cases, dealers have replaced cylinder heads in an effort to eliminate this seepage. This bulletin is intended to clarify our policy in relation to this problem, and to suggest some countermeasures that we have found to be effective. In cases where it can be confirmed that the spark plug sealing washers are not leaking, accumulation of a stain, or oil residue, near the spark plugs can be traced to oil seepage from the joint between the combustion chamber "skull" and the aluminum cylinder head casting. Since the spark plugs are threaded into the iron skull, rather than into the soft aluminum casting, this joint must "come to the surface" near the spark plugs. Although it is no mystery how oil reaches the outside of the engine, it is difficult to determine the source of the oil. Apparently, oil reaches the joint from the oil-bearing chambers through internal porosity in the aluminum casting; such porosity is extremely difficult to avoid. Once oil enters the joint, it has an almost unimpeded leak path to the outside because the skull is not bonded to the head casting. Our studies have shown that machines experiencing this problem can be graded into three broad categories, based on the severity; each category should be dealt with in a different manner: 1. A stain or oily residue collects near the spark plugs over a period of several days or weeks. Seepage of this magnitude should be considered a normal, inescapable consequence of the cylinder head design, and no repair should be attempted. Customers complaining of such seepage should be assured that no defect exists; suggest more frequent cleaning of the engine. 2. More severe seepage causes definite accumulation of liquid near the plugs; following a hard run, oil droplets or streaks can be found on the air cleaner covers, etc. Although a "defect" is not necessarily indicated by this seepage, countermeasures are often necessary to satisfy customers. We have found that seepage can be slowed or stopped in the following manner: a) Remove spark plugs and completely clean the region around the plug holes so that the joint between the skull and the casting can be seen. b) Using a dull punch, punch a ring of depressions, tangent to each other, in the aluminum immediately outside of the joint. 3. Liquid oil "bubbles" from the skull/head casting joint, puffs of vapor can be seen when the engine is suddenly accelerated. In these cases, a definite defect is indicated, i.e., actual separation of the skull and head casting. In most cases, however, the cylinder, rather than the cylinder head , is the faulty part. We have found this problem to be most commonly related to "sinkage" of the cylinder sleeve in the cylinder casting, such that the upper surface of the cylinder sleeve is below the upper surface of the cylinder casting. When this "sinkage" occurs, the 125 Honda 250-305 Super Hawk Restoration & Maintenance Guide combustion chamber skull is not forced into intimate contact with the cylinder head casting and severe oil or vapor leakage, near the sparkplugs can occur. The recommended repair is, of course, to locate and replace the faulty part. Source: SL #68 4/29/66 HONDA MOTORCYCLE SERVICE BULLETINS PISTON DAMAGE As spring and summer approach and Honda customers will be traveling more miles at higher speeds, it is important to review one of the problems which seems to give the rider, the dealer, and our Warranty Department more trouble than it should. This problem is piston damage from seizure (scoring and scuffing) and holes in piston crowns. The majority of the pistons damaged result from causes, which can be corrected by a good Hondamatic Dealer Service Department and a properly instructed Honda Owner. So let’s talk about causes and cures: Heat in one form or another is the primary cause of piston problems. If the excessive heat build-up is relatively slow, piston seizure results. If the excessive heat build-up is fast and has a place it can concentrate, we can expect a hole in the piston crown. Cause: TOO HOT A SPARK PLUG FOR THE RIDING CONDITIONS It is extremely important that both owners and mechanics be well aware that the extremes of temperature encountered between summer and winter, between slow and high speed, and between low and high load conditions, require a spark plug which matches the condition of load and temperature. It is important that both the owner and mechanic be completely familiar with at least two spark plugs for the machine in question; namely, one plug with a higher number for higher speeds, higher engine loads and higher temperature conditions, and one plug with a relatively low number for lower speeds, low engine loading and lower temperature operation. It must be understood that it is the combination of speed, loading, and outside temperature which determine the heat range of the spark plug to be used, rather than any one of the factors (in other words, even in freezing weather, a bike which is ridden at high speeds and/or high load conditions may require a relatively high plug number, NGK Numbering System). Cure: A general rule of thumb for choosing the right plug is to use the highest numbered plug, which will not foul (based on the premise that we would rather foul a plug than seize or hole a piston). In summation on plugs: teach your customers “a two-plug system” - (1) a high plug number for summer and/or hard riding, and (2) a low number plug for winter and/or slow riding. Cause: TOO LITTLE EXHAUST VALVE CLEARANCE An exhaust valve which cannot fully seat cannot get rid of its heat to the cylinder head and will then overheat and cause pre-ignition, which in turn overheats the piston and causes failure. Cure: Always be sure valve clearance is set to factory specifications outlined in repair manual. Cause: EXCESSIVE IGNITION ADVANCE This causes general heat build-up and contributes to pre-ignition, which in turn causes further heat build-up, creating a rather vicious circle ending in failure. Cause: EXCESSIVELY RETARDED IGNITION TIMING Retarded ignition timing can increase exhaust valve temperature, which in turn causes preignition and can cause a heat build-up and result in piston failure. Cure: Set ignition timing to factory specifications. Again, be sure that ignition timing is verified with a strobe timing light. While the above causes may be considered as the primary causes of piston failures, as related to a stock machine, we should also be aware that the following often contribute to the problem: 126 Honda 250-305 Super Hawk Restoration & Maintenance Guide UNAUTHORIZED modification of the intake or exhaust system, modification of the engine to raise the effective compression ratio, improper jetting of the carburetors, overloading the engine or “lugging”, and improper or insufficient lubrication. It is hoped that this information will result in at least two benefits at the dealer level: (1) reduced number of piston failures, and (2) better analysis of the causes of piston failure when it does occur. NOTICE: Warranty on Piston Damage: AHM-Warranty Department will not accept warranty claims for seizures or holes in piston crowns from a machine which has had the muffler system removed or modified in any way. Source: Honda Service Letter #33 3/15/67 Not mentioned in the above service letter is the effect of excessive oil consumption on the combustion process. If an engine is using excessive oil either through worn valve guides (remember that there are no valve stem seals on these engines) or from worn/broken piston rings, the extra oil that winds up in the combustion chamber will increase the tendency towards the detonation process. Excess oil is a fuel and a low octane fuel at best. It is great for two-strokes, but a diesel engine will literally “run-away” with itself, if an oil leak feeds into the intake system anywhere; the oil acting as a fuel source. The bottom line here