HONDA 250 MODEL C72 -!! HONDA 250 MODEL CS72 HONDA 250 MODEL CB72 PREFACE This Shop Monuol contoins general dato and informotion. ond procedures relative to motorcycle mointenance. over-houl and repairs for the models covered by Hondo 250 and Hondo 300 equivalent to Model C72 ' C77, CB72 ' CB77, CS72 ' CS77. Therefore, information in this manual will be suitoble instruction for servicemen ond mechanics of Hondo to assist them to efficiently service and repair these mochines. Now. in thi5 cose, mechonicol arrangement means to repair o motorcycle when it i s out of order and restore i t to the ordinary stote as well as to prevent it from any trouble by periodically inspecting the motorcycle. The contoins of this book ore divided into five chapters, including main stondords, disossembly-ossembly, construction, wiring diagram and trouble shooting. Each chapters ore separated into sections. is divided into 2 sections - Engine and Frame. Disassembly-assembly lthe 2nd chopterl The section of Engine i s described both model C72.77, CB72.77. but that of Frame is done only model CB72.77. In regard to the Frome of model C 7 2 . 77, pleose refer t o the previously published Shop Monuol for Hondo 1 2 5 . 150. An effort has been mode to produce a monuol avoiding fundament01 principle ond theory by explaining the actuol mechanism. Special emphosis has been placed on illustrotions ond charts to make it eosy for the service man lo undersfand without reading every line. W e hope this will be of Some use to you. This rnonual will be revised without notice. January. 1960. HONDA MOTOR CO., LTD. TECHNICAL SECTION EXPORT DEPARTMENT No. 5-5. Yaeru-cho. Chvo-ku. Tokyo. Japon MAINTENANCE STANDARDS,C 72 *77 For maintenance operation for HONDA 250 ' 300, Maintenance Standards, specification and dimension ore listed hereofter for reference. EXPLANATION : Maintenance Items Items t o be inspected, service-wise. Standard Value This indicates the manufacturer's standard size o r the standard size after newly assembling o r adjusting, and shows the size-limit of completed part in the permissible limit of adjustment. Repalrlng Llmlt Unusable wear limit of parts requiring correction o r replacement, function-wise. Remarks Unmarked numbers are run unit and inch unit shown underneath, and others according t o the unit indicated. UNIT IN CHART : Unmarked numbers are m/m unit and inch unit shown underneath, and others according to the unit indicated. CONTENTS 1. GENERAL PERFORMANCE .............. . . . ......... . . . . . . 1 ... . . . . . . . . . . . . .. . . . . 1 ... ........ .. ..... 2 ........... ....... 3 ... ........ . . ..... 5 . . . . . . . . . . . . . . . . .... . . . . . . . .. . . . . . 5 ... . . . . . . . ........ 6 G. Magneto. Contact Point .... . . . . . . . ... . . . . 7 H. O i l Pump. Oil Filter . . . . . . . . . . .. . . . . . . 8 I. Kick, R . Crank Case Cover . . . ....... . . ...... 6 J. Under Crank Cose and Cha .......... ........ 8 2 . ENGINE A . Cylinder. Cylinder Head B. Crank Shaft IPiston. Connecting Rod1 C. Cam. Timing and Valve . D. Upper Crank Case .. ...... ........................ . E. Clutch, L Cronk Cose Cover F. Transmission .......................... 3 . FRAME ....... A Hondle B. Front Cushion .... .. ............................ C. Front Fork. Steering. Tank . . . . . . . . . . . . .. . . . . . . . . . . . . . . . .......... ........ 9 10 9 .. ........ . . ...... .............................. .. ........ ... ..... 10 ............................ . . . . . . . . . . ... ..... 11 ........ ... ..... 11 11 ............ ........ ........ ......... . . ..... ... . . . . . . . . ... ..... D. Frame Body E. Saddle. Stand F. Rear Fork Chain Case G. Rear Cushion . . . . . . . . . . . . . . . . . . . . H. Front Wheel I. Reat Wheel . .... c 11 12 MAINTENANCE STANDARDS (Model C72) This mointenonce standards is listed only about the data o f Model C72. In this list. dimentionr without units indicate '' mm lupper step1 and '' inch '' ldown rtepl. and others according to the units indicated. 'I 1. GENERAL PERFORANCE 1 Item Compression pressure I I 1 Stondord 8.5kg/cm2 120.87 Ib/inz 42-45 km/ 26.04-27.90 mile/ 4 120 cc/IOOO km e F " ~ I consumption Lubricont conrumotion Max. speed 7.0 99.54 Ib/ina 29 17.98 Check with kick 35 km/h 121.7mile/hl 200/1000 or less more 120 cc/620 mile !00/620 mile 130 km/h 80.60 mile/h 55'80mile/h Standard lepoirinq Limi 90 less The posture is leaning forword one thirds of the body 2. E N G I N E A. Cyllnder, Cylinder Heed llem Cylinder h e r dio. Max. out of round Taper O v e r size of cylinder Over size Cylinder heod valve sheet Width 4ngle Compression mi0 Cylinder head gorket Flotners rurface Cylinder heod gorket Thickness Cylinder stut Tightness ~ U I 53.99-54.00 2.1255-2.1 259 within 0.001 within 0.001 0.25 0.00984 1.0-1.5 0.0393-0.0590 459 8.3 0.326 within 0.03 0.001 1 1.0--1.1 0.039 0.043 2.1 m-kg 15.189ft Ib - 54.1 more 2.129 0.05 more 0.00019 0.05 mow 0.00019 3 category of 0.25 10.00981 over size 2.0 more 0.0787 0.06 more 0.0023 The capocity of the combustion chamber. 16.94 cc In case of binding \ B. Crank Shaft (Piston, Connecting Rod) item Piston Slondord l o p diameter 53.55-53.60 2.108-2.1 10 Mox. dia. +O 54-o,02 Out of round D-10.140.1 61 =d =D 'epoiring Limit 53.5 less 2.106 53.9 less 2.122 Rernoikr [he progressive direction of the lower Darts of skirt D-iO.0050.0061=d Piston & cylinder Min. c l e o r m c e Piston pin Dia. Piston over size O v e r size Toper Top.2nd ring Thickness Width Tension End gap Top. 2nd ring R ring Cieoronce groove Oil ring Thickness Widlh Tension End gap O i l ring R ring groove Clearance Piston over size Over size Pisfon pin Out. dio. Total length 0 15.0- 15.0006 0.59-0.5907 0.25 0.0098 D-0.08d-0.08 D-0.0031d-0.003 2.4-2.6 0.094-0.102 1,780-1.795 0.0700-0.0706 1.75-1.05kg itopl 1.70- 1.00kg i2nd 1.653-2.315 Ib 1.543-2.205 i b 0.1 5-0.35 0.0059-0.01 37 0.01 -0.04 0.0003-0.0015 2.4-2.6 0.0944-0.1023 2.780 2.795 0.1094-0.1 100 0.7-0.9 kg 1 S435- 1.9845 I 0.1 -0.3 0.0039-0.01 18 0.01 -0.04 0.0003-0.001 5 0.25 0.0098 14.994- 15.0 0.5903 0.5905 45.5-45.7 1.7913- 1.7992 - - 2 0.1 more 0.0039 15.05 more 0.5925 3 cotegory of 0.25 i0.00981 over size 2.3 less 0.0905 1.7 less 0.0669 0.6 kg less langentiol tension 1.3230 ler In case of binding 0.8 more 0.0314 0.1 more 0.0039 2.0 less 0.0787 2.7 less 0,10629 0.5 less 1.1025 Ib 0.8 more 00314 0.1 more 0 0039 langentiol t e n i o n In coie of binding 3 category of 0.25 i0.00981 14.95 less 0.5885 over size ' Item Piston pin & piston Cleoronce Connecting r o d small end Con. r o d m o l l end & piston pin In. dia. Cleoronce Stondord rpoiring Limi' 0-0.012 0-0.0004 15.016- 15.043 0.591 1-0.5922 0.016-0.049 0.0006-0.001 9 0.05 more 0.00196 15.08 more 0.5936 Swing Con. r o d small end Axial c l e ~ r a n c e Diogonol clearmce Big end.rmall end of con. rod Amount of porallel Distortion Baranser weight Out. dio. crantpin R. L. crank rhoft Dia. of rhoft Crank rhoft bearing Axiol clearance Radial clearance Cront rhoft M a x . swing combination Cam choin C. Cam Overall length - 0.0031 3.0 more - - 0.5 more 0.0196 0.05 more 0.00196 OVer 0.1 0.0039 OVer 0.1 0.0039 24.95 or le! 0.9822 30.6 or less 1.204 O V e r 0.1 0.0039 over 0.05 0.0019 O Y e r 0.1 0.0039 728 28.66 Max. amplitude t o miol direction of cronk pin At length of 100 mm 13.93 in1 At length o f 100 mm 13.93 in1 Center beoring In case o f supporting Center beoring. the swing o f both ends Timing and Valve Mechanism Slandord Item Ex. In. d v e guide In. dia. Ex. Y&B Overall length Out. dio. o f stem Thickness of head In. d v e 0.07-0.33 0,0027-0.012 0.006-0.016 0.0002-0.0006 within 0.02 o.00078 within 0.02 o.ooo7a 24.99 25.00 0.9838- 0.9842 30.82-30.86 1.213- 1.214 0.005 0.00019 0.014-0.016 0.0005 0.0006 0.03 less 0.001 I 723.0-723.8 28.46-28.49 In cold. push in softly b y fingers 0.08 more 0.118 Lower end of t o n . r o d Remarks Overall length Out. dio. o f stern 7.0- 7.0 I 0.2755-0.2759 aa.65--88.85 3.490-3.498 6.97-6.98 0.2744-0.274a I .o 0.03937 89.18-89.38 3.51 I -3.518 6.97-6.98 0.2744-0.274a Repairing Limit 7.05 0.2775 88.2 or iePI 3.472 6.95 or less 0.273 over 0.5 or less 0.01968 88.7 orless 3.492 6.95 or less 0.273 Rsrnorkr - I Item epairing Limi I .o Thickness o f head 0.03936 Ex. In. valve Ex. valve stem ond Clearance guide In. v d v e stem and guide Volve spring outer Free length Tension Valve spring outer Volve spring inner 1.0-1.: Width 0.0393-0.059 0.02-0.04 0.0007-0.0015 0.01-0.03 00039-0.0011 43.82 1.725 11.6-12.4kg 24.2-25.8kg 25.57-27.3Ib 53.36-56.8Ib within 1. Decline Free length Tension Cam shaft Shaft dio within 1. Cam rhoft and bearing Lift length] t At 0.059 33.4 less 1.314 At t At within 0.01 0 059 19.95 less 0.785 0.05more 0.0019 26.7 less 1.051 Height o f corn 0.0003 26.98-27.02 1.062-1.063 Clearance 0.003-0.03 0.08 more 0001 I-0.001 1 0.0031 i50 (-1 of iournol Valve timing Ex. [at 1.1 m m 10.0431o f At 1.5 more 0.0393 19.98- 19.99 0.786-a787 Bend of shaft 0.5or lev 0.019 O Y e l 20 0.787 over 0.08 0.0031 over 0.07 0.00275 423 or less 1.665 1.5 more 0.03937 34.66 1.364 3.9-4.3kg 14.5--15.5kg 8.59-9.48 Ib 31.97-34.17Ib Decline Opening angle l+I efare lower dead point Closing ongle - P. 1 25" fter upper i5- No *SO P. i5" No 74.2 less 2.922 0.3 more In c dead point 10" Valve timing In. [at 1.1 mm 10.0431of Lift length] . Opening ongle elore upper 1 deod point 10' Closing angle fter lower dead point Cam sprocket Bottom diameter Rocker arm To fix Steps 74.766 2.943 on slipper face 25" 0.0118 ~ A I I - Standard Repairing Limii 130-13.027 0.511-0.512 12.966-12.984 13.1 more 0.515 12.9 less 0.5078 0.1 more 0.0039 Item I In. d m Rocker arm cronkpin I Out. dia. Cleorance t o racket orm Ex. In. v d v e adjurl Tappet cleclrcln~e Cam chain tensionel Free length spring Tension Corn chain tensioner Out. dio. roller 0.510-0.51 I 0.16-0.61 29 0.006-0.024 0.09-0.11 0.0035-0.0043 73 2.874 16.0-16.2 kg 35.28-35.71 Ib 59.2-59.8 2.33-2.35 In dio. In Cam chain guide roller dim. of axle Out. dim bin Chain guide roller In. dio. Cool stote 70 less 2.755 10 lerr 22.05 58.5 less 2.303 Standard Repoiring Limit 34.0-34.02 1.338-I .339 12.0-12.01 0.472-0.473 13,966-13.984 0.549-0.550 14.0-14.01 0.5511-0.5515 34.2 more 1.346 12.2 more 0.4803 13.9 less 0.547 14.1 more lfem Hale. shift drum out of rtondard Remorkr - Slondord Item Clutch center In. dim Out-round swing Primary drive sprocket Bottom diometer Clutch friction disc Thickness Strain 25.0-25.021 21~0-21 084 0.984-0.985 0.826-0.830 within 0.1 0.0039 39.1 1-39.21 1,5397-1.5436 4.8-4.9 0.1889-0.1 929 within 0.2 0.0078 5 Llrnll 24.9 20.9 less 0.980 0.822 0.2 more 0.0078 38.3 less 1.5078 4.4 less 0,1732 0.5 more 0.0196 KSmYrr, Standard !cpairing Lirnii within 0.2 0.5 more 0.0196 13.0 less 0.5118 Item Clutch plote Strain Width of hook Teeth ond outer of Rotary play ClUtCl, pressure plate Clutch spring Free length Tension ?. 0.0078 13.7 13.8 0.5393- 0.5433 within 0.2 0.0078 33.4 1.3149 15.3-16.7 kg 19.8 kg 33.736-36.823 I 43.659 Ib - 0.8 more 0.0314 32.4 less 1.2755 15.0 less 123 0751 25 mm 10981 of binding length At 23 mm 10.901 of m m . lift Tranrrnlrrion ,poiring Limi Mission case lubricot- Copocity ing oil Main rhoft Out. dio. Main shaft and M 2 Clearonce 8"t o f - 0.396 gal US. 24.959 24.98 0.9826- 0.9834 0.07-0.074 gear Axial direction o f moin Cleoronce rhoft Turning direction of Clearance M3 gear Teeth surface of geor Axis ploy 0.1 - 0.75 0.0039 0.0295 0.03-0.078 0.001 1-0.0030 0.089-0 178 - reloling to mission Top gear bush lad, In. dio. Top geor bush 20.56 In. dim Top gear bush 8 moin Clearance shaft Bottom dia. Drive sprocket Rotan/ ploy Primory driven Bottom dio. sprocket Moin shaft beoring a top gear Axis play 18.0- 18.018 0.708-0.709 20.5 20.52 0.8070-0.8078 0.04-0.082 0.0016-0.0032 - 71.5-71.51 65.649 65.776 2.814-2.815 2.584 2.589 0.03-0.078 - 136.06- 136.1 6 5.356-5.360 0.005 6 Remarks In crank and mission rtandord 24.9 less 0 980 0.1 more 0.0039 1.2 more 0.0472 0.1 more 0.0039 0.2 more 0 0078 18.1 more 0.712 20.6 more 0.81 I 0.1 more 0.0039 70.5 leis 64.7 less 2.77 2.54 0.5 more 0.01 9 35.3 less 5.326 0 1 more 0.0039 Spline ports Counter rhoft & C2 Rotary play QfXX Low gear bush In. dio. Low geor bush & 14mm Clearonce bush Kick starter spindle Out. dia. Kick startcr spindle & Clearance each bush Kick spindle pole R-port Kick r p h d l e pole Free length spring Looting Primary chain 0.01 -0.098 1.00039 -0.0038 17.13-17.15 3.674 0.675 0.02-0.058 1.00076- 0.0022 14.341 14.353 0.564-0.565 0.06-0.09 0.0023- 0.0035 - - 0.5 more 0.0196 17.2 more 0.677 0.1 more 0.0039 14.25 less 0.561 0.15 more 0.0059 uith step 0.3 m o r e 14 0.551 I 5 -"I 0 0.1968-0.3937 0.01 18 2.0 less 0.787 0. Magneto, Contact Point Item Contact breoker Repoiring t i n Slondard Tension orm spring Contact point 0.2-0.4 0.85- 1.05 kg 0.441 -0.882 1.874-2.315 0.3-0.4 0.01 18-0.0157 Ignition liming Crank angle Spark advancer; beginning of a d v m c e Rotary number I100 Rotarv number 3000 r.0.m. n out o f standar after upper dead point 5" r.p.m. angle Spark odvoncer : end of advance angle COW of 24.5 mm 10.9641 of binding length n case of 25.9 mm 11.0191 O"t of ston of mox. lift R LE6.E -?6 I.O 01 -s PPZ'Z LS 8 L00'@--ZLP000'( 8Po'o-z 10'0 lSOO.0 - 6100'0 E10-50'0 OEEO'O -05E00~0 P0.0-680'0 z8000- iP000 01z~0-901'0 6 IOO'O"86000~0 so@-Sz00 LSIO'O P'O 6EOO.O 10.0 I 'I10ua 8 J. Under Crank Case and Change Item Shift drum Standard Out. 1 din. Out. dia. of oxiol port Shift drum & hole of Cleorance crank case Shift drum Groove width Shift fort In. dio. of hole Thickness ot end Bend n t end Setting stud bolt of upper. under crank care Torque Stud Torque I 33.95-33.97 1.336- 1.337 33.9 less 1.334 11.966--11.984 0.4722-0.4718 0.025-0.075 ,00098-0.0029 11.9 less 0.4685 0.2 more 0.00787 9.0 more 0.354 34.1 more I .34 4.5 less 0.177 0.8 more 0.031 )"t of rtondard 8.50 - 8.515 0.334 0,335 34.0-34.02 1.338-1.339 4.9-5.0 0.1929-0.1 968 0.1 within 0.0039 0.5-0.7 m-kg 3.616-5.063 ftll I 7-2.0m~kg 12.29-14.46ftll - Remorks epairing Limit 16 X PI.0 )8 x P I .25 3. FRAE A. Handle ~ Slondord Throttle grip Ploy Throttle Length & inner Brake l w e r Ploy wire diffei. ence between outer Clutch wire ditto 2- 4 0.0787-0.1 57 61 2.4015 25-30 0.984- 1.181 Repoiring Limit out 01 stondord Check by external out of Check by lever end Check by lever end 4.645 Clutch lever Play 15-25 0.590 - 0.984 periphery rtondord I18 Length Remarks out of rtondord Front Cushion B. Item Front curhion under Standard 3ut. dia. bush Pivot bush 8 rurpen- Cleoronce sion orm Pivot c0ll.r Overoll length Pivot bush 8 ~ o l l o r Clea.once Front cushion Stroke Front cushion damper Damping force 011copocity Front cushioh spring Free length Tension Fall 26.04-26.07 1.025- 1.026 0.037-0.08 0.I01 4-0.00314 24.5-24.6 0.964 0.968 0.016-0.07 ,00062- 0.0027 60.3 2.374 38-45 kg 83.79-99.22Ib 39 cc Repoiring Lim out of stondori - 278 8 10.976 127.5kg 281.13 Ib I ' within 0.3 more 0.0118 20 less 44.10 25 less By 0.5m/sec 119.68in1 o White spindle 268 less 10.551 I10 l e s 242.55 out of rtondord c. Front Fork * Steering Item Stondord Steering heod stem nut Torque Steering heod Angle 6.5-7.5 m-kg 47.014-54.2 ftlb 90" 60" Carter Trail Fuel tank . Fuel Tank Copacity 75 2.952 11.88 3.117 gal U.S. Repairing Limit Remorks out o f standard Angle betweer trident and head pipe .nee# vur. ""88 Reor fork pivot bolt OIO. , Rear Fork I In. dio. 12.6 more 0.496 Chain Case * I Item Reor broke torque link 1/4 0.0098 12.2- 12.3 0.480-0.484 bush F. . Hole end Reor fork pivot bush Out. dia. Drive choin Amount of rog Standard - 1 Repoiring Limit 12.1 12.2 0.476-0.480 28.0-28.03 1 .I 02-1 . I 03 12.4 more 0.488 0.393 0.787 - out of standard Standard Repairing Limit 10-20 I Remarks 0. Rear Cushion Item Rear cushion Stroke Rear curhion damper Domplng force O i l capacity Rear cushion spring Free length Tension Tongentiol on 61 2.401 50-56 kg 1 10.25-123.48 39 cc 218.4-218.9 8.598-8.61 8 150-166 kg 330.75-366.03 1' within 30 less 60.15 30 less 207 less 8.149 143 kg less 315.315 Ib out of rtondord Remarks At 0.5 mlsec of piston 119.681 White spindle oil 860 ."!