MHONDA SHOP MANUAL ° c3750 K8 , ca750 F3 HOW TO USE THIS MANUAL This Shop Manual covers emission controlled motorcy- cles manufactured after December 31, 1977 Some pro- cedures may not apply. Follow the Maintenance Schedule recommendations (page 1—13 and 1—14) to ensure that the vehicle is in peak oper- ating condition and the emission levels are within the Federal Clean Air Act standards. Performing the Iirst scheduled maintenance is very important It compensates for the initial wear that occurs during break-in. Sections 1 through 3 apply to the whole motorcycle while sections 4 through 19 describe parts ol the motorcycle grouped according to location. Find the section you want on this page then turn to the table ol contents on page 1 ol that section Most sections start with an assembly or system illus- tration. service information and troubleshooting lor the section. The subsequent pages give detailed procedures lor the section It you don't know what the source of the trouble is, go to section 19, TROUBLESHOOTING. ALLWFORMATION, ILLUSTRATIONS. DIRECTIONS AND SPECIFICATIONS INCLUDED IN THIS PUBLL ' CATION ARE BASED ON THE LATEST PRODUCT I INFORMATION AVAILABLE AT THE TIME OF I APPROVAL FOR PRINTING. HONDA MOTOR CO.. LTD. RESERVES THE RIGHT TO MAKE CHANGES I AT ANY TIME WITHOUT NOTICE AND WITHOUT INCURRING ANY OBLIGATION WHATEVER. I NO PART OF THIS PLUBLICATION MAY BE REPRO- DUCED WITHOUTWRITI’EN PERMISSION. HONDA MOTOR 00.. LTD SERVICE PUBLICATIONS OFFICE CONTENTS GENERAL INFORMATION LUBRICATION INSPECTION AND ADJUSTMENT ENGINE FUEL SYSTEM ENGINE REMOVAL 8i INSTALLATION CYLINDER HEADNALVE CYLINDERIPISTON CLUTCH I:l CRAN KCASE El CRANKSHAFTICONNECTING ROD II“ TRANSMISSION III CHASSIS FRONT WHEEL/SUSPENSION IE REAR WHEELIBRAKEISUSPENSION IE: HYDRAULIC BRAKE Ill BATTERY/CHARGING svsTEM IE IGNITION svsTEM “a ELECTRIC STARTER IE LIGHTS/SWITCHES 3‘ ELECTRICAL TROUBLESHOOTING IE. Date of Issue :Dec., 1977 ’r‘iHnNnA MOTOR CO.,LTD. MODEL IDENTIFICATION CB750K The Irame serlal number is stamped on the The legaI vehicle identrticatron number (VIN) leIt side of the steering head is on the right side of the steering head. The engine serial number is stamped On the The carburetor Identification number IS on top at the crankcase. the left of the carburetor bodyv Date of Issue :Dec..1977 E HONDA MOTOR CO..LTD. HONDA €B750 . EMISSION CONTROL INFORMATION LABEL CB750K and CB750F'S manufactured aner December 31, 1977 have an Emissron Control Inlormatlon Label on the frame as shown. It contams basic tune-up specificauons for CB750K or CE750F'5 manufactured after December 31, 1977. Refer to thus Shop Manual Ior more details, EMISSION CONTROL INFORMATION LABEL Dale of Issue :Dec‘.I977 QHONDA MOTOR CO.,LTD. HONDA C8750 1 GENERAL - INFORMATION D GENERAL SAFETY . sure the area ls wall-ventilated. Never run the engine in 3 “wow area. The unaust contains poisonous carbon l l SERVICE RULES p. . Use the special tools designed for this product. . Install new gaskets, O-rings. cotter pins, lock plates, etc. when reassembling , When torquing bolts or nuts, begin with the larger diameter or inner bolt first, and tighten to the specified torque diagonally, unless otherwise specrlied. . Clean parts in cleaning solvent upon disassembiy. Lubricate any sliding surtaces before reassembly, . Alter reassembly, check all parts tor proper installation and operation. . Use only metric tools when servicing this motorcycle. Metric bolls, nuts, and screws are not interchangeable with non N020! GENERAL SAFETY SERVICE RULES SPECIFICATIONS TORQUE VALUES TOOLS 1—1 1—1 1—2 1—4 1—5 WIRING DIAGRAMS 1—6 CABLE & WIRING HARNESS 1—8 ROUTING EMISSION CONTROL SYSTEM 1—11 I MAINTENANCE SCHEDULE 1—13 I! the engine must be running to do some work, make - manoxldrr gas. " swarm Rte-Lam m- ram-u , umrume.uumm dc «em all»... Chum WW ham‘. ambit!» Moscow The battery electrolyte contains sulfuric acld. Protect your eyes, skin and clothing. In cast of contact, (lush morouumy with water am) can a doctor 1) your eyes ‘ were exposed. I wan‘lT‘ Gil? T Q'Mdrlmirnmizmm “mum Wm M& Use genuine HONDA or HONDA recommended parts and lubricants or their equivalent. Parts that do not meet HONDA 5 design specifications may damage the motorcycle English fasteners. The use at incorrect tools and Iasténers may damage the motorcycle, Date of Issue :Dec..1977 ©HONDA MOTOR CO~LTD. 1-1 SPECIFICATIONS GENERAL INFORMATION CB75O HONDA I CB750K Font peg hergm Gruund clnarance Dry wlighx Tvna From suspension Trml am suspumron Tram From ur- we Rm m siz- Tire prenure I From km From bukl Rur brak- Fuol c-pamy Fuel rmvw clpaciw Crsm [Dawns 1mm horlzonlal) Trall 325 mm (12.8 m) 135 MI!” 5.3 in) 232.5 kg (513 um Modal I CB750F Dimansiuns ‘ Overall (mm 2,210 mm (37.0 m) 2,230 mm (39.3 ml Ovarall width I 360 mm (33.9 in) 330 mm [34.6 in] Overall high I 1,185 mm (46.7 in) ‘ 1,185 mm [46.7 inI wrml base 1,480 mm (53.3 m) ‘ 1,495 mm (53.9 m) Suat hmghl 830 mm (32.7 a.) 310 mm (31.9 in) 330 mm (13.0 in) . 1511 mm( 5.9 in) 231 kg (503 lbs) Doubl- cudll I T-Iescop‘m fork ‘ 141.5 mm (5.5 m) Swmu arm 86.3 mm (3.4 m) 3.25H-IS “PM Anon-18 (APR) I 2.0/2.25 kg/cm‘ (23/329511 . 2.0/2.3 kg/cm’ (23m ps-I I Dual arse bnkt Disc broke 17.5 m. (4.5 u s an 4.5111112 us gall 62.5 113.5 mm (1.51") 101.6 mm (4.0 in) 3.50H-19 [HPRI 4.SDH~17A (APR) 2.0 kg/cm’ [28 psiI 2.25/18 kglcml (32/40 vs!) Dru: brako Internal expanding she-s 19.5 lit (51 U S gal) 1,0 m (1.1 u s g.” 32 I 115 mm (4.5 m) From Mark all Cauchy ‘36-I45 cc (5. —5.3 01) a! dram-n9 1‘5—155 cc (5. —5.4 all a! dlsassamblv ‘ Enamo 1 Typn Antoni-d our: 44mm ‘ (mind-r .rrmq-m-m 4 cyIma-r "Min. I Bore ma mm 61 x 63 mm (2.402 x 2.430 ml . Diwlmemam 735 Ix: (44.9 cu m Compression rauo 9.01 1 I 9.2 . 1 Val" "am Cham duven overhead camshaft 3.5 In (3.7 U S at) Forest! pressure and dry sump 13‘1 kg/cm‘ (18540 Psi) I on capacrty I Lubricuinn sysram I Cylmdar compression pressure Intake valva upen [at 1.0 mm (m) 5" name I u" BTDC (are (in) 56' 5101: 53‘ BTDC cum (al1.0 mm (in) 40’ ABDC . 40’ A300 (are lam 115' ABDC I 114'” ABDc Exhaust valve open (at Ln mm mo «0“ BBDC ; 40’ BBDC ; (at (1 Mr) 93“ BEDC I 96“ aanc I Close (ar 1.0 mm mo 5‘ BTDC I u‘ not: (ar (1 lift) I is“ 57m: J 67“ E101: Date of Issue :Dec.,1977 C HONDA MOTOR CO..LTD. \ GENERAL INFORMATION CB750F ‘ CE750K Va|ve clearance IN E X Glll ihlfl plnam Elmnul lumuon |9nitlon nmlnq Full advanca Starllnu lyscsm Alt-mate" Ban-w capacily Spark plua u.s.A. mndnl: For cold :Ilmala (below 512,41 F) sunuam Fa! emndau mgr. speed rlflmg Gamma" modal: Spavk plug gap Lint": Haadliqht flaw/hlgh) Tail/make llghts Turn slgna| ligm (Flam/real) Meier/indicatu' lllhts Parklng llgm 005 mm (0002 In] 0.08 mm (0.003 In! Englna dry weigh! 39 kg use lbs) Carbumar if; 7 7 7 7 7 W 7 7 Typa A cavhuve'uvs, mm. valve, 23 mm (LI in) ID. numhav szA \ PDAzs Flam lml ”5:05 mm 10.511 :lmzn n.) ".5105 mm (o.51uu.ozo in) Mm. in No, 105 \ Na.110 ml. spam Loom loo rpm Fast idle spud 2,750‘750 rpm Vacuum alumna: betwun cvlmdevs 40 mm (1.6 m) Hg maxlmum Pllm screw E See page 4-“ Drive min ' V Clukch WII mullI-plile Transmisslan 5 speed conslam mesh Prlmary uducnon rule 1,986 Gm val-n I 2500 ll 1.703 ”I 1333 IV 1.133 v 0,969 Flnal reduction run: 3011 2J3: 17N~273~475, left foot opal-lad ”qu“ svslnm Banevy and lgnlnon “F" mark (10 BYDC) sun: or mle spud 25' 1.5 at 2,300 to 2,500 enwlne rpm Elacmc or luck smlu Thus phase A.C. gamralov 12VA0.21kw [5,000 rpm 12v, 14AM ND XZZESVU or NGK D7EA ND XZAESVU or NGK DBEA ND x2755» ov NGK DsEA ND X24ESR»U m NGK DRBES-L 0.6—0] mm [0024—01125 ml lZV-40/50W 12V»E/27W (3/32 OP} SAE No, I157 IZV723W (32 cP) SAE No. 1034/1073 I2Vr3.4W (2 CP) SAE Nu. 57 12V-8W (3 CP) Date of Issue :Dec.‘1977 C‘HONDA MOTOR C0..LTD‘ 1-3 GENERAL INFORMATION HONDA C3750 TORQUE VALUES ENGINE 1* 7, 7 "1 , ,1,,,,i,,,, *7 *7 Illm ‘ Q'ly ‘ Thread dla. Torque ku-m “1417) 1 §;rrnlug 777777 1 74 7 ‘ 7 '7" "#127513 (9.7:1177’ 2 Valvl afliusfinn hol- cip ‘ 8 1 3D 1 D — 1.4 (7.2 — 10.1) 3 van adjunmg lock flux 8 s 1 1 1 — 1.5 (3.0 '— 10.9] 4 Cyllndsr head nut 16 3 2.0 — 2.5 [14.5 7 18.1) 5 Cam smock-t mm 2 7 1 3 » 2.2 113.0 — 15.9) 5 A.c. Gan-mar ball 1 12 10.0 - 12.0 172.3 — 35.8) 1 7 Stanmg clutch outav 3 3 2.0 2 2 5 114.5 — 13.1) 1 3 Clutch mm lock mu 1 15 4.0 — 4.2 123.9 — 30.41 1 9 Connacting rod mu 3 7 1 3 — 2.2 113.0 ~ 15.9) 1 10 Crlnkcasn be“ 3 a 2 0 — 2.5 (14.5 713.1) 1 11 Cranium mm s 0 13 — 2.2 113.0 — 15.9) ‘ 12 011mm canker mm 1 1 20 2 7 V 3.3 119.5 - 23.9) 1 13 on drain ball 1 I 12 3 5 - 4.5 125.3 - 32.5) 1 14 0.1 prlswvlswnch 1 15 — 2.0 110.0 - 14.5) 1 15 0.1 plucap J1 1 20 10—1.): 17.2—10.1) J FRAM E k7 . 7 7. . 2i, 1 ”.27 7 .7? mm ow "mm du. Yoruua kv-m (mu) 1 s« "1137mm nut ' 7 1 1 '7'? 24 '77'“ 3.0 — 12371579— 36.3) 2 Fork mp hridg. ball 2 7 0.9 -1.3 (3.5 — 9.4) 3 Fork butmm mug. hall 2 10 3.0 — 0.0 (21.7 — 23.9) 4 015k am- sitting Hut 5 3 2.3 — 3.3 (20.3 — 23.9) 1 5 From m. run 1 12 5.5 — 3.5 139.3 2 47.0) 3 Hear axlc nm 1 I8 3.0 — 10.0 (57.0 — 72.3) ‘ 7 5.11.1 dvmn smock" run 4 12 5.5 — 5.5 (33.3 ~ 470) 1 3 Swing lrm mm bolt 1 14 5.5 — 7.0 (19.3 — 50.5) ‘ 9 Eng‘ - humor mm 3 12 5.5 - 6.5 139.3 — 47.0) ‘ 10 Fork 00!: 2 23 4.5 - 5.5 132.5 — 29.3) 1 11 01111»:- nut ‘ 4 1 22 2.5 — 3.5 113.1— 25.3) 1 STANDARD TORQUE 1mm Torque kg-m 1m») } hem Towns kg-m (11-11,) 1 5 mm ban, "ii '7 0.715 — 0.5 133— 4.3)7 7 a 7 571.?" {my 1 0.35 — 0.57 1273 2 3.5) ‘7 2 5 mm hon. nut 03 — 1.2 15.3 - 8.7) 7 6 mm yum 1 0.7 — 1.1 (5.1 ~ 3.0) :1 13 mm boll. nm 1.3 — 2.5 113.0 - 13.1) 3 6 mm flame be“. In“ 1.0 ~ 1.4 (7.2 — 10.1) 4 10 mm bolt. nm 1 3.0 — 4.0 [21.7 - 28.9] 9 8 mm flaw boll, mn ‘ 2.4 7 3.0 (17.4 — 2L7) ‘ 5 12 mm 5311.100 1 5.0 — 5.0 (36.2 - 43.4) 1 10 10 mm flange huh, nu! 1 3.0 2 4.0 121.7 — 23.9) 1‘ 1-4 Date 0‘ Issue :Dec..l977 ’C HONDA MOTOR C0..LTD. HONDA C3750 GENERAL INFORMATION | TOOLS SPECIAL TOOLS Tool Name Yonl Noe R‘ference Page 1 48 mm pin spanner 0790272000000 12—19, 12—20 D 2 Valve adlusung wrench ‘ 079084230000 3—4, 6—19 3 From wheel reeerner wrench 1 079104230101 12—5, 12—9 4 Rear wheel reeerncr wrench 079104330000 ‘ 13—4, 13—7 5 weer wheel rererner wnnch 079104290000 1 13—7, 13—0 a Snap ring plier ‘ 079144220001 I 14—14 7 16 mm lock nu! wranch 07916—539000] 8—4, 8—8 ' 3 Huh)! puIICr 07933—300000!) I 9—21 l7—fl 0 Valve gulde tumour/Install" } 079024000000 6—10 10 Burning remover l 079054000500 ‘ “—6 11 Bum-g rlrrver ‘ 079454710200 1 11—15 12 3e mg drlvev 079404350200 ‘ 114,124 13 Hanna flvlvuv 079404500000 1 13—7 14 9.11 race drlvu 079054710000 12—19, 1240 15 Fork sul rlrwar ‘ 079474290000 12—15 10 Drwer handll I 079494710000 1 11—7 17 Dvivil handla ”7949—5110000 1 12—7, 13—7 15 Pismn n'nn :nmnnsxur 12) 079544000000 1 7—3 19 Velue spring cornereeecr 079574290001 3 6—0, 6—14 20 Piston base (2) 0796114000000 ‘ 7—5 21 Rial shock absorber campvamv 079594290000 ‘ 13—11 . 22 Villa gmdo name! 079044110000 6—“) 2:1 Flon level gaug- 07401—0010000 4—10 24 Spuk plug wrencn 079094000000 34 25 6 mm halluw sat wrench 07917—3230000 12—11, 12—15 26 Flal nur wrenclr 07021 4010000 14—11 27 ‘ Sprockm holder 079224000000 ‘ 0—0, 0—3 29 ‘ Pln an r 07904—090001» ‘ 4—6 29 Bearing dvivar 079404290000 13—7 :0 nor an leer 079994000000 7—3 :1 Blarinu remover w-lgrrr 079364710200 11—6 32 Bunting drlvll 07945—3330200 ‘ II—14 33 Toul us. 1 — 07997—0010700 . OPTIONAL TOOLS Tool Name 1001 No. Reference Paw: Vacuum gauge :0: Vacau rn gauges Gauul anachmem (A) Gaugu anachmam (B! oil pressure gauge armban— c111 pvessuv- gauge anacnmene 07404—0010000 075Mv30001 00 07510—30001 00 075107 3000200 07506~3000000 075| 0—3000000 1 :1-0 3—9 3—9 3—9 2—4 244 Date of Issue :Dec.,1977 @HONDA MOTOR CO.,LTD. WIRING DIAGRAMS CB75OF GENERAL INFORMATION am $ m m may.” HONDA C8750 . m w MAM; 0030Z—4IO —6702 mm: mm mm. sum. -. W mm m nun mm muulnw _ - ‘Date of Issue :Decnlfl77 EHONDA MOTOR C0.,LTD. GENERAL INFORMATION HONDA C3750 " CB750K 9: 4:. .gssaiisilx ant-37:2:— 35m .235! SEE. , .2 3.53! ‘ h Xutiw gang /, a » . :25: U- \ Z; .- EEEES new g 6 :22. 