is: If your engine is making visible blue smoke at idle or at full power, then it is a candidate for pre-ignition and/or detonation and adjustments to the ignition timing, in particular. Obviously, the best solution is to repair the source of the problem to begin with, but if you are nursing a bike along for awhile longer, then take time to retard the timing a little and perhaps increase the jetting to richen the mixture up, which cools the combustion temperatures somewhat and prevent piston seizures and holes in the piston crowns, too. ***************************************************************************** LOW OUTPUT DYNAMOS-DEALER PROCEDURE In an effort to increase battery and headlight life, Honda Motor Co., Ltd. is currently in the process of modifying all of the six pole dynamos on export models (except model C-l02) to lower output types. These changes seem to have gone unnoticed except for model CB-77; several dealers have been reporting low battery problems with this model, when the low output system is used. Although the low output dynamos are admittedly marginal in many cases, our experience and the experience of several dealers who have been dealing with these machines for several months, leads us to believe that the low output dynamos will work. Therefore, we suggest the following two-point program to assure the effectiveness of the dynamo modifications: POINT 1: DEALER PERFORMANCE We anticipate that most problems, with the low output dynamos, will occur due to battery overdischarging during the starting operation on electric-starting models. The major reason for hard starting is poor tuning by the dealer. Therefore, we must again stress the instruction give in our bulletins CB #103 and HM #103 regarding complete initial tune-ups for every machine. 127 Honda 250-305 Super Hawk Restoration & Maintenance Guide If the battery is not in top shape when the machine is sold, you cannot plan on the low output dynamo fully charging it. Incorporation of the low output dynamos makes the instructions for initial battery preparation given in our bulletin GM #116 even more important. Furthermore, dealers should carefully check all new machines for possible electrical trouble spots. For example, adjustment of the brake light switch should be carefully checked. Many new riders get into the habit of riding with their toe on the brake pedal; the brake light switch should be adjusted such that the brake light is not turned on under these conditions. Another easy to overlook point: check headlight aiming; lights should be aimed in such a way that use of low beam is encouraged under most riding conditions. POINT 2: RIDER INSTRUCTION Even the best-prepared machine can experience low battery problems if the rider is not aware of the proper starting and riding techniques. This is especially true of sport models such as the CB77, operation of which is outside of the experience of most new riders. Most dealers have found that, after the break-in period, little problem is experienced with the low output rotors. Comprehensive initial rider instruction can avoid most of the break-in period problems. Starting procedures should always be stressed; if the rider is left to learn these by trial and error, he will undoubtedly run his battery down a few times. The important points can be summarized as follows: 1.) A cold engine should be primed by kicking once or twice with the key off, choke closed. b.) When cranking electrically, the throttle should be kept almost completely closed, c.) When using the electric starter, do not crank over five seconds continuously, followed by a 20 second rest period. d.) If the engine has not started after about 15 seconds of cranking, use the kickstarter, e.) If the engine does not readily start, check for fouled spark plugs. f.) When starting a cold engine on a cold day, use of the electric starter is not to be recommended. The break-in period is a difficult time not only because the new rider may have starting difficulties, but also because the rider is apt to be keeping the engine speed very low; so low, in fact, that the battery may not be charged. Some problems may arise here because of misinterpretation of our break-in speed recommendations. Maximum break-in speeds should not be thought of as absolute maximums. They are intended to be maximum continuous speeds. It is definitely beneficial to exceed these speeds momentarily on occasion. As important as the maximum speeds are, so is a set of minimum speeds. This is particularly true of sport models. A new rider should be cautioned to avoid “lugging” at all times. One penalty of owning a sport model, such as the CB-77, is the necessity of keeping the engine speed above a certain minimum value. Each new CB-77 rider should be cautioned to avoid riding at engine speeds below 3,500 RPM. In fact, we recommend that engine speeds between 4,000 and 6,000 RPM be maintained, even during break-in. 128 Honda 250-305 Super Hawk Restoration & Maintenance Guide If you have been advising your customer to turn their light switches on and place their dimmer switch in the center position, as an “emergency start” or “quick charge” measure, this practice should be stopped. All dimmer switches are being modified such that there is no more center-off position. With the new switches, in the center position both headlight filaments are on. Riding with this type of switch, left in the center position, will “quick discharge” the battery. All customers should be cautioned to keep the dimmer switch in either one position or the other, never in the center. In concluding, we would like to caution against making low output dynamos a scapegoat for other problems. If the particular machine has an electrical defect, find it and correct it; do not blame the dynamo, If your organization is not geared to conduct the proper initial preparation of each new machine, and new rider, improve your organization; do not blame the dynamo. If these dynamos are not workable we will modify them, but they must be given a fair chance to work. AMERICAN HONDA MOTOR CO., INC. 9-125 Service Department ==================================================================== SL #18 1/18/74 RECOMMENDED FRONT FORK FLUID AND CAPACITIES American Honda recommends the use of ATF (Automatic Transmission Fluid) in front forks of all Honda motorcycles. ATF is superior to 10w/30 motor oil for use in telescopic forks because it does not become aerated as motor oil during fork operation. Also, fork seals tend to have longer service life when ATF is used. Honda motorcycles of current manufacture are shipped from the factory with the correct volume of ATF in the front forks. The front forks should be drained and refilled after the first 1500 miles of operation. Thereafter, front fork fluid should be changed every 12 months, or 6000 miles, which ever occurs first. AMERICAN HONDA MOTOR CO., INC. Motorcycle Service Department +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ SL #24 8/10/66 ALLOY FORK ASSEMBLY *To facilitate maintenance and to reduce weight, the bottom cases of the front forks have been changed from carbon steel to aluminum alloy on certain models. *Assembly of alloy units differs from the steel type, and the following procedures should be adhered to in order to prevent fork misalignment leading to possible rider injury: CB77 & CB72 *Place the speedometer cable drive unit into the right side of the wheel hub by fitting the dogs on the speedometer gear housing into the slots in the wheel axle housing. *Position the front wheel assembly between the front forks so that the brake panel is adjacent to the left fork; Insert the axle through the axle holders and wheel hub from the left side. *Align the brake panel anchor arm and secure with bolts. Crimp the lock tabs against the bolt heads. *Tighten the axle nut. Tighten the right axle