/ql OEC.IZ P'/Q S'I E6F0'0 'J!qI!M 0'1 U!4W SO0 S06S.O 0's I s91z ss 1 6 0 9 - 188'9 Z'SLI-8'PLI LLIO-LEI'O F'P-S'E 9989-PS8'9 P'PL I I'PL I 9LP.O 89P'O I'Z 1 - 6 I I 9L6' I 096. I ZOS- 86P l8F'I - P L E ' I I SE-6'PF 85980-0S980 E66'1Z-ZL6'1Z -- 100 z0.0- so0 0 p'DP"0,S 1. Rear Wheel F i n d driven sprocket Bottom dio. Reor wheel hub bearing Axial ploy Radial play Rear axle distance collar Reor axle sleeve Overall length Reor wheel axle Out. dia. Rear brake shoe Bend Overall length Out. dia. Rear brake lining Thickness Rear broke shoe spring Free length Rear broke cam Thickness Rear broke pedal Foot width Rear wheel rim Loterol deflection Rear tire Air pressure Standard lcpoiring Limit 145.76 5.738 0.005 within 0.000196 0.01 -0.02 44.7 less 5.696 0.1 more 0.00393 0.05 more 73.8-74.2 2.905-2.921 9.5-9.7 0.374 -0.38 1 16.9-17.0 0.665-0.669 0.05 within 174.1 -174.3 6 854-6.862 3.5-4.5 0.137 -0.I 7 7 27.88 1.0976 11.9-12.1 0.468-0.476 20-30 0.7874-1.181 I 1.0 within 0.0393 2.0 kg/cm' 28.44 Ib/ina Rsmorkr 16.85 leis 0.663 0.2 more 0.0078 Cutter out. dio. 3.0 less 0.118 32.0 more 1.259 out of stondord 3.0 more 0.181 out of standard MAINTENANCE STANDARDS,CB72 77 For maintenance operation For HONDA 250 * 300, Maintenance Standards, specification and dimension are listed hereafter for reference. EXPLANATION : Maintenance hems Items to be inspected, service-wise. Shndard Value This indicates the manufacturer's standard size or the standard size after newly assembling or adjusting, and shows the size-limit of completed part in the permissible limit of adjustment. Repairing Limit Unusable wear limit of 'parts requiring correction or replacement, function-wise. Remarks Unmarked numbers are run unit and inch unit shown underneath, and others according to the unit indicated. UNIT IN CHART : Unmarked numbers are m/m unit and inch unit shown underneath, and others according to the unit indicated. I CONTENTS ............................................ 19 ...................................... 19 ............................ 21 ................................ 27 ................................................ 25 .............................................. 30 1. GENERAL PERFORMANCE 2. ENGINE A. Cylinder, Cylinder Head B. Crank Shaft, Connecting Rod, Piston C. Cam Shaft, Valve, Cam Chain.. D. Upper, Under Crank Care E. Clutch, Crank Care Cover L/H F. Transmission G. Gear Change 3. H. Kick, Crank Case Cover R/H I. O i l Pump, Oil Filter J. A.C. Dynamo, Starting Motor K. Contact Breaker ... .................... 30 ....... ........... ............... 32 ............. 32 .......... .. 30 FRAME .A. ........ Cushion . . ...... 33 .................. 33 .................. 35 Handle 6. Front C. Steering Stem, Front Fender.. D. Fuel Tank E. Frome Body F. Stand .. .................................................. 36 ............................................. .. ........................ G. Rear Fork, Rear Fender H. Rear Cushion .................. I. Front Wheel ................................................ 35 J. Rear Wheel ................................................ 39 K. Electric Equipment .................................. 40 MAINTENANCE STANDARDS (Model CB72, C B 7 7 ) In this list, tne dimensions without units indicate "mm" and others occording to the units indicated. Mork lupper stepl and "inch" Idown stepl, * is exclusively used only for model CB77 and others ore common both model CB72 and 0377. 1. GENERAL PERFORMANCE I t e m Repoiring Limit Standard e %el Consumption Compression rotio Lubricating oil canrumption less I 2 0 cc/620 mile 1500cc. 16PS more l8PS more Lubricoting oil capacity Reor wheel output 2. out standard out rtondard 62' Caster Trail Remarks 8.0kg/cm less Measure with kick 1 13.76 Ib/in' 26km/ 8 less Speed 40km/h 124.8m.p.h.l 73 Br mpg out rtondard 2004 IOOOkm more 2oocc/ 620 mile out standard Check with oil gauge 12.5PS less (Max. output1 14PS less 10.5 kg/cml 149.31 Ib/in2 45 km/ 127 Br m.p.g. 9.3-9.7 120 cc/IOOO km Compression pressure 1 85' (Referential value1 (Referential voluel ENGINE A. Cylinder, Cylinder Head I t e m Cylinder sleeve Difference between mox. in.,dio. and min. in. dio. In. dia. Cylinder barrel Height Cylinder sleeve Out. dio. Cylinder sleeve Inlaying space Standard 1 Repoiring Limil Remorkr within 0.01 0.0003 0.05 more 0.00196 After boring. honing should b e enforced 54.00-54.01 2.1259-2.1263 60.00-60.01 2.3622-2.3625 83.45-93.5 3.285-3.681 62.02-62.03 2.441 -2.442 67.02-67.03 2.638-2.6389 0.02-0.05 .00078-0.00196 54.10 more 2.1 29 60.10 more 2.366 After boring. honing should be enforced 19 out standard IReferential valuel Be pressed i n at the normal temperature ~ i t e m Cylinder IOYerSiZeI O v e r size Cylinder head In. dia. (Cam shaft bearing par Cylinder head lrocker orm pin1 In. dio. Cylinder heod lrocker orm pin1 Cylinder head lottoching force) Cylinder heod Combustion chombei Standard 0.25 0.0098 41.994-42.01 1.653-1.653 17.0- 17.01e 0.669-0.669 29.3-29.7 CI capacity Bend 0.03 less 0.001 0.03'less 0.001 Bend lheod cover attach-ing Repairing Limi Remarks 3 category of 0.25 42.06 more 1.655 17.05 more 0.671 0.06 more 0.002 0.06 more 0.002 focel Cylinder head Iinlet port1 In. dia. Carburettor imulator Gap of the in. dia. of inlet port Width Cylinder head gostet Cylinder pocking Width Tachometer gear In. dio. of Bush Tachometer gear Out. dia. of Bush Tochometer gear Tightness ''0" ring, 14m/m 25.5 1.003 0.5 lerr 0.0196 I .o more 0.039 1.0--1.1 0.039-0.043 0.3-0.4 0.01 18-0.0157 7.0-7.015 0.275-0.276 13.982- 14.0 0.550-0.551 0.4 0.015 When lighting When lighting 7.2 more 0.283 Unless omission. there ore no troubles Tochometer gear ond bush Cleoronce Cylinder head cover Flatness Breather rield plote Thickness Breother sield plate Attoching direction 0.028-0.043 1.00 I 1 0.001 6 - 0.2 more 0.0078 0.03 lern 0.001 I .o 0.0393 put forward 0.06 more 0.002 Unless omission. there ore no troubles Be careful of the (In orrow r -ylinder r -yiinder head cover heod cop Zylinder heod cap "0" ring Tighting torque righting torque 3ia. mark 1.9-2.3 m ~ k g 3.74-16.63ft E l.9m-kg less 0.45 m-kg 3.25 i t E b 3.2 0. I 2 5 L35m-kg les !.53 f t d b 20 13.74 f t E b !.5 less 1.0984 ~ 8 sports are equal B. Crank Shaft, Connectlng Rod, Piston Itern Crank shaft comp. Crank angle II 81 Crank angle Ill 81 Sprocket. center crank shaft Tooth Bottom dio. Gear, center crank shaft Stondard Repairing Limit 180" 360' 16 36.285- 36.286 1.42854- 1.42857 No. o f tooth 22 sprocket Thickness of cross over teeth 15.295-15.337 0.602-0.603 15.1 less 0.594 Out. dia. 47.9-48.0 1.885-1.889 38.003-38.015 1.4961-1.4966 0.006-0.014 47.7 less 1.877 38.05 more 1.498 0.05 more 25.991 -25.999 1.0232-1.0235 25.95 less 1.021 Out. &a. Radial ~leorclnce Center crank weight Out. dia. o f pin Center cronk shaft. pressed port in. dio. 25.0-25.02 0.984 0.985 R. cronk shaft. bearing In. dig. 25.907-25.921 1.01 9- 1.020 Out. dia. 29.983-29.993 I . I 804- 1.1808 port R. crank shaft. bearing part Crank shaft comp. Max. swing R. Crank shaft key Width groove Thickness Length - 0.03 less 0.001 4.0-4.03 0.157-0.1 58 4.0-4.1 0.1 57-0.1 61 be processed with one cutter 0.00401 0.1 more 0.003 4.10 more 0.161 [Referential vc~luel [Referential voluel - In. dia. 25.907 25.92 I 1.019-1.020 L. crank shaft pressed port Out. dio. 30.002-30.015 1.181 1.186 25.95 less 1.021 * 30.004-30.009 *29.97 less 1.179 1.1812--1~1814 Primary drive sprocket No. of tootn Measuring 15 39.1 1-39.21 21 iReferentiol voluel 29.95 less 1. I 79 L. cronk rhoft pin, pressed part - No. of cross teeth 3 38.9 lerr I t e m Oil filter drive sprocket No. of tooth In. dio. Meomring bottom di Connocting rod small end In. dia. Twirl Connecting rod big end Thickness In. dia. Axial ~ l e o r o n c e Diagonal clearance qeedle roller 3vt. dio. .ength 'iston Din \lo. reqd. 3ut. dim 3veroll length ' i t o n heod Iia. 'iston skirt lia. 'iston illipre Standard 24 25.0-25.01 0.9842- 0.9846 45.1 5-45.348 1.777-1.785 15.016- 15.043 0.591 -0.592 without 0.02 0.0007 17.97- 18.03 0.707-0.709 31.005-31.015 1.220- 1.221 0.07-0.33 0.002-0.01 2 0-0.008 0-0.0003 2.502-2.51 0.0985-0.0988 13.45- 13.5 0.529- 0.53 I 48 pcr 14.994 15.0 0.590-0.5905 45.9-46.1 1,807- 1.814 51.9- 52.1 2.043- 2.05 I 53.65-53.7 2.1 12-2.1 14 59.65-59.7 2.348-2.350 53.98-54.0 2.125-2.126 59.98-60.0 2.361 -2.362 irst step )- 0.06-0.07 )-0.0023 -0,002 econd step )- 0.12-0.14 )-0.004 -0.005 0.14-0.1 6 0.005-0.006 - 22 Repairing l i m i Rsmarkr 26.0 more 1.023 45.05 less 1.773 15.1 more 0.594 0.1 more 0.0039 17.5 less 0.688 31.04 more 1.222 0.5 more 0.0196 0.05 more 0.0019 2.5 less 0.098 14.95 lers 0.588 IReferentiol volue 53.6 less 2.110 59.6 less 2.346 53.9 less 2.122 59.9 less 2.358 out-standard At the pin boss diagonol directi, Meorure at the ~ boss diogonol direction out-standard Measure at 5 m, 10.1961 upper pc from the foot of I t e m Piston ring groove Groove width ITopl Piston ring groove Groove width 1Secondl Piston ring groove Groove width loill Piston ring groove Out. dio. Piston & cylindei Min. clearonce Piston oversize Oversize Piston ring ITopl Width Piston ring ISecondl Thickness Piston ring iTopl Tension End gap Piston ring (Second1 Width Thickness Tension End gap Standard 1,505- 1.52 0.0592- 0.0598 1.505-1.52 0.0592- 0.0598 2.805-2.82 0.110-0.111 48.1 -48.2 1.893-1.897 53.3-53.4 2.098-2.1 02 Repairing Limi Remarks 1.55 more 0.061 1.55 more 0.061 2.95 more 0.1161 47.9 less 1.885 53.1 less 2.090 0.06 more 0.0023 0.25 0.0098 1.4 less 0.0551 1.4 leas 0.0551 2.2 less 0.0866 2.4 less 0.0944 0.102-0.1 10 0.5 kg less 0.62-0.82 kg 1.367-1.808 It 1.102 Ibr '0.6 kg less 0.7-1.0k.g 1.543-2.204 I t 1.323 Ibr 0.6 more 0.15-0.35 0.023 0.0059-0.01 3 '0.65 more 0.2-0.4 0.0255 0.0078-0.01 57 1.48- 1.495 1.43 less 0.0582-0.0588 0.0562 2.4-2.6 2.2 less 0.0866 0.0944 -0.102 9 . 4 less 2.6-2.8 0.102-0.1 I0 0.0944 0.5 kg less 0.6-0.8 kg 1.323- 1.764 I t 1.102 Ibs '0.6 kg less 0.7-1.Okg 1.543-2.204 I t 1.323 Ibr 0.15-0.35 0.6 more 0.0059-0.013 0.023 0.2-0.4 '0.65 more 0.0078-0.01 57 0.0255 3 category of 0.25 10.00981 oversize 1.45- 1.46 0.057-0.0574 1.45- 1.465 0.057-0.0576 2.4-2.6 0.0944 -0.102 2.6-2.8 23 Tangential tension When ottoching Tangential tension When attaching Itern Stondord Repairing Limi Remorkr ~ Piston ring loill Width Thickness Tension End gap 'iston ring & groove Cleoronce 2.4-2.6 0.0944-0.102 2.78-2.795 0.109-0.110 2.78-2.795 0.1 09-0. I 10 2.6-2.8 0.0944-0.1 10 0.7-0.9 t g 1.543-1.984 Ib 0.9-1.15 kg 1.984-2.53 Ibs 0.1-0.3 ,00393--0.0118 0.045-0.07 2.0 less 10.07871 2.7 less 0.106 2.5 less 0.0984 0.5 kg less 1.102 Ibr 0.7 kg less 1.543 Ibr 0.8 more 0.0314 0.15 more 0.0059 0.15 more 0.0059 0.1 more 0.00393 0.1 more 0.00393 ITopi 0.04-0.07 'iston ring & groove Clearance 0.01 -0.04 Cleorance 0.01 -0.04 (Second1 'irfon ring & groove loill 'irtan ring oversize Oversize 0.25 0.00984 Tangential tension When otlaching 3 category o f 0.25 10.00981 oversize Cam Shaft Valve Cam Chain I t e m Cam ft [Bearing part Out. dia. w i n g part1 Height Ift Lift Cam sprocket complete Nos. of teeth Stondard 19.996-20.009 0.787-0.787 in31.67-31.71 1.246-1.248 x. 30.54-30.58 1.202-1.203 in 5.69 0.118 Ex. 4.56 0.179 32 Bottom dia. 74.766 2.943 24 Repoiring Limi Remorkr 19.95 less 0.785 31.4 1.236 30.2 less 1.188 Max. lift I 74.2 less 2.921 SZ 899'0- 699'0 916.91 -P66'91 IIs'o-oIs'0 P86'Z 1-996'2 I zIs'o--IIs'o LZO'E I- o r 1 6E0.0 01 6SLZ'O-SLZ'O IO'L-O'L 6SLZ'O SLZ'O IO'L-O'L II E629L-ZS8'SL - II 016'6Z-P9Z'LE 61 L'PE-P'PE 61 L.81-691 sSal 8.0 LOL' I 9E'FP OZEPP -PL9' IP ZZS.81-8SL'9I 61 I'OZ-6'81 61 P'8-9'1 0.0 LLP'L PS'LE ZPS'E" IPS'E 86'68-96'68 -16-06 ISLZ'O-8PLZO 66'9-06'9 6F0'0 01 P6P'E-E6P'E 9L.88-PL'88 .16-06 PPLZO"OPLZ'0 L6'9-96'9 E6E0'0 0' 1 96P'8Z--P9P'8Z B'EZL-O'EZL 61z-ia Stondord I t e r n Repoiring Limi Remarks ~~ Rocker arm shaft [Oil port1 Tappet cleormce In. dia. In. Cam choin tensioner roller :om 2.5 0.0984 0.08-0.12 0.003-0.0047 40 1.574 Ex. Out. dio. choin temioner Free length 63.3 2.492 7 kg 15.435 Ibr roller [Spring1 Tension Volve timing ex before lower dead point 35' after upper dead point 10' before upper dead point 5' after lower dead point 30" Opening angle Closing angle Valve timing In. Opening angle Closing angle D. out-standard Cold type 38 less 1.496 Aging and crank of rubber should not be. 60.0 less 2.362 5.5 t g less 12.127 Ibr Referential valuecontrol by over 011 length out-rtmdard Check ot 1.1 m/m 339 0.0452Iln case of lif out-standard Check at 1.1 m/m +SO 0.0452 Iln case of lif out-standard Check at 1.1 m/m +5' 0.0452 Iln case of lif out-rtondard Check at 1.1 m/m 355" 0.0452Iln case of lif Upper * Under Crank Case ltsrn I ~ Stondord Repoiring Limii Upperaunder crank case lPort of center beoringl In. dio. 65.97-65.987 2.597-2.597 66.04more 2.59 Upper.under crank case [Part of bearing l/H. In. dim ~/~76.97-76.987 ~ / ~ 6 4 . -65.987 97 3.0303-3.0309 2.557-2.558 61.985--61.996 2.440-2.4407 76.93 more 64.93 more 3.0287 2.5566 2.04 more 2.442 R/HI Uppereunder crank case [Part of mission rhoftl In. dio. Upper-under cronk case (Part of kick roindlel In. dia. Upper-under crank case [Seam rurfocel Cylinder attaching foce of upper crank case Flatness Flatness - 25.1 more 0.988 within 0.03 0.001 within 0.03 0.06 more 0.002 0.06 more 0.002 25.0-25.021 0.984 0.985 0.001 26 Remarks Combined with upper and under and then measure Combined with upper and under and then meos u r e C w b i n e d with upper and under and then measure Combined with upper clnc under ond then meos u r e I t e m L/H cover attaching face of upper crank Standard Flatness within 0.03 Repairing Limit 0.001 0.06 more 0.002 59.5 2.342 59.0 less 2.28 14.0- 14.018 0.551 -0.5518 13.966- 13.984 0.549-0.550 2.9-3.1 0.1 14-0.122 2.0 0.078 within 0.03 0.001 14.1 more 0.555 13.9 less 0.547 2.8 less within 0.03 0.06 more 0.0023 Remarks case Cam chain guide roller Out. dia. In. dio. , . -om chain guide roller Out. dia. pin 3il level gouge " 0 " ring 22 mrn Dio. Tightness Flatness Jnder crank case oftaching face of C O W Aging and cronk of rubber should not remain 0.110 0.5 less 0.019 0.06 more 0.002 L/H Jnder crank c m e lSeam rurioce of upper. underi Flotnerr Jnder crank case reom Slip out of L/H or 0.001 I surloce R/H E. Clutch. Crank Case Cover L/H within 0.05 0.0019 I t e m Sfondord 0.1 more 0.0030 Repairing Limi Remorkr ~ Clutch friction disc Thickness In. dim Flatness Clutch plote Thickness Flatness Out. dia. Clutch center and clutch plate Clutch center and mission shoft Clearance of rotary direction Clearonce o i rotary direction 2.9-3.0 0.1 14-0.1181 112 4.409 within 0.2 0.0078 2.0 0.078 within 0.2 0.0078 135 5.314 within 0.3 0.01 18 within 0.1 0.0039 27 2.5 less 0.984 One set i s 6 sheets 0.4 more 0.C15 1.6 less Use 5 sheets 0.0629 0.4 inore 0.015 0.3 more 0.0118 0.3 more 0.0118 Cleorance a t out. dio. of plate BZ LS10'0--811OO P'O-E'O 8lSS'O- ISS'O 810.P I-0'PI L610'0 amu S'O 98z'z-E8z'z 9QO8S-0'85 €000'0 10.0 U!U1!M !I I9'PE-EL'€€ ~IL'SI-E'SI E6C0.0 ssai 0.1 PIE'I P'EE 60P'P ZI I 6EOOO 1'0 U!L(k!M 9200'0- 100.0 L90'0 LZO'O S9PE-P9P'E SEO'88-0'88 909E'S -ZO9F'S 9 l'9E I-S l ' 9 F I - lS8'11 LP P'DP"04S I t e r n ~ ~ Slondord ~ Main shaft and MI gear Clearance of rotory Mission gem direction Bock rush Top gear In. dio. Top gear (lifter rod por In. dia. Top gear IBurhI In. dia. Top gear bush and Clearonce mission shaft Drive sprocket Bottom dio. Drive sprocket Clearance IRotory direction1 Counter rhoft In. dio. (gear side1 Counler shaft Out. dio Bush 1 4 mm In. dio. Out. dio Counter shaft and Cz gear Clearance o f rotary direction Low gear Crossover thickness Kick stortor spindle onc bush 14 mm Clearonce Bush C 14mm Out. dia. In. dia. Mission geor gear ratio Kick spindle pole spring Repoiring Limit ~ 0.03-0.078 1.00118-0.00307 0.089-0. I 7 8 0.0035-0.0070 18.0- 18.018 0.708-0.709 8.0-8.015 0.31 4-0.31 5 20.5-20.521 0.807-0.8079 0.081 0.00318 65'649-65.776 2.584 2.589 0.03-0.078 1.001 18-0.00307 24.37-24.385 0.959-0.960 24.96-24.939 0.982-0.981 14.375- 14.393 0.565-0.566 24.98-25.01 3 0.983-0.984 - 0.01 -0.098 1.00039-0.0038 21.667-21.714 0.853-0.854 0.022 0.052 1.00086 0.00204 17.094--17.1 12 0.672-0.673 14.413--14.431 0.567-0.568 - - First 3.12 2nd I .74 3rd 1.27 TOP I .oo Free length 14 0.551 29 0.1 more 0.0039 0.2 more 0.0078 18.2 more 0.716 8.06 more 0.317 20.6 more 0.81 I 0.1 more 0.0039 64.7 less 2.547 0.25 more 0.00984 24.4 more 0.9606 24.9 less 0.980 15.2 more 0.598 0.2 more 0.0078 21.6 less 0.850 0.15 more 0.0059 17.05 less 0.671 14.53 more 0.572 13.5 less 0.531 [Part of 20.5@ I I t e m Kick spindle pole bush I Out. dio. Deflection Roller 5 X 6 . 