32:: 5.3.5 5: 552 5: «ES; 5533: 53.5.52 34§§§¢ 1-7 ©HONDA MOTOR CO‘LTD. Date of Issue :Dec.,1977 GENERAL INFORMATION CABLE AND WIRING HARNESS ROUTING ‘ MAIN WIRE HARNESS VOLTAGE REGULATOR STARTER MAGNETIC SWITCH ‘ FUSE BOX FUEL TANK OVERFLOWTUBE BATTERY BREATER TUBE CRANKCASE BREATHER DRAIN TUBE I ”(I rfiy (*4 TOAIRCLEANER IN E o CARBURETOR OVERFLOW TUBE ‘ wRIMARY CORD CLUTCH CABLE 8 Date of Issue :Dec.,1977 1- ©HONDA MOTOR C0.,LTD. HONDA C3750 GENERAL INFORMATION BRAKE HOSE ' CLUTCH CABLE FRONT BRAKE LIGHT SWITCH WIRE CLUTCH SWITCH WIRE TUHN SIGNAL \\ SWITCH WIRE -_ . STARTER/ENGINE STOP SWITCH WIRE WME BAN 08 THROTTLE CABLES AIRAEI FRONT BRAKE LIGHT SWITCH WIRE ' THROTTLE CABLE (CLOSE SIDE) TH ROTI'LE CABLE (OPEN SIDE) ’ STARTER/ENGINE STOP SWITCH WIRE RIGHT TUFIN SIGNAL WIRES CLUTCH CABLE —\ TACHOMETEFI CABLE “ \ \ CLUTCH CABLE . LEFT TURN SIGNAL WIRES CHOKE CABLE I . C L THROTTLE CABLES I/ , SPEEDOMETEH CABLE / Date of Issue :Dec.,1977 1 -9 © HONDA MOTOR CO.,LTD, MAIN HARNESS REAR HARNESS ALIGN WHITE TAPE WITH CLAMP TO A C GENERATOR 1 _ 1 0 Dale of Issue :Dec,.1977 ©HONDA MOTOR CO.,LTD. GENERAL INFORMATION EMISSION CONTROL SYSTEM Models CB750K and CB750F are equipped With two separate Emission Control Systems. EXHAUST EMISSION CONTROL SYSTEM The exhaust emission control system is composed of a laclory pre-sel carburetor. No adjustment should be made except to the idle speed will the throille stop screw. CRANKCASE EMISSION CONTROL SYSTEM The engine is equipped with a "Closed System“ to prevent crankcase emissions from entering the atmosphere. Blow-by gas is returned to the combusion chamber through the air cleaner and carburetor. Liquids are collected in the drain tube. CARBU RETOR BREATH ER TUBES BREATH E R SE PARATOR AIR CLEANER TRANSPARENT SECTION (Alter Dec 31 ' (Before Jan 1. ‘75) C: FRESH AIR DFIAIN PLUG <— BLOW7BY GAS Date or Issue :13“. 1977 1 1 1 @HONDA MOTOR CO..LTD. - HONDA C3750 EMISSION CONTROL INFORMATION LABEL . GENERAL INFORMATION CB750's manufactured alter December 31, 1977 have an Emission Comm! InIormation Label located on the Irame as shown. It contains basic tune-up specifications for CB750's manufactured after December 31. 1977. EMISSION CONTROL INFORMATION LABEL 1 _1 2 Date ui Issue :Dec.,1977 (“HONDA MOTOR CO LTD HONDA C3750 GENERAL INFORMATION . MAINTENANCE SCHEDULE (CB75DK) Impact, Clean, Adjust, LIIIIrIcaIII or Human» i Clun n: Raglan A: Adjust . P-rIorIn IIuI Pra-ridg Inspection in III; Owner’s Manunl at nth mainlanance pmlod. ‘ \ _ Frequancy “mm” C> 1 Odomner reading (Num (3)) \ 0.0m": ' VA 1 7 A A 1%“ ‘5‘ 5 a; 5-: is I a . Erwin. oil ‘ Vii R 900 "II (3000 km) Enginl uiI filtll ‘ Vul’ H R R H * EnnInI oil rerun 7 77' V E * Cr k u mun r 7; 7 : c I: c 7' V R I: 77?.” 127 ' Prawn. WW-” ‘ I I I hp 3-: Spark pm. I I R I rm 3-: h V k ‘ I E I I Ply 3-4 I I' I " my?“ I , I I Page 3-5 A A A Pm 1-7 E ' Thvonll our. on I I I I Paul 3-7 ' Carbumcr It“. won: i 7: W V" 7' Y I I W 7 I I I 7 , . ' Cnrbu Mgo/ "7 ”I A _ I I I , , Pm- 3-377 , I ' Carbumor symhronsn , I I I I , ”P... 3-9 I» Drivn chain __ I EVIfySOOmi (1000 km) Pm 3-10 A Momh I I I I m 2-11 Mnmh I I “R I I 7939. 3-12 E , 7 if I 2 Var a j , .= I I I I I Pljg 3-14 § I I I I I I 7 Papa 1-14 *3 ' ank- linmxwitch 5 I I I I I I ma 3-15 ,5 0 Hudlighllim - I I I I I I Pm 3-16 ,! Clutch Inc may I I I 1 I I I I FE. 3-15 E Sid. mm: | I I I I I I ' 7' ~23 - Susy-mien I I I I I I " Nu“. baIIS, fut-nor: I I I I I I P.” 3-19 . ” Whulsltpokli I I I I I I Page 3-15 -* smring had buflnu 7'— I I l I Pm 3-19 ' Should In sorvrcnd by an aurhnrixed HONDA deal-r, IInIzs the owner has proper tools and «nice data and is InscIIIInicuIIv qu " In In. inI-rest :4 MIN. we Irommund “Its. items bl sun/iced ONLV by an mnhonzld HDNDA dquf. NOTE: . (I) More luqusm service may be requlrad when "dung In rain or aI lull IIImIIle apenmgs. IAppIIas Io mmrcvclas buIII alter December 31, 1977.] [2) More frequent service may he required when riding In dusty awas. [:I) For higher adommor readings, upset a II.- frequency Interval mahlsned new, Date of Issue :Dec..1977 ©HONDA MOTOR COI,LTD. 1 13 HONDA GENERAL INFORMATION C3750 (CB750F) . |: Imp-u, GI. , Adiuu, Lubncm o: Human II Hungary. :2: Clnn a mum. A: AdIusI Parfurm thl Fre-vida Inspection .n ma Ownar's Manual at each maintenance peuod. I \ quemv l xxzvu-IF, 3 L Odgmftn reading (Nola (:II) . 2 hrs! 7‘“ ‘ I I "7 _x I E E: E; 73E 5; Hanna ‘ V 53 eggs g3 83 g: _,,, if a as $2 fifi 23 EE eé Imn Ev-rv ‘ 7 77 . ' ’ ' ‘ ' EannI aII Vm I a Haul-cu way 1800 In. (anon Inn) Pau- 2-2 . Eg‘ a 0 mm ! v." I R R R a R R Pain 2-2 _ E ‘ mo 77 ‘ A 7 F 7 Pin. 2-3 77 c7 7 c I: c mm 3-2 G R C R C Pin] 1-2 E 7 7 i ‘ 7I77 I777 iIfiiI I Pug-u 7‘} irifismirk plugifl I R I R I P.9- 3:; if mm I ‘ I I 7‘ 7| .77 I I Pu. 3-4 2 , 3 Ikl! win? 7,- I I I I I I Pug. 34 ‘9 " |gniuun (Imml , 7 7 l : 7‘ l ‘ ' ' , 3'913'5, ,7, ‘_ g 7 A A , A A A _ A {mi-"9:27 , I I I I I I Pm 3-7 7 I 7 I I I I I Pug. 3.3 ‘ Durburllor wok-Mm £qu 7 77 I77 7777! I I I 9.9. 3~8 . 7 ' urburim syncménin 7 77 777 7 7 I ' I I I I 7 I 7 7 7—7 I I Evuy aoo nu (Iooo km) Mom I I I I I I 7 Man». I I I I 'n I I E 7“ > 2 Va: n , if _._. I I I I I v... 3-14 E - man. I I I I I I v.9. :I-Ia I 77' Erak- gin “741ch 7 7i 7 I I I I I I P;3-15 _§ - deIiiIn .Im 7 7 7 7 l I I I I I I ‘2 Clutch Im play ‘ I I I I I I S 5.56;?" 777 77 77 7 I I I I I knit“ g 7 ‘Ehifimson 7 i7 ’7 7 ‘ I I I I I I m- 3-13 . Nuts, bum, hum-rs I I I I I I Fag. 3‘13 " Whuls I I I I I I Pm 3-15 . I I I Page 1.19 " Should I). “wind by an aukhorlzad HONDA dmlar, unlefi [he unmet has proper Xnnls Ind slvvice dfll Irvd is mochanically nullifiod. .. In “M imamst of sllolv, w. recummlnd (Ills. imns In summed oNLv by an authonzad HONDA dealer. NOTE: U) Mar- fvlq'uam sea-Inc: may be mqmmd whan ndIng "1 ram 01 a: mu III-um- openings. (Apphes lo mnmmycl: buill an" Decemb-I . 3‘, 1977. (2) Man fraqnam serwca may be required when lidlnq in dusty mas. (J) For higher odomam reldmgs. reps-I n “In fnqulncy Inleml mahlkhod hire. 1 _ 14 Date of Issue :Dec.,1977 DHONDA MOTOR CO.,LTD. LUBRICATION ‘7 NORMAL r] <. ‘ f1 ._ , :Tf :1 11% CLOGGED on FILTER «‘2 / 7 \ cmsurv ‘ ' ”i panama C‘MWOFM a Rocxsnnw > cwcmm } i‘ m 55.7»; (mm: Piston ~77 , 7 um ' cnmann i n 7 wsToN ‘7 7—- COMNYERSMAFT RElIEF VAN/E .- 'RANSM‘SS‘ON L chcH on smAmzn ‘ . ‘% OILPAN % PmMAfivCHAIN 4%- 5n mm "’ ELEMENY ~-7[ 7 —— ovL TANK LEAK sYoPPER VALVE 1 ? T T : ! ,---- .... 5 usuvsnv SCAVENGE Pump 2 Date of Issue :Dec..1977 ©HONDA MOTOR C0.,LTD. 2. LUBRICATION TROUEEEHBBTING SERVICE INFORMATION ENGINE OIL LEVEL ENGINE OIL CHANGE ENGINE OIL FILTER CHANGE ENGINE OIL SCREEN OIL PRESSURE TROUBLESHOOTING Oil Level Too Low: 1. Normal consumption of oil 2. External oil leaks 3. Worn piston rings Low Oil Pressure: 1, Faultywarningligntswncn 2. Pressure reliet valve stuck open 3. Plugged oil screen A. Main all pump worn NMNT’MMMI thNN-l—b SERVICE INFORMATION WORKING PRACTICE The oil pump can be disassembled with the engine in the heme Specification System type: Forced pressure and dry pump Oll capacity: 3.5 liters (3.7 us. at )at engine assembly. 2 5 liters (2.6 Us. at lat OII Change Oil speclflcaticn: HONDA 4-STROKE OIL or an equivalent. API service classification: SE Viscosity: General, all temperatures SAE row-4o Alternate above 15°0159°F SAE 30 0°C!32“F—15“C/59°F SAE 20 or SAE 20W below D°CI32 “F SAE10W SPECIFICATIONS OIL PUMP REMOVAL OIL PUMP DISASSEMBLY OIL PUMP INSPECTION OIL PUMP BASE DISASSEMBLY OIL PUMP ASSEMBLY High Oil Pressure: 1 Pressure ieliet valve sluck closed 2 Plugged oil tiller, gallery, or oil control orifice 3 Incorrect OII being used No Oil Pressure: 1. Oil level too low 2. Drive pin sheared or missing from main Oilpump Standard Value Service Limit Outer rotor-tO-body clearance Tip clearance I 0.15—0.22 mm I0 0060~ODOB7 In) 015mmt0.0060ln) 035 mm (00138 in) 0 20 mm (0.0079 in) Ftotor-to-Cover Clearance I _o.35 mm (00138 mi 0.1 mm (0.0039 In) Date of Issue :Dec“ 1977 ’D HONDA MOTOR C0..LTD. ENGINE OIL LEVEL Warm up the engine to the normal operating temperature. CAUTION II the oil pressure light does no! go out, stop the engine immediately as severe engine damage may result. Stop the engine and place the motorcycle on the center stand. Idle the engine at least 30 seconds belora stopping the engine to prevent a low reading, it the engine has lust been operated at high RPMs, Remove the right side cover and check the oil level With the tiller cap dipstick Do not screw the cap in when making this check. It the level Is below the lower level mark, (ill to the upper level mark with the recommended oil. ENGINE OIL CHANGE J21? , . Engine oil change is BWmed wtth engine at normal operating tempera‘ ture and the motorcycle on its center stand to assure complete and rapid draining. Remove the right slde cover. Remove the oil filler cap. oil tank drain plug, crankcase drain plug and oil hlter case to drain theoil. NOTE_ Turn the Ignition switchOFF Operate the kick starter several times to dram any residual oil_. .7 Check that the sealing washers on the drain plugs and the oil filter case O-ring are in good condition. Reinstall the oil filter case and both drain plugs. Fill the oil tank with 2.0 liters (2.1 U 5 qt) of recommended oil. LUBRICATION CRANKCASE DRAI PLUG 3,54: 5 kgm (25 3732 5 n-Ib) / HONDA CB7 50 UPPER " LEVEL MARK LOWER <— LEVEL MARK N 2-2 Date of Issue :Dec.,1977 ©HONDA MOTOR C04.LTD, HONDA C3750 LUBRICATION OIL SPECIFICATIONS: Use HONDA ASTROKE OIL or an equivalent. API service classification: SE Viscosity: General, all temperatures SAE 1OW-40 Alternate above 15°CI59°F SAE 30 0”Cl2°F-15°Cl59°F SAE 20 or SAE 20W below CFC/32°F SAE 10W Reinstall the oil filler cap. Start the engine and allow to idle lor a lew minutes. Stop the engine and add approximately 0.5 Ilton (0.5 U 5 qt) ol oil and check that the all level is at the upper mark and there are no oil leaks. Reinstall the right cover. ENGINE OIL FILTER CHANGE Drain the oil lrorn the oil tank and crankcase. (See page 2—2) Remove the oil filter element from the oil filter case. Check operation at the bypass valve in the oil Illter bolt. Check that the O~rings an the oil filter bolt and oil filter case are in good condition. Install a new oil filter element. Reinstall the oil filter case and both drain plugs. Fill the oil tank with the recommended oil. (See page 2—2). Stan the engine and allow to idle for 2—3 minutest Stop the engine, recheck the oil level and make sure there are no oil leaks. ENGINE OIL SCREEN Drain the oil lrorn the oil tank and crankcase (See page Z—zlr Remove the oil pan securing bolts and oil pan. EL‘EMENT OIL FILTER BOLT 2 7—3 3kg-m (19.5—23 Bit-lb) OIL FILTER O-FlING CASE Date of Issue :Dec.,1977 ©HONDA MOTOR CO.,LTD. LUBRICATION ‘5. Remove the oil screen from the oil pump base. _ Clean th bll screen in clean solvent. Replace the oil screen il damaged er broken. Reinstall the oil screen and oil pan. NOTE Install the neutral switch wire clamp as shown. Fill the oil tank with the recommended oil. (See page 2—2.) Start the engine and allow to idle for 2—3 minutes. Stop the engine. recheck the oil level and make sure there are no oil leaks. OIL PRESSURE Connect the oil pressure gauge. Check the oil level. Warm the engine up until the oil tempera- ture is 60°C (140°F). Check the pressure at 3.000 rpm. STANDARD: 3.5—4.5 kglcm‘ at 3.000 rpm, 60°C (140°F) Check that the oil pressure warning lamp goes out. If the oil pressure warning lamp stays on, step the engine immediately and determine the cause. 