holder nuts and then the left holders nuts, in that order. AMERICAN HONDA MOTOR CO., INC. Service Department 129 Honda 250-305 Super Hawk Restoration & Maintenance Guide TROUBLE SHOOTING From the Honda 250-305 Service Manual Procedures of diagnosis for finding out causes of trouble and their probable causes are described as follows: 1. Engine does not start or hard to start (1) Remove the carburetor float chamber and check for fuel flow, if fuel is not supplied enough; 1. Clogged fuel line 2. Clogged fuel tank cop vent hole 3. Clogged fuel cock 4. Clogged carburetor line or stuck needle valve (2) Remove the spark plugs, attach them to the spark plug caps, turn on the ignition switch and rotate the crank shaft with starter motor, while the electrodes are grounded. If the spark plugs do not spark well or no spark occurs 1. Faulty spark plug, (to make sure, check the spark plug with spark plug tester or replace with new one.) 2. Sooty or wet spark plug 3. Dirty contact breaker point 4. Faulty condenser or wiring connections 5. Incorrect adjustment of contact breaker point 6. Short circuit or breakage in ignition coil or wiring 7. Damaged combination (ignition) switch (3) Check compression pressure at the cylinder with a compression gauge. If low or lacks compression in either cylinder, check 1. Incorrect tappet clearance 2. Incorrect seating of valves in valve seats 3. Excessive wear in valve 4. Excessive wear in piston ring, piston cylinder 5. Blown out cylinder head gasket 6. Seized valve in valve guide 7. Broken rings 8. Faulty valve timing (4) Start engine following the procedure of starting, but engine seems to start but won’t continue running; check for: 1. Incorrect choke setting 2. Incorrect setting of carburetor idle airscrew or idle speed screw 3. Damaged carburetor insulator or gasket 2. Engine does not develop full power Stand the motorcycle on the main stand and rotate the rear wheel by hand when gear is set in neutraI, if wheel does not turn easily; 1. Dragging rear brake-incorrect adjustment 2. Damaged wheel bearing 3. Too tight drive chain tension, incorrect adjustment 4. Check the tire air pressure and inflate to the specific amount. 5. Check the clutch for slip and if it is found slipping; (a.) Improper adjustment of clutch (b.) Worn clutch facing or warped steel plates (c.) Weakened clutch springs (4) Measure the highest revolutions of crankshaft with a tachometer. If the engine does not develop full revolution; check for: 1. Dirty or improperly adjusted carburetor 2. Clogged air cleaner 3. Insufficient supply of fuel to the intake 4. Clogged muffler 5. Faulty ignition coil or contact breaker points 6. Faulty seating of valve 130 Honda 250-305 Super Hawk Restoration & Maintenance Guide 7. Incorrect ignition timing 8. Excess weak valve springs 9. Faulty spark plug; test the spark plug with spark plug tester (5) Check oil level in the crankcase and adjust the level to the specification, too little or an excess amount of oil can result in trouble. (6) Inspect for excess heating of engine; 1. Excess carbon deposits in combustion chamber 2. Inferior grade of fuel is used 3. Slippery clutch 4. Lean air-fuel mixture; improper size of main jet in carburetor, low float level 5. Dirty cylinder and cylinder head (7) Check for the engine developing or knocking during quick acceleration or successive running at high speed and if it is so; the probable causes are came as No. (6) 3. Engine runs erratic and/or with mis-firing (1) Adjust air screw of carburetor properly and if it still runs under same circumstances. 1. Faulty ignition timing 2. Damaged carburetor insulator or packing 3. Faulty spark plug 4. Faulty condenser 5. Faulty ignition coil 6. Faulty contact breaker point 7. Incorrect tappet clearance (2) Check for missing at high speed and if the engine is still under the same. 1. Insufficient supply of fuel 2. Incorrect valve timing 3. Damaged or weak valve springs 4. Other causes mentioned in No. (1) 4. Excessive oil consumption or exhaust blue or black smoke (1) If the engine exhausts smoke while continuous running at high or low RPM. 1. Worn cylinder or piston rings 2. Piston rings installed upside down. 3. Broken rings 4. Excess clearance between exhaust valve and guide (2) If the engine exhausts smoke just after when closing throttle valve suddenly from certain opening 1. Excess clearance between inlet valve and guide 2. Clogged air vent hole or plastic tube 5. Clutch jerks or engages abruptly (1) If the machine moves off with jerking or the engine stops at the moment when the clutch is engaged. 1. Uneven tensions of clutch springs 2. Distorted clutch plates or facings 3. Sticky movement of clutch plate in the clutch outer or inner 6. Gear shifting does not operate correctly (1) When the changing gear does not engage. 1. Worn notch on the shift drum 2. Stuck shift fork to the shift drum 3. Worn shift fork 4. Broken shift drum 5. Bent shift arm (2) If the gear jumps out while running 1. Worn dogs on the gear shifter 2. Worn or distorted shift fork 3. Worn groove in shift drum 4. Worn gear cotters 5. Weakened shift drum stopper spring 7. Engine runs with unusual noise when the tappet clearances are adjusted correctly: 131 Honda 250-305 Super Hawk Restoration & Maintenance Guide (1) If knocking noise is heard from cylinder when accelerating engine. 1. Excess clearance between cylinder and piston 2. Worn wrist pins or small end of rod (2) If chattering noise is heard even if the cam chain has been adjusted 1. Excess worn cam chain 2. Worn camshaft sprocket or loose rivets 3. Excess worn cam chain tensioner spring or roller (3) When knocking noise is heard from crankcase. 1. Worn crank shaft big end 2. Worn crank shaft bearing (4) Clutch makes noise when operating clutch lever. 1. Excess clearance between the clutch plate and clutch outer 2. Excess clearance between the clutch center and clutch plate 8. Troubles in steering (l) If it is felt that the steering is hard at turning 1. Over-tight steering ball races 2. Damaged steering 3. Tight or sticky steering damper 3. Bent steering stem (2) Steering wanders or pull to one side while running. 1. Worn front and/or rear wheel bearing 2. Bent front fork, frame or rear fork 3. Distorted front and/or rear wheel rim 4. Loosened spokes 5. Worn rear fork pivot bushing or front arm pivot bushing 6. Bent front fork or frame or rear fork 7. Incorrect rear wheel alignment 8. Uneven strength of cushion springs on one side 9. Troubles of brakes (I) The brake does not actuate properly even after the free play is adjusted properly 1. Worn brake shoes (may be glazed) 2. Worn brake cam 3. Worn brake pedal shaft 4. Brake shoe contaminated with oil or water 5. Stuck brake cable or rear brake link 6. Lack of grease in brake cam (2) Brake squeaks when applied. 1. Excess worn brake shoe 2. Contaminated surface of brake shoe 3. Warped or pitted wall of brake drum 4. Excess wear of brake panel spacer ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ RESOURCES Here is a list of some of the known (but certainly not all) resources for obtaining parts and information about many aspects of the CB72-77 series machines: American Honda Motor Corporation - Honda Dealers. There isn’t a lot or parts left in Honda’s warehouses, but it is always worth having your dealer check for obsolete Honda parts that come right from the manufacturer. At least, Honda continues to supply microfiche for these models. www.vintagehonda.com Bill Silver’s contact information website for all things Honda from the 60’s, specializing in 250-305s, in particular. Supplier for: CA/CB/CL72-77 Restoration Reference Guides, 250-305cc Engine Repair Guides, Classic Honda Buyer’s Guides (Motorbooks Int’l); stainless steel mufflers and Probe Electronic Ignition Systems. 