2 5 No. Reqd Gear shift fort In. dia. Gear shift drum Out. dia. Drum and shift fork Clearonce Gear change pedal In. dio. Stondord I Remarkr Show by mox. swing o f loosing Repairing Limit 34.0-34.025 1.338-1.339 33.95-33.975 1.336- 1.337 0.025-0.075 o.ooo9a-o.oo~9~ 17.0-17.027 0.669-0.670 Remarks 34.2 more 1.346 33.9 less 1.334 0.25 more 0.0098 17.3 more 0.681 Kick, Crank Case Cover R/H Standord I t e m Kick stortor gear Shaft Out. dia. Kick stortor gear and cover R/H Cover R/H Clearance 1. 1 Gear Change I t e m H. Repoiring Limit 4.5 less 0. I77 12.5 less 0.492 20 more 0.7874 0. I96 13 0.51 I 5-10 0.196-0.393 12 pieces Overall length Primary chain 1 5 pin 0. Standord Repoiring Limit - 14.341-14.353 0.564 0.565 0.016-0.104 o.ooo62-o.ao4o9 within 0.05 0.00196 Flatness RWWXkS 14.25 leis 0.56 1 0.3 more 0.01 18 0.1 more 0.0039 0 1 1 Pump, Oil Filter I t e m Oil pump drive gear 1 Teeth width Bend Oil pump drive gear and kt. cronk geor Oil pump gear top and inside w d Back rush Cleoronce I Stondord 4 0.157 0.05 0.00196 o.oa5-0.127 0.00334 0.050 0.025-0.05 o.oo9a-o.0019 - 30 1 Repairing Limit 0.1 more 0.00393 0.15 more 0.059 0.1 more 0.00393 1 Rernorkr Adiurt by pocking r I t e m Oil pump gear Back rush Oil pump gear side Cleoionce face and ride cover Oil pump gear and pin Clearonce Oil filter shaft and oil Clearance filter rotor oii filter rotor Out. dia. Oil filter choin J. Loosing Standard I 0.1 06-0.21 0.00417-0.0082 0.04-0.089 0.001 5-0.0035 0.013-0.05 0.00051 I-0,0019 0.012-0.048 0.000472-0.00188 57 2.244 5-10 0.1 96-0.3937 'epairing Limil Rernorkr 0.4 more 0.015 0.1 more 0.0039 0.3 more 0.001 18 0.1 more 0.0039 15 more 0.5905 Measure the amplitude at the center A.C. Dynamo Starting Motor i t e m Spork performance on 3 Needle gap ignition Charging performance Charging current Slondard more 300 r.p.m. 0.314 2.0-3.0A !epoiring Lim Rernorkr 7 le** 0.275 3 Needle gap out-standar Start of charging, a1 on dynomo 1700 r.p.m.. after that. ot 500 r.p.m. Dynamo starter and 0.5 0.0196 0-0.06 0-0.00236 0.5 m-kg 3.615 ft Ib Clearance rotor Starting clutch outer Out. dia. gop and dynamo Cross screw 6 x 2 4 Tighting torque 0.8 more 0.0314 0.1 more 0.0039 out-rtondor When lighting, screw rock should needed. Clutch roller spring Free length Clutch roller spring In. dio. ICopl Out. dia. Starting sprocket of Out. dia. clutch outer journal Starting motor Voltoge 25-31 0.984- 1.220 4.1 -4.25 0.161-0.167 5.2-5.3 0.2047 -0.2086 37.175-37.2 1.463-1.464 12 v 24 less 0.944 4.3 more 0. I69 5.0 less 0.196 37.1 ICIS 1.460 Horse power 0.4 KW out-rtondor Roting 30 iec out-rlandor 31 be Repoiring Limit Stondord I t e m ~~ ~ Contact point 0.01377 before upper dead point Crank ongle Ignition timing out-rtondord 0.35 Max. gap 30 less 7" more 50 Spark odvoncer advanced beginning Spark odvancer advanced finish Spark advancer R. P. M. 1100 r.p.m. (501 R . P. M. 3300 r.p.m. out~rtandard 145") out-standard 370-439 400 Crank angle out-range advonced max. advanced ongle i t e m Type Main jet I * PW22H PW26 # *# * Cutter way * Air screw *# * A40 100 135 A0 3 0.7.bX4 0.7q5X2 Needle jet Jet needle Slow jet Repairing Limit Standard 2.6 4 22402-2 step 24231-3 step # 3 width 1.2 ~ cutting depth 0.05, 2 nothing I I return 1 % retur" - # 35 32 . Remorkr . K. Contact Breaker 1 I t e m Valve scot Carburetter ~ Stondord Remorkr 2.56 , * 2.oq5 Pilot outlet 1.2+ Power jet # 160 Power oir jet # 90 3. FRAME BLOCK A. Handle Standard fepairing Limit 4- 8 0.157- 0.314 55 out-standard I t e m Circumference direction Ploy of throttle grip Length 3ifference between outer and inner of circumference 2.165 throttle wire r Length J u t c h wire difference 133 5.236 out-standard 25- 30 0.984- I . I 81 15-25 0.590-0.984 out-stondord between outer and Inner r &tch Ploy lever 3roke lever +ant fork cover cesion 1 B. 6.5 0.255 39 1.535 Out. dia. Check b y lever end out-standard 6.0 less 0.236 Front Cushion I I t e m Front cushion Type Stroke Oil capacity Front cushion spring Free length l o n e step1 Stondord 80 3.149 both of R. and L. 250 cc 185.5 7.303 33 out-standard out-standard 180 less 7.086 Reference value I t e m ront cushion spring Free length (Two step1 Overall length Available winding Standard Repairing tin 221.5 8.720 407.0 16.024 32 216.5 leis 8.523 396.0 less 15.590 Remarks Reference value NO*. IFirrt step1 Available winding 30 Reference value 374 14.724 24.1 kg 53.14 Ibr 62 Reference w l u e Nor. ISecandory step1 Height in case of bind Torque in c o x of bind Overall winding Reference value rtandar Nor. Dia. of coil Coil out. dia. ront fork pipe comp. Out. dia ront fork valve In. dio. ront fork pipe piston Space between fork "(II". within 0.1 Bend. root fork pipe piston pipe 0.0039 0.15 more 0.0059 37.45-37.475 1.474-1.475 32.98-33.019 1.298-1.299 37.4 less 1.472 33.1 more 1.303 0.055-0.1 09 0.0021 -0.0042 0.2 more 0.0078 0.02 0.00078 Foot face not degree ront i0r.k bottom case lo. dia. Out. dia. root fork bottom piece In. dio oxis port IRI ront fork bottom piece In. dio. axis part ILI eol housing bottom cose inloylng space In. dio. Reierence v d u e 4.5 0.177 25.0-25.5 0.984- 1.003 37.5-37.539 1.476-1.4779 41.236-41.275 1.623-1.625 15.0-15.043 0.590-0.592 20.0-20.52 0.7874 0.807 41.3-41.362 1.625-1.628 - The bend of pipe nut. when made the plating port o fulcrum out-stondor 37.65 more 1.482 41.15 1.620 leis 15.1 more 0.594 20.2 more 0.795 41.5 more 1.633 34 . Standard Seal housing and oil 46.0-46.039 1.811-1.812 0.06-0.3 0.0023-0.01 1 36 1.417 33.0-33.039 1.299- 1,300 37.466-37.491 1.475- 1,476 173.8- 174.2 6.842-6.858 42 1.654 34.4-34.6 1,354-1.362 In. dio. SBd Inlaying space Fork pipe guide Overall length In. dio. Out. dim Front fork upper Overall length Front fork upper IUpper part1 Front fork upper Out. dio. Out. dio. Cover cushion inlaying port1 In. dia. Front fork under cover Overall length Front fork under cover IUpper part1 Out. dio. ,epairing Limit xt-standard wt-standard 33.1 more 1.303 sut-rtandord Jut-standard out-standard 33.2-33.4 1.307- 1.314 175 6.889 54 2.125 38.5 In. dia. Remarks out-standard 1.515 Fork rib upper cover inlaying part Fork rib under cover inlaying port 54.5-54.7 2.145-2.153 55 2.165 38.1-38.3 1.499-1.507 In. dia. Out. dim In. dia. out-rtondorc C. Steering Stem, Front Fender I I t e m Stem and bottom cone Binding rpoce I Standard 0.007-0.041 1 Repoiring Limit 0.004 less race Steering head stem nut Binding torque Steering stem top cone race inlaying port Steering stem front fork pipe inloying part Out. dio. In. dia. 6.5-7.5m-kg 5 m-kg less 47.01 -54.24 ft Ib 36.16 ft Ib 25.979-26.0 1.022-1.023 38.-38.062 38.25 more 1.496-1.498 1.505 35 1 Remorkt I ~ Stondord Steering stem bottom bridge I Stopper angle Repoiring Limit I out-standard 76' Remorkr Measured by jig lreferentiol value1 Idouble. ride k 5mml Steering top cone race In. dio. Front fender Plank Material 26.0-26.021 1.023- 1.024 0.8 0.031 SPC-I out-standard Standard Repoiring Limit Fuel Tank D. I t e m Volume Fuel tank Reserve E. e 14 3.698 golur 1.2-1.5 0.31 7-0.396galus e Frame Body Stondord Heod pipe comp. top boll race Binding space H e o d pipe comp. bottom race 1 Repoiring ' . Limit . . 0.051 -0.0575 0.002-0.0022 out-standard 0.001 -0.051 out-standard Out. dia. M" Steel ball top No. Reqd. 0.009 I8 pcr out-standard Steel boll bottom No. Reqd. I9 pcr out-standard Reor fork center bush In. dia. 14.01-14.02 0.551 -0.551 Binding spoce 0.03-0.08 0.001 -0.003 Steel ball Remarks 36 14.1 more 0.555 1 Remarks I t e m Stondard Step arm comp. In. dia. Step arm fixing bolt Out. dia. Main stand pipe Thickness Main stond the hole of binding port Main stand setting bolt In. dim Main stand setting sprins Free length Out. dia. Load 12.2 0.480 16.957- 16.984 0.667-0.668 2.3 0.090 14.0-14.027 0.551 -0.552 13.9- 13.968 0.547-0.549 a6 3.385 87.5 kg 192.937 Ibr Repoiring Limi Remarks 12.7 more 0.499 16.7 less 0.657 14.3 more 0.562 13.5 less 0.531 83 less 3.26 In case of binding, m m . stretch and load lreferential "CllUel Broke pedal 17.0- 17.027 0.669-0.670 20-30 0.787- 1.18 In. dia. Cleorance 0. 17.2 more 0.677 out-rtandorc Rear Fork, Rear Fender Stondord I t e m Repairing Limi Kemorkr ~ ?ear fork pivot In. dia. Tear fork pivot bush Out. dio. In. dio. Pressed rpoce 7ear fork. pivot bolt Out. dio. Overoll length Drive chain Type 26.0-26.021 1.023-1.024 26.04-26.08 1.025-1.026 20.05-20.08 0.789-0.790 0.01 9-0.08 0.0007-0.003 13.925- 13.968 0.548-0.549 30 1 I 1.850 DK 530 20.5 more 0.807 Clearance 13.8 less 0.543 94 teeth Teeth Slack After pressed i n give a finishing touch to the in. dia. 9- 13 0.354-0.51 1 37 out-standarc Standard I t e m Reor brake stopper arm Overoll length out-standard Rear Cushion I t e m Stroke Rear cushion Oil capacity Declined tension Rear cushion spring 1. Remarks 0.7 more 10.0-10.2 0.397-0.401 9 0.354 385 15.1571 In. dia. Thickness H. Repairing Limit 1 i Stondoid 60 2.362 52 cc 60-67 kg/O.Sm/r 13227-147.70 Ibs/OSm/r Free lengte 210 Load 8.267 37.5 tg 82.687Ibr 1 Repairing Limit 1 Rerno rk I out-standard out-standard 207 less 8.149 In case of 185 mm lbinding hightl 72.76 Ibs Front Wheel Itern Front axle diitonce collor Front brake cam Overoll length Thickness Front brake shoe Out. dia. Front broke lining Thickness Brakc drum In. dio. Brake shoe spring Free length Load Front axle Out. dim Slandard 49.9-50.1 1,964-1.972 10 0.393 199.8-200 7.866-7.874 5 0.196 199.85-200.15 7.868-7.879 63.0-63.5 2.480-2.499 5 kg 11.025 Ibr 14.966- 14.984 0.589-0.589 Repoiring Limi Remarks 8 less 0.314 Shave out. dia. 2.5 less 0.098 201 more 7.913 66.5 more 2.618 3.5 kg less 7.717 Ibs 14.9 less 0.586 In case of 67.5 mm lretting length1 2.657 I I Itern Standard 238 9.370 0.05 0.00019 Overall length Front axle Bend Front wheel rim Swing Front tire Dimension I I 1. I I Remarks 0.007 3.0 more 0.118 0.0393 2.75-18 0.108- 0.708 I .7 kg/cmZ 24.174lb/i 15.0- 15.018 0.590-0.591 In. dio. Repairing Limit 0.2 more 1 .o Air pressure Front panel axle 1 4PR out-rtondord 15.1 more 0.594 1 1 Rear Wheel Standord I t e m bpoiring Lirn Remarks ~~ Final driven sprocket Bottom dia. Reor axle distance Overall length mllor Reor wheel axle Out. dia. Bend Oveioll length Rear brake shoe Out. dia. Rear brake lining Thickness Reor wheel rim Swing Rear wheel tire Air pressure Dimension Rear brake pone1 axle In. dio. Rear bra& In. dia. Broke cam ponel torqr In. dia. 151.8 5.975 100-100.2 3.937 3.944 19.947-19.98 0.785-0.787 0.05 280 I 1.024 199.8-200 7.866-7.874 5 0.197 1.O 0.0394 2.2 tg/cma 31.284 Ib/in 3.00- 18 0.118-0.708 20.0-20.033 0.787-0.789 10.1 10.2 0.398-0.402 - - 15.0-15.043 0.591 -0.592 39 150.8 less 5.936 out-rtandar 19.8 leis 0.780 0.2 more Shave out. dia. 2.5 less 0.0984 3.0 more 0.118 4PR 20.1 0.791 10.5 0.41 15.3 0.602 OP OOPT OOET OLZT SEZT m'd'i 0 0 2 3 %S+OUWOI uwos VP v9 8-9 VZ 3 d 0 8 2 1-092 I AZ I HVO I w 6 ~81'0 a L'O vs I uoqd SOI-S6 AOP 3 V AOE 3a V8ZO M P V8S'O MS'L VL9'Z MOEISE DISASSEMBLY AND ASSEMBLY In this chapter, mainly Disassembly operation was explained. and for assembly special attention was only called for where needed, as both operation are similai. CONTENTS 1 . ENGINE IC72 . 771 A . Engine replacement .......................................... 45 B. Cylinder .................................................... 51 C. 1. Cover .................................................. 56 D. R . Cover ............................ E. Mission ICrankl . . . . . . . . . . . . . . . . . . . . . . . . F. Cylinder Head G. Oil Pumo ........................ ............................ ..... ................ 60 . . . . . . . . . . . . . . . . . . . . . 62 ..... ................ 64 .. ... ................ 68 .. ... ...... 70 .... 76 2 . ENGINE ICB72.77) A. Engine Replacement B. Cylinder .................... ............................ . C . Engine Minor Overhaul Assembly .. ... . . . . . . . . . . ........ .. ... . . . . . . . . . . . . . . 77 3 . FRAME ICB72.771 ._ . % A . Rear Fork ............................ B. ............................ Front Fork . . . . . . . . . . .... ....... .... .. . . . 78 81 DISASSEMBLY AND ASSEMBLY 1. ENGINE ( C 7 2 * 77) A. Engine Replacement (L. ride,) Ditmrernbly Precaution Tools Assembly 1. L. Exhaust pipe Tighten not to Ieok ex ioint nut houst gas. 10% rocket wrench 2. L. Exhourl pipe muffler 14% rocket wrench 17% spanner Fig. 2 3. L. step bar Be cautious of the porition of serotion in case of fitting. Ar- semble with putting in position at the punch mock.. Tightening torque 2.lkgm 14% spanner II5ft. Ibl 4. Gear chonge pedal Fitting ongle. One rerotion foreword in- dined f r o m horizontal position. iO% spanner 45 Dirarrembly Assembly Prec.ution Tools 5. L. frame dust shield Fig. 5 6. Plug cop Air vent tube Fig. 6 7. Corburetter Fit securely setting nut 10% spanner 8. Breother pipe Tiglitening torque 2.1 kgm 115ft lbl Engine hanger bolt I 7 Z s o ~ k e twrench Tightening torque 4.4kgm 13211. Ibl 17% sponner Fig. 8 46 Dirorrsmbly Precaution Assembly TOOIS 9. 1R:sideI R. exhaust pipe i o b t ioint nut Tighten not to leok exhaust gas. Refer to L. side '10. R. exhaust pipe muffler Refer t o L. side 11. P step bar Assemble with nutting in position at the puncn mark, tightening torque 2 . l i g m 115ft. Ibl Refer to L. side 12. Starting motor cable Dirarrombly 13. Promulion hsembly TOOIS Refer to L. side R. dust shield forehead T-Handle driver 1#31 14. R. crank case cover T-Handle forehead driver 1#31 10% socket wrench Fig. 10 IS. Clutch wire Fore driver f.g. II 16. Drive choin ioint Drive sprocket cover Pliers Fig. 12 48 Dimrrembly krmbly Prscaulion Tools 17. Chain loint clip Fig. 14 18. Engine wiring Fig. 15 19. Plug cap Air vent tube Re'er to L. r o e Fig. I 6 Dirorrably Procaution Assembly Tools 20. Carburener setting Set lever of fuel cup nut stop. 10% spanner Fig. 17 17% rocket wrench 17% spanner 22. Engine setting bolt 14% socket wrench 23. The point of toking down engine In Case Of age 50 be CoUtioUs not to dam. on fender. Fig. 19 fitting. the front 8 . Cylinder Dirorrembly Precaution Assembly Too!$ I. Condenser 9% rocket wrench Fig. 20 2. H e a d cover To tighten setting nuti on the heod cover. follow order shown here repeat 2 to Pay attention t o lhe color of nuts. 01 and 3 times 10 tighten securely. a@l@@+white nut O@@*yellow ""I 14% rocket wrench Fig. 21 3. Corn chain teniioner 10% socket wrench F'q. 22 4. Sparking plug Plug rocket wrench Fia. 23 51 Dlransmbly Prec 0 "ti0 n Tools Assembly Steering top cone race box wrench Fig. 24 5. Corn chain Tightening torque 2.lkqrn l15ft. ibi \ In case of dirasrernbly and fitting of the cam chain. be care- ful not to drop clip into the cylinder heod. Tie o wire at the end of chain to prevent chain from dropping into the cylinder. Fig. 26 Fitting direction of clip: fit the ioint t o the direction of revolution of the 1-1 Fig. 27 52 crank Prasdtlon Assembly Dirorrsmbly TOOIS Combination process a C o i n c i d e ' T ' punch mark on the dynamo rotor with the arrow mark on the starter. 14% spanner Fig. 28 @ Coincide punch mark on the right tooth surface of the com sprocket complete with tha center line of the cylinder head. and combine ' of crank sprocket Fig. 29 shaft by chain. 6. cylinder head Beforehand. rocker shaft i valve arm, ond cam votw shodd be rubarrembled. Plastic hammer r -.*- Fig. 30 ->T .- P O ~ottention to "0' r]ng and gasket. 