2- 4 Date or Issue :Dee..1977 @HONDA MOTOR CO.,LTD. HONDA C3750 LUBRICATION ‘ . OIL PUMP REMOVAL The oil pump can be removed with the engine mounted on the frame. . Drain the oil from the oil tank and oil pan. Remove the oil pan lrom the lower crankcase. (Model GB750F: Before removing the oil pan, remove the exhaust pipe.) Unscrew the three oil pump mounting bolts and remove the oil pump. OIL PUMP DISASSEMBLY Remove the oil screen and loosen the lour screws at the pump base and remove the oil pump Dodyr wash the oil screen in solvent. Be sure to replace the oil screen with a new one if rt is damaged, OIL PUMP BODY Date of Issue :Dec., 1977 I QHONDA MOTOR C0.,LTD. HONDA LUBRICATION C3750 To remove the oil pump rotors, disassemble the side cover and remove rotor A (delivery side : ) OILPUMPROTOR SHAFT Remove the dowel pin and pull the shalt out from the rotor body‘ This will permit rotor B (scavenge side) to be removed. DOWEL PIN Check the oil pump side cover for cracks. SIDE COVER ROTOR A OIL PUMP INSPECTION ' __U Outer Rotor to Body Clearance Inspection Measure the clearance between outer rotor A and body. SERVICE LIMIT 0.20 mm (0.0079 in) Tip Clearance Inspection Measure the clearance between inner and outer rotor tips. SERVICE LIMIT 035 mm (0.0139 in) > 2- 6 Date of Issue :Dec.,1977 QHONDA MOTOR CO..LTD‘ HONDA C3750 LUBRICATION . Rotor to Body Clearance lnspecrion Measure the clearance belween straighl edge and rotor. SERVICE LIMIT 0.10 mm (070039 in) OIL PUMP BASE DISASSEMBLY Oll Leak Stopper Valve Disassembly Remove the oil leak stopper cap screws. . The oil leak stopper cap, spring and oil leak stopper valve can be removed lrom me on pump. Fleliel Valve Disassembly . Unscrew the relief cap. The rellef valve and spring can now he re- moved. Date of Issue :DeC‘71977 ©HONDA MOTOR C0..LTD. HONDA C3750 OIL PUMP ASSEMBLY \\ 0 ye \ p ., SUCTION SIDE Insert the pump drive gear shalt in the I 0 pump cover B and install the dowel pin. I ’ COVER A / Install the inner and outer rotors B in the oil pump body, and insert the on pump drive INNER ROTORA D‘SCHARGE SIDE gear with cover B and dowel pIn, OUTER ROTOR A NOTE Install the rotors with lacing the punch mark to the outslde. OUTER ROTOR 3/}1 Install the dowel pin in the scavenge side INNER ROTOR B at drive shalt. COVER B/ Install the inner and outer rotors A in the DRIVE GEA/ pump body. Install the cover A and tIghten the screws. CAUTION Be sure to install the O-rings on the covers. LUBRICATlON OIL LEAK STOPPER VALVE Alter completlng the rotor assembly, turn the shalt by hand to assure that It turns smoothly. OlL LEAK STOPPER VALVE AND RELIEF VALVE ASSEMBLY Assemble the oil leak stopper valve, spring, OAring and oil leak stopper cap, and tighten the two screws, Assemble the rellet valve, rellef valve sprlng tlghtenlng In the rellet spring can securely. OIL SCREEN OIL PUMP BASE Assemble the gasket and two dowel pins between the oil pump body and oil pump base with toursorewe. Install the metal all screen. OIL PUMP BODY 2- 8 Date of Issue :Dec.,1977 ©HONDA MOTOR COt,LTD. r000 HONDA C3750 LUBRICATION Immerse the pump in oil and turn the pump gear until it is filled with oil before reinstal~ ling Itonthecrankcase. OIL PUMP INSTALLATION install the dowel pins and O-rings. Install the pump with the three bolts. Install the oil pan using a new gasket. Route the neutral switch cord as shown. Relill the oil tank up to the proper level with the recommended oil. Start the engine and operate for a few minutes. Stop the engine and recheck the oil level with the dipstick. Add all to the upper mark. Date of Issue :Dect,1977 C HONDA MOTOR C0..LTD. 3. INSPECTION & ADJUSTMENT . ENGINE CHASSIS SERVICE INFORMATION 3—1 DRIVE CHAIN 3—10 CRANKCASE BREATHER 3—2 BATTERY 3—11 AIR CLEANER 3—2 BRAKE FLUID 3—12 . FUEL LINES 3—3 BRAKE PAD WEAR 3—14 I 3 SPARK PLUGS 3-3 BRAKE SHOE WEAR 3—14 VALVE CLEARANCE 3—4 BRAKE SYSTEM 3—14 . CONTACT BREAKER POINTS 3—4 BRAKE LIGHT SWITCH 3—15 IGNITION TIMING 3—5 HEADLIGHT AIM 3—16 SPARK ADVANCER 3—5 CLUTCH FREE PLAY 3—16 CAM CHAIN TENSION 3—7 SIDE STAND 3—17 THROTTLE OPERATION 3—7 SUSPENSION 3—18 CARBURETOR IDLE SPEED 3—8 NUTS, BOLTS, FASTENERS 3—19 CAHBURETOR CHOKE/FAST IDLE 3—8 WHEELS/SPOKES 3—19 CARBURETOR SYNCHRONIZATION 3—9 STEERING HEAD BEARING 3—19 . Refer to Section 2 Ior ENGINE OIL, ENGINE on. FILTER AND ENGINE on. SCREEN. SERVICE INFORMATION ,, SPECIFICATIONS cavsoK CB750F Spark pluggap: o.6—o.7mm(o.024—o.028in) Coldllre I‘fixm'b anf: ”‘2‘” F " EQL Spark plug type; pressures E , Rear. 2.25 (32) Rea 2.0128) U.S.A.model~ NGKDBEA,NDXZAES-UISIandard) kg/cm2tpsi) U°‘°Ye"‘°'° Fm“ ”‘23) Fm“ 225“” NGK D7EA. ND X22ES-U(Forcold cIImaIs ”paw???" RE": 2599). Rea“ 23W) belcw 5°C,A1°F) Vehicle NGK DQEA, ND X27ES-UiFor extended high . capac'lvload 163 ”“36”” speed riding) I "m“ , , ,7, Canadian model- NGK DR8ES-L,ND XZAESR-U Tire . Front: 3.50 H19 Front: 3,25H19 5‘18 Rear: 4.50 H17A Rear: 4.00MB Valve clearancelN: 0.05 mm (0.002in) ‘ EX: 0.08 mm (0.003in) T' b d Front: BrldgesIone521F2 Contact breaker point gap: 0.3—0.4 mm10.012—0.016in) "9 'a" DQHIOD F6 Ignition timing: “F" mark (10"BTDC) static or at idle speed Rea" Br'dgesmne 521“? Fulladvance: 25:15” BTDC at moo—2,500 rpm L Dun'OD K37 Mark " Throltle free play: 2—6 mm (0.08—0.24 in) Idle speed: 1.000 : 100 rpm Fast idle speed: 2.700 L750 rpm (cold engine) Synchronlzation vacuum diHerence between Cylinders (maximum): Within 40 mm (1.58 in) Hg Drive Chain free play: 15-25 mm (Sis-1 in) Rear brake Iree play (CB750K); 20—30 mm (0.8—1.2 in) Clutch free play: 10—20 mm (0.4—0.8 in) TORQUE VALUES Spark plug: 1.2—1.9 kg-m 18.7—18.7 IHb) Valve adjusting hole cap: 1.0—1 5 kg»m (7.2—10.1fI-lb) Valve adjusting screw lock nut: 1.1—1,5 kg»m (ED—10.9 fI-lb) Oil filter bolt: 2.7—3.3 kg-m (19.5—23.9 It-lb) Oil drain plug: 35—45 kgm (253—325 fI-Ib) Rear axle nuI: BIS—10.0 kg-m (57.9—72.3 II-lb) Spoke nipples: 0.3—0.4 kg-m (2.2—2.9 II-Ib) Date of Issue :Dec.. 1977 ©HONDA MOTOR CO.,LTD. HONDA C3750 INSPECTION & ADJUSTMENT GRAN KCASE TRANSPARENT x BREATH ER SECTION e NOTE Applies to motorcycles manutactured atter December 31.1971 3%“ ‘ DRAIN TUBE . \ DRAIN PLUG Remove the drain plug from the drain tube / A] -, to draln deposits. / / DRAIN TUBE Reinstall thedrain plug. ,, ‘ NOTE / Service more lraquently when driven DRAIN pLUG in rain conditions or at lull throttle openlngs or ii deposits can be seen in the transparent section at the drain tube. AIR CLEANER Remove the two air cleaner mounting bolts and remove the air cleaner lower case and element. Clean the element by tapping it lightly to loosen duet Blow away the remalning dust by applying compressed alr from inside the element. Replace the element periodically if it is fouled excessively, broken or damaged. Clean the lower case. Reinstall the element and lower case with the two mounting bolts. 3- 2 Dare 0! Issue :Dec..I977 ©HONDA MOTOR cotun. 7Y0 c HONDA. C3750 INSPECTION & ADJUSTMENT FUEL LINES Replace any parts which show deterioration. damage or leakage. Open the fuel valve to make sure that the fuel filter screen is not clogged. Replace or clean the fuel filter screen il necessary. (See page 4—3.) SPARK PLUGS Disconnect the spark plug caps and remove the spark plugs. Visually inspect the spark plug electrodes for wear. The center electrode should have square edges and the side electrode should have a constant thickness. Discard the spark plug it insulator ls cracked or chipped. IV the deposits can be removed by sandblasting. the spark plug can be reused. Adiust the spark plug gap by bending the side electrode carelully. SPARK PLUG GAP: 0.8—0.7 mm (04124—0020 in) RECOMMENDED SPARK PLUG: 1U.S.A. Model) Fnrcnld cumu- PM ”man mgr. (sum 55c. u ‘Fl swam speed owing ND NGK ND NGK ND ch xzzEs-u my x24Esru DBEA XZIESU DSEA lCanadian Model) NGK DRBES-L or ND XZAESR-U Check the sealing washer condition. Reinstall the spark plugs and reconnect the spark plug caps. NOTE First turn the spark plug finger tight, then tighten with a spark plug wrench. 0.6vD 7 mm— (0 024-0 028 In )— Check : sealing . damage Check 'gaD deposit , dirt ‘ wear Check : damage : crack Date of Issue :Dec‘,1977 ©HONDA MOTOR C0.,LTD. INSPECTION 8- ADJUSTMENT c3750 VALVE CLEARANCE NOTE Inspect and adjust valve clearance while the engine is cold. (Below 35°C. 100°F) Raise the seat. Turn the fuel valve “OFF“ and remove the Iuel lube and Iuel tank. Remove the valve adjusting caps and point cover. Rotate the crankshalt clockwrse slowly until the “1.4 T" mark is aligned with the index mark on the crankcase. Make sure that the No. 1 piston is at T.D.C. (Top Dead Center) on the compression stroke. Check the valve clearance for the valves marked with “ o " in the chart below. STANDARD VALVE CLEARANCE: IN. 0.05 mm (0.002 i ) EX. 0.08 mm (0.003 in) It adjustment ls necessary, loosen the adjusting Screw lock nut and turn the adjusting screw until there is a slight drag on the leeler gauge. Tighten the look nut and recheck the clearance Rotate the crankshaft one full turn (360°) clockwise and align the “1.4 T" mark with the index mark. Check and adjust the valve clearance for the valves marked “0" in the chart. Adjust if necessary same as prevrously described. Reinstall the contact breaker point cover, valve adjusting caps, iuel tank and fuel tube. CONTACT BREAKER POINTS INSPECTION AND CLEANING Remove the point cover. Open the points slightly and check con- dition. II the contact suriaces are level out grayish In color or are slightly pitted, llle them lightly with a point file. Clean the point Contact surfaces with an electrical contact cleaner to remove any oil iilm crdirt. CylinderNo. No.1 No.2 No.3 No.4 IN. 0 o o 0 Ex- , ° ° 0 0 IN 005mm(0002ln) ADJUSTINGSCREW EX 008mmi0 003m) VALVE CLEARANCE ‘ ADJUSTING WRENCH \ 07908—3230000 CORRECT ONE SIDE CONTACT BURNED REPLACE PITI'ED REPAIR OR REPLACE BADLY WORN Date of Issue :Dec..1977 C HONDA MOTOR C0.,LTD. HONDA C3750 INSPECTION & ADJUSTMENT . REPLACEMENT If the points have a noticeable transfer of metal from one side to the other have evidence of heavy arcing or are worn at an angle, replace the points. After installation, adjust the point gap and ignition timing. NOTE Reconnect the pornt leads properly, POINT GAP Rotate the crankshaft clockwise and measure the maximum point gap with a feelergauge. POINT GAP: 0.3—0.4 mm (01712—0916 In) Adjust by loosening the contact breaker plate locking screw and moving the contact breaker plate. Fletighten the locking screw and recheck both point gaps. IGNITION TIMING NOTE . Adjust the contact breaker point gap before adjusting the ignition timing. - Adjust the No, 1 and 4 cylinder first. STATIC TIMING Prepare a battery and continuity light (12V- 3W). Remove the right side cover and disconnect the ignition coil primary wires. Connect one lead of the continuity light to the“1.4" point arm and the other lead to the battery positive (+) terminal. Ground the battery negative (—) terminal to the frame body. Rotate the crankshaft clockwise slowly and align the “1.4 F" mark with the index mark. The timing for the No. 1 and 4 cylinders ls correct if the light dims when both marks align. YELLOW LEAD LOCKING SCREW POINTGAP 0 3—0. 4 mm / (o 012—0016Inlfi 2.3 BREAKER ARM CONTINU ITY BATI'ERY(+) LIGHT(12V73W) / TERMINAL Date of Issue :Dec,,1977 ©HONDA MOTOR C0..LTD. 3-5 Adjust the “1.4" timing as icllows: Loosen the three base plate locking screws and rotate the base plate. It the timing is advanced. rotate the base plate clockwise. ll the timing is retarded. rotate the base plate counterclockwise Hetighten the base plate locking screws and recheck the timing. Change the connection of the light lead from the "1.4" point arm to the “2.3“ point arm. Rotate the crankshaft clockwise slowly and align the “2.3 F“ mark with the index mark. Timing (or the No. 2 and No. 3 cylinders is correct ii the light goes out when both marks align. Adiust the “2.3" timing as lollows; Loosen the two right base plate locking screws and rotate the right base plate. Retighten the two right base plate locking screws and recheck the timing. Remove the continuity light, connect the primary wire leads and install the point cover and right slde cover. DYNAMIC TIMING Connect a tachometer and a stroboscoplc tlming light. Connect the high voltage cord at the tlming light to the No.4 cylinder high tension cord. Start the engine and make sure that the engine Idle speed in neutral is at 1.000!100 rpm. The timing lor the No. 1 and 4 cylinders is correct it the ”1.4 F“ mark aligns with the index mark. Adjust the timing as described above tor use with a continuity light Change the connection oi the stroboscopic timing light high voltage cord lrorn the No. 4 cylinder high tension cord to the No. 3 cylinder high tension cord. Timing for the No. 2 and 3 cylinders IS correct it the "2.3 F" mark aligns with the index mark. Adjust the timing as described above for use with a continuity light. Disconnect the light and tachometer and install the point cover. SPARK ADVANCER INSPECTION (DYNAMIC TEST) Connect a tachometer and a strobosc0pic timing light. With the engine running over 2,500 rpm, check that the index mark is within the lull advance marks. if not. check the spark ad- vancer operation. Repair or replace as re- quired. 