132 Honda 250-305 Super Hawk Restoration & Maintenance Guide www.honda305.com Michael Stoic’s wonderful website dedicated to the wondrous Super Hawks and their derivatives. Michael supplies numerous Super Hawk-related items for sale, too, as well as links to other related sites/suppliers. www.vjmc.org The home of the Vintage Japanese Motorcycle Club (No. American club) www.vjmc.com is the UK branch with over 6,000 members. www.vjmw.com is the Australian website for vintage Japanese bikes www.cjmc.org The Northern California-based club for vintage Japanese motorcycles. AIRCONE, Inc. (exhaust system components- custom built megaphones) 240 Elliott, Henderson, NV 89015 702-566-1077 (702) 566-0232 Fax David Silver Spares, in the UK, lists thousands of new parts for vintage Hondas and usually has a small amount of Honda 250-305cc specific parts available. Website address: www.davidsilverspares.co.uk e-mail address: SALES@davidsilverspares.co.uk Classic Motorcycle Supply, in Holland, has more than 150,000 line items of Honda parts, including 250-305 parts. Website: www.cmsnl.com Probe Electronics, Mark Whitebook, located in Capistrano Beach, CA is the original source of the electronic ignition systems for 250-305s. You can order them directly from the author. Ed Moore, e-mail: emo@ktc.com) or 830-895-0654. Ed is a renowned restorer of 250305 Scramblers and an ace engine builder. 105 Molina Rd, Kerrville, TX. 78028. Special thanks to Ed for some of the photos supplied for this book and for his wise feedback. Les Barker, at Vintage Advantage in WA at 360-699-4964 (1644FAX) features racing parts for 250-305s, including newly-renovated, camchain tensioner rollers, guide rollers, oversized titanium valves and other performance parts and machine work. Megacycle Camshafts (415) 472-319590 Mitchell Boulevard, San Rafael, CA 94903, can regrind cams & reface rocker arms and supply other racing products. Kibblewhite Precision Machine (650) 359-4704580-G Crespie Drive, Pacifica, CA 94044 wfkpmi@earthlink.net makes racing quality clutch and valve springs. Tony Milk, in the UK (A B Milk, 240 Norwich Rd., New Costessesy, Norwich, NR5 0LQ, tele/fax 01603 743862) features numerous racing parts for vintage Honda roadracers, including specially cast brake panels with integral air scoops, plus megaphone exhausts and fairings, etc. Gerry Ascott, 9 Somerset Crescent, Melksham, Wiltshire, SN12 7LR. Tele 01225 702816 makes reproduction CB77 chain guards. Retrobikes (www.olypen.com/retro), in Port Angeles, WA 360-452-9043 (0517FAX) features an on-line website catalog of all the NOS Honda parts that they stock. www.motorcyclememories.com features motorcycle-related literature, including copies of parts manuals for most models. www.motorcycleshopper.com has free classifieds and listings of clubs and wrecking yards in the US. Dennis Murfin, U.K. distributor for Honda racing pistons, which use CB350 rings. E-mail: DJMURFIN@aol.com Honda 250 reproduction tank badges T. Sawyer, 88 Fulwich Road, Dartford, Kent, DA1 1UT England Larry Shultz has lots of vintage Honda parts, literature and related items. e-mail: Larrymcyc@aol.com www.westernhillshonda.com Honda dealer located in Ohio. They have a searchable online database. www.ohiocycle.com Nick Fetzer’s Ohio Cycle website and source for vintage Honda parts, including some reproduction items for 250-305s. Bill Orazio: Large inventory of vintage Honda parts. Contact: billorazio@aol.com 133 Honda 250-305 Super Hawk Restoration & Maintenance Guide NGK Spark Plugs (U.S.A.), lnc. Corporate Headquarters 6 Whatney Irvine, CA 92618 tel: 949-855-8278 fax: 949-855-8395 *CROSS REFERENCE: NGK spark plug D8HA= ND spark plug X24FS-U* Acknowledgements: Special thanks to: Ed Moore for his contributions to this book (photos/corrections). James Yahnke, for giving my computer the “firepower” to create this book. Graeme Duckett gets a nod for giving me a copy of the 285-page, CB72-CB/CP77 master parts book, which was a great resource. Graeme is a die-hard 60’s Honda collector and restorer in New Zealand. American Honda, who has provided a great deal of resource material through the service bulletins, parts bulletins, advertisements and promotional information created during the period of 1961-67. Note: American Honda and the parent organization, Honda Motor Co., Inc. in Japan, did not sanction the creation of this book. All rights to the name and logo of HONDA are reserved by those organizations. Honda trademark materials used herein are solely for the purpose of model identification and are in no way representative of any division of the Honda Motor Corporation. Thanks, also, to the contributions of my numerous “Honda friends,” many of which are members of the VJMC clubs from around the world. We all share a deep love and respect for these fine Honda products. 134 Honda 250-305 Super Hawk Restoration & Maintenance Guide 135 Honda 250-305 Super Hawk Restoration & Maintenance Guide 136 Honda 250-305 Super Hawk Restoration & Maintenance Guide 137 Honda 250-305 Super Hawk Restoration & Maintenance Guide 138 Honda 250-305 Super Hawk Restoration & Maintenance Guide 139 Honda 250-305 Super Hawk Restoration & Maintenance Guide 140 Honda 250-305 Super Hawk Restoration & Maintenance Guide 141 Honda 250-305 Super Hawk Restoration & Maintenance Guide 142 Honda 250-305 Super Hawk Restoration & Maintenance Guide 143 Honda 250-305 Super Hawk Restoration & Maintenance Guide 144 Honda 250-305 Super Hawk Restoration & Maintenance Guide 145 Honda 250-305 Super Hawk Restoration & Maintenance Guide 146 Honda 250-305 Super Hawk Restoration & Maintenance Guide 147 Honda 250-305 Super Hawk Restoration & Maintenance Guide 250cc above High/Low Compression pistons 305cc below 148 Honda 250-305 Super Hawk Restoration & Maintenance Guide 149 Honda 250-305 Super Hawk Restoration & Maintenance Guide 150 Honda 250-305 Super Hawk Restoration & Maintenance Guide 151 Honda 250-305 Super Hawk Restoration & Maintenance Guide HOT TIPS: If you have difficulty removing threaded fasteners, try applying some direct heat with a torch or heat gun to the part and then quickly touch a candle or piece of paraffin to the parts. The wax will usually wick into the threads and lubricate them for an easy release. Kroil (The Oil that Creeps) from Kano Labs www.kano.com) (is an excellent petrochemical product for penetrating deep into rusted parts, as well. Finally, remember that motorcycle repair and restoration involves toxic chemicals (used motor oil, gasoline, various types of cleaners) and potentially dangerous exposure to asbestos (gaskets and brake shoes). Use gloves, masks, safety glasses and other appropriate safety gear to prevent unnecessary exposure to items that are not in the “food group” classifications. Think before you act and work with caution. Remember to dispose of all toxic chemicals and materials properly in approved containers. Enjoy the repair and restoration process and then enjoy the ride! Bill “MrHonda” Silver Copyright 2005, Bill Silver’s VintageHondaBooks www.vintagehonda.com All rights reserved. Storage, transmission, copying and reuse of any part of this publication by any means; electronic or mechanical, is strictly prohibited without written authorization and permission of the author/publishers. 