53 Di$oiiembly Precalltion Assembly Tools 1. Cylinder In setting the cylinder on the piston. divide piston rings in 3 portsseparotely and put the ring retainer on the piston and Plortic hammer push in the cylinder laying the stopper Fig. 32 between piston and case. Cylinder Put in knock pin ond packing securely 0. Piston Use new piston pin clips, avoiding such clips lost elosticity. Thin nose pliers Fig. 33 In orsemblying piston. put the punch mock on the head of piston t o the foreward direction. Fig. 34 54 Dirmrmbly hrombly In fitling the piston. be careful on selection of clearonce with cylinder previously. If the cylinder is over-sired, select piston fittable lo this cylinder and asem- ble. 9. Piston ring After setting rings on the piston. check to ovoid any hooking between ring and piston. In fitting rings. be careful upper and lower surface of the rings. IGenerolly o n the upper surioce maker’s punch mark is shown.) Fig. 35 I” case of “Sing OVer sired cylinder. use a ring fittable with the cvlinder. 55 Assembly Disassembly ,. ?,G ' Piec~ution Tools 1. L. COYer In fitting L. cover, be Pocking careful the oil filter Dowel oin cover not t o bite On 0 dowel pin of the oil filter shaft. T-Handle foreheod driver 1#31 10% rocket wrench Plastic hammer Fig. 36 2. O i l f,,,s, Set oil filter drive sprocket pin facing R. outword. Fig. 37 3. Lock washer Foreheod driver Plastic homrner Fig. 38 4. Lock ""I After tightening perfectly. turn up the torque of lockwarhIf not torque and nut coincided. nut should be locked er. after turning t o the tightening direction Fig. 39 without loosing it. 56 , .: I ..I .,.. . .. C.' .~ '.+ +' Dkanmbly Assembly Precaution Tools . .. 5. Clutch pressure plate To tighten plate setting bolls. lighten them evenly. 0% diagonally shown picture. in the Check ex- istence of spring. 10% socket wren c 1 Fig. 40 6. Clutch lifter (oint piece In osrembly. check op- ' eration of oil metol guide. Fig. 41 7. 25% set ring Be careful ., about crinple snip ring rernOYer -~ Fig. 4 2 8. Clutch center Fis. 4 3 57 1 . i Dirmsmbiy Plecoutio" Assembly Tools 9. Clutch plate Clutch friction Pay attention for order 4% order of fitting. disc In dirorrembly . assembly. do ond if perpendicdarly t o the cronk shalt and troni mission Eain shalt Fig. 44 Be coreful about size. fig. 45 10. Shift spindle Fig. 46 11. Shift drum stopper Shift drum stopper guide 107, socket wrench 17% socket wrench Fig. 47 58 i . Dirosrornbly P,sco"llon Assembly Took in tightening stopper bolt of tick starter. the mark On the end of kick starter spindle seen hole. should be through the D. R. Cover Diratrernblv Arrembiy Precav1,on Tools 1. Starting motor coble 10% spanner Fig. 49 2. Storting motor R. L. ride cover 1-tlondlc i forehead driver 1#21 Fig. 50 3. Starting motor 10% socket wrench *. 4. N e u t r a l switch Fig. 52 60 5. A.C. dynamo storter After starter arrem- bled. check rototion of the starter sprocket. 10% rocket wrench -- 6. A.C dynomo Rolor 14% rocket wrench PIortic hammer Dynamo rotor puller 17% spanner Fig 54 7. Starting rprockel stopper 10% socket wrench Plortic hammer Forehead driver Fig. 5 5 8. starter rorocke1 Fig. 56 s, 61 E. Mission (Crank) Ditorrembly Assembly Precavt,on Tools 1. upper crank case Setting nut 14% socket wrench * 2. In tightening nut and Under crank case sett;,,a nut & bolt bolt. foilow order as shown in figure starting *temporary 3. Under crank <' Fig. S9 4. Main rhofl 62 .u . _ .;.. C D S ~ 10% rocket wrench' tightening and then 14% rocket wrench actual tightening. Plastic hornrner Assembly Dirasrembiy ' Precoutlon 10011 5. Counter shoft Fig. 61 To set bearing oil sed do it securely. Fig. 62 Point liquid packing on the case. N o t e : l e a k the sur. face of packing be fore pointing. D o n ' t use with attaching cleansing oil or oil. Paint without chok- ing oil holes. Fig. 63 63 F. Cylinder Head Assembly Disassembly Pracoutlo" Tools 1. Cylinder head con 23% Fig. spannet 64 T-Handle forehead driver 1#21 Fig. 65 . . 3. R.L. m,.y m6 cylinder head ride cover T-Handle forehead driver 1#31 Fig 66 10% rpclnner Tappet adjusting rock. et wrench Fig. 67 ' Assembly Ditortembly Precoulion Tools 5. Attach tag oh L and Valve R. valves not to be mixed each other. Valve lifter Thin nose pliers 6. Rocker arm crank "i" Rocker arm ln rock arm crank pin. pay ottenlion t o outer diameter of inlet rocker or,n pin and of exhaust rocker arm pin t o insert inside the cylinder head. Former pin is larger than diameter of that of the latter. Rocker arm crank Pin exlralor Cutting-grooves on the rocker orm crank pin t w o ploces are set for oil passage and retreat for stud bolt. So need spe- cia1 attention t o 01locate pin to assem- ble. 7. Cam shaft lock nut Forehead driver Plastic hammer 65 c n ". ' F ' Dirorrembly Prac0"tio" Tools Atrembly 8. R. corn shaft Forehead driver Plastic hammer Fig. 72 Assembly of process L. cam sholt. Alter coinciding spline.put the red line of the point shalt com on the punched mark Plostic hammer 01 the cam sprocket ilocing upwordi then Fig. 73 insert. 9. Cam shalt lock nut L. cam shoft 10% rocket wrench Fig. 74 10 h assembly the cam +~ shaft .coincide the spot where o tooth of spline of the cam sprocket complete IS lacking with the corresponding spot on the cam shaft ond Fig f then insert 75 66 \ L Disarrsrnbly ' . Precoution Assembly Tools 11. Cam sprocket comp. Put the punched rnork upword ond corn shaft rocker nut to the right side. \ 89 P ! 4. Side cover Refer lo the engine minor overhaul and assembly. T-Hondle forehead driver 1x31 5. Oil pump ride cover dowel pin Oil pump gear A Oil pump gear B Oil pump drive gear Fig. 82 I OL T , I 1 Disassembly Arrsrnbly Precaution , Tnnl. I 4. L. exhaust p ~ p eloin1 nut L. exhaust muffler Fig. 88 Fig. 89 6. Speed- tachometer cable Fig, 71 90 .. .. . -. -- .. .. - - I / Dirausmbly Assembly Precaution Tool. 11. R. exhaust pipe ioint nut R. exhaust muffler 10% rocket wrench 142 14% rponoer Refer to L. ride 12. Dynamo cover 13. R. crank care cover Clutch wire Drive rprocket cover Fig 14. Drive choin Pliers Refer to the item 01 frame. 73 96 Dirmrmbly PreCDYlion Assembly Toois 15. Air cleaner case 16. Throttle w i r e Fig. 97 17. Aircleaner connect- ing tube About throttle wire refer to the item of Engine Replacement for Model CB 72. 77 T~Hondle forehead driver 1#21 Fig. 98 18. Engine wiring Fig. 99 I 74 19. Cantoct breakei cover Contact breakei Fig. 100 20. Engine hanger bolt Fig. 101 21. Engine setting bolt Insert T-Handle foreTote h e a d driver. out the former driver and dawn engine loy to take out the latter driver. 14% spanner 14% rocket wrench 17% spanner B. Cylinder Dirarrembly Assembly P,eCO"t,O" TOO89 10% rponner Cylinder head cover Cam chain teniioner Refer to Model 72 77 Engine Replacement. C. Englne mlnor overhaul and assembly Dirarrernbly I Arrembly P,eCO"llO" TOOii 1. 1. L. Cylinder head ride cover T-Handle forehead driver 1#31 i Fig. 10 5 3. FRAME (CB72 * 77) A. Rear Fork Precavtion Airarnbly Dirarrmbly Tools 1. Rear brake wire comp. 14% spanner Fig. 104 2. Rear broke stopper arm Pliers 14% spanner Fig. 10s 3. Cotter Pi" Axle nut Pliers Fig. 106 4. Rear wheel axle Plastic nomme Fig. 107 78 Dirmrembly Assembly Precaution Tools 5. Drive chain c Fig. 108 6. Reor wheel 7. Chain c o w iOX spanner 10% socket wrench Fig. 110 8. R. rear cushion i 7 X rocket wrench 17% spanner Fig. 11 1 79 Dirasrembly Procoution Arssmbly Tonk In assembly, put the screwed ride of the reor cushion under bolt hole to face outward. Fig. 112 9. muflier Exhaust Refer t o the previously Change pedal mentioned items o f Broke Engine Repldcement. pedal Step bar 10. R. step bar brockef 17% socket wrench Fig. 113 11. L. step bar bracket 17% rocket wrench Plastic hommer Fig. 1 1 4 1 B. Front fork\ Disassembly Procaulion Assembly Tools 1. Hend liqhl T-Handle forehead driver 1#2i F'g. 115 2. Wiring Draw out only white. red and blue wires. Fig. 116 3. Wire Hornerr lermi"01 Fig. 1 1 7 4. Speedometer cable Tachometer coble Pliers Fig. 118 81 Dirarrsrnbly Assembly Promullon Tools 5. Broke wire 14% spanner Fig. 119 Fig. 120 6. Front brake slopper arm Plastic hammer Foreheod drive Fig. 121 7. Speedometer cable on'y Pliers Fig. 122 82 \ Diliorrombly Arrombly Precaution Tools 8. Cotter pin 13X.281 Front wheel axle nut Pliers 23% rocket wrench Fig. 123 9. Front wheel axle 14% spanner Plastic hommer Fig. 124 10. Front fork comp. Front fender 10% spanner \\ Fig. 125 II. Starter switch ass y H-handle foreheod driver 1#21 Fig. 126 ' / Dirorrembiy Prscout,on Assembly Tooir 12. Throttle grip pipe T-Handle forehead driver i#21 Fig 127 13. Throttle wire como. Fig. 128 14. Clutch wire comp. Front brake wire comp. Clutch wire adjust bolt. Fixing nut Fig. 129 Pliers IS. Snap pin 6% Steering damper' (lock spring nut spring Plote Friction dirk i Fig. 130 Pliers 84 \ Di~arrornbly Precaution Assembly Tools 16. Hex. bolt 8 X 30 Steering handle pipe comp. In assembly. pay attention on punched mark. 14% socket wrench Fig. 131 17. Steeiing damper knob comp. {lock spring Damper lock spring I set bolt. 17% rocket wrench Fig. 132 18. -r- Speedometer ass'y t Fig. 133 19. Front fork bolt Steering head stem nut. Stem nut 26% spanner 35% spanner Fig, 134 P' Assembly Dirarrernbly Fork top bridge 2 . Steering head threoj comp. Steering top corn race Fig. 136 22. Steering stem comp Fig. 137 Fig. 138 86 PraCa"ti0" Tools Pr.Co"ti0" Tools Assembly Dirosembly 23. Front fender Take out on orrow morked bolt. Fig. 139 24. Front fork cornp. Fig .Put lhe under front fork cover with welded :lip (IS 140 . - . I the R ride. ._ Fig. 141 Inside o f the clutch outer, the primary driven sprocket is fixed by rivetting and as primary chain i s set o n this sprocket, p o w e r i s transmitted t o the transmission main shaft through the primary chain from the crank. Handle the clutch lever, the clutch lifter thread turns right by clutch wire, and the lifter threod i s pushed out inside by the screw inside of clutch adjuster fixed on the R. crankcase and push outside the clutch lifter piece 11 1 1 through clutch lifter rod. As the clutch pressure plate 191 is pushed o n side by the clutch lifter ioint piece. clutch spring 1101 is compressed t o free 161 171 o f each 4 pieces. Therefore rotation of 151 161 161 161 161 is n o t transmitted t o 181. Note : Number of clutch plate and clutch friction disc i s four sheet each for Model C72 and 5 sheets eoch for Model C77. CB72, 77. 0 Prerrure 0 Clutch 0 Clutch plate spring @ 6 mm bolt @) Clutch center 0 Clutch lifter ioint piece 25 mrn circlip @ @ @ @ @ a Fig. 3-2. plate L. crankcase cover Clutch friction disc Primary driven sprocket 6mm rivet Mission rhoft @ @ @ @ Clutch outer boss Clutch lifter rod Clutch lever Clutch lifter threod Clutch adjuster @ R. crankcore cover 0 Cross section of clutch for Model C72 ' 0 0 Clutch friction disc L. crankcase cover @ 6 X I9 washer 8 6 x 2 4 Hex. bolt 0 Clutch spring @ Clutch lifter ioint piece @ Oil I guide metal Fig. 6. @ @ @ @ @ Clutch pressure plote Clutch center Clutch plote Prirnory driven sprocket 6 m m rivet Clutch outer @ Mission shoft Q Clutch lifter rod @ Clutch lever @ Clutch lifter threod 0 Clutch adivster @ R. crankcore cover 0 3-3. Cross-section of clutch for Model C77, CB72. 77 Transmission system 1. Function and kinds Following clutch, function of transmission i s t o convey power transmission. and convert torque b y means of meshing geors of different number of teeth. As shown in Fig. 3-4 if driving gear i s smaller Ihan driven gear, No. of rotation of the driven side will b e smaller transmitting large torque. Here it is called reduction ratio showing the rotio o f each gear numbers. There a r e t w o systems of gear meshing for transmission of auto-bicycle i.e. selective sliding system and constant meshing. L 103 Reduction ratio=- A B 6 A Torque ratio=-- Drive geor (No. of teeth A1 Driven gcor (No. of teeth 61 3-4. Fig. Relation between reduction ratio and torque ratio By selective sliding system. shift gear i s slided by gear shift fork to get adequate reduction ratio b y changing gear t o b e meshed, and by constant meshing system, each geor can be rotated freely always each gear in meshing state, and can b e changed reduction ratio by actuating optional gear b y means of special clutch. Fig. 3-5. Cross-sectional figure of tronirniarion seat 2. Construction and function The trmrmission rotary type. shown. system of Honda 250 - 300 i s constant mesh and advance 4 stage In Fig. 3-5 to Fig 3- 9, neutral. first. second, third and to stage are Function of transmission as shown in Fig. 3-5 and Fig. 3-10 is as follows, that is power i s transmitted from crankshaft t o primary drive chain, clutch outer, clutch center and transmission. n kil Fig. 3-6. The first n Fig. 3-7. The second Expiaining in order, from the crank rotation i s transmitted to the clutch, and the trclnsrnission shaft i s rotated to turn the l o w gear 171. starter spindle IlPI. The l o w gear turns sliding over the kick- As the counter shaft 2 gear 191 which i s connected with the spline 105 on the counter shaft complete can move freely axially, move this t o the left side b y gear shift fork t o mate with l o w gear Fig. 3-61 then the l o w gear the counter shaft as one b o d y t o transmit power t o the top gear 1121. axial movement of mainshaft gear i s restricted b y the gear cotter 1141 and the set n Fig. 3-8. - The third -a - P U Fig. 3-9. The fourth (Top1 106 I L Here the ISimilorly counter shaft 3 gear 11 I ) . ring 1151 but not restricted rotationally. P combines with R LO I 80 1 C. Final drive mechanism The drive mechanism from crank to the rear wheel is colled final drive mechanism. The main parts are as shown in figure, primary reduction lintermediate reductionl. clutch, mission, final drive lpropeller shaft, final reductionl wheel and W e . 0 Clutch 0 Drive @ Transmission shaft @ Drive chain @ Primary chain sprocket (9 Crankshoft @j Fino1 driven sprocket Fig. 3-12. 109 AUXILIARY PARTS 4. A. Funnel type breather Breather chamber o f funnel type i s located on the rear upper side of the upper crankcase. Inside the chamber breather b o d y is supported b y a spring and back pressure is guided along the direction as shown in the figure separating oil t o outside of crankcase. Here a check valve is fitted to avoid outside vapour t o be sucked, 0 Breother 0 Breather body @ Breother chamber 0 Breather valve spring @ Cotter pin valve body Breather valve @ Breather support spring @ Breather valve lplain view1 Fig. 4-1. B. Kick starter mechanism Kick spindle pawl for Model C72. 77 mates with the inside groove of l o w geor b y pawl spring to rotate l o w gear. When not in kick. the head o f pawl i s pressed down b y kick spindle metal bush so that l o w gear attains free state. I10 0 Kick W starter spindle @ Low gear complete @ Kick spindle pone1 Fig. 4-2. For M o d e l C072, 77 considering relation with the chassis, advance step kick system was applied. A piece of gear was set inside the R. crankcase cover to reverse direction of rotation and can start engine transmitting rotational power t o the kick spindle pawl. Fig. 3-31 r 0 R. crankcore cover comp. @ Kick starter gear 0 Kick 1 Fig. 4-3. C. orrn @ Kick i t o r t e r pinion 0 Kick starter spring @ Clutch lifter thread cornp. Crankcore cover Cam chain tensioner Inside com' chain chamber located at center port of cylinder cam chain lDK219-94L) i s set to transmit rotational motion of crank t o cam shaft, and corn chain tension is applied to make high speed motion of cam chain correctly and smoothly. tension works to suppress waving of chain Here the com chain b y pressing corn chain. In Fig. 4-4. 6mm bolt fitted on the tensioner push bar be loosen, the roller will be pushed out b y a spring t o give ' a adequate tension on the chain. can be done b y this set screw. According to slackness of chain adiustment To make sure tightness o f chain, it is favorable t o adjust putting the cronkshoft ot the bottom dead center. Po 0 Cam chain tensioner 0 Cam chain tensioner 0 Tenrioner holder spring @ 6mm bolt chain tensioner push bar @ Corn chain tensioner a r m 0 Cam Fig. 4-4. 0 Cam @ Com sprocket choin chain guide roller @ R. corn shaft flywheel 0 Cam 0 Cam @ Center crankshaft chain teniioner Fig. 4-5 112 5. CARBURETTOR The carburettor i s a device for supplying fuel and air into the engine. The performance of the carburettor will depend upon such factors as most suitable mixture proportion of atomized fuel under all conditions of speed and load of the engine. Therefore it must has precision for each part and high resistonce f o r wear to assure the reliable performance for a long period, and so it i s required inspection and maintenance. The revised parts of M o d e l C72 f r o m Model C71 are as follow. I 1 I Elimination of manifold. 