3-6 Date of Issue :Dec.,1977 ©HONDA MOTOR C0..LTD. HONDA C3750 INSPECTION & ADJUSTMENT O CAM CHAIN TENSION Start the engine and allow it to idle. Loosen the cam chain tensioner lock nut and tensioner bolt 1/2 turn. When the cam Chain tensioner bolt is loosen» . ed, the tensmner will automatically position itself to provide the correct tension. Tighten the tensioner bolt and lock nut. THROTTLE OPERATION Check that there is no detenoratlon. damage, or kinks in the throttle cables, and that the throttle grip tree play is 2—6 mm . (113 —1/4 in) on the outer edge at the throttle grip flange Check lor smooth throttle grip rotation lrom lully closed to lully opened positions at all steering positiOnst Check that the throttle grip automatically returns from fully open to fully closed po- sition when released. Adjust or replace, Il necessary. Throttle grip lree play can be adjusted at either and oi the throttle cehle. Major adjust‘ ments must be made at the lower adjuster after removing iuel tank. Adjust. by looseing the grip play adjuster look nut and turning the adjuster as required, Tighten the lock nut. . Make minor adjustments at the throttle ngp. Date of Issue :Dec.,]977 ®HONDA MOTOR C0..LTD. INSPECTION & ADJUSTMENT HONDA C3750 CARBURETOR IDLE SPEED NOTE The engine must be warm for accu~ rate idle adjustment. Ten minutes of stop and go driving will be suIIicient. Warm up the engine, shiit to NEUTRAL. and place the motorcycle on its center stand. Adlust the Idle speed with the throttle stop screw. IDLE SPEED: 1,000+100 rpm (IN NEUTRAL) NOTE The pilot screw is iactory ore-set. Do not adjust the pilot screws unless the carburetors have been overhauled. CARBURETOR CHOKE/FAST IDLE CHOKE MECHANISM MAINTE- NANCE Check lor smooth choke knob operation. make sure that the choke is fully closed. Adiust, by loosening the choke wire clamp and moving the choke wire. Retlghten the clamp, holding the choke lever fully closed. Adiust the choke operating Irlotlon by turn- nlng the adlueter. The choke knob must move smoothly and stay where positioned. INCREASE FRICTION Date of Issue :Dec..1977 (C HONDA MOTOR COHLTD s9 c3750 FAST IDLE ADJUSTMENT rtormed whtle the eng ne IS cold Pull the choke up all the way :0 "Fully Closed.” Start the engine. Open the throttle a small amount and close It. Repeatthrsz 3tlmes Check that the soecrfred fast idle speed )5 reached Withln ‘15 seconds. FAST IDLE: 2.750 750 rpm (COLD ENGINE} To adjust. stop the engine. turn the fuel valve “OFF", disconnect the iuel line and remove the tuel tank. Pull the choke knob out completely and turn the achustrng screw until it touches the cam surtace Push the choke knob In and turn the adjusting screwrnzturns. install the tuel tank and fuel line Recheck the fast Idle CARBURETOR SYNCHRONIZATION NOTE Pertorm carburetor synchronization wtth engine at normal operating temperature, transmissron in neutral and the motorcycle on rts center stand. Turn the tuel valve OFF and remove the tuel tube and luel tank. INSPECTION & ADJUSTMENT Prepare a longer tuel tube and reconnect it between the tuel tank and the carburetor Posrtlon the tuel tank higher than normal Remove the plugs irorn the carburetors and Install the vacuum gauge adaptors Connect the vacuum gauges Start the engine and adjust the “file to 1,000 i 100 rpm Check that the maxrmum ditter ence to vacuum readlngs l5 wIthIn 40 mm (1.6 m) Hg. A'WACHMENY A 0 ATTACHME NT B C A Revvsed Mav,1978 @American Honda Motor Co . Inc 1978 , All R-ghts Reserved INSPECTION 8: ADJUSTMENT Adjust, by removrng the top covers from the No. 1. 3 and 4 carburetors The No 2 carburetor can not be aciusted. because it is the base. Loosen the lock nuts and turn the adiusting screws to achieve the maximum vacuum dilterence between cylinders within 40 mm (1,6 in) HQ, Retighten the lock nut and recheck the idle speed and synchronization. DRIVE CHAIN Place the motorcycle on its center stand. with the transmission in neutral and ignition switch OFF. Turn the rear wheel slowly and inspect the drive chain and sprockets for damage or wear, A drive chaln WIth damaged rollers, loose pins, or missing O-rings must be replaced. Replace any sprocket which IS damaged or excessively worn, Lubricate the drive chain NOTE 7“ H 7 Never install e new drive chain on worn sprockets or a worn chain on new sprockets. Both chain and sprockets must be in good condition. or the new replacement chain or sprockets will wear rapidly When a new drive chain is installed. a new adiuster wear label must be at- tached according to the replacement I mimK9@Q:-,,,, , CLEANING LUBRICATION Clean the drlve chain with kerosene and wipe dry. CAUTION Do not use a steam cleaner, hrgh pres- sure washers or solvents as these wrll damage the O-rrngs. r- ubricate the drive chain with SAE 80 or 90 gear oil. _CA UTION Do not use commercial aerosol chain lubricants. They contain solvents which could damage the Grings. . DAMAGE KEROSENE WIPE DRY 1/3) LUBRICATE C:3£::Kv«J1::XCZD SAE 80 OR SAE 90 GEAR OIL 3-10 Dale,- nI Issue Dec.,1977 i HONDA MOTOR C0,.LTD. Ennutua C3750 INSPECTION & ADJUSTMENT . CHAIN FREE PLAY Measure the amount of drive chain lree play midway between the sprockets on the lower chain run. . FREE PLAY 15—25 mm (SIB—1 in) To adlust as iollows: Remove the cotter pin from the rear axle nut, and loosen the nut. Loosen the lock nuts on both adjusting bolts. Turn both adjusting bolts equal number cl . turns until the correct drive chain free play is obtained, CAUTION Be sure that the index mark aligns wlth the same graduation on the scale on both sides of the swing arm. Check the chain wear label. ll the red zone on the label aligns with the rear ol swing arm. the chain is worn excessively and must be replaced. Tighten the axle nut and install a new cotter pin. . TORQUE: 8.0—10.0 kg-m(57.9—72.3 It-lb) Check that the rear wheel rotates lreely by turning it by hand. (CB750K), Adjust the rear brake it necessary. REPLACE CHAIN BATTERY Raise the seat and remove the tell side cover. The etecirolyte level must be maintained between the upper and lower level marks. . 'he electrolyte level is low, remove the cattery liller caps and add distilled water. If suliation forms or sediments (paste) ac- cumulate on the bottom, replace the battery with a new one. NOTE . Fill the battery up to the upper level mark at periodical inspection. NOTE Add distilled water only. Tap water will shorten the service life 01 the battery. NEW CHAIN - The battery electrolyte contains sulfuric acid. Date of Issue Dec..197’l if HONDA MOTOR CO..LTD. HONDA INSPECTION & ADJUSTMENT C3750 BRAKE FLUID FLUID LEVEL CAUTION - Belare removing the reservoir cap, make sure mat the reservoir is level. - Avoid operating the brake lever or pedal with the cap removed. Brake fluid will llaw out if the lever or pedal is operated. Check that the brake fluid reservoir is iilled to the level mark. Fill the reservolr with DOTS BRAKE FLUID to the level mark ii the fluid is below the level mark. Check the entire system for leaks ii the level is low. CA U TION Do not mix brands a! fluid in the reser» voir, They may not be compalible. FLUID REPLACEMENT CAUTION - Install the diaphragm an the laser valr when operating the brake pedal (037505) or Drake lever. Failure to do so will allow brake fluid to squirt out of the reservoir during brake pedal or lever operation. I Avoid spilling fluid on painted surfaces, Fluid Draining: Loosen the caliper blender valve and pump the brake pedal lCB750F) or lever. Stop pumping operation when no iluid llnws out of the bleeder valve. 3- 1 2 Date of Issue :Dec..1977 DHONDA MOTOR C0,,LTD. HONDA C3750 INSPECTION & ADJUSTMENT . Fluid Filling: J BRAKE FLUID CAUTION BRAKE RESERVOIR Do not mix brands of fluid. They may not be compatible. . Close the bleeder valve, fill the reservoir and install the diaphragm. To prevent piston overtravel and brake lluid seepage. maintain a 20 mm (3/4 in) distance lrom the handlebar grip when bleeding the front brake system. . Pump up the system pressure with the lever or pedal until there are no air bubbles in the fluid ilowing out oi the small hole in the reservoir (until lever or pedal resistance is tell). Air Bleeding: NOTE Check the lluid level often while bleed- ing the brake to prevent air lrom being pumped into the system. Pull the brake lever or depress the brake pedal until resistance is tell. Loosen the bleeder valve about 1/2 turn and . slowly pull the lever back or depress the pedal as far as possible and hold, Tighten the bleeder valve. NOTE Do not release the lever or pedal until the bleeder valve is closed. Release the lever or pedal gradually and wait several seconds alter It reaches the end oi its travel. Repeat the above steps until there are no air bubbles in the fluid flowing out at the bleedervalve. Fill the reservoir to the UPPER FLUID LEVEL Check the entire system lor leaks while . operatingthe brake. A contaminated brake disc in pad re duces stopping power. Replace con- taminated pads, and clean a contami- . nalod disc with a high quality degrees I lay agent Date of Issue :Dec..1977 C HONDA MOTOR C0.,LTD. INSPECTION & ADJUSTMENT BRAKE PAD WEAR Check the brake pad tor wear. Replace the brake pads it the red line on the pads reaches the edge of the brake disc. (Refer to Section 14). CA UTION Always replace the brake pads in pairs to ensure even disc pressure. BRAKE SHOE WEAR (CBT5OK) Replace the brake shoes it the arrow on the brake arm aligns with the reterence mark “v” on full application of the rear brake. BRAKE SYSTEM Check that there is no deterioration. damage or leaks in brake tubes and fillings. (CB750K) Check the brake rod for loose connections, axcesslve play, bending or damage. Inspect the brake stopper arm tor a loose connection or damage. Inspect the mounting of the rear brake arm to the brake cam to make sure the locking bolt is tight and the splines undamaged. Check that the cutter pin is properly installed. Replace or repair it necessary. BRAKE PEDAL HEIGH (CB750K) Loosen the lock nut. Adjust the brake pedal height by turning the pedal stopper bolt. Tighten the lock nut. 3-14 Date of Issue :Dec‘,1977 C HONDA MOTOR C0.,LTD. HONDA C3750 INSPECTION & ADJUSTMENT . BRAKE PEDAL HEIGHT (CB750F) Remove the rubber cap. Loosen the lock nut. Adjust the brake pedal height by turning the adjusting nut. Clearance between the . brake pedal arm and the loot peg should be not less than 5mm (1/4 in). Tighten the lock nut. lmREASE/ HEIGHT; BRAKE PEDAL FREE PLAV (CB750K) check the brake pedal lree play FREE PLAY: 20—30 mm (GM—111M") . Turn the rear brake adjusting nut ll necessary. BRAKE LIGHT . SWITCH Adjust the rear brake light switch so that the brake-light will came on when the brake pedal is depressed 20 mm (3/4 in) when the brake begins engagement. . Adjust by turning the switch adjusting nut. NOTE Perform brake light switch adjustment after the brake play (CB750K) and pedal height have been adjusted. b Date of Issue :Dec, 1977 © HONDA MOTOR CO.,LTD. INSPECTION & ADJUSTMENT HEADLIGHT AIM NOTE Adjust the headlight beam as specified local laws and regulations. An improperly adiusted headlight may blind oncoming drivers or tail to light the roar! tor a safe distance. VERTICAL ADJUSTMENT Remove the side marker reflectors. Loosen the headlight mounting bolts and tilt the headlight as required, install the side marker reflectors. HORIZONTAL ADJUSTMENT Turn the adjusting screw clockwise to locus the beam toward the Ialt side at the rider. Turn the screw counterclockwise to locus the beam toward the right side. CLUTCH FREE PLAY Measure clutch free play at the lever end. FREE PLAY: 10—20 mm (sis—3M In) Make majoi' adjustments at the clutch housing. Loosen the lock nut and turn the clutch cable adjuster. Tighten the lock nut. Minor adjustments can be made with the clutch cable adjuster on the clutch lever. Loosen the lock nut and turn the adjuster. Tighten the lock nut. NOTE Do not expose the adjuster threads MORE THAN 8 mm (0.32 in) at the clutch lever and more than 17 mm (0.67 in) at the housing. Check the clutch operation. It adjustment cannot be made, screw both adjusters in all the way. LOCK NUT TLEss HA 8 N INCREASE DECREASE DJUSTEFI 3-16 Date of Issue :Dec..1977 ©HONDA MOTOR CO.,LTD. HONDA. C3750 INSPECTION & ADJUSTMENT . Remove the clutch cover, loosen the clutch lilter adjusting screw lock nut and turn the adlusting screw in until a slight resistance ls lelt. From this position, turn the adiusting screw counterclockwise 1I4—1I2turns. Turn the adjuster at the clutch hosing so that the lever tree play is approximately . 