152 Honda 250-305 Super Hawk Restoration & Maintenance Guide Details, Details, Details… Thanks to all of you who have purchased a copy of my new CB72-77 Repair and Restoration Guide and parts/owner’s manual combo CD. I spent about a year, on and off, preparing the information for this work. As I was about to release this edition, I began to consider that, perhaps, I was writing “over the heads” of some “novices” out there, who are new to vintage Honda twins and/or to motorcycle repair, in general. I thought I should add in some foundational information, which covers Honda motorcycle repair and service procedures, in general, as well as some special tips for those who might not have “cut their teeth” on old bikes and machinery. So, here we go with the “details”… Fasteners (Screws, bolts, nuts, washers, cotter pins, spring pins, etc.) I mentioned, in the main portion of the book, how important it is to loosen screws and bolts before you take the whole motorcycle apart. Loosening and removing fasteners can be a frustrating, costly and potentially damaging episode in the various chapters of a restoration story. Use of high quality solvents, like Kroil, Napa’s Seafoam, WD-40, PB Blaster and others, will often be of great assistance in the loosening and removal of various fasteners on the bike. Usually, the most challenging ones are the Phillips (Cross-head) screws, which are primarily found on the engine side covers. Most of these are the 6mm type, utilizing a #3 Phillips head screwdriver (or APEX bit for impact driver tools). Because these screws are plated steel, residing in threaded aluminum screw holes, corrosion builds up in the threads due to a combination of electrolysis (dissimilar metals) and heat/cooling cycles of the engine assembly in operation and/or the outside environment where the bike is stored. Most of these screws are installed in “blind holes,” so there is nowhere for any moisture to leave the screw/hole set. There is also no way to introduce a penetrating oil or solvent into the threads to help loosen the bond between the parts. The primary and most effective way to loosen screws in blind holes (or most any other ones) is to “smack them in the head ” with a long hardened screwdriver bit, like the ones found in Impact Driver kits. Most hardware stores will carry the longer versions, which are ideal for some of the recessed areas where the short tips don’t protrude enough to be able to get a clean hit on them, either alone or in the impact driver tool. Using the long bits like a center-punch, center the bits in the clean recess of a Phillips head screw and strike it sharply with a large ball-peen hammer, once or twice. This will “shock” the screw threads and break the chemical bond of rust and corrosion enough to allow the second attempt, with the bit in an impact driver, to generally loosen the screw from the threaded hole. I have mentioned this method before, but it bears repeating for the newcomers. If you find a Phillips screw head that is already damaged, there are a couple of options left. Assuming that you already tried hitting it with the APEX bit, which you should do in all cases, as it often helps you remove a screw that you thought was hopeless, then you can try to “catch the edge” of the screw head with a small sharp chisel and rotate the head enough to get movement started. If the above attempts prove fruitless, then you can always drill the head off of the screw, using a 5.5mm or 6.0mm drill bit. In some cases, you can find drill bits that are left-handed, which will work the screw in a counter-clockwise direction as it burrows down inside the screw head. Often the 153 Honda 250-305 Super Hawk Restoration & Maintenance Guide combination of the twisting and heat generated by the bit will loosen the screw. In the worst case, the screw head is drilled off and you can slide the part over the remaining threaded or shouldered section of the screw. Once you remove the cover, put a pair of Vise-Grips or other gripping tools on the screw shank and rotate it out. BE SURE to clean the threads of the old screw if you need to reuse it and tap the thread holes out with a good quality 6mm (in this case) tap, using lots of penetrating oils as you slowly run the tap in and out a little at a time, until the threads are clean all the way to the bottom. Don’t leave any residual oils in a blind hole as it can cause a new screw to form a “hydraulic lock” in the hole, when there is nowhere for the oils to squeeze back out again. On Hex-head bolts (6-sided), the best tool to use for removal is a matching 6point socket, wherever possible. If the bolt head is corroded and has lost some of its actual dimensions, the 6-point socket will minimize “rounding off” the bolt head, especially when the socket slips for some reason. Many cheaper tool sets use 12-point sockets, which will OFTEN ruin a bolt head, unless the contact is completely square and the fit is snug. In some occasions, the bolt head might be damaged to an extent where the 6-point socket will not fit over the bolt head. In these cases, a 12-point socket can often be driven over the bolt head enough to reshape the damaged section, allowing for removal with the 6-point socket, again. Try to avoid using “adjustable jaw” pliers to remove bolts, as they generally don’t hold the bolt head tight enough to prevent slippage and damage to the part and perhaps your body parts. ALWAYS lubricate all threaded fasteners lightly, prior to reinstalling the fastener. Even when you use new screws in dirty or dry threaded holes, the potential for the two parts seizing together is almost certain. Note that either flat washers or a combination of flat and locking washers are used to retain bolts on a motorcycle. The flat washer gives the bolt head a firm surface to rest and prevents the bolt head hex corners from digging into the metal below the head. Locking washers are generally “split” washers, where the washer is parted at one edge and turned outwards to grab the bottom of the bolt head and the flat washer below, ensuring a tight hold on the bolt. Other kinds of washers are “wave” (≈) washers, which look like a potato chip in cross section. These washers will just flatten out as the bolt head is tightened down, but they do not dig into the metal of the bolt head or the flat washer, if used. Other types of locking washers are “conical shaped” and “daisy-chain” with multiple locking edges. Other than the conical washer on the end of the crankshaft, which helps hold the oil filter chain sprocket in place, you will generally see regular “split-type” locking washers for most applications on the bike. Tab washers are soft metal washers with either internal or external “tabs,” which can be bent over, to surround a bolt head or fit snugly into a recessed locking bolt (usually these have 4-slots milled into the sides and require a special wrench for tightening). Examples of tab washers are used on the end of the crankshaft nut, rear sprocket nuts, the front brake arm (both ends) and to retain the shift fork bolts, as part of the shift drum assembly. Snap rings, come in either internal or external styles. Either a special multipurpose snap ring pliers tool or separate internal/external pliers can be used to contact the small “ears” on the snap rings to expand or contract the ring for removal. Snap rings are used on the inner clutch hub, the starter motor drive sprocket (both external) and to retain Type 2 fork seals (internal). NOTE: Snap rings are manufactured by “punching” them 154 Honda 250-305 Super Hawk Restoration & Maintenance Guide from a sheet of material. This process leaves one side with “sharp” edges and the opposite side with rounded edges. When installing any snap ring, always place the ring so the “sharp” edges are facing you, giving the ring edge the best chance to “grab” the shaft or ring groove to prevent accidental dislodging of the ring/part. Cotter pins or spring clips/hitch pins (similar to heavy-duty bobby pins) are required in the rear brake rod mounting bolt ends, the carburetor choke links and front & rear axles. Clamps (Handlebar and Front Axle (Type 2 forks) The clamping blocks used to retain the handlebar to the fork bridge, as well as the two used to retain the front axle in the alloy, Type 2 fork assemblies must be installed in a particular way. If you look at them from the side (or place them on a flat surface) you will notice that the two flat plane surfaces are not even with each other. When installing the clamping blocks, note the highest portion and place it towards the FRONT of the motorcycle. As you begin to position the handlebars (or axle), tighten the forward bolt FIRST, then use the rear bolt to “pinch” or clamp the bar (or axle) tightly in place. Tightening the parts in this manner assures maximum clamping force and stability of the part placement. Having the “closed” portion of the clamp facing forward also reduces the amount of dirt and moisture getting into the clamp joint and ultimately prevents it from working its way quickly into the threads. This “clamping” technique should also be used for the both of the handlebar switch housings. Tighten the forward edge first, then the rear, until the part is snug. Again, this procedure prevents oncoming moisture and dirt from entering the switch contacts. 