121 Fitting type down draft type. 131 Addition of power jet. Comparing M o d e l CB72, 77 with Model C72, 77 2-carburettor system was adopted to increase horse power b y eliminoting branch to suction post. Concerning the power jet mentioned above. when MJA i s set, the best condition i s at 4000 r.p.m., and at 8000 r.p.m. mixture becomes lean, but when MJB i s set os 8000 r.p.m. the best and at 4000 r.p.m. becomes rich. Therefore to get fovoroble condition between 4000 r.p.m. and 8000 r.p.m., MJA was selected to apply the power jet from 6000 r.p.m. to meet high rotation developing performance at medium and high power. 0 Power jet @ Blind plug @ Power air jet Fig. 5-1. Power jet system 113 Construction I 1 1 Air from the oir cleaner posses through the suction p o r t 11). lower side of the throttle valve 161, main~bore - 181 and inLCthe cylinders. This air streom produces a partial vacuum in the area around the power nozzle 1241, b y which fuel in the floot chamber 121 flows through power jet fuel pipe 1231, power jet 1221 to the power nozzle 1241. through the power air jet 1211. A t this area. fuel i s mixed with air introduced Then they are mixed with air flowing from the suction port. vaporized and drawn into the cylinder (Fig. 5-21. 121 Main fuel.~ system ___~ Air from the air cleaner posses through the suction port I l l , lower side of the throttle valve I61 main bore 181 and into the cylinders. This air stream produces o partial vacuum in the area around the needle jet 141, b y which fuel in the float chamber 121 flows through the main jet 1101 into the needle jet holder 131. area, fuel is mixed with air (bleed air1 introduced through the air jet holes 191 provided around the needle jet holder 131. As this I51 and the Then fuel and air travel the gap between the needle jet 141 ond the jet needle 171. and discharge to the lower side of the throttle valve. Then they ore mixed with air flowing from the suction port, vaporized and drawn into the cylinder (Fig. 5-21. 131 . Slow speed fuel system lpilot system1 ~___ ~~ ~~ Air from the suction p o r t ( 1 1 passes through the outside 1121 o f the air screw i l I1 which regulates the rote of air flow. Then air passes through the bleed holes 1141 of the slow speed jet 1131 t o the slow speed jet 1131 where introduced into fuel stream from the orifice 1151 provided with the bottom of the slow speed jet 1131. The rich mixturc produced at this area discharges to the lower side of the throttle valve ond i s mixed with air flowing from the suction port I l l and drawn into the cylinder. The minor mixture adjustment i s made b y means of the air screw I1 11. Turn the air screw to the right t o enrich the mixture and to the left t o mixture. lean the The mojor mixture adjustment is made b y replacing the slow speed jet 1131. Replace the jet with one carrying bigger number t o enrich the mixture and with one carrying smaller number t o lean the mixture Fig. 5-21. 141 Float chamber The carburettor must supply the correct mixtures which suit t o the throttle opening and the engine running speed. The floot In this connection. the fuel level must be held constant. system i s a device to maintain this constant height. floot system is given in the following. I I4 The operation of the Fuel from the tank enters the float chamber 121 through the passage 1161. the valve seat 1171 and valve 1181. As fuel enters the float chamber. the float 1191 will raise and move the valve I l B i upperword b y means of the float arm 1201. will be restricted. When the v ~ l l v etouches the valve seat, flow of fuel As fuel level drops. the float lowers. opening the valve to allow fuel to enter the float chamber. Thus. any change in the fuel level causes a corres- ponding movement of the float. opening or closing the valve to maintain the fuel level constant. , There i s a spring installed, against vibration, between the needle valve and its b o d y at the location where the valve contracts the float orm 120). (Fig. 5-21 151 .~ Choke system ~ The choke valve 1211 must be in a closed position with the choke lever moved upwards, and in a open position with the choke lever moved downward, as shown in Fig. 5-2. 115 I61 Adjustment a ) High speed fuel mixture adjustment Fuel mixture between full and half open throttle positions i s controlled b y the To determine whether the main jet i s correct, slightly close the choke main jet. valve with the engine running at full throttle 1. If the engine speed increases, the fuel mixture i s t o o lean. 2. If the engine speed decreases. the main jet i s correct o r too big. Replace the main jet as necessary in such cases. bl Moderate speed fuel mixture adjustment Fuel mixture between half and one eighth throttle positions i s controlled b y the adjustable jet needle and cut away of throttle valve. I . If the muffler is black smoking, the mixture is t o o rich. tower the jet needle t o the next lower position. 2. If the engine misfires or hesitates when accelerated or driven ot moderate speed, the mixture i s t o o lean. Raise the jet needle t o the next upper position. The throttle valve cut owoy carrying larger number bring the mixture leaner while one carrying smaller number bring mixture the richer. Since the change on the cut away affects the engine performance below one eighth throttle position, the replacement of the throttle valve should be done carefully. cl t o w speed fuel mixture adjustment Fuel mixture between one eighth and idle throttle positions i s controlled b y the air screw and throttle cut away. I. Adjustment " in I ' must b e done b y the air screw mostly. to enrich the mixture and " out " Turn the air screw t o lean the mixture. 2 . If the correct adiustrnenf connot be obtained b y the turning of air screw, replace the throttle valve. I71 -~ Fuel level adjustment ~~ As shown in Fig. 5-3, fuel level is determined b y the height H measured from the bottom of moin bore, which varies among each different engines. However, since the fuel level connot be measured easily, i t is recommended t o determine b y height h, of the float. Float adjustment 01 Place the corburettor uoside down 116 @ Float 0 End of floot valve @ Float orm 0 End of floot Fig. 5-3. @ Parts of carburettor body @ Fuel standard level 0 Moin bore boltam line Meorurement of fuel standard level b l When the float i s supported with fingers, find the position where the float arm i s about t o touch the t o p of the floot volve or the position having clearance o f 0 , l m m . 10.04 in.1 c1 At this position height difference between the end of floot and the carburettor b o d y should equal t o h and if it is more or less than this amount, adjust the height, raising or bending the float o i m corefully. h of Pw 22 26.5 mm (1.043 in.) h of Pw 26 22.5 mm (0.885 in.] Note : At the tip of the floot valve there is inserted o spring which creeps inride when pushed. As i t prevent to show the octuol position where the v d v e is to be closed. i t is necessary to be cautious to see the contact point between the float arm and tloot valve. 117 6. FRAME Construction of frame body The frame supporting engine contacts with ground through the front and rear wheels and is the skeleton of whole chassis. design. Further it has important feature affecting its form and The main function of frame is t o maintain chassis strength, supporting engine, rider, and load on the carrier. and has t o endure shock due t o roughness of r o a d through tyre and shock absorber. On the other hand it requires rigidity from viewpoints of control ability, and further requires lightweight to attoin better running performance. M o d e l C72. 77 is. The frame b o d y of Hondo 250 * 300 made of steel o f stress skin construction and adopted such cross sectional form as refregerator having round corner. t o bending moment and torsion. The type of form has high strength Therefore this would b e most fovoroble form of con- struction for motor cycle frame having high rigidity from manufacturing viewpoints. Especially welding is done b y new type of seam welder to attain reliable connection and also uniform products having beautiful outlook. O n the other hand for the frame o f Model CB72. 77. as main strength members, high carbon steel tubings were adopted to attain light weight and to increase rigidity. 0 Gasoline @ @ @ @ @ @ @ @ Fig. 6-1. Frame body far Model C72, 77 118 tonk Carrier Spare seat Reor fender stay Rear fender Shock absorber Reor fork Seal box Frame body 0 Main pipe 0 Coil setting 8 L. plote 0 Tube holder 8 R. r u b ~ i u b e 0 Battery support stoy 6)Sub-tube crors~member 0 R. sub-tube holder @ R. L. rear cushion upper brackets sub-tube holder bottom plote R. step holder piece Muffler setting pipe Center pipe @ R. @ @ @ @ Steering heod pipe @ Fuel tank holder @ Key hale Fig. 6-2. Frome body for CB72. 77 119 @ Front down tube @ Driver's iube @ Engine hanger ploie ruh-tube Main switch bracket L. bottom plate Center pipe bushing L. Step holder piece 8 L. @ @ @ @ 7. SUSPENSION A. Front wheel suspension The front fork of Model C72, 77 i s made of pressed steel and for Model CB72. 77 telescopic fork was adopted t o increase rigidity and t o attoin better running stability rough road. on As the cushion, the link system made it possible t o reduce wheel base variation and t o attain better feeling on riding and better controllability. As shown in the figure of shock absorber, it consists of the main spring and double cylindricol oil damper. The spring tokes up compression l o a d ond the damper takes up recoiling force. For Model C72. 77, left and right front cushions ore combined b y the suspension arm as one body, but f o r M o d e l CB72, 77 there is no suspension arm. In the oil damper of M o d e l CB72, 77 there contains white spindle oil 220 cc, and moximum stroke i s 80 mm (3.1496 in.). 0 Front cushion bottom metal comp. @ Front cushion spring front damper inner pipe 0 Front damper piston @ Front cushion rebound stopper spring Fig. 0 Front damper collar @ Front damper oil seal 0 Front damper rod 7-1. Cross~sectionof front cushion for Model C72, 77 Q Front cushion 0 Hinge 0 Suspension orm @ Supporting hinge Wheel axis , .a Fig. 7-2. 120 @ Fork drain cock pocking @ Front damper v ~ l v e Q Fork pipe stopper ring @ 334610, oil seal @ Front fork seal housing @ Front fork upper cover 0 Front fork rib @ Front fork upper cover @ Front fork bolt @ Front fort oil seal retainer @ Ring, 40.5X3.0 @ Front fork washer @ " 0 ring, 9.4 X 2.4 @ Fork piston knock pin @ Fork top bridge @ Front fork pipe guide 'I @ Front fork cover pocking @ Front cushion spring @ Fork bottom bridge @ Front fork piston 0 Front fork bottom case @ Front fork drain cock bolt @ Front fork pipe comp. Fig. 7-3. Crors~sectionof front cushion of Model CB72. 77 6. R e a r wheel suspension The rear wheel i s pivot type construction equipped with also shock absorber. The principle of construction of the shock absorber i s alike that of the front wheel excepting such point as side pressure don't act on the sliding part and construction of orifice on the absorber i s different. side 0s Special attention was paid on the suspension system on the pivot performance of shock absorber, rnonufocturing around the pivot and rigidity of reor fork affect on feeling of riding greatly. As the rear fork of Model CB72, 77, main strength members were made o f high carbon steel tubing to attain light weight and to raise rigidity. Q Rear cushion metal 0 @ Reor rebound stopper spring comp. 0 Rear Reor cushion spring a Reor damper inner-pipe Fig. 8 Rear 7-4. Cross-section of damper oil seal damper rod. reor cushion of Model C72. 121 ! .1 zz I ow3w 8. A. STEERING SYSTEM Steering handle Special attention was paid in designing the steering handle as this affects feeling of riding and easy control. Especially f o r Model C72, it wos aimed to take riding posture easy t o correspond quick manipulation of control, which would be determined b y the form of the handle, saddle and step. Moreover on control parts, adjustment equipment8 ore attached according to each riders' choice. 0 L. These features could b e said t o symbolize Honda's kindness. front winker 0 R. steering handle @ Throttle wire 8 Winker switch @ R. grip rubber @ Throttle lever lens @ L. steering handle lever @ Horn button @ Head light switch 0 L. grip rubber @ R. front winker lens Fig. 8-1. lever Handle of Model C72, 77 The handle complete of M o d e l CB72, 77 i s mode of one piece of steel tubing attached t o the fork top bridge b y means of the handle pipe holder. fixed on the front cushion b y 2 front fork bolts. make it easy to replace the handle. 123 The fork top bridge is Each wire i s exposed in assembly to 0. Speedo-tachometer arr'y 0 Steering hondle comp. 0 Handle pipe holder @ Steering damper knob Fig. 8-2. B. Handle assembly of Model CB72, 77 Steering .~ Construction of steering of Mode! C72. 77, as shown in the Figure, is such having boll bearing and steering damper o f friction plate system to meet requirement from controllability and stability at !ow and high speed running. , \ Fig. 8-3. Crorr section of steering head of Model C72. 77 124 For Model CB72. 77, the steering stem which has cone lathe inside supported on the front cushion b y means of 8 x 3 2 hexagonal bolt is the rotational axis centering frame On the steering stem, steering damper is head pipe and i s important part for steering. attached and can be adjusted according to r o a d condition, running state and loading condition. If the knob o f steering damper be turned to the right. steering damper spring nut i s raised upward t o clamp steering damper ’friction disc by meons of steering damper plate A and B, consequently handle steering becomes heavy. On the contrary. if the knob be turned to the left, steering damper spring n b t i s lowered to make gap beiween plater A and B to become easy steering. [Fig. 8-41 0 Steering damper knob comp. @ Damper lock spring set bolt 0 Steering damper lock spring @ Steering heod Stem nut 0 Fork top bridge @ Steering top thread 0 Steering bottom cone race @ Steering heod dust seal @ Steering domper friction disc (@ Steering damper plote E @ Steering damper spring @ Cotter pin, 2.0 X I5 , @ Steering top cone race @ Steel I ball, 1/4* @ Steering top ball race @ Steering head pipe @ Steering item @ Steering bottom ball race @ Steel ball. 1/4” @ Steering damper plote A @ Steering damper lock nut @ Steering damper spring nut . Fig. 8-4. Cross section of steering of Model CB72, 77 125 9. BRAKE INSTALLATION As reliability and durability of brake instaliation are indispensable condition for it, rnanu~ focturing brake was paid special attention. Rear wheel braking i s done b y expanding the brake lining installed i s the brake drum which is octuated by link motion to turn the brake cam by pushing right foot. Here special attention was paid to emit friction heat generated t o get better durability. For the front brake, by right hand operation wire transmits force to work and brake mechanism is alike with the rear instullation. 0 Brake cam 0 Brake lining @ Broke drum Fig. 9-1. 0 Broke shoe width 30 @ Broke shoe anker pin @ Brake drum inner dia.. @ Broke shoe out die. 0 Broke Fig. 9-2, 126 cam @ [ Front fork Fig. 9-3. MEMO 127 10. CONSTRUCTION OF WHEEL A. Front wheel Front wheel body made of aluminum casting of whole width hub containing boll bearings and brake drum inside i s fitted with brake panel and speedometer unlt by wheel oxis and nuts. To assemble the front wheel to the chassis. tif slide pipe by the axle fitting. on the lower end of front fork Reaction occured during braking can be caught by the left side bearing through the stopper of the brake panel. . Fig. 10-1. Cross Section of front hub 128 . 6. Rear wheel The rear wheel of Model C72, 77 is consisted of wheel bearing, rear wheel hub of aluminium equipped with the brake drum, the final drive flange serving chain case partially and brake panel. O n the left side. the brake panel is equipped through the distance collar, and between the wheel hub and the final drive flange there i s fitted rear wheel damper. On the right side of the wheel hub containing ball bearing, the chain case is equipped through the final drive flange fitted with the rear wheel damper and the final driven sprocket. and is tighten on the rear axle passing through the left side of the rear fork through the distance collar on the left side. The rear #heel damper absorbs not only abrupts variation of rotation during braking and driving force of the rear wheel hub. hut also is useful t o protect transmission mechanism. The reor wheel of Model C672, 77 i s consisted of hall bearing (63041. the rear wheel hub of aluminium casting equipped with the broke drum and the brake panel. On the left side there equipped the rear brake panel of twin c a n type through the panel side collar and on the right side of the wheel hub. and the final driven sprocket are fixed b y the sprocket setting bolt, and fixed on the rear fork b y the rear axle through the rear side collar. Fig. 10-2. To draw out the ieor wheel f r o m the frame [Model CB72, 771 129 1, I 0 Reor wheel damper 0 Final Fig. 10-3. drive flange 0 Final Cross-section of reor hub . I30 driven sprocket 1 1. A. AUXILIARY EQUIPMENT Air cleaner The air cleaner element made of filter paper i s stored at the center part of the body utilizing a point of excellence that the frome is made of $eel sheet. It is aimed t o get better filter effect b y expanding surface area and also t o prevent rain water t o enter. For Model CB72, 77, as 2 carburettors ore equipped, air cleaners are fixed on sides each. 0 Air cleaner connecting tube Fig. 11-1. 0 Air cleaner element Air cleaner of Model C72. 77 0 Air cleaner connecting tube 0 Air cleoner element 0 R. air cleaner support stay @ Tool box 0 L. Fig. 11-2. Air cleaner for CB72, 77 I31 complete oir cleaner support $toy both Muffler 8. Construction of exhaust muffler. ~~ ~ Exhaust pipe conducts exhaust gas from cylinder head t o muffler. Curvature of this pipe affects horse power developed exhaust gas conducted through exhaust pipe i s damper inside of muffler by chocking passage and further discipote sound of the diffuser pipe to get silencing effect. I 0 Diffuser Fig. 11-3. Cross-section of Muffler of Model C72, 77 0 Muffler Fig. 11-4, pipe @ Diffuser pipe Crosr~sectionof Muffler of Model C072. 77 132 ELECTRIC EQUIPMENT 1. Ignition system (Ignition coil, Magneto, Contact breaker, Spark plug1 2. Electric power generator (Rotor t y p e A.C. Generator, D.C. Dynamo) 3. Rectifier (Selenium rectifier) 4. Battery 5. Looding (Illumination light, Winker, Horn, Starter) Electric system i s important part for the motorcycle alike nervous system for humankind. Even a portial damage at engine ignition, light at night or horn function will affect quite often i t s smooth running. W e adhere on JIS standard f r o m viewpoint of monufacturing and traffic transportation motorcycle low and security standard for laws and standards. 133 CONTENTS 1. SYSTEM .............................................. 137 ............................................ 140 .................................................. 143 D. Spark Plug . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144 E. Plug Construction ............................................ 145 Wiring Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150 A. Ignition Circuit 8. Contact Breaker C . Condenser 2. 3 CHARGING SYSTEM A. A.C. Generator ............................................ 152 B. Celenium Rectifier ............................................ 154 C. Battery .................................................... 156 D. Cell Starter ................................................ 162 E. Maintenance of Starting Motor ................................ 166 F. Starter Magnetic Switch ...................................... 169 SAFE GUARD PARTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171 135 1. SYSTEM O F ELECTRIC EQUIPMENT As ignition system. ignition coil and contact breaker are used. For electric generator, Rotor-type A.C. Generator i s used, charging battery through selenium rectifier and discharging according t o several loading. 0 Heod 0 Horn 0 Relay light 0 Main switch @ Wire harness 0 Ignition coil GI Rotor-type A.C. generator @ Selenium rectifier @ Battery @ Stop switch @ Tail or stop light Fig. 1-1. A. Ignition circuit 1. Ignition system In gasoline engine, at the favorable time of the uppermost position o f compression stroke mixture gas should be burned and exploded by any means of ignition. For both Model C and Model CB, high tension battery ignition system i s adopted Fig. 1-21. i i 0 Ignition coil @ Condenser 0 Contact breaker @ Spark plug Fig. 1-2. Ignition system 137 2. Ignition coil Ignition coil is the same construction with that for Model C72. For M o d e l CB72, 77-1 type, there equipped with one coil each corresponding to 2 cylinders right and left, as the crankshaft angle i5 180 degree. But f o r Model CB72, 77-11 type, alike Model C72. one coil of simultaneous ignition system is equipped as the crankshaft angle is 360 degree (Fig. 1-31. Fig. 1-3. Ignition coil A. Construction of ignition coil _ _ -~ Ignition coil is shown in Fig. 1-4 where fine enamel wire o f 0.08 mm dia. is wound over the iron c o r e about 1.000-2.000 rounds as the secondary coil on which further enomel wire o f 0.6 mm dia. i s wound over it about 200- 300 round as the primary coil. And stored in the cylindrical case after insulating process ond drawing out the terminals (Fig. 1-41. 0 Battery @ Insulation @ ignition coil @ Secondary ride @ Primary side @ Primary current 0 Contact breaker @ Point cam @ Condenser @ Spork plug Fig. 1-4. Cross-section of ignition coil 138 Q CC Primary terminal 3 Secondary termina' ;& InPUlotio" 8 Iron core 6)primary coil @ Secondory coil Fig. 1-5. Function diagram of ignition coil of Modal CB72. 77 6. Function of ignition coil ~~~ ~~~ The principle of ignition coil is similar t o that of induction coil. As shown in Fig. 1-5, rotating cam axle and crank with constant periodical relation. there generates high voltage on the secondary coil CIS follows. a . When the point o f the contact breaker is closed primary current flows in the direction as shown b y a r r o w and generates magnetic flux inside the iron core. b. When the point i s opened by the cam. the magnetic flux which i s generating b y primary current i s going to disappear suddenly. c. Due to large variation of magnetic flux and large number of winding, there generates high voltage in the secondary coil. d. Here generated high voltage will charge on distributed static electric volume of the secondary coil itself. then 0s it voltags increase, further start charging on volume of high tension cord and plug continuing increase e. of voltage. When voltage increases up to ample amount. spark will occur at the plug gap. As soon as spork started sparking voltage drops down instontaneously. Accordingly electric load charged on the distributed stotic electric volume will be discharged totally (volumetric sparkl. And continues discharge of energy contained in the wire by disappearing magnetic flux linduction sparkl. f. Magnetic flux approaches down to zero instantly where voltoge no m o r e maintoin spork voltage and discharging spark disappears. 9. Still energy in wire due to remaining minute magnetic flux will generate damping vibrotion inside secondary and primary coil. and disappear acting as resistance loss on the circuit. h. Then returning com angle to original state to actuate the function 0 s stated i a l to f o l l o w the same process repeatedly (Fig. 1-5-1-71. I39 OP I Generally contact point pressure i s designated between 700 and 900 gr. and t o prevent wear of the cam follower grease should be applied on oil felt. Required characteristics for point are as follow. 1 1 High unti-wearing property. 21 High heat conductivity. 31 High melting point. 41 High unti-oxydation. 51 Have a moderate hardness. 0 Fixing hole of 0 Oil felt 0 Breaker arm Contact breaker @ Point @ Terminal @ Spring 0 Point fixing screw @ Base of contact point Fig. 1-8. Fig. 1-9. Contact breoter assembly 02 points for Model CB72. 77-1 type 0 1 point for Model C72. 77, for CB72. 77-11 type Fig. 1-10, 141 Contact breaker of Model CB72, 77-1 type Generally f o r automotive use. 4- 5mm 10.157-0.196 in.] tangsten i s applied. Sparking i s generated b y magneto cam contacting and breaking of timing of crankshaft and cam shaft b y the contact breaker. ; Fig. 1 - 1 1 . Contact breaker of Model C72, 77, and Model CB72, 77-11 type I O n e cam i s profiled at the end of the point shaft connected with the spark odvonce ~ I inside of the cylinder head for Model CB72. 77-1 type, and 2 sets of contact breakers ore set relatively at 90 degree on the base. and designed to operate at correct timing of L. and R. cylinders. 2 coils, 2 points, 1 mount corn for Model CB72, 77-1 type. II 1 I I j 0 One mount corn :j ! I .. . Fig. 1-12. ~ Point shoft corn profile (Model CB72. 77-1 typel ~ i For Model C72, 77 and Model CB72, 77, 2 cams are profiled on the point shaft and 1 contact breaker i s fixed on the base. I I Here simultaneous ignition system is adopted as explained in the porogroph about the ignition coil. M o d e l CB72, 77-11 type : 1 coil, 1 point, 2 cams and simultaneous spark. 1 ! ! I I \ I42 Q Cam - _--__-Fig. 1-13. Note - Point corn prafil (Model CB72. 77 and Model 0372, 77-11 type1 : Surfoce of point becomes rough with working time elopse weor if ottoched oil or greore on rhe point surface. Especially there occurs exiraordinary Further if ottoched oil or grease on the point surface be left d o n e for il long time. it solidifies and forms insulating surfoce to effect ignition be impassible. So special precoution is needed to prevent attaching oil. If the surface of point becomes rough or dirty. use o fine file or sandpaper to polish and odjust, ond i f case i s more worser. take out the contact breaker base and the breaker base and the breaker arm, polish both contact surfaces with oil stone. case special attention i s needed t o avoid one side wear. very b a d influence for a new part or In this This one side wearing affects repaired part. Therefore centering and parallel adjustment of both contact point i s essential requirement. Also if there i s found t o o much play within axle hole of the breaker arm i t i s needed to replace with new one. On the other hand, terminals of contact breaker and insulating parts of wire have t o maintain ample insulating standard. 50 that special precaution i s required to keep clean avoiding vapour. oil, dirt t o be attached. wipe In case of adiustment of the surfoce of point its surface with clean cloth stoined with trichrene t o avoid grease, oil or dirt to be attached. C. Condenser Function of condenser i s to avoid harmful spark between points, ond if taken i t s volume value too lorge spark performance becomes worse. adequate value between Therefore generally it i s selected 0.1 and 0.35 microfarad. On the other hand i t i s required such feature t o resist high voltage as high voltage of I43 several hundred volt acts on the condenser at the point opening instance. So it i s prescribed i n the JIS standard that i t should resist more than one minute under such condition as A.C. 700V (50 or 60 c/sl maintaining insulation of more than 5 Ma after heating 30 minutes at 80DC [Fig. 1-14. 1-151. Fig. 1-15. Condenser (Model C72. 77 and Model CB72, 77-11 Simple test for condenser is done like the following. typel After checking insulating value by mega, disconnect both poles of condenser from mega while mega i s running. then short both poles by wire. At this instance, if spark occurs large enough. it i s decided the volume value i s good standard. By use of the service tester it can be tested precisely volume value and insulating performance. D. Spark plug Spark plug plays the most important part within ignition system of engine, and it takes charge of starting engine, receiving high voltage generated by ignition coil or magneto 144 to make combustion of mixture gas b y high voltage spark occured spark gap within plug in the combustion chamber. a ) Conditions needed to embody for spark plug There ore five explained CIS subjects t o be solved t o fulfil i t s function perfectly, which will be follows. IAI Current Electric current flows through the shortest way, and always tries to spark out of spark gap. At manual temperature electric insulating character of insulation is high, but at high temperature this character decreases. Therefore it i s needed high insulotion material which is hard t o decrease its character even at high temperature. IBI Explosion pressure Inside the cylinder, 3 5 - 4 5 atmospheric pressure due t o explosion always seeks path to escape. If air tightness of plug i s inadequate, combustion gas of high temperature will penetrate inside it to loose its function due to overheating. ICI Combustion head Temperature of combustion of mixture gas will reach up to 2000°C. It is needed t o discipate this heat sooner t o develop engine performonce preventing over heating of plug. sparking in advance or burning electrode. ID1 Carbon in case o f incomplete combustion If get dirty on the insulating port. engine will fail i t s smooth running due to high voltage leaks partially ond poor sparking. ( E l Lead compound 4-ethyl lead i s contained in gasoline t o control explosion, and lead oxidized compound is mode due to combustion. If it i s deposited on the plug. this com- pound becomes a medium having conductivity ot high temperature and high voltage current will escape as explained before. E. Construction of plug Here is shown the plug used generally f o r automobile Fig. 1-16]. 01 Electrode As material of electrode it i s required to b e hard to wear, l o w sparking voltage, high heat conductivity. high resistant to oxidation. manufacture. high conductivity and easy t o At present Nickel olloy or heat resistant olloy is used (Fig. 1- 17). I45 9P I LP 1 during engine revolution o r b y oil penetrated into the combustion chamber. This deposit i s electric conductible itself, and makes short circuit o f high voltage Accordingly weaken spark to decrease engine power misfiring and in electricity. worst case will stop engine revolution. To prevent such phenomenon surface of insulator should be heated enough t o cut off carbon deposited, and this i s called " self cleaning temperature " labout 45O0C-6OO0C according t o engine statel. On the other hand, it burned sparking part of plug at higher temperature, sparing part will become over heated point which invites harmful knocking t o burn mixture gas before hand than sparking the plug, which affect decreasing of engine Therefore it i s requested that temperature of whole body of spark plug power. should b e maintained less than that of premature sparking (less than 800°C according t o engine statel. As a result it can b e said " sparking part of plug i s no good if t o o cooled also if too hot" . bl Escaping of heat Heat received from combustion gas escapes as shown in the figure and sparking port maintains a certain temperature balancing heat quantity escaping and receiving. cl Necessity of different types of plug having each different heat value.-Difference of heat quantity received by each plug. Heat quantity of plug received from engine depend on kinds of engine lair cooled or water Fig. 1-19, w a y of escaping cooled, 2 cycle or 4 cyclel, design lcompression ratio, shape of combustion chamber, plug position1 heot and running state [speed, loading, different fuel, flat ground or climbing slope1 grcotly. Therefore i t i s necessary t o furnish different types of plug to function satisfactorily under each different operating condition. This rote of escaping of heat is called " h e a t value of plug ", and it is determined by its construction, form, dimension and material. It is called " c o l d type " (for high temperature usel which discipates heat easily and i s hard t o be over heated. and on the contrary such types as hard t o discipate heat and easy t o be heated i s called " hot type perature usel. In Fig. 1-20, difference between types functionally are shown. I ' (low tem- 0 tow temperature use [hot typel 0 Medium temperature use (medium typel 0 High temperature use (cold typel Fig. 1-20, Different plug for heat condition 0 0 Dirty - 0 Smooth -- * 0 lgnltlon A Fig. 1-21. H o t type plug (for low temperature use1 MEMO I49 riinninn = t o o early Wiring Diagram of HONDA 250 300 (CB72, CB77) Starter button S W ~~ - 2. A. CHARGING SYSTEM Rotor-type A.C. Generator The principle of generation of electricity b y Rotor-type A.C. of the flywheel magnets. Generator is same as that Magnetic flux in the iron core of coil turn its direction as much times as number of magnetic pole for each a turn of the magnetic iron. For each a turn of the magnetic iron, as magnetic flux in the iron core changes with ~~ magnetic pole number ~. 2 cycles 13 cycles per one turn for 6 poles generator), so there generates A.C. voltage in the generating coil due to this variation of magnetic flux. The more magnetic force of magnetic iron, and the earlier rate of change of magnetic flux in the core ithe more quick the rotation of magnetic iron, and the more number of magnetic poles) ond also the more number of winding of coil, the large A.C. voltage i s generated [Fig. 2-1, 2-31, All these conditions couldn't be satisfied from viewpoint of manufacturing, and among magnetic force of magnetic iron, number of magnetic poles and number of winding of coil there is such inter relation as to increase one sacrificing other. Rotor-type A.C. Generator Due t o defects of (Flywheel, generating coil of Generotor), which works with wrong voltage variation and not equipped with a voltage regulator, there occur too ~ I I much raise o r drop of voltage i f take the loading at random not using regular loading. But recently these defects have been overcome b y magnets manufacturers' effort. On the other hand for magnetic weakening of magnetic iron preventive measures have ~ been token in the course of design. (Fig. 2-21 A point of excellence of Rotor-type A.C. Generator due to it simple and strong construction is almost no trouble and lack of wear parts. Special feature of using Rotor-type A.C. Generator combined with ignition coil is to tnake it possible emergency starting I Fig. 2-1. Rotor-type A.C. Generator 152 which is impossible t o b e followed b y Rotor-type A.C. Generator. Frequently there occurs perfect discharging carelessly from capacity battery mounted on motor cycle, due t o its small capacity. For the battery ignition system, it is impossible to spark unless replacing battery or recharging. but for the Rotor-type A.C. Generator system it i s still possible t o spark by kicking even after perfect discharging of battery due to its feature of steep and high induction voltage of Rotor-type A.C. Generator under light load where generated voltag b e conducted ta ignition coil in D.C. or A.C. as it i s through selenium rectifier. Therefore it enables emergency starting b y switching of adequate circuit connection. 0 A : Generator Coil 0 Fixed core Ikon core 0 Rotor lmognetic iron1 0 Yellow and coil1 @ C:rrrkrhoft Fig. 2-2. 0 Brown Construction of Rotor-type A.C. Generotor Fig. "Id ICornrno" "*el 2-3. Circuit diagram of Rotor-type A.C. Generotor 0 Battery voltage E g 0 Charging current Z g Fig. 2-4 (a). l"I"(II @ White ldoy and night1 A : Volt B : Amp Choracterirticr of Rotor-type A.C. Generator ldoytimei 153 10. 5. 4 . 5. 32 1 . 01 o muo. 2uoo 3000 AOUU sooo @ Battery voltoge EB 0 Charging current 2s Fig. 2-4 (b). 6. 6000 m o moo qooo iom A : Volt B : Amp Characteristics of Rotor-type A.C. Generator (during night1 Selenium rectifier The selenium rectifier is used f o r rectifying the D.C. current from the A.C. current, always combined with Rotor-type A.C. Generator or A.C. generating coil. There are several kinds of construction, material and form for this rectifier. but the principle i s some utilizing its special character of easy flow current t o one direction and closing t o other. Types of rectifier generally used are selenium rectifier, copper oxide rectifier, and germanium rectifier. i s shown i s Fig. 2-5 (01, Rectifying unit t o rectify b y the selenium rectifier and is composited b y rectifying plates combined with end plates b (A1 Rectifying plate 0 lnruloting membrone @ Electric pole 0 Selenium @ Positive direction 0 Bore plate (nickel ploted steel or aluminum1 (BI A sign of rectifier or rectifying plate @ Direction of current B Fig. 2-5 (a). I54 and spacers of required number in series or parallel and further according t o rectifying system it i s set in comb-like arrangement o n different rectifying circuit style. Rectifying plate i s shown in Fig. IAl, where o n the base steel sheet or aluminium plate o f nickel plated circular or rectangular form, refined selenium mixed with an adequate amount of impurity is spattered in vacuum and further ready fusable alloy of Cd, Bi or Sn i s pured on its surface to make electric pole after perfect heat treatment t o make it active metal selenium. Then it becomes possible t o get such phenomenon as current i s easy to flow to positive direction and almost shut t o flow t o another direction i f put current t o the reverse direction t o that shown b y arrow. This i s called rectifying action of selenium rectifying plate. This characteristics caused by unsymmetric conductivity due to the layer of barrier on the contacting surface between pole and metal selenium of semiLconductivity. i s very harmful effect As moisture on the selenium rectifying plate. unit-moisture processing i s done b y moisture resistant point to prevent corrosion. The selenium rectifying unit which i s common for Model C72, 77 and Model CB72, 77 is connecting in bridge and number of selenium rectifying plate becomes much and the ignition coil works for both cycles of positive and negative loading. Durability o f the selenium rectifier depends on temperature largely, and it i s prohibited to raise more than 30°C. So i s requested not to flow over current for a long time. @ All wave rectifier 0 Generating 5 A.C. volt& coil @ D.C. @ Battery @ Loading Fig. 2-5 (b). O n the other hand, there is so-called resisting reverse voltage which more voltage i s put to reverse direction there occurs puncture [Here punctured part turns t o be insulating substance at once and this damage self-restores its function reducing effective rectifying area. The more number of puncture, the more rectifying efficiency will be decreased to 155 b e overheated). Therefore i t is necessary t o raise t o t a l resisting reverse voltage by putting required number of plates in series corresponding to A.C. voltage generated by the generator coil. In Fig. 2-5 (bl, put A.C. voltage b e t w e e n terminals P.O. of the generating coil as IAl : IB) : IC\= 1 : 2 : 1, i t i s evident ICI is most suitable f o r high A.C. voltage rectifier as the reverse voltage p e r one rectifying p l a t e i s smallest. G e n e r a l l y speaking i s selenium rectifying system for use o f automotive A.C. generating coil ICI>(Bl>iAl. is the o r d e r t o select corresponding t o voltage. 0 Selenium rectifier CI : @d b : c : d : os'y Red terminal Brown terminal Volt Yellow terminal Fig. 2-5 (c). Remorks : Special precoution is necessory in using selenium rectifier not to run engine under such condition as no loading stote lfar instonce unlaoding state of battery during daytime or taking out state yellow of fusel. CIS high voltage generated by generating coil under no load or light iood condition acts t o the reverse direction. This leads t o puncture trouble and will damage the selenium rectifier if continued a long time. On the other hond, there occurs ageing chonge in the selenium rectifier for Q long term use increosing internal resistance in the rectifier plote t o decreose output voltage and t o increase temperature. The largest cause of ageing chonge is temperature raise and at more thon 70°C in the rectifier this chonge occurs rapidly, therefore it i s required t o select cool position t o equip it. There is such tendency as to increase current t o reverse direction if selenium rectifier has not been used for o long time. In such case, before using wise voltage slowly during one hour from lower votoge labout half of standordl t o restore its function. C. Battery All the b a t t e r y f o r automotive use a r e lead storage b a t t e r y and its construction i s as shown i n the figure that i s a n o d e plate g r o u p a n d cathode p l a t e g r o u p ( o n e p l a t e m o r e thon a n o d e group1 a r e put together i n turn inserting separator b e t w e e n a n o d e and cathode plates, a n d these combined plates a r e stored i n the cell lebonite o r stirol model d i p p e d with electrolysis solution. One unit as shown in the figure is called o n unit cell a n d 156 , LS I be poured in and seai tightly a pouring orifice. yet i s t o be used initial charging i s necessary. Therefore when battery not charged This i s done after pouring electrolysis solution charging with regular initial charging current for about 70 hrs. continuously to attain both pole plates a perfect charging state for the first time. It i s iequired the initial charging should b e done perfectly, otherwise this battery will not display its volume 100% for future use and its life be shorten seriously. Precaution necessary b e f o r e starting for use : Inspection should be done before use of battery finished initial charging as follow : 1 1 I Inspect if there i s something unusual or not, as damage, happens sometimes during transportation. Especially due to damage on the case there happens leakage of solution. 121 Peep inside through pouring port after taking cop, or check the level of solution to be on regular height. If i t s level is lower, check damage if any on the case. If no damage, supplement dilute sulphuric acid of same specific gravity with other cell. 131 If time elapsed more thon t w o weeks after the initial charging, i t i s necessary t o supplement charge t o supply amount of self discharged electricity while let alone. During this supplement charging, it i s desirable t o check level of solution to adjust regular height and further measure and keep record of voltage, specific gravity and temperature for each celi for future reference. Fig. 2-8. Precautions while in ure Supplement chorging of Bottery : I I I Inspect battery periodically, once a week f o r automotive use. month or after each 1.000-2.000 krn 1620-1860 1 59 rniiel running. At least twice ,a I21 Special attention should be paid on the level of solution and if short supply distilled water o r drinking water [no content of metal 0s ferrous]. If the case of battery is transparent there i s shown level of solution. but generally the height of solution should be adjusted about 13mm 10.51 in.] over the separator. If the pole plate be exposed in the air due to drop o f level, there occurs oxidation on the plate making white sulphuric lead which decrease volume of battery, and effect the performance of exposed plate to be serious cause of inner shorting. So many troubles are experienced due t o this cause. therefore it wouldn't b e exaggeration t o say that i s the most part of causes to shorten i t life. I31 Keep always in charged state. If used f o r a long time in insufficient charged state trouble called sulphation will be accelerated and at last i t invites such difficulty as t o make it hard to restore original substance b y usual charging. pole plate warps easy to short. On due to over discharging separator gets damage. supplement change before the discharge limit. Sign of level of solution Fig. 2-10, Precaution for me 160 Therefore it is requested t o f i g . 2-8-2-101 ~ Fig. 2-9. Such the other hand, if used with thin solution For the battery, MBl4-12 applied. type (Voltage 12V. volume 10 hours rate 10Ahl is Duration of battery i s expressed b y hours from the complete charging state t o the complete discharged state using electricity f o r each separate loading while in stationary stote. shorten so much, This relotion could be presumed froln the following table. Kinds of loading on bottery ~~~ Therefore i f the loading overlapped duration will b e Mean consumption of c w r e n t Standord ~ Head light 35/35w Starting motor 0.4kW Magnetic storter switch 3w Winker lamp IOWX2 Tail light 4w Stop light 8W Speedometer lamp 3w Stop Ignition 3A I 0.25A ~ ! HW” 10 hrs 30 hrr - 3.5A 0.8-l.2A loop In COW 40 hrr I A * Running - Listed on other part 0.35A 0.7A 0.25 A - 2 hrs Listed on other port 10-50A ~ 3.5 A Neutral lamp * Duration of bottery ioppraximatel 1.5A 40 hrr 1.6 hrr - 6 hrr of point closed and switch on For instances, if the head light 35W i s on, consumption is 3A only and duration will b e about 2 hrs. but if the taii lamp 10.35A1 and ignition 13.5AI were used simultaneously total consumption will be 6.85A. From the figure above shown duration becomes 35- 40 minutes. While in running, charging is done corresponding t o engine revolution, so that difference between charging and discharging current will behave charging or discharging. Charging current>discharging +charge current bottery Chorging current< discharging current +discharge battery Especially as large current flows while in use o f starting motor, it is required to control less thon 5 seconds for one action, after that takes rest 10- 15 sec. t o repeat next action. There occurs rapid drop of voltage if large current taken out from the battery but it restores the original voltage if taken a rest. . Therefore continuous pushing on the starter button causes voltage drop preventing restoration t o the effect of earlv exhaustion. 161 -<”> Fig. 2-1 1. Relation between discharge current ond duration for MEJ 4-12 type 112 V, IOAHl battery 0 Selenium rectifier @ Dynamo 0 Battery mhm 7’ Fig. 2-12. D. @ Fuse connector 0 Fuse M A 1‘ Red 2‘ Dock brown 3‘ Yellow 4’ White 5’ Black 6‘ White red spiral 7’ Earth to frome Charging current circuit diogrom Starting Motor a1 Starting circuit The starter switch of push botton style is equipped on the righr side of the handle. Pushing i t , the storter mognetic switch i s operoted t o f e e d current of about lOOA t o the storting motor from the battery for Model C72, 77, and about 60A for M o d e l CB72, 77 t o rotate the starting motor. The starting motor is equipped in front o f the crankcase and the crankshaft i s rotated b y starting chain through the overrunning clutch from the dynamo side. I62 0 Starter switch 0 Combinotion w i t c h 0 Starting motor @ Starting motor cable 0 Starter magnetic switch @ Starter battery cable 0 Battery I' Block red spirol 2' Yellow red spirol Fig. 2-13. 0 Brush 0 Brush spring @ Field coil @ Pale Cole 0 Terminal @ lnternol gear 0 Ball Wiring of starting motor @ York @ Armoture bearing @ Sprocket shaft @ Sprocket @ Gear housing 0 Cover 0 Commutator @ Planetary gear @ Center bearing holder Fig. 2-14. band @ Commutator end frome @ Bearing bush Starting motor bl Reduction of starter To get required t o r q u e a n d revolution t o r o t a t e the crankshaft by reducing r e v o l u t i o n of the m o t o r mechanical reduction is necessory. 163 To complete this i n high w e i g h t the primary reduction i s done b y planetary gear and further the secondary reduction b y starting chain. Primary reduction ratio 5.78 : 1 lplanetary georl Secondary reduction ratio 2.77 : 1 lchainl Total reduction r d i o 1691 : I As the starting motor does not run constantly there seldom occurs wear but t o prevent moisture its construction is closed type. Therefore after each 5.000-10.000 km run the follcwing points should be checked with case @ Check wearing on carbon brush and commutator. @ Eliminate carbon powder lblow off b y compressed airi. @ Supply grease in the gear case. If required b y any reason t o take out the starting chain, do not disassemble the starting sprocket from the motor. By any chance if the starting sprocket were taken out it is necessary to disassemble @ lnternnl gem g! Planetary 0 Sprocket @ Fig. 2-15. Fig. 2-16. Starting motor attached I64 on engine Sprocket gear shaft 0 Planetary gear @ Motor shaft @ InternLll gear @ Sprocket shaft 0 Sprocket Fig. 2-17. Reduction mechanism were taken out it i s necessary t o disassemble even the planetary gear and the starting sprocket should be combined before reassemble the starting motor. If the sprocket were set in, without disassemblying the starting motor b y mistake there happens rotation impossible due to hitting against the case b y the planetary gear. (Fig. 2-15-2-171 cl Dismounting the starting motor a. Take off the starting motor cable from terminal. b. Loosen each two screws o f 6 m m tightening the starting sprocket cover and take off the cover. c. Loosen two screws of 5mm on the starting motor side cover and take off the side cover. d. While loosening 4 bolts of 6mm fitted on the crankcase and taking out the starting motor from the engine case, it will be separated from engine b y removing the starting sprocket from the chain. (Fig. 2-181 Fig. 2-18. 165 Maintenance of the Starting Motor E. I. Removal of the carbon brush a. Take off the cover bond complete of the commutator b Loose 2 bolts fitted on the Commutator end frame and take It out c. By taking out the carbon brush pressing spring, take out the carbon brush loosening the connecting screw of the field coil and carbon brush. 0 Mica piece @ I , Commutator [Copper1 @ Motor shaft A. Fig. 2-19. Cross-section of Commutator 2. Commutator The commutator is as shown in Fig. IAl while in use copper pant get wear to turn like (61. In such cases i t i s requested t o adjust t o b e (Al. It i s advisable to rely on specialist shops as this adjustment requires highly technics [under cutting of mica). Fig. 2-19] 0AC Generotor rotor @ Starting clutch-outer 0 1 0 2 X l l 5 roller Fig. 2-10. Generator starter ond starting clutch 3. Over running clutch This transmit rotation from the starting motor t o the crankshaft, but reversally from the crankshaft con not rotote the starting motor. This construction i s quite same with Model C72. I66 IFig. 2-20] 1. If twns the starting motor a. When the starting chain i s pulled along the direction o f a r r o w 0 s shown in the picture. b. By rotating the sprocket. the clutch outer is turned when the roller i s joined with the starting sprocket and the clutch outer moving t o the narrow side. Accordingly the dynamo rotor i s turned which is fixed with the clutch outer as one unit. c. On the rotor i s fixed on the crankshaft by a key of 4mm rotation of the clutch outer is transmitted on the crantshoft. d. The starting clutch roller spring is useful for smooth running of roller without awl irregular meshing. Furthermore o spring cop i s used to make smooth motions of the starting clutch roller spring and the roller. 2. When the engine starts running a. Rotational speed o f the crankshaft becomes faster than that of the sprocket. b. Tronsmii+lon !,om the starting motor i s cut, due to centrifugal force o n the roller which presses the spring and moves to the wider space of the clutch outer. Fig. 2-21. Picture showing principle of function of the, overrunning clutch IAl Fig. 2-22. Picture showing principle of function of the overrunning clutch IBI 167 3. Lubrication Lubrications for the over running clutch i s done b y oil dropped through the hole IAl in the figure which passes through the groove at three parts IBI and starts inside of the inner oil sea1 2035 o f 20mm bush and the lock oil sea1 326575 t o prevent burning. Therefore after disassembly it is necessary to clean oil holes (A1 and IBI by compressed air. 4. Precaution about maintenance As life of the over running clutch depends on the function of roller, special attention i s needed f o r its handling. a. Grease put o n the roller should b e used designated one. lPart No. 7191 11, silicon greosel This designated grease have several features, that i s high resistant to cold and hot 1-40°C-'2000CI, least variation f o r frictions coefficients due to temperature and other variation. Before putting this grease cleanse each port b y gasoline, and after drying up, paint grease thinly all over the surface of the roller. b. Be careful about magnetic force N o t only roller or roller spring, but also parts around the clutch should be avoided from magnetizing. Any time resistance will unfovorobly affect smooth running of roller. NO. I Part name ~ I Starting choin 2 StarAng sprocket ~~ ~~ ~ - ~ 3 Roller -- 4 Clutch outer ~~ ~~~ . I I I1 '1 3 ~ Starting clutch roller I 1 " ]- F. Startor magnetic switch Current t o rotate the starting motor will reach about 100A. wire is needed, and also the switch t o make contacting part. To reduce resistance big on or off should be larger size at the Accordingly it will be difficult to find such place as easy t o operate switch. feeding current directly on the starting motor. In such cases, switch utilizing magneto can be equipped at the most convenient place between the battery and the starting motor and put the switch t o operate this magneto separately t o make possible remote control with least current. 1. Principle of function a1 If current flows on the primary side, an electromagnet actuates t o attract iron core resisting spring force. b. The contact point at the end of the iron core connects the secondary circuit. [Fig. 2-241 I Fig. 2-23. Starter magnetic switch 0 Magnet coil iprimory coil1 Contact [operating side1 0 Terminal @ Contact {fixed ride, secondary ride1 0 Contact return spring 8 Return spring 0 Moving core 0 Fig. 2-24. Construction of starter magnetic switch 2. Precaution a1 When put voltage of 12V between both terminal o f the primary circuit, if heard cracking sound, the contact point of the primary circuit i s connected. I69 bl If used for a long time, contact point gets were and damage t o increase resistance. and sometimes no current flows leven i f sound of cracking is heard, sometimes the starting motor forced to stop]. In such cases, disassemble i t and polish the contact point with a file or a sandpaper. To disassemble take this switch from the body. c) Operational current o n the primary side less than 12V, 3.5A. Figi2-26.~- Disorrembly:of mognetic switch iorremble port1 170 IFig. 2-5. 2-61 3. PARTS FOR USE OF SAFE GUARD Speedometer, Tachometer For Model C72, 77 i s equipped only a speedometer but not o tachometer. The speedometer is generally magnetic type, and rotation proportional to that of the wheel i s transmitted to the speedometer b y means of a flexible cable. For the tachometer, magnetic tachometer i s used alike the speedometer and rotation proportional to that o f the cam shaft in the cylinder head i s transmitted t o the t a c h o ~ meter. (Fig. 3-11 . - ~~ Fig. 3-1 Fig. 3-2. Speed tochomster Dial of Speed-tachometer The speedometer is consisted of speed indicator and distance meter, and speed i s expressed b y h / h , and running distance i s integrated up t o 99.999 km b y the distance meter. The tachometer shows revolution number per minute b y indicator ir.p.m.1. Constructionally it is same type with speedometer and stored in the some case of the speedometer. Only different points ore that on the dial plate. no integration mechanism ond different sign and measures I I Construction of the speedometer a n d tachometer is shown i n the figure. The magnets r o t a t e w i t h some rotational speed with that of the flexible cable a n d the induction disc lof aluminium or c o p p e r made1 moves w i t h indicator as o n e unit. The magnet shelter disc furnishes magnetic field t o generate e d d y current o n the disc by the rotating magnet. @ Dial @ Induction disc axis 0 Indicator @ Hair spring 0 Magnet shelter disc ichorcoal disc1 @ Induction disc 0 Magneto Fig. 3-3. Principle of rpeedometei ~ I I Fig. 3-4. Parts of speedometer 0 No. 1 shaft @ No. 2 shaft 0 No. 3 shaft @ No. 4 shaft 0 No. 5 h\,hoft 0 Magneto 0 Magneto shelter disc @ Indication disc @ Total Fig. 3-5. Construction of totol distance mete! 172 P By means of this eddy current the magnet shelter disc i s moved b y proportional revolving force t o the magnet and indicator shows on the dial balancing with reaction of the correctly adjusted hair spring. When the cam i s stopped, (on the tachometer, engine i s stopped1 the indicator and the induction disc come bock to the zero b y restoring force of the hair spring. For the speedometer revolution of the front wheel i s reduced in the gear box, and the cable turns 1400 revolutions per 1 km running, on the other hand for the tachometer, revolution of the cam shaft i s reduced further. Reduction ratio of the tachometer axis to the crankshaft i s 3 : 20. [Fig. 3-41 Total distance meter reduction JIS Regulation 1 I two or wheel car tri 1 Flexible shaft , 1400 Reduction rdio 1 Speedometer indication 1 1/1400 11637 ’, 60km/h 60km/h L, The distance meter is shown constructionally on Fig. 3-5. this magnet shaft cutted worm on it transmit its rotation os No. 2-shaft No. 3-shaft No. 4-wheel No. 5-wheel reducing each speed. On the dial of the total distance meter figures 0s 0, 1, 2 . . . 9 are marked, and teeth ore cut so as to rotate each wheel f o r one turn, the succeeding wheel rototes revolution. (Fig. 3-51 MEMO 173 ‘/lo ‘3 TROUBLE SHOOTING TROUBLE SHOOTING Procedures o f diagnosis f o r finding out causes of trouble an their probable causes a r e discribed as follows : 1. Engine does not start or hard to start Ill Remove the corburetter float chamber and check for fuel flow, if fuel i s not supplied enough ; 121 1- 1. Clogged fuel line 1-2. Clogged fuel tank cap vent hole 1-3. Clogged fuel cock 1-4. Clogged carburetter line or stuck needle valve Remove the spark plugs, attach them to the spark plug caps. turn in the ignition switch and rotate the crank shaft with starter motor while the 1 - 1 grounded. electrods a r e I f the spark plugs do not spark well or nil ; 2-1. Faulty spark plug, Ito make sure, check the spark plug with spark plug tester.1 2-2. Sooty or wet spark plug 2-3. Contoct breaker point 2-4. Faulty condenser 2-5 Incorrect adjustment of contact breaker point 2-6. Short circuit or breakage in ignifion coil or wiring 2-7. Damaged combination switch 131 Check compression pressure at the cylinder with a compression gauge and if lack o r nil o f compression is indicated in either cylinder; 0 3-1. Incorrect tappet clearance 3-2. Incorrect seating o f valves in valve seats 3-3. Excessive wear in valve 3-4. Excessive wear in piston ring, piston cylinder 3-5. Blown out cylinder head gasket (41 3-6. Seized valve in valve guide 3-7. Faulty valve timing Start engine following the procedure of starting but engine seems t o start but won't continue running ; 4-1. Too wide opened choke shutter in cold weather 4-2. W i d e opened air screw of carburetter adjusting air-screw 4-3. Damaged carburetter insulator o r gasket 177 7 2. Engine does not develope full power Ill Stand the motorcycle on the main stand and rotate the rear wheel by hand when the charging gear i s set in neutral, if wheel does not turn easily; 121 1-1, Dragging remr brake-incorrect adjustment 1-2. Damaged wheel bearing 1-3. Too tight drive chain tension, in correct adjustment Check the tyre air pressure and inflate to the specific amount. (31 Check the clutch f o r dip and if i t i s found slipping ; 3-1. Improper adiustment o f clutch 3-2. W o r n clutch facing 3-3. Weakened clutch springs 9 141 Measure the highest revolutions o f crankshaft with a revolution counter and if the engine does not develope full revolution ; 151 4-1. Choked carburetter a t somewhere 4-2. Clogged air cleaner 4-3. Insufficient supply of fuel t o the intake 4-4. Clogged muffler 4-5. Faulty ignition coil o r contact breaker points 4-6. Faulty seating o f valve 4-7. Incorrect ignition timing 4-8. Excess weak valve springs 4-9. Faulty spark plug; test the spark plug with spark plug tester Check oil level in the crankcase and adiust the level t o the specification, o r excess amount of oil result in the trouble. 161 (71 Inspect f o r excess heating of engine and if found i t same; 6-1. Excess carbon deposit in combustion chamber 6-2. Inferior grade o f fuel i s used 6-3. Slippery clutch 6-4. Lean air-fuel mixture : improper size o f main jet in carburettei 6-5. Dirty cylinder and cylinder head Check for the engine developing or knocking when i t submit t o quick accerera. tion o r successive running at high speed and if it is so ; The probable causes are came as No. 16). 178 3. Engine runs erratic and/or with miss tiring Ill Adjust air screw of carburetter properly and still runs under same circumstances. 1-1. Faulty ignition timing 1-2. Damaged carburetter insulator o r packing 1-3. Faulty spark plug 1-4. Faulty condenser 1-5. Faulty ignition coil 1-6. Faulty contact breaker point 1-7. Incorrect tappet clearance 121 Check for missing at high speed and if the engine is still under the same. 2-1. Insufficient supply of fuel 4. 2-2. Incorrect valve liming 2-3. Damaged o r w e a k valve springs 2-4. Other causes mentioned in No. 1 1 ) Excessive oil consumption or exhaust blue or black smoke If the engine exhausts smoke while continuous running at high or low RPM Ill 121 1-1. Worn cylinder or piston rings 1-2. Reversely assembled rings in piston 1-3. Excess clearance between exhaust valve ond guide If the engine exhausts smoke iust after when closing throttle valve suddenly from certain opening ; 5. 2-1. Excess clearance between inlet valve and guide 2-2. Clogged air venl hole or plastic tube Clutch ierkr or engages unsmoothly Ill If the machine moves off with jerking or the engine stops at the moment when the clutch engaged. 6. 1-1. Uneven tensions of clutch springs 1-2. Distorted clutch plates o r facings 1-3. Sticky movement o f clutch plate in the clutch outer G e a r shifting does not operate correctly Ill When the changing gear does not engage. 1-1. W o r n notch on the shift drum 1-2. Stuck shift fork t o the shift drum 1-3. W o r n shift fork 179 If the gear jumps out while running : !?I 7. 2-1. W o r n dogs 2-2. W o r n o r distorted shift fork 2-3. Weakened shift drum stopper spring on the gear shifter Engine runs w i t h unusuol noise when the tappet clearances assumed correctly: If knocking noise i s heard from cylinder when accereroting engine Ill 1-1. 121 Excess clearance between cylinder and piston If chattering noise is heard even if the cam chain has been adjusted ; 2-1. .Excess worn cam choin 2-2. Excess w o r n cam choin tensioner spring or roller 131 W h e n knocking noise i s ~ h e a r dfrom crank case 3-1. W o r n crank shaft big end 3-2. 141 8. W o r n crank shaft bearing If the clutch incures noise when operating clutch lever. 4-1. Excess clearance be!ween the clutch plate and clutch outer 4-2. Excess clearonce between the clutch center and clutch d a t e Troubles in steering I11 If it is felt that the steering is hard a t turning; 1-1. Over-tight steering boll races 1-2. Damaged steering 1-3. Bent steering stem (21 Steering wanders o r pull to one side while running. 2-1. Worn front and/or rear wheel bearing 2-2. Distorted front and/or rear wheel rim 2-3. loosen spokes 2-4. W o r n rear fork pivot bushing or front arm pivot bushing 2-5. Bent front fork or frome or reor fork 2-6. Incorrect reor wheel alignment 3-7. Uneven slrength o f cushion springs on both side 9. Troubles of brakes /I1 The brake does not octuate properly even after the free play i s adjusted correctly 1- 1 Worn broke shoes I21 1-2. Worn brake cam 1-3. Worn brake pedal shaft 1-4 Brake shoe contaminated with oil or water 1-5. Stuck brake cable or rear brake link 1-6. Lack of grease in brake cam Brake squeaks when applied. 2-1. Excess worn brake shoe 2-2. Contaminated surface of brake shoe 2-3. Warped or pitted wall of brake drum 2-4. Excess wear of brake panel spacer MEMO 181 __ ~~ ~~ HONDA 250.300 MODEL C72, C77, C572, CS77, CB72, CB77 SHOP M A N U A L HONDA MOTOR CO., LTD. SERVICE DEPARTMENT. FORtIGN SALES DIVISION 4 5~5 . Yaeru. Chuo-ku. Tokyo. Japan Printed b y YAMAGATA PRINTING CO.. LTD. # 1-3. Tolorhima-dori. Nirhi-ku. Yotohomo, Japan June 1965