20 mm (3/4 in). Adjust tinal free play at the clutch lever. Tighten the lock nuts. Check clutch operation. SIDE STAND Place the motorcycle on its center stand and lower the side stand. Attach a spring scale to the lower end of the side stand and measure the return torce. The stand condition is correct it the measurement . fall! within 2—3 kg (4.4—6.8 It!» If the force is too high, check and lubricate the pivot boll. Check the stand. bracket and spring tor damage. Replace or repair il necessaryt Check the rubber pad lor deterioration or wear. . Replace if any wear extends to the wear line as shown, NOTE when replacing, use a rubber pad having the mark "OVER 250 lbs \ . ONLY". I 1 WEAFl LINE 1‘ WEAR LINE " Date of Issue :Dec.,1977 ©HONDA MOTOR CO..LTD. 3' 1 7 INSPECTION & ADJUSTMENT SUSPENSION FRONT SUSPENSION Do not ride a vehicle with iauity sus- pension. Loose, worn or damaged suspension companlnts may impair vehicle sta» bility, safely and rldu control. Check the action of the front forks by com- pressing them several times. Check the entire Iork assembly for leaks, or damage. Replace any components which are unrepairablet Torque all nuts and bolts REAR SUSPENSION Place the motorcycle on its center stand. Move the rear wheel side ways with iorcs to see it the swing arm bushings are worn‘ Replace il excessively worn. Check the entire suspension assembly to be sure it is securely mounted. damaged or distorted. Torque all nuts and bolts USHINGS Pump grease through the grease Iitting at the swing arm pivot. Use multipurpose grease. type NLGI No.2. 3- 1 8 7 Date or Issue :Demm C3 HONDA MOTOR C0..LTD. HONDA C3750 INSPECTION & ADJUSTMENT O ERTS, 3%;3’ STE ‘ Coldtire I Up to ZODIb Front: 2.0(28) Front: 2.0 (28) Check that all chassis nuts, bolts. and . '; load Rear 225(32) Rear- 20(25) . - ‘ pressures ' ' ' fasteners are tightened to their correct kglcm’tpsi) Up toyehicle Front. 20(25) Front, 2.2562), torque values. (page 1—4). WH EELS/SPOKES TIRE PRESSURE NOTE Tire pressure should be checked when the tires are COLD. Check the tires for cuts. imbedded nails, or other sharp objects. WHEEL SPOKE RETIGHTEN (CBTSOK) Fletighten the wheel spokes and recheck rimrunout. TIGHTENING TORQUE: 0.3—0.4 kg-m (2.2—2.9 tt-lb 14—34 In-Ib) STEERING HEAD BEARING NOTE Check that the control cables do not interfere with the handlebars rotation. Raise the front wheel off the ground. Check that the handlebar rotates treely. It the handlebar moves unevenly. binds or has vertical movement, adjust the steering head bearing by turning the steering head adjusting nut With a pin spanner. (See page 12720.) I lcapacnyload IRear 2.3(40) lRear: ‘ 2.8 (40) ' Vehicle capacity load 163 kg (360 lbs) limit . Front: 3.50Hl9 Front: 3.25H19 T "a ”an" ‘ Rear: 4.5a H17A Rear: 4.00H18 Front: Brldgestone $21F2 Tire brand Dunlop F6 Bridgestone $21R2 Dunlop K87 Mark II Minimum recommended tire cenler tread depth .5 mm (1/16m) : 2.0 mm (3/32 In) - 0 3—0 A kg-rn (2 2—2 Bit-lb 14734 In-lbl Date at Issue :Dec.,1977 CHONDA MOTOR COWLTD. _. : HONDA : C3750 FUEL SYSTEM % / +K-MODEL Dale of Issue :Dec,.1977 C HONDA MOTOR C0.,LTD. TROUBLESHOOTING Engine Cranks But won‘t Start . No luel In tank . No iuel iocylinders . Too much fuel to cylinders V No spark at plugs (ignition maiiunction) . Air cleanerclogged UIAmN‘ Engine idles Roughly. Stalls, or Runs Poorly Idle Speed Incorrect V Ignition malfunction Low compression V Fiich mixture V Lean mixture Air cleaner clogged V Airleaking into maniiold . Fuel contaminated V Carburetors not synchronized wmugzmzammr- “W“ 4 FUEL SYSTEM C3750 - TROUBLESHOOTING 4—1 FLOAT CHAMBER DISASSEMBLY 4— 7 SERVICEINFORMATION 4—2 CARBURETOR ASSEMBLY 4— a FUELTANK 4—3 FLOAT LEVEL 4—10 CARBURETOR REMOVAL 4—4 ACCELERATOR PUMP ADJUSTMENT 4—11 CARBUHETOR SEPARATION 4—5 PILOT SCREW INITIAL SETTING 4—11 THROTTLE VALVE DISASSEMBLV 4—6 IDLE MIXTURE 4—11 No.30ARBURETOR DiSASSEMBLY 4—6 HIGH ALTITUDE ADJUSTMENT 4—12 ACCELERATOR PUMP REMOVAL 4—7 CRANKCASE BREATHER SYSTEM 4—13 Lean Mixture Carburetor iuel jets clogged 1 2, Vacuum piston stuck Closed 3. Fuel cap vent blocked I. 5 6 7 Fuel lilter clogged . Fuel line kinked or restricted . Float valve at fault Float level too low Rich Mixture bum—- Choke stuck closed Float valve deieciive Float level too high Carburetor airiets clogged Date of Issue Dec.,1977 CHONDA MOTOR C0.,LTD. HONDA C3750 FUEL SYSTEM SERVICE INFORMATION WORKING PRACTICE Gasoline is extremaly flammable and is explosive under certain conditions. Do not smoke or allow llamas or sparks in your working area. when disassembling luel system parts‘ note the locations oi the O-vings Replace them with new ones on reassembly, The Heat bowls have drain plugs that can be loosened to dram resrdual gasolme. SPECIAL TOOL FLOAT GAUGE 07401—0010000 SPECIFICATIONS 7 7 7 Model 7” 77 W '7 7 63er I V ' 037501: — Fuel Low-lead gasoline With 91 octane number or higher Fuel tank capaclty 17.5m.14.e US gal., ‘ 19 5m,(51 U 5, gal, 39lrnp.gal.l 43lmp.ga|.) Carburetor type 4 plSIOne valve Venturl dia 28 mm (1 1024 in) Setting 1 Setting mark PDAZA PDAZB Mainjet ‘ NO 105 NO 110 Float level ‘ 145*0.5mm(0 571'002In) 145 0,5mm10571‘0.02m) L Idle speed 1000 ‘100 rpm ' 1.000 100 rpm J 4_ 2 ' Dale oI Issue :Dec..1977 C HONDA MOTOR C0.,LTD. HONDA C8750 FUEL SYSTEM . FUEL TANK Turn the fuel valve “OFF". Remove the fuel line from the fuel valve. Replace the fuel line with a new one if cracked or deteriorated. Place a pan under the fuel valve and turn the fuel valve ”ON" or “RES". and Inspect the fuel strainer screen and filler cap vent hole forcloggihgt KEEP AWAY FROM SPARKS OH OPEN FLAMES. WORK IN A WELL- VENTILATEDAREA. KEEP GASOLINE IN A SAFE PLACE. Drain fuel from the fuel tank if the fuel strainer screen is clogged. Unscrew the fuel valve lock nut and remove the fuel stralner screen and packing. Clean or replace the fuel strainer screen if necessary. Wash the inside of the fuel tank with solvent if there is water or anyother foreign matterinthefuel. Install the fuel strainer screen, packing and fuel valve. NOTE Do not overtighten the fuel valve lock nut. Alter assemhl-ng. fill the tank with fuel and check for leaks. PACKING “Q FUEL STRAINER SCREEN LOCK NUT FUEL VALVE / Date of Issue :Dec.,1977 CHONDA MOTOR C0_LTD. 4-3 CARBURETOR REMOVAL Turn the luel valve ”OFF" and disconnect the fuel line at the fuel valve. Open the seat and remove the tuel tank. Remove the air cleaner lower case by loosening the two mounting bolts. Loosen the air cleaner connecting bands and remove the two air cleaner hanger bolts. Remove the air cleaner upper case lrom the carburetors. Remove the throttle and choke cables train the cable holder and disconnect them tram the choke shati levers. Loosen the carburetor insulator bands an remove the carburetor assembly. FUEL SYSTEM 4-4 Date of Issue :Dec..l977 CHONDA MOTOR C0.,LTD, HONDA C3750 FUEL SYSTEM ‘ CARBURETOR SEPARATION Remove the carburetor assembly from the engine. . Remove the rear stay from the carburetor assembly by loosening the four bolls. Remove the throttle return spring lrom the stopper arm. Remove the stay plate by loosening the eight screws‘ Remove the accelerator pump spring‘ Unhook the choke reliel spring at the choke lever. Remove the carburetor top by removing the two screws‘ . Loosen the link arm fixing screw. Loosen the lock nut and remove the throttle lever set screw. Date of Issue :Dec,.1977 ©HONDA MOTOR C0.,LTD. t—_____ FUEL SYSTEM Remove the choke valve from the choke shatt by removing the two screws. Remove the accelerator pump tuet tubes. Separate the carburetors. THROTTLE VALVE mnome VALVE DISASSEM BLY Remove the link arm from the carburetor. Loosen the two screws and remove the throttle valve and let needle trom the link arm. SCREWS JET NEEDLE ’4'» LINK ARM N O. 3 CARBU RETOR PIN REMOVER and DRIVER 0794470980000 DISASSEMBLY (THROTTLE STOPPER REMOVAL) Place the throttle link on sultable supports or blocks. CAUTION Use care when driving out In give light, hammer blows to the drilr. 4- 6 Date of Issue :Dec,,1977 ©HONDA MOTOR CO.,LTD. HONDA C3750 FUEL SYSTEM . ACCELERATOR PUMP I 8 3 REMOVAL Remove the accelerator pump from the No. 2 carburetor by unscrewing the three screws. FLOAT CHAMBER DISASSEMBLY Remove the carburetor assembly from the engine. Remove the float chamber from lhe carburetor by loosening the three screws Pull the float arm pin out and remove the float. Remove the main jet. NOTE The slow jel must not be removed since it Is a press lit. ACCELERATOR PUMP w, ‘1; *5 MAIN JET \§ FLOAT PILOT SCREW ‘e R NEEDLE JET § ©" ' FLOAT VALVE $9 JET NEEDLE HOLDER O ../ SLOW JET Date of Issue :Dec.,1977 CrHONDA MOTOR C04‘LTD. Inspect the pilot screw, jet needle, needle jet and tloat valve for hardened deposits, grooving, or damage and clean or replace as required. Inspect the main and slow late for clogging, and blow with a compressed air it necessary. CARBURETOR ASSEMBLY Assemble the caburetors, reversing the disassembly procedure Observe the following notes: Connect the throttle valve to the link arm so that the cut-away is lacing the choke valve FUEL SYSTEM HONDA C3750 EILOT SCREW / JET NEEDLE FLOAT VALVE Q NEEDLE JET Date of Issue :Dec..l977 C HONDA MOTOR C0,.LTD. HONDA C5750 FUEL SYSTEM . The link arm which is not equipped with an adjusting screw should be inskalled in me No.2 carburemr, LINK ARM N0 Y,2 AND 4 CARBURETOR Install the choke shaft levers and springs as shown. Date af Issue :Dec‘J977 ’5‘ HONDA MOTOR CO..LTD. 4'9 HON DA FUEL SYSTEM C3750 Allach the choke plale lo the choke shall. NOTE \ 3131?};2352327$3355.?“ as CHOKESHAFT CHOKE VALVE LOCK WASHER FLOAT LEVEL Measure lhe lloat level. NOTE Measure the level where (he float arm just makes contact with the float valve ll necessary, adlusl the lloal level by bendan the lloal arm. carefully FLOAT LEVEL: 14520.5 mm (0.571t0.02 In) HEX, HEAD SCREWS FLOAT LEVEL GAUGE FLOAT LEVEL 14 505 mm (0.57110 02 in) 4-10 Date 0f Issue :DeC».l977 CHONDA MOTOR CO.,LTD. HONDA CB75° FUEL SYSTEM ACCELERATOR PUMP 9.5-10.5.“ WWW“, ADJUSTMENT /BEN[1)‘HERE Remove the carburetor assembly from the engine. (page 4—4) Measure the pump rod-to-pump arm clearance with the throttle valve closed. Adjust the clearance by bending the pump arm tongue. CLEARANCE: 0—0.02 mm (0.008 in) Measure the pump arm-tocarburetor stay clearance with the throttle valve closed. Adjust the clearance by bending the pump arm. CLEARANCE 15—105 mm (EMA—0.413") PILOT SCREW INITIAL SETTING NOTE L __ The pilot screw is factory preset. Do not adjust unless the carburetor is overhauled Turn the pilot screw clockwrse until it seats llghtly and back It out to the specillcation. This is a preliminary setting prior to the tinal pilot screw adjustment PILOT SCREW OPENING: CBTSOK: 11/2 CB750F: 13M CAUTION Damage to the pilot screw seat will occur if the pilot screw is tightened. IDLE MIXTURE NOTE Use a tachometer with graduations of 100 rpm. 1. Warm up the engine to operating temper ature. Stop and go driving for approximately 10 minutes will be sufficient. 2. Attach a tachometer. 3. Adjust the idle sped with the throttle stop screw. IDLE SPEED: 1,000i100 rpm (IN NEUTRAL) 0—0.2 mm eIee; ‘9 (o—o.ooa in) I L) It BEND HERE FRONT PUMP ROD No 2 CARBURETOR Date of Issue :Dec.,1977 ’g HONDA MOTOR C0.,LTD. FUEL SYSTEM NOTE Adjust the No.2carburetorlirstt 4, Turn the pilot screw in or out to obtain the highest engine speed. 5. Check the idle speed. adjust with the throttle stop screw it necessary. 8. Turn the pilot screw in gradually until the engine speed drops 100 rpm. NOTE It the pilot screw seats betore lower» lng the engine speed 100 rpm, con» tinue to step 7. 7. Turn the pilot screw 1-1/4 turns open lmm the position obtained in step 6. B. Fleadiust the idle speed with the throttle stop screw. NOTE Pertorm steps A thru a for the remain- ing carburetors. HIGH ALTITUDE AD- JUSTMENT The carburetor idle speed may have to be re adlusted for high altitude riding (2000+ m. 6,500 4- ft). IDLE SPEED: 1,0001100 rpm NOTE Headlust the pilot screw it the engine Idle rough, misses or stalls, according to the Instructions on page 4—1 1. 4-12 Dale of Issue :Dec.‘1977 @ HONDA MOTOR CO.,LTD. . HONDA % C3750 FUEL SYSTEM ‘ CRANKCASE BREATHER SYSTEMW‘X CB750F (MANUFACTURED AFTER DEC.31‘1977) 7‘7 7\ , ,, AIR CLEANER I . BREATHER TUBES / BREATH ER SEPARATOR , TRANSPARENT E SECTION ® CB750K (MANUFACTURED AFTER DEC.3I. 1977) BREATH ER / SEPARATOR TRANSPARENT SECTION \ DRAIN TUBE DRAIN PLUG Date of Issue :Den..1977 QHONDA MOTOR C0.,LTD. 1., - INSTALLATION I SERVICE INFORMATION 5 1 I ENGINE REMOVAL 5—2 . ‘ ENGINE INSTALLATION 5 5 LOW fif_, ,f ,, A, fifi . SERVICE INFORMATION WORKING PRACTICE The engine must be removed in serwce the following parts Rocker arms Camshaii Valves Cylinders/plsions Cranksnah Crankweignls Kick starter Connecting rods . Transmission Engine weight: as kg 094.0 Imdw TORQUE VALUES Engine hanger bolts 12 mm Flange boll' 5 5—6 5 kgm (39 8—470 IND) 10 mm Flange Doll: 3 0-4 0 kg-ml217—28.9Ilrlb) Dale of Issue :Dec,,1977 5-1 SHONDA MOTOR CO.,LTD. HONDA. C8750 ENGINEREMOVAL & INSTALLATION ENGINE REMOVAL Drain oil from engine (See page 2—2). Turn the fuel valve OFF. Ralse the seat and remove the overflow tube, fuel lines, luel tank and lelt side cover. Remove the alr cleaner. Remove the air cleaner lower case lirst to facilitate oper» atlon. Remove the carburetor (Page 4—4). Dlsconnect the electrical wrres, 5- 2 Date of Issue :Dec.,1977 CHONDA MOTOR C0.,LTD. HONDA C3750 ENGINEREMOVAL & INSTALLATION Remove the beft rear crankcase cover. Remove the cotter pin and loosen the rear axle nut Loosen both chain adiusters and push the rear wheel lorward. Remove the drive sprocket and drive chain (page 3—10), Remove the spark plug caps and tachometer cable. Remove the brake pedal, foot pegs and muffler. Date of Issue :Dec.,1977 ©HONDA MOTOR CouLTD. ENGINEREMOVAL & INSTALLATION Disconnect the oil hoses from the engine Remove the engine hanger mackets and butts. Remove the engine toward the right. NOTE Avoid damaging painted and finished surtaces of the motorcycle. 