155 Honda 250-305 Super Hawk Restoration & Maintenance Guide Seal installation Replacing engine seals is best accomplished when then engine is disassembled, in most locations. Seals that are installed in the centerline of the two crankcase halves are the hardest to replace externally. The outside diameter of the seals is slightly larger than the inside diameter of the crankcase bores, so there is a clamping force applied to the seal, holding it securely in place. Trying to drive a crankshaft or countershaft seal in from the outside, when the cases are assembled usually peels off a part of the outer edge of the seal material. When this happens the seal is less likely to hold in place when subjected to heat, crankcase pressure and high shaft turning speeds. Whenever possible use a seal driver tool, of the correct size, to properly locate and insert the seal into the case holes. Use lots of oil on the seal and the corresponding hole (and shaft), so the seal will have the best possible chance of squeezing into the hole with a minimum of material loss. Once installed and “squared up” correctly, thoroughly clean the outer edges of the seal and cases and apply a thin coat of high-temp silicone sealant to help anchor the seal and to alleviate any potential seal leaks at the outer edges. It won’t be pretty, but this should allow you to operate the machine for a long time without having to split the cases to correctly install the seals. The same rules apply for the smaller seals, which are sealing moving shafts. If you can’t find a suitable socket to use as a seal driver, then have a machine shop fabricate something out of mild steel or even brass to suit the task. Replacing the fork seals on the Type 1 forks (using the screw-on seal holders) can be a nightmare. Place the seal holder upside down, on a block of wood, to lessen the chances of damaging the chrome surfaces and use a small, long, thin, narrow chisel to catch the edges of the seal, a little at a time. Just keep working your way around the seal until it releases. I have spent 5 to 10 minutes on each seal holder, removing the seals, so don’t get in a big hurry or become frustrated when they seem to stay in place, in spite of repeated, forceful hammering. Remember to remove the wire retainer rings FIRST! On the Type 2 forks, once you get them out and apart, you will have to remove the snap ring and any backing washers first. Then, you can just grab the fork tube and pull upwards a couple of times to pull the seal out, along with the fork bushing, etc. Reinstalling the seal again requires a lot of care and a seal driver, if possible. You can use the old seal, placed on top of the new one, as a driver, gently tapping the new seal into the fork housing recess. Once the new seal is bottomed out in the housing you can grab the edges of the old seal and pull it back out. Reinstall the washer and snap ring, being sure that the snap ring is FULLY installed in the ring groove. Bearings Most of Honda’s bearings will install with a little light oil and a bit of tapping with a plastic mallet. Bad crankshaft ball bearings can be moved off of the end of the shaft with a pair of chisels, wedged behind the bearing races. This is a bit brutal and can damage the bearings, so it is best not used on a bearing that you want to save. Borrow a bearing removal tool or take the part to a machine shop so they can press the bearing off carefully, with out damage. The transmission bearings should slide off pretty easily by hand unless there is a lot of varnish on the shafts. In cases where the bearings are a tight fit, the bearings can be heated in clean motor oil to help expand them slightly for installation. Be sure to oil all bearings and bushings during and after installation. For those pesky roller bearings, you can pack the races with some Vasoline or other 156 Honda 250-305 Super Hawk Restoration & Maintenance Guide petroleum jelly products. This will keep the rollers in place while you install the outer races and bushings. Steering head bearings are a challenge, because they are so small and there are so many of them to keep in place during assembly. Wheel bearing grease is a good thing to use in this application. Use LOTS of it, as it not only will glue the bearings in nice rows, but it is the necessary lubricant for the steering head bearings, once everything is snuggled down in place. Wheel bearings in the front and rear hubs often need to be heated up before they will drop out from their housings. An electric heat gun is handy for this application, but if the rim and spokes have been removed, the hub can be placed in a small oven or on a hot plate, propped up so that the bearings will drop out of their hiding places at about 200° or so. There is an axle spacer inside that keeps the bearings apart when the axle is tightened up. The spacer has little fingers on it that hold it centered in the hub, so axle insertion is easy. The fingers can be forced down, exposing the inside edge of the inside bearing race to a sharp-edged drift or long punch. Using this foothold, you can often move the bearing out of the hub, inching along the radius, slowly. In cases of a snug fit, you can pack the bearing with high-quality axle grease (or just use a set of new sealed bearings) and then pop them in the freezer for about 10 minutes to cool them down, causing a bit of shrinkage to occur. Warm up the hub again and the chilled bearings should drop right in! Electrical Issues There is a detailed explanation of the charging systems of the Super Hawks in the main book section, already. What I would encourage anyone who is working on a bike that has had the wiring harness “spliced” or repaired in any manner, to carefully look at every piece of the harness and make professional repairs at every place of question. Honda does supply the same metric-sized “bullet connectors” (male and female), which the bike had when it left the factory. DO NOT use “Scotch-lock” connectors; “crimp-on” splice connectors or SAE-sized bullet connectors to make repairs. Buy, borrow or beg a soldering gun and some “shrink wrap” and learn to make a permanent, secure and electrically sound wire connection. If you can find a similar wiring harness from a 1960s Honda motorcycle, you should be able to salvage plenty of correctly colored wire to make repairs to most wiring harnesses. Unfortunately, Honda no longer sells wiring harnesses for Super Hawks, so you will either have to hunt down a good used harness or do the necessary repairs to your existing harness. Check EVERY wire connection as you connect components to the harness as well as every GROUND connection, where wiring or grounded components must complete a circuit. You will notice that the headlight only comes on, when the rim is touching the headlight shell, which is one instance of how important clean wire and ground connections can be, when troubleshooting a problem. If you have painted (or powdercoated) all of the chassis (like frame, fenders, fork ears, tail light bracket, headlight case, etc.), be sure that you have not painted over a planned ground path for one of the electrical components. Be careful not to mix up those green and green-white wires in the headlight case. Green is 12v HOT and Green-White wires are GROUND. Don’t mix them up or you will blow a fuse or worse! 157 Honda 250-305 Super Hawk Restoration & Maintenance Guide Special Markings Honda used “punch marks” to indicate the relative positions of certain components, to facilitate the assembly process. OEM Honda handlebars always have a set of punch marks in the middle section of the handlebars, so the “set-up” personnel can install the handlebars correctly the first time. You should be able to see the punch marks on the outside of either of the handlebar clamps, centered right on the parting line of the clamps and the fork bridge. (Sort of like this: ____ -I I_____I I- ____). The brake arms and brake cams have similar, matching, punch marks, as does the kickstarter arm and shaft for alignment purposes. Often when parts are re-chromed, the platers polish out the punch marks, so you have to “eyeball” everything instead. Shims Honda Super Hawks were not built with any “shims” (washers or flat metal inserts), but in some cases adding a thin, flat washer added here and there is a good idea. Two critical areas are the front fender mounts and the mounting of the exhaust system. If the fender stays cause the front forks to bind, due to misalignment problems, then the forks will not respond smoothly. In the case of the exhaust system, forcing the muffler mounts to fit the frame will often result in both an unwanted harmonic vibration and probable failure of one or more of the muffler brackets. Often, the mufflers will crack right behind the rear top mount, mostly because of misalignment problems, where bolts were forced into the mounting holes and tightened down putting the parts into a stressed condition. Take time to loosely fit the parts to the frame and observe whether the mounting bolts will easily insert and tighten the parts together without having to close large gaps in the process. If the fender or muffler seems to match up in most cases, except one, then add a washer or two of the correct thickness and diameter, so you can bolt the parts in places without stressing the mounts. Rust & Corrosion Any unprotected metal will be subjected to varying degrees of some type of corrosion. Steel, whether it is painted, plated or coated will develop rust anywhere there is the slightest hint of a lapse in the coating barriers. Aluminum develops scale and turns white and chalky in the presence of moisture. Beyond the natural susceptibilities of these materials, you have the added challenges of ozone, sunlight, chemical (gasoline, oil, battery acid) and innumerable heat cycling of the parts that make up a motorcycle. Honda painted the steel parts of the CB72-77s, using an automated, electrostatic process that was applied directly to the raw metal. Any imperfections in the thinly-painted coating allows the kind of corrosion that you often see in original bikes… a spider-web effect under the paint. In restoring these machines, it is usually best to have the parts stripped of the original paint and repainted or powdercoated to preserve them properly. Powdercoating any parts, steel or aluminum, requires that the parts be cleaned, usually by sand or bead blasting them to raw base metal. Parts can also be chemically stripped, but must be immediately treated to prevent the reoccurrence of corrosion. Honda left the die-cast center cases uncoated from the factory, but the closed, shiny surface tends to repel a lot of corrosion, except in particularly damp climates. 158 Honda 250-305 Super Hawk Restoration & Maintenance Guide The two outer engine sidecases, clutch and kickstarter, are painted with a semi-flat silver paint which is often recreated by using Krylon Dull Aluminum spray paint or its equivalent. The early sand-cast cylinders and cylinder head were treated with some kind of very tough, heat-resistant coating that is difficult to remove. Many people make the mistake of bead-blasting the top end components, leaving a rough, porous surface that invites dirt, grime and corrosion. There are several kinds of high-temperature engine paint in silver colors (engine aluminum or cast coat), which will protect the blasted parts, sealing the surfaces against future damage. Those of you, who want to do a 100 pt show-quality restoration, will want to reuse the original fasteners, which were unmarked from the factory. Since 1967, Honda has subscribed to the ISO standard, which requires descrete marking of the bolt heads, screw heads and other fasteners. Use of these replacement screws will be obvious to any judge familiar with Honda motorcycles. If the original screws can be replated, try using a Bright Zinc finish, which can be done easily and cheaply by many shops. Some parts of a Super Hawk are also cad (cadmium) plated, but this finish is very toxic to process and is best left done in other coatings. Cad-plated parts are items like the front and rear footpegs, centerstand mounting bracket and sidestand arm. Protection & Safety Doing any kind of mechanical repair work can present various kinds of safety hazards, most of which can be prevented by use of proper safety gear. Most shop mechanics today use latex or nitrile gloves to protect their hands from absorbing toxic chemicals that are part of the repair process. Used motor oils, gear oils, gasoline, battery acids, etc. all have the potential to cause damage to the human body. Putting a little barrier between you and the chemical exposure is definitely a good idea. When Honda was producing motorcycles, back in the 1960s, the use of asbestos in gaskets, brake shoes and clutch friction materials was a common practice. Using a particle mask, eye protection and gloves will greatly lessen your exposure to this kind of toxic contamination, when working on your machine. Consider all used gasket scrapings, brake shoes, clutch discs and the like to be articles of toxic waste and dispose of them appropriately. Consult with your local recycling or refuse hauling companies for advice as to how to keep from further polluting the ground water systems with these items. I hope that this additional material has enlightened you, somewhat, about some of the subtleties of the repair and reassembly processes, which might come up during your restoration or repair. Work safely and enjoy the experience. If you feel like you are getting “stuck” somewhere in the process, take a break and ask for help. You can always contact me through my website: www.vintagehonda.com or try the members at the www.vjmc.org website for the Vintage Japanese Motorcycle Club. Tips from Restorers Valuable notes from Chase Knight who is restoring three CB77s in Florida. Hello Bill, As things have now settled down a bit after completion of this first bike, and I organize in preparation for the second, I've sorted out a few notes that I've made along the way. I'd like to relate these to you, first to make sure that I'm not totally off-base with some of these, along with a few things that have helped me in this project. 159 Honda 250-305 Super Hawk Restoration & Maintenance Guide Steering Stem Bearings: Although the parts listing states that 38 1/4" balls are required, there are actually 18 that go in the top race, and nineteen that go in the bottom (different diameter races). This makes a total of 37, so I would hope that no one tries to put that extra one where it doesn't go. I went ahead and obtained the Pro-Flo tapered bearing kit for mine. If you use the spacer washer that comes with this kit, you will not be able to use the standard bottom dust seal. A steel spacer ring can be turned, having a 34.8mm OD, 30.0mm ID, with a thickness of 8.7mm. This can then space the lower bearing assembly, allow the use of the dust seal, and restore proper front end geometry. Hagon Rear Shocks: I went ahead with a set of these. Very nice, functionally and visually. The chrome version with the exposed chrome spring was my choice, not totally resto looking, but it's what I wanted. As these shocks have a substantially thicker lower clevis material than standard, putting the locking nut on the backside of the lower bolt will only engage a couple of threads and not look too good (or function very well). As you noted in the CD, put the bolts in from the outside with a lockwasher, and don't bother with the (now inside facing) nut. Tires: Tires Unlimited in Dayton, OH seem to be the best source for these, particularly the front ribbed Cheng Shin 2.75 x 18. Spokes: Buchanan's Spoke and Rim (or Sudco) have the nicest items in this area. Great fit, excellent appearance and low maintenance. Handlebars: As far as the "flat" bars go, the repro part from Retrobikes is right on. I've returned bars to Sudco and Ohio Cycle that were supposed to be CB72/CB77, but aren't even close. Sprockets: I have six OEM front sprockets now, one new, five used, and none of these are hardened. No wonder these things wore as badly as they did. Sprocket Specialists supplied their #506 15 530 hardened steel item, which is properly drilled and tapped for the retaining plate. To me, this is a must if you intend on really riding the bike. Got some nice rear sprockets from them, too. Clutch: Went the aftermarket route here. The Barnett HPK-40K friction plates, and HP-216 steels, have OE thicknesses, and go right in. There is virtually no clutch drag when released (even without the two wire retaining rings). Also my old ritual of using the first kick starter stroke of the day to "unstick" the clutch seems to be no longer required. Also obtained their MT-10-4 clutch springs, but they're a bit stout. Might install just two of them across from each other at a later date if I feel the need for it. Battery Cables: One of the real "unobtainum" parts for these. Went to my friendly neighborhood NAPA Auto Parts store and got some stranded copper 6 gauge battery cable, and some appropriate 1/4" and 3/8" ring terminals. Center to center distances on the terminal bolt holes when completed were: 27" for the solenoid to starter cable; 107/8" for the positive battery to solenoid cable; and 10-1/2" for the negative battery to 160 Honda 250-305 Super Hawk Restoration & Maintenance Guide ground cable (used the upper rear motor mount bolt for the ground attachment point). Bent the battery end of the terminals 90 degrees to fit correctly. Wiring: The Vintage Connections/Del Gundlach terminal kit (with the really professional crimping tool) is probably one of the nicest items I've used. Wired the Probe ignition in so cleanly, it appears stock. Carburetors: One other thing to check is to see if the little metal tab that's inserted through the carb main body that keeps the slide from spinning is indeed tight. A few of mine weren't, so a little bead of two-part epoxy held them in, and prevented any possible vacuum leaks. And, as we've discussed before, the float level should be measured from the metal surface of the carb body that the float bowl gasket seats against (easily accessible from the notch adjacent to the float bowl wire retaining clip if the gasket's already in place). I realize that this may be obvious to most, but a lot of the drawings that are out there may lead you to believe that the outer lip of the carb body is the reference point. Cam Chain Tensioner: Yes, I know that this one's pretty far out, but the seal that the tensioner plunger stem (?) passes through is a 3077, available from your local bearing supply house. Transmission: Your recommendation of using the offset cotters can not be overstated. It is one of the best things that can be done to enjoy the ride. Paying attention to transmission shaft endplay (again, use shims obtainable from your local bearing supply house) also makes a notable improvement. In the parts catalog, the 91004-259-000 bearing (item 24), should cross-reference to a 6206HS, not the 6202HS as listed. Clutch Lifter Rod: Another strange happening, one of mine had the flat end insert (the end that goes against the 5/16" bearing in the clutch lifter) fall out of the tubing. It obviously can't go anywhere once assembled, but if in the side cover installation process it fell out, that would not be good. Aluminum Footpeg Brackets: Indeed a challenge finding two of these that are straight. As I had a few really bent ones to experiment with, I found that putting it in the good old propane grill at about 400-450 degrees for 10 minutes would make it a lot easier to straighten. This really reduces the possibility of cracking, but as we're dealing with a really hot piece of metal here, the caution element is of utmost concern. Also, let it air cool, do not use water to hasten the process. Upper and Lower Engine Cases: To achieve a fresh "die cast" look (not an over-polished appearance), good results were obtained by cleaning throughly, then thoroughly massaging with 000 brass wool and Commercial Grade Windex. The Commercial Grade seems to have some different qualities than the household version (more "slippery" and doesn't evaporate as fast). 161 Honda 250-305 Super Hawk Restoration & Maintenance Guide Cleaning: As long as we're on this subject, I had been a Simple Green user for over a decade. However, the product does etch aluminum! If you've got something of aluminum that's just been detailed, and perform the final cleanup with Simple Green, you may become unhappy quickly. I have had excellent results with De-Solv-It, one of those orange chemicals that seems too good to be true, but hasn't let me down yet. No aluminum etching, spray it on your dirty tools, let set, and the grease and grime literaly falls off. Good stuff, but can be difficult to find. Think I need to get an endorsement contract for this one. Tachometer Drive: One of the part numbers that doesn't seen to appear in any of the listings, is the bolt that retains the tachometer gear bushing assembly. This is a countersunk cross head 6mm x 10mm bolt (perhaps 93600-06010-0A or 93700-0601002). Cylinder Head Cover: The copper sealing washers that go under the head stud nuts seem to have gone through a number of changes/ superseding /deletions. I was able to get some very acceptable 90745-703-000 washers from my local Honda dealer after much diligence on his part. Dipstick: The current part number for the o-ring seems to be 91307-425-003. Steering Lock Cover: Another seemingly unlisted item is the bolt that holds this piece on (the metal version,anyway). It's an oval head cross head 3mm x 10mm piece (perhaps 93500-03010-02). Speedometer Cable: Although the cable housing itself appears the same for the early "counter rotating" version as the later "clockwise" model, the cable itself is wound differently. The early cable strands should appear as having a "left hand thread" pitch to them, while the later ones look to be a "right hand" thread. It may be possible to use the wrong one for a while, but the cable will try to "unwind" and get rather unpleasant. Black "Plastic" Parts: Things like the steering damper knob, air filter cover knobs, headlight switch knob, etc. can get fairly faded and eroded with age. As this might not be what we're used to thinking of as "plastic" since it's really porous (more like bakelite), detailing it is another challenge. I started by wet sanding with 600-grade wet paper and worked my way down to 2000 grade. After a thorough cleaning, they still don't have the most pleasant appearance. So an application of Kiwi black paste shoe polish, massaged in completely, and then buffed with a soft cotton cloth really brought them to a shine! Chase Knight, Daytona Beach, FL Best wishes for a great ride on your Super Hawk…… Bill “MrHonda” Silver 162