5.4 Date at Issue :Decwl977 @HONDA MOTOR COWLTD. HONDA C3750 ENGINEREMOVAL & INSTALLATION Q ENGINE INSTALLATION The InstaHation sequence is the reverse 01 removal. NOTE - Do not damage parts durmg Inskal- . Iauon. . FIII the crankcase to the proper level 1 (Page 2—2). 1 - Route the wrres and cabies proper (y(Fage1— 9.10)‘ . Perform the following inspections and adjustments: Throttle cable free play (Page 3—7) Clutch lever free play (Page 3—16) Drlve chain Kension (Page 3—10) Check the operation o! a” eleclncal ac- cessones. Torquevalues: IOmmHangeboM/nul 30—4,0kg-m(21.7—289n-Ib) 12mmllangebofl/nul 5,5—65kg-mt3‘38—4701t-lbb 5 5—6 5 kg—m (39. -—47 0 it-lb) 5—65 kg- :1 , , 30—40 kg (39.87470fw‘(21.7—239'f1-(b) ( o ' Date of Issue :Dec.,1977 5 5 I: HONDA MOTOR CO‘.LTD. " f; HONDA CYLINDER HEAD/VALVE ‘% C3750 q. Date of Issue :Dec.,1977 C HONDA MOTOR COHLTD H mm. CYLINDER HEAD/ ° 6- VALVE C3750 TROUBLESHOOTING 6—1 SERVICE INFORMATION 6—2 CYLINDER HEAD COVER REMOVAL 6—3 . ROCKER ARM AND ROCKER ARM SHAFT REMOVAL 6—3 CAMSHAFT AND CAM SPROCKET REMOVAL 6—4 CYLINDER HEAD REMOVAL 6—1 CYLINDER HEAD DISASSEMBLY 6—9 ' ‘ VALVE GUIDE REPLACEMENT 6—10 VALVE SEAT REPAIR 6—12 CYLINDER HEAD ASSEMBLY 6—14 CYLINDER HEAD INSTALLATION 3—15 CAMSHAFT ASSEMBLY 8—16 ROCKER ARM AND ROCKER ARM SHAFT INSTALLATION 6—17 TROUBLESHOOTING Engine topend problems can usually be dlagnosed by a compression test Norse problems can usually be traced to the top-end ol an engine with a sounding rod or stethoscope, Low Compression or Uneven Compression 1. Valves — Incorrect valve adlustment — Burned or bent valves — Incorrect valve liming — Broken valve spring 2. Cylinder head — Leaking or damaged head gasket — Warped or cracked cylinder head ’ 3. Cylinder and piston (Relerto Section 7) Compression TOO High 1. Excessive carbon buildup on piston orcombustionchamber Excessive Noise ’ l Incorrect valve adjustment . Sticking valve or broken valve spring Damaged or worn rocker arm or cam Loose or worn cam chain . Worn or damaged cam chain tensioner . Loose balancer chain . Worn cam sprocket teeth Natalppro—s Date of Issue ’Dec.,1977 ‘ 6 1 C HONDA MOTOR C0.,LTD. ' HONDA C3750 SERVICE INFORMATION . WORKING PRACTICE CYLINDER HEADNALVE All cylinder head maintenance and inspection necessitates engine removal tram the trame. Camshaft lubricating oil is led to the cylinder head through an oil control orifice located in the engine cylinder head. Be sure this orifice is not clogged and that the O»ring and dowel pins are in place before installing the cylinder heads. . During assembly, apply molybdenum disuliide to the camshaft bearings to provide Initial lubrication. Pour clean engine oil into the oil pockets In the cylinder head to lubricate the cams SPECIAL TOOLS Valve guide remover/installer 07942—3000000 Valve guide reamer (IN/EX) 07934—6110000 . Valve spring compressor 07957—32900!“ Valve adjusting wrench 07908—3230000 SPECIFICATIONS ITEM 7 7 7 STANDARD SERVICE LIMIT Camshaft and camshaft holder Camshaft bend 0—0 03 mm (0—00012m) 0.10 mm (0.0039 in) Cam height IN. 3600mm (1 4173 in) 35.86 mm (1.411Bin) EX. 35 50 mm ".3976 In) 8536 mm (1.3921 in) Camshaft holder 0.D. 21939—21960 mm (08637—08646 In) 21.890 mm (0.8618 in) , A |.D. .. 22020—22041 mm (03669—08678 "1) 22.100 mm (0.8701 in) . Rocker arm and rocker armshaft Rocker arm l.D. 12000—12018 mm (04724—04731 In) 12.050 mm (0 4744 in) Rocker arm shaitr_ 0D. 11965—11984 mm (04710—04715 in) 11.940 mrn (0.4701 in) (Minder head Warpage 0—0.05 mm (0—0.0020 in) 0.10 mm (0.0039 in) Valve seat Width 1.0 mm (0.0394 In) 1 5 mm (0.0591 In) Valve and valve guide Valve stem 00. IN. 6.58—6.59 mm (02591—02594 In) 6.55 mm (0.2579 In) EX. 6.55—6.56 mm (0 2579—02553 In) 6.52 mm (0.2567 in) Valve guide LD. IN/EX 6.60—6.62 mm (02598—42606 In) 6.65 mm (0.2618 in) Valve spring free length Inner 40.30 mm (1.5866 in) 39.14 mm (1 .5409 in) Outer 43.05 mm (1 6949 in) 41.74 mm (1.6433 "1) Valve lace width INIEX 1 0—1 3 mm (00394—00512 in) 2.0 mm (0.0787 in) (Minder compression 10.0— 12 0 kglcm2 (1422—1701) psi) Valve clearance IN 005 mm (0.0020 In) EX 0.08 mm (0.0031 in) 6- 2 . Date of Issue :Dec.,1977 QHONDA MOTOR C0..LTD. HONDA c3750 CYLINDER HEAD/VALVE 5“ CYLINDER HEAD COVER REMOVAL Remove the engine. (Refer to section 5.) Unscrew the three 6 mm screws and ' remove the breather cover. Loosen the sixteen 6 mm screws and re- move the cylinder head cover. ROCKER ARM AND . ROCKER ARM SHAFT REMOVAL Unscrew the two snail fixing bolts and me shaft smpper bolt. Date of Issue :Dec.,1977 ’22 HONDA MOTOR COHLTD. CYLINDER HEADNALVE Turn the crankshaft so that the two rocker arms are not contacted by the valves. Pull the rocker arm shalt out. Repeat the above procedure on the other shafts. NOTE Mark the rocker arms to insure that they are reinstalled In their original .poeitions. CAMSHAFT AND CAM SPROCKET REMOVAL Remove the cam chain tensions! holder from the cylinder. Unscrew the two cam sprocket mounting bolts. NOTE Be careful not to drop the bolts into the engine. Remove the tour cam shalt holder caps. 6-4 Date at Issue :Dec.,1977 E HONDA MOTOR CO..LTD. HONDA C8750 CYLINDER HEADNALVE . Remove cam chain Irom the sprocket and pIace it at (he IeIt Side of the camshaft. Remove the camshaft NOTE Hold the cam chain With a piece OI wire as shown to prevent i! Irom dron‘ ping mm the engine, Remove the camshafl holders Irom the cyllnder head‘ , ’ NOTE Mark each pan to ensure original as- sembly. ROCKER ARM INSPECTION ‘ Inspect each rocker arm for wear or damage. Measurethe rockerarm |.D. NOTE . II rocker arm requires replacement. "1' spent me camshafl lobes lor scoring, chipping‘ orllat spotsv CAM CHAIN LD. SERVICE LIMIT: 12.050 mm (0.4144 In) WEAR OR DAMAGE Date of Issue :Dec.,1977 @IHONDA MOTOR C0.,LTD. HONDA C3750 CYLINDEFI HEADNALVE ROCKER ARM SHAFI' INSPECTION Measure me rocker arm shalt CD. at the rocker arm comacting Iace. CAMSHAFT BEARING BORE Install the camshan holders and caps on the cylinder head. NOTE Ensure that the marklng on each cap agrees wiIh that on Ihe corresponding holder‘ Tighten (he camshaft holder cap setting bolts and nuts. Torque vaIue: 0.8—1.1 kg-m(6.0—8.0It-Ib) Measure the camshan bearing bore veni- caIIy as shown, CAMSHAFT BEARING INSPECTION Measure the camshafl bearing OD. 0.0. SERVICE LIMIT: 11940 mm (0.4701 In) 0.D‘ SEIZVICE LIMIT: 21‘590 mm (0.8616 in) 6-6 Date of Issue :Decnl977 C HONDA MOTOR COI.LTD. HONDA C3750 CYLINDER HEADNALVE CAM LOBE HEIGHT . 'M LOBE HEIGHT senvrc: LIMIT: IN: 35.35 mm (1.4115 in) ex: 35.36 mm(1.3921 in) Inspect the cam surtaces Ior wear or damage. Measure the cam Iobe height. CAMSHAFT RUNOUT Set the camshaft on a stand or V blocks. Set a dial indicator on the center main journal, Measure the amount of runout. Actual runout Is 1/2 the Total Indicator Headlng (TIR). CAMSHAFT FIUNDUT ‘ SERVICE LIMIT: OJO mm (0.0039 in) CYLINDER HEAD REMOVAL . Remove the sixteen cylinder head mm] washers and six 6 mm bolts. NOTE Loosen the nuts and bolts In the sequence shown in 2 or 3 steps. Remove the cylinder head. Remove the four O-rings and the M0 oil orifices. REVISED: MARCH, 1930 HI: 68313 © American Honda Motor Co.. Inc. 1950 ~ All Rights Reserved 6 ' 7 MSV 1490 8003 HONDA CYLINDER HEADNALVE C3750 Clean carbon deposils from the combuslion chamber. Inspect me spark plug holes and valve areas carefully for cracks‘ Remove any head gasket material from the cylinder head. NOTE The gaskel will come off easier if soaked in solvent. Clean me head gasket surlaces thoroughly of any gaskel material wim an on stone CYLINDER HEAD INSPECTION WARPAGE §’ERVICE LIMIT: 0.10 mm (0.0039 In) 4 Check the cylinder head for warpage wilh a slralgm edge and a feeler gauge. 5 NOTE Check lor warpage in an X paner 6-8 Dan at Issue :Dec..1977 ©HONDA MOTOR co.,LTD. HONDA I. CYLINDER HEAD D DISASSEMBLY Remove the valve spnng callers, relamers‘ springs, and valves‘ Reler to each valve assembly so that they may be reassembled in then original po- silions. VALVE SPRING FREE LENGTH Measure the lree length ol the valve springs. VALVE AND VALVE GUIDE INSPECTION Check that the valve moves lreely m me gmde. Measure and record each valve stem OD C3750 CYLINDER HEADNALVE VALVE SPRING COMPRESSOR O79577329000I SERVICE LIMIYS: INNER: 39.14 mm (1.5409 in) ‘ FREE LENGTH ‘ OUTER: 41.74 mm (1.6433 InI I l I 0.D. SERVICE LIMITS: IN: 6.55 mm (02579 in) EX: 652 mm (0.2567 inI Date af Issue :Dec.. 1977 CHONDA MOTOR CO.,LTD. CYLINDER HEADNALVE Ream the valve guides to remove any carbon build-up, '-LVE GUIDE REMOVER . 443110000 VALVE GUIDE I.D. INSPECTION Measure and record each valve guide I.D. Subtract each valve stem OD. from the corresponding valve guide ID. to obtain the stem to guide clearance. STEM TO GUIDE CLEARANCE SERVICE LlMlTS: IN: 0.10 mm (0.0039 In) EX: 0.13 mm (0.0051 in) NOTE . Ii any stem»to-guide clearances ex- ceed the service limlt, determine ii a new gulde with standard dimensions (page 6—2) would bung the clearance within tolerance. Replace any guides If necessary and ream to iii. - Ii any stem-toguide clearance would still exceed the service limit with new guides, replace the valves and guides. VALVE GUIDE REPLACEMENT Support the cylinder heaSI and remove the valve guide. NOTE Be careful not to damage the cylinder head. Install a new valve guide into the cylinder head from the top. Ream the new valve guide after installing. CAUTION Use cutting oil on the reamer during this opera/ion. Clean the cylinder head thoroughly to remove any metal particles. u7942—3000000 6-10 Date of Issue :Dec.,1977 A 0 HONDA MOTOR CO..LTD. HONDA CB750 CYLINDER HEAD/VALVE VALVE FACE WIDTH AND VALVE ,1 ‘ . / SEAT INSPECTION ’ Clean all intake and exhaust valves ’ I thoroughly to remove carbon deposits. Apply a light coating oi valve lapping compound to each valve face. Lap each valve and seat using a rubber hose. Remove the valve and Inspect the lace. CA U TlON The valves cannot be ground. II the face is burned or badly worn, replace the valve I f Meatsuze the wrath of the valve lacs VALVE FACE SERVICELIMIT: 2,0mmt0.0137in) can at: . It the valve lace contact is too wide. too narrow or has low spots, the valve must be replaced. Inspect the seat. Measure the width of the valve seat. It the seat is burned or badly worn. or too wide or too narrow. the seat must be ground, NOTE Follow the relacer manufacturer's apar- ating instructions. Date 0f Issue :Dec.,]977 _ CC‘HONDA MOTOR C0,,LTD, 6 11 CYLINDER HEAD/VALVE HONDA C3750 VALVE SEAT REPAIR NOTE Follow reiacer manulacturer’s operaI~ ing instructions Inspect each cutting stone for cracks. Fletace the cutting stone to the correct angle. NOTE Each tlme a stone is removed and re- installed on the grinder, it must be re- laced on a dressing stand. Install the pilot Dar Into the valve guide firmly and lubrlcate lI lightly with thin oil Use adequate eye protection when Using the 375 degree stone, remove 1M 01 the eXIstlng valve seat material \( “F" model ~.53_5 EX 32 mm(1 260 in) ‘K ‘model IN 32mm(1260m) EX29mmlt 142m) iN34mmfl 339mfli,, i "P'model IN 37mmlI 457 int EX34 mmfl 339m) "K“model IN 35mm(1 378 in) EX32rnmfl 260m) “F“model IN 37 mmll 457m) EXSA mml‘l 339m) ‘K' model IN 37 mmlI 457m) EX34 mmtt 339ml MOVE UPAND I DOWN LIGHTLY‘ iii VALVE SEAT GRINDER RPILOT BAR A /\ OLD SEAT WIDTH 6-12 Date of Issue :Dec,.1977 ’C HONDA MOTOR C0.,LTD. HONDA C3750 CYLINDER HEAD/VALVE Use the 63.5 degree stone and remove the bollom 1M 0! the am seat InstaII the 45 degree Itmsh cut stone and cut the seat to the proper wtdth Check the contact between the valve and valve seat usmg Prusslan Blue II the contact area on the vaIve Iace l5 too high‘ the seal must be lowered‘ using the 37 5 Ge 9(66 stone II the contact area on the valve lace vs too Iow. the seat must be raised. usmg the 63.5 degree cutttng stone, OLD SEAT WIDTH \ 615‘! , \ 1 (Immro U394In) \ CONTACT TOO HIGH OI. D SFAT WIDTH CONTACT TOO LOW I I ' \ OLD SEAT WIDTH Date of Issue :Dec.,1977 i: HONDA MOTOR COHLTD HONDA CYLINDER HEADNALVE C3750 Alter cutting the seat. apply lapping com- I f . Y, . pound to the valve lace. and lap the valve z '* < . using lighi pressure. ‘ ' Aller lapping. wash the cylinder head and valve clean of residual compound. CYLINDER HEAD ASSEMBLY NOTE_ Install new valve stem seals whenever disassembled. ¥ Lubricale each valve stem with a thin coat of oil and insert the valve in the valve guide. Install the valve springs and relainers. CA U TION Install the valve sprtnés with the narrow pllch end facing the cylinder head NARROW PlTCH END Install the valve cutters. Do not compress the valve spring ’ more than necessary to install the valve callers. VALVE SPRING COMPRESSORB795' 5359mm: 6-14 \, Date 01 Issue :Dec.,1977 EHONDA MOTOR COuLTD. HONDA * C3750 CYLINDER HEAD/VALVE tipped hammer to be certain the cutters are . Tap lhe valve stems gently with a rubber firmly sealed CAUTION Support the cylinder head above the work bench surface to prevent passl~ . ble valve damage. CYLIN DER HEAD KNOCK PIN AND . KNOCK PIN AND INSTALLATION STUD GASKET ‘ STUD GASKET 3 install the O~rings, stud gaskets, knock pins, 2‘ and head gasket on the cylinder. KNOCK PlN AND sruo GASKET (ca7soxl Mount rhe wfinder head, placing the cam chain through it. TORQUE: 8 mm NUT 2.0 — 2.5 kg-m (14.5 — 18.1 ft-lb) Tighten the mounting nuts and bolts in the numerical sequence shown in 2 or 3 steps. CAPNUTS E. (03750? 1 .l NOTE @@ ‘ ‘ CE750F only - The num numbered . 5, 6, 7, and 8 in the tightening 527 [Q ‘ quence are cap nuts. Be sure to use CiAP NUTS 5 copper washers under these nuts. (CB7SDF) i —J ¢ Install new O‘rings and insert the head cover dowels. Make sure the oil orifices are clean and un- obstructed. lnstall them in the cylinder head. NIW REVISED: MARCHJSEO H/c 68313 © American Honda MotorCo., |nc.1980- All Rights Reserved 6 ' 15 MSV 1490 8003 NEW CYLINDER HEADNALVE CAMSHAFI' ASSEMBLY Install the camshatt holders NOTE Be sure that the camshaft holders are correctly located. and cam chain from the left side. NOTE Make sure the timing mark on the cam sprocket faces to the left. Position the No. 1 and 4 pistons at TDC by aligning the No. 1 and 4 '"I’" mark on the spark advancer with the index mark on the crankcase. Rotate the camshaft so the timing index line on the right end is parallel with the top sur- face of the camshaft holder. Align the bolt holes in the cam sprocket and camshaft by rotating the sprocket. Slip the cam chain over the sprocket. Install the sprocket on the camshaft with the two mounting bolts and tighten them to the specified torque. Install the camshaft holder caps. CAUTION Camshaft holders and caps are match- ed sets and can be identified by the matching numbers stamped on each holder and cap. Slip the camshaft through the cam sprocket TORQUE: 1 8—2 2 kgm (130—15 QIHD) REVISED: MARCH, 1980 H/C 65313 © American Honda Mmov Co., Inc. 1950 ~ All Rights Reserved MSV 1490 8003 HONDA C3750 CYLINDER HEADNALVE Tighten the bolt and nuts to the specified torque. Insert the push bar into the cam chain tensioner. Install the tensloner on the cylinder. Loosen the tensioner adjusting bolt. Retighten the bolt and lock with the lock nut. Cam chain adjustment must be periormed atter installing the engine. ROCKER ARM AND ROCKER ARM SHAFT INSTALLATION Turn the crankshait so that the base circle of the cam is up. Install the rocker arm shaft, and install the mounting bolts. NOTE Rocker arms Nos. 1 and 3, and Nos. 2 and 4, are interchangeable. Do not in- terchange them, Install them correctly in the positions they were in before disassembly. 0.6—1 .1 kg-m (4.3—8.0 tt-lb) ADJUSTING BOLT PUSH BAR Date of Issue :Dec.,1977 CHONDA MOTOR C0.,LTD. CYLINDER HEAD/VALVE Adjusl the valve clearance (Refer (o sechon 3.) Pourclean engine OII Into the oil packers In the cylinder head to lubricate the cams. Install the cylinder head cover with sixteen screws. Install the breather cover wllh lhree screws. 6-18 Dale of Issue :Dec..1977 E HONDA MOTO R CO.,LTD. HONDA “é ca7so CYLINDER [PISTON : Dec.,1977 f HONDA MOTOR CO..LTD. Dale of Issue “$3" 7. CYLINDER/ PISTON TROUBLESHOOTING 7—1 PISTON RING REMOVAL 7—5 SERVICE INFORMATION 7—1 PISTON RING INSTALLATION 7—5 ‘ CYLINDER DISASSEMBLY 7—2 PISTON ASSEMBLY 7—7 I . PISTON REMOVAL 7—3 CYLINDER ASSEMBLY 7—7 I TROUBLESHOOTING . Compression Too Low or Unstable Overheat 1- Worn cylinder or Plsmn ""95 1 Excess-ve carbon build-up on piston or combustion chamber wall Excessive Smoke (Dilrup) 1. Worn cylinder or piston Knocking or Abnormal Noise 2 Improper installation 04 piston rings 1 Worn piston and cylinder 3. Scored or scratched piston or cylinder 2, Excesswe carbon burld-up wall SERVICE INFORMATION WORKING PRACTICE oil is led to the cylinder head through an orl control onllce located in the engine case Before installing the cylinder . All cylinder and piston maintenance and Inspection necessitates engine removal lrom lne lrame Camshalt lubrication head, make sure that the OH passages are not clogged and that the dowel pins are installed properly, SPECIAL TOOLS PISTON BASE 07955—3000000 PISTON RING COMPRES5OR 07954—8000000 ROTATION BAR 07999—3000000 Item W Standard 7 7 ServiceLirnit Cylinder Cylinderl D 6100 —61 01 mm (2 4016a2 4019 in) G1 10 mm (2 4055 in) Warpage across tori nl cvlmoer 0 —0 05 mm (0 70 002 inl 0.10 mm (0 0039 ml Pislun ring Piston rlrlg wrdlh Top 1.170 —i 190 mm (0 046 ~0 047 mi r 1.120 mm (0 044 ln) Second 1 165 —1160mrri (0.045970 0465M) 1110mm (0 0437in) I Pistoiiriug end gap Top 0.2 —04rnm (0 003 ‘0016ml 0,7 mm (0 028m) Second 0.3 —0.9mm to 012 —0 035 ml 1.2 mm (0 047 in) . Pision rinQ-to»groove ciearancu rap 0.04 —o.o7 mm ID 002—0 003 mi 015 mm (0 car In) Second 0025 —0 055 mm It) 0009—0 0022 in) I 0.165 mm (0 0065 m) ‘ Plslon i I Pislon O D at skirt 60 955—60935 mm [2 399872 4009 in) I_ 60.850 mm (2 3957 In) L Piston pm Dore I5 002715.008 mm 10 590670 5909 U1) 15.080 mm (0 5937 In) I COWIDCI'VIU rod I r.r.rnecixrigrod\ ‘ I RETAINER WRENCH 07910—329000!) RETAINER WRENCH D7910~2830000 I 3-4 Dale of Issue :Dec..1977 L HONDA MOTOR COHLTD‘ HONDA BRAKE LINING THICKNESS INSPECTION (K-MODEL) BRAKE DRUM I.D. INSPECTION REAR BRAKE SHOE REPLACEMENT (K-MODEL) Remove the brake arm. Remove the coner pin. Replace the brake shoes wiih new ones. Appiy a light COBIH’IQ of grease to (he iace oi the make cam WARNING Coniaminated brake linings reduce slapping power. Keep grease oil the brake linings. Wipe excess grease at! Me cam. C3750 REARWHEEL/BRAKE/SUSPENSION SERVICE LIMIT: 2.0 mm (0.0787 in) sench LIMIT: //—. 133 mm (7.2047 In! Date of Issue :Dec., 1977 ©HONDA MOTOR C0.,LTD, 1 3-5 REAR WHEEL/BRAKE/SUSPENSION BRAKE DISC THICKNESS INSPECTION (F-MODEL) Measure the thickness of the disc. BRAKE DISC WARPAGE INSPECTION (F-MODEL) Measure the warpage of ms disc HONDA. C3750 SERVICE LIMITS: F-MODEL: 4.0 mm (01 515 in) 13-6 Date of Issue :Dec.,1977 ©HONDA MOTOR CO.,LTD. HONDA C8750 REARWHEEL/BRAKEISUSPENSION . REAR WHEEL ASSEMBLY Pack all bearing cavities with grease and drive the rlght bearing into the wheel hub. NOTE . - lnstallthe nghtbeanngtirst. - Install the bearing With the sealed endtothe outside. - Do not allow the bearing to tilt while driving. Pack all bearing cavities with grease and . drive the left bearing into the wheel hub. Install the oil seals and retainers. DRIVEN SPROCKET INSTAL- LATION ' Attach the driven sprocket to the hub Tighten the nuts. Bend the tanged washer locking tabs up against the sides oI the nuts DRIVER HANDLE 0794976110000 BEARING DRIVER (RIGHT) 07946~3290000 BEARING DRIVER (LEFT) 07946‘3600000 RETAINER WRENCH ILEFT) 07910—2830000 RETAINER WRENCH (RIGHT) 07910—3290000 Fix / TANGED WASHER 5 575 5 kgm (39 3747 0 IHDI Date at Issue :Dec..1977 ‘1: HONDA MOTOR CO..LTD. 13-7 ) HONDA c3750 REAR WHEELIBRAKEISUSPENSION FINAL DRIVEN SPROCKET WEAR ‘ Replace the driven sprocket i1 worn or damaged‘ NOTE At the same time, check the drive X ‘ chain and drive sprocket. : Q j T : NORMAL WORN ‘ DAMPER RUBBER INSPECTION Replace the damper rubbers if damaged or dakerlorated, Lubricate drive sprocket with grease durlng assembly‘ Dale of Issue :Demsrr 13' 8 ,.‘ 7 , : HONDA MOTOR C0..LTD. HONDA CB75° REARWHEEL/BRAKEISUSPENSION . REAR WH EEL INSTALLATION Insert the axle from the left swde, through the wheel adiusler, lelt swing arm, rear wheel, right swung arm, and wheel adjuster. . Install the axle nut. NOTE Rotate the adjuster bolts so that the index marks are aligned with the same scale on both sides, Torque the axle nut. and install the cutter pm . Spread the cotter pm ends NOTE - Do not use a steam cleaner or a compounded chain lubricant such as chain spray as these will ruin the rubber O-ring. - Lubricate the drive chain with SAE 80 or 90 gear oil 0 Adjust the drive chain slack to 15— 25 mm (SIB—1 in). - Use a genuine HONDA drive chain - Alter installing a new chain. adjust the tension, / SIDE PLATE ROLLER BUSHING/RIVET . RED ZONE SWING ARM END ALIGNING POINT will l‘lllt‘ll‘l‘ . ©> l K-T mg REPLACEMENT POINT ( Date uf Issue :Dec.,1977 _ ©HONDA MOTOR C0,,LTDt 1 3 9 REAR SHOCK ABSORBER SHOCK ABSORBER REMOVAL Remove the rear bumper, exercismg care not to damage the wrring To remove the left shock absorber, remove the chain guard. Remove the upper nut lirst‘ then remove thelower bolt NOTE Belore removing the shock absorbers. rotate the adjusters to the softest po- sition. SHOCK ABSORBER DISASSEMBLY Compress the sprlng to remove and install 0@ fr ' ' UPPER JO‘NT the upper seat, g1? NOTE 7 UPPERSEAT , "' Install wrth tightlxwoundgnd UP. LOCK NUT—- __ / v) ”2,3 Apply locking agent to threads %% ‘ SHOCK ABSORBER SPRING FREE LENGTH ‘l’llllllll SERVICE LIMIT: 225.9 mm (9.0118 in) D I I :D .,1977 1 3- 10 SQRDZHJOTSR c0..LTD. HONDA C5750 REARWHEELIBFlAKE/SUSPENSION . SHOCK ABSORBER ASSEMBLY TIGHTEN Install the spring with the tighly wound and C facing up. Apply liquid lock to the threads and under- LOOSE“ I side ol the lock nut. SCREW IN AS NECESSARY SHOCK ABSORBER INSTALLATION Torque the nuts and bolts. NOTE , __ A Alter installing the shock absorbers, . check fie operation. V SHOCK ABSORBER ADJUSTMENT Adjust the spring tension wuth the adjuster. . The standard position Is "I" m m N v SOFT fifi HARD ICEHONDA MOTOR CO..LTD. Date of Issue :Dec.,1977 1 3-1 1 REAR WHEEUBRAKE/SUSPENSION SWING ARM SWING ARM REMOVAL Remove the rear wheel (Page 13—21 Remove the shock absorbers (Page 13—10). Remove the swing arm pivot bolt SWING ARM DISASSEMBLY \ 7 / fl: / GREASE 03% CENTER / COLLAR GREASE SWING ARM ASSEMBLY Drive the pivot bushing into the swing am applying hamming lhroughapad. ' PIVOT BUSHING PAD / ‘ I ‘ Apply careful hammer blows through a ode to avowd damaging bushmg D l (I :D ,.1977 1 3' 1 2 .CaHE‘IGDZSgOTS; C0.,LTD. HON DA CB750 REARWHEEL/BRAKE/SUSPENSION SWING ARM INSTALLATION Torque the swing arm plvot nut. Install the shock absorbers (Page 13—1 1) Install the rear wheel (Page 13—9l (39.8—50.6 - Date of Issue :Dec.,1977 C HONDA MOTOR CO.,LTD. 13-13 HONDA ‘l 4 HYDRAULIC C3750 DISC BRAKE TROUBLESHOOTING 14—1 SERVICE INFORMATION 14—2 BRAKE FLUID REPLACEMENTIBRAKE BLEEDING 14—3 . FRONT BRAKE PAD REPLACEMENT 14—5 FRONT BRAKE CALIPER 14—3 FRONT BRAKE MASTER CYLINDER 14—14 . . REAR BRAKE PAD REPLACEMENT —F-MODEL 14—16 REAR BRAKE CALIPER -—F-MODEL 14—17 REAR BRAKE MASTER CYLINDER 14—20 TROUBLESHOOTING Brake lever/Pedal $0" or Spongy Brakes Grab or Pull Io One Side 1. Air bubbles In hydraulic system 1 Pads contamunated 2. Insulfiment lluid in hydraulic system 2 Detect In one side of front braking system 3, External leak in hydraulic system 3, DISC or wheel mISaIlgned 4. Internal leak In hydraulic system Brakes Chatter or Squeal Brake Lever/Pedal Too Hard 1 pads contaminaied 1. Frozen piston (s) 2, EXCESSIVe runout on OISC (s) 2. clogged hydraulic system 3. Cahpermsialled Incorrectly 3. Pads glazed or worn eXCeSSIVEIy 4 Dlsc or wheel misaligned Brake Drag 1. Hydraulic system sticking 2. Incorrect adjustment ol leveror pedal . 3 Frozenplstoms) Dale of issue :Dec.,1977 é, HONDA MOTOR COHLTD. V 1 4'1 HYDRAULIC DISC BRAKE HONDA C3750 SERVICE INFORMATION WORKING PRACTICE The front and rear brakes can be removed wrthout disconnecting the hydraulic system. Once the hydraulic systems have been opened, or ii the brakes (eel spongy, the system must be bled. Do not allow ioreign maierial to enter the system when filling the reservorrs. Avoid spilling brake fluid on painted suriaces or instrument lenses, as severe damage wrll result. TOOLS CIRCLIP PLIERS 07914—3230001 FLAT NUTWRENCH 07921-0010000 TORQUE VALUES FRONT BRAKE CALIPER SET BOLTS FRONT BRAKE CALIPER BOLTS REAR BRAKE CALIPER BOLTS REAR BRAKE TORQUE LINK BOLT BRAKE OIL HOSE JOINT BOLT 3.0—4.0ka (21 7—28.91talb) 3.0—4.0 kg~m (21 7—28,9tt~lh) 2.4—3.0 kg-m (17.4—21.7ft-lb) 1.8—2.5kg-m(13.0—18lit-lb) 2.5—3.5kg-m(181—25.3It-lb) SPECIFICATIONS Item . Wk 7 _ Standard _. Service Limit Front master cylinder Cylinder l.D. F~model 17460—17503 mm (06874—06391 in) 17.515 mm (0 6396 m) fl K~model 14000—14043 mm (0 5512—06529 in) 14.055 mm (0.5533 In) Piston O.D, F-model 17417—17444 mm (06857—05866 in) 17.405 mm (0.6852 In) W 7 K-mod_el 13;9§7—13 934 mm (05495—0 5596 In) 13.945 mm (0.54901n) Front caliper Cylinder l.D. F-model 38,l80—38 230 mm (15031—15051 in) 38 240 mm (1.5055 In) K-mogsl 7472 850—42900 mm (1.68701115990m) 42.915 mm (1.6896 in) Piston O.D F-model I 35098—30143 mm (1.4999—15019-n) 38.090 mm (1.4996 In) 7 ._ _ ilf:model 42 820 mm (1.6858 In) 42.805 mm (1.6652 in) Flear master cylinder Cylinder l.D. ‘ 17 AGO—17.503 mm (0.6874—0.6891m) 17.515 mm (0.6896 in) Piston 0.0. 17.417a17.444 mm (0,6857—0.68681n) 17.405 mm (0.6852in) Rear caliper Cylinder |.D 381810—38 230 mm (15031—15051in) 32 240 mm (1.5055 in) PlslonOD 38098—38.14Bmm (1.4999—1.5019m) 38 090 MM (14996in) 14-2 Date of Issue :Dec.,1977 CHONDA MOTOR C0,.LTD. HONDA C3750 HYDRAULIC DISC BRAKE BRAKE FLUID REPLACEMENT/AIR BLEEDING Check the lluld level with the reservoir paral- lel with the ground. CAUTION - Install the diaphragm an the reser- voir when operating the brake lever Failure In do so will force Ihe fluid out of the reservoir by the system pressure pumped up by the one rali'orr ol the brake lever - Avoid spilling fluid on painted surfaces Place a rag over the luel tank when ever the system is serviced. BRAKE FLUID DRAINING Remove the bleeder valve dust cap, Connect a bleed hose and place one end in a clean container Loosen the caliper bleeder valve and pump up the system pressure by operating the brake leverlpedalv Stop operatlng the Ieverl pedal when IIurd has stopped llowmg out ol the bleeder valve. BRAKE FLUID FILLING CAUTION l 7 - Check the lluid level clten while bleeding the brake to prevent air from being pumped into the system - Do not mix dilferenl brands of Iluld since they are no! compatible Close the bleeder valve. till the reservoir andinstallthediaphragm To prevent piston overtravel and brake fluid seepage keep a 20 mm space to the handlebar grip when bleeding the tram brake system. Pump up the system pressure With the leverl pedal until there are no air bubbles in the lluid llowing out ol the reservorrs small hole [until the lever/pedal becomes hard). BRAKE FLUID RESERVOIR DIAPHRAGM HONDA BRAKE FLUID DOT —3 NEVER RE-USE Date of Issue :Dec,.1977 C‘HONDA MOTOR C0.,LTD. 14-3 HON DA HYDRAULIC DISC BRAKE C8750 AIR BLEEDING (FRONT) Pull the brake lever back. Screw out the bleeder valve 1/2 turn, and retighten. HONDA BRAKE FLUID D013 NOTE Do not release the lever until the bleedev valve has been closed. DIAPHRAGM Release the lever gradually and wait for several seconds alter It reaches the end ol RESERVOIR its travel. Repeat the above steps until air bubble cease to appear in the fluid llnwing out ol the bleeder valve, Fill the reservoir up to the UPPER FLUID LEVEL. Check the entire system lor leaks by operating the lever. WARNING A contaminated brake dlsc or pad IU‘ dunes stopping power. Replace con~ ternlneled pads, and clean a contemi» neled dlsc with a good quality degree slug agent. AIR BLEEDING (REAR) IF-MODELI NOTE ____ To prevent piston overtravel and brake fluid seepage, keep the pedal a 20 mm (05 in) distance lrorn being fully de- pressed, Depress the brake pedal. Screw out the bleeder valve about 1l2turn. and retlghtsn. NOTE Do not release the brake pedal until the bleeder valve has been closed. Release the pedal gradually and wait for several seconds alter II reaches the end ol its travel. Repeat the above steps until arr bubbles cease to appear in the lluid llowmg out at the bleeder valve Fill the reservoir up to the UPPER FLUID LEVEL. CAUTION Avoid spilling fluid on painted surfaces, Do nut mix different brands of fluid since they are not Cnmpal‘lble. MASTER CYLINDER NEVER RE—USE ABOUT 20mm 14-4 Date of Issue :Dec..1977 CHONDA MOTOR C0..LTD, HONDA C3750 HYDRAULIC DISC BRAKE . BRAKE PAD REPLACEMENT F-MODEL . The front brake pads require replacement il the red Imes on the top ol the pads reach the edge ot the brake dlSC. Remove the caliper bolts. Remove the brake caliper. pads and shims. NOTE Do not operate the brake lever during dlsassembly. Install new pads and shims NOTE Install the shims with the mark ”f lacing up. Push the piston all the way in and torque the caliper bolts. Date of Issue :Dec.,1977 xi; HONDA MOTOR C0..LTD. HYDRAULIC DISC BRAKE FRONT BRAKE PAD REPLACE— MENT K-MODEL Replace the pads it the red lines on the top ol the pads reach the edge of the brake disc Free the brake hose from the tender clip. Remove the caliper bolts and caliper. Remove the pads and wipe cleanl NOTE Do not operate the brake lever during dlsassembly. Apply high temperature silicon grease to both outer circumlerence and caliper as shown betore assembly. 00 not use molybdenum brake grease. As- sembly is the reverse order at dlsassembly Brlklng performance will decrease if grease contacts the pads/disc rubbing surlaces. 1 4-6 Date uf Issue :Dec.,1977 ii HONDA MOTOR C0..LTD. HONDA C3750 HYDRAULIC DISC BRAKE . Loosen the lock nut and lully screw out the catiper adjusting bolt. Insert the brake hose into the lender clip‘ tnstall the pads A and E. and tighten the caliper bolts BRAKE CALIPER ADJUSTMENT With the front wheel oft the ground. screw . the adjusting bolt in until pad 8 contacts he brake disc, then screw out 1/2 turn. Inspect brake operaliun nelore riding the mutarcycle. Date of Issue :Dec.,1977 C HONDA MOTOR C0..LTD. HYDRAULIC DISC BRAKE l FRONT BRAKE CALIPER—F MODEL CALIPER REMOVAL Drain brake fluid from (he sysiem (Page 14—3). Disconnect the brake hose. CAUTION Avoid spilling brake fluid an painted surlaces. Remove the brake caliper. Remove the brake pads. CALIPER DISASSEMBLV Remove the brake pad spring. Remove the boot cm: and boot. <——— CALIPER PISTON SEAL PISTON PAD SPRING BOOT RING Place a shop towel or rag over the vision and position (he caliper with ihe piston p facing down. V , 4 . Apply a small amount oi air pressure i0 (he . ,. fluid ouiiel, to remove the piston. I Do not use high pressure III or bring the Mule ion class to Me inlet. 1 4 8 Date of Issue :Dec.,1977 ' ’CHONDA MOTOR conLTD‘ HONDA C8750 HYDRAULIC DISC BRAKE NOTE Remove the piston seal from the caiiper by pushing it into the piston cylinderand then lilting It out. PISTON O.D. INSPECTION Check the piston tor scoring, scratches nicks or other defects and replace II necessary‘ CYLINDER INSPECTION Check the cylinder tor scoring, scratches or other detects and replace If necessary, Remove the caliper bracket. Remove the pin. NOTE Do not damage the boot. SERVICE LIMIT: 38.090 mm (1‘4996 In) VI ‘ SER CE LIMIT.‘ 38.240 mm (1.5055In) PI N\fl%$fCOVER \ \éfifl M BRACKET Date at Issue :Det.,1977 “Q HONDA MOTOR C0‘.LTD. 14-9 HONDA C3750 HYDRAULIC DISC BRAKE CALIPER ASSEMBLY . Assembly of the brake caliper is the PAD SPRING reverse of disassembly. PISTON SEAL . PISTON BOOT CALIPER . PISTON DUST COVER CLIP Install a new piston seal in the groove in the cylinder and apply a thin coating oi silicon grease to it. Insert the piston into the cylinder, install the piston boot and clip. Install the brake pad spring. NOTE Be sure the pad spring is installed cor- reclly. Install the brake caliper and tighten the bolts installthe brake hose. Fill with DOT-3 brake fluid and bleed the system D H :1) .,1977 1 4'1 0 caégownisfiorg; co,,LTD. HONDA C3750 HYDRAULIC DISC BRAKE BRAKE CALIPER REMOVAL K— MODEL Drain (he brake fluid from the system Disconnect the brake hose. BRAKE CALIPER DISASSEMBLY TO REMOVE AND INSTALL, USE ,/ FLAT NUT WRENCH 0792170110000 Date of Issue :Dec..[977 E HONDA MOTOR C0,.LTD. 14-1 1 HYDRAULIC DISC BRAKE PISTON O.D. INSPECTION Examine the piston for scoring, scratches or any other defects and replace if SERVICE LIMIY: 42.805 mm (1.6552 in) necessary. CYLINDER I.D. INSPECTION Check me cylinder for scoving. scrakchas or SERVICE LIMIT: 42.915 mm (1.3593 In) any other deIecls and replace it necessary. BRAKE CALIPER ASSEMBLY Before assembling the brake caliper, apply grease to me slldlng face of me caliper holdarpin‘ f DISC COVER CALIPER HOLDER PIN f1 ; ..1971 1 4" 1 2 glangZSKO'IPS; CO.,LTDI HONDA CB750 HYDRAULIC DISC BFlAKE . Install a new piston seal. Coat the piston with sillcon grease and install It. NOTE Insert the plston until 1t bottoms Apply Sllicon grease to the brake pad outer circumlerence and Install Insert and bend over pad B‘s cotter pm. Blaklng periormanco will decrease if silica" grease is applied ta the pads] disc contact surfaces Install the caliper and torque the bolts, Insert the brake hose into the tender 0le and connect the hose to the brake caliper tlttlng. Adjust the caliper. (page 14—6) Fill wlth DOT'3 brake lluld and bleed the system Date of Issue :Dec.,1977 14-13 ii HONDA MOTOR CO..LTD. HYDRAULIC DISC BRAKE FRONT BRAKE MASTER CYLINDER DISASSEMBLY Drain the brake hydraulic system. Disconnect the brake hose. NOTE when removing the brake hose bolt. cover the and of the hose to prevent contamination. CAUTION Avoid spilling brake fluid on painted surlaces. Remove the brake lever. Remove the master cylinder. Remove the curcltp from the master cylinder body. Remove the stop plate. secondary cup and piston. Flemove the prlmary cup, sprung and check valve It may be necessary to apply a small amount of air pressure tothetluid outlet to remove the piston and primary cup. ClRCLlP PLIERS “IV 07914— 3230001 l“_' T MASTER CYLINDER BODY SPRING . PRIMARY CUP PISTON SECONDARY CUP STOP PLATE . CIRCLIP MASTER CYLINDER BODY BOOT—a 14-14 Date of Issue :Dec.,1977 ’ HONDA MOTOR COWLTD. HONDA C8750 HYDRAULIC DISC BRAKE MASTER CYLINDER I.D. INSPECTION Check the master cylinder for scaring~ scratches, nicks or other detects MASTER PISTON CD. IN- SPECTION Measure the master piston O.D MASTER CYLINDER ASSEMBLY Reassemble the master cylinder in the reverse order at disassembly. Coat all parts with clean brake Iluid before assembly. Install the check valve on the spring. Install the spring and valve together. When Installing the cups, do not allow the lips to rum inside our. Be certain the CIID/l- is seated firmly in the :roove Alter reassembling, till the reservmr to the UPPER LEVEL and bleed the brake system (Page 14—11). SERVICE LIMIT: F-MODEL: 17.515 mm (0.889 in) K7 I Brush length 12—13mmtova724—0.5113ml 7mmlo.2756inl l SPECIAL TOOL ROTOR PULLER 07933~ 3000000 TORQUE VALUE A.C. GENERATOR ROTOR FIXING BOLT 10 o—I2 o kg-m 172 320—86 784 ft-ID) Date uf I<~u.~ 390.1977 L’ HONDA MOTOR ClLL'I'D. 17-1 ELECTRIC STARTER STARTER MOTOR STARTER MOTOR REMOVAL Disconnect the starter motor cables at the magnetic switch. Remove the starter motor cover and remove the starter motor. NOTE Remove the carburetor first. it the engine is mounted in the frame. BRUSH INSPECTION Remove the starter motor case screws and the brush cover. NOTE Look for spacers-on the armature shaft ends. Replace them in their proper po~ sition. Inspect the brushers: measure brush length, Measure brush spring tension. COMMUTATOR INSPECTION Measure the diameter of the commutator and height of the segments above the insulator. NOTE Do not use emery or sand paper on the commutator. SERVICE LIMIT: BRUSH LENGTH: 7 mm (0.2755 int BRUSH TENSION: 400 gr(14.108 oz) COMMUTATOFI 17-2 Date oi Issue :Dec.,1977 CHONDA MOTOR C0.,LTD. HONDA. C3750 ARMATURE COIL INSPECTION Check for continuity between pairs of com- mutator bars‘ and between commutator bars and armature shaitv Replace the starter motor if the armature coils are open, or shorted to the armature shalt. FIELD COIL INSPECTION Cheek ior continuity for the cable terminal to the motor case and irom the cable terminal to the brush wiret Replace the starter motor ii there is no continuity in the field coil or it it is shorted to the motor case, STARTER MOTOR ASSEMBLY The positive primary cold is insu- Iliad. - Align the mark on the case with the mark an the cover. ELECTRIC STARTER Date aI Issue :Dec.,1977 EHONDA MOTOR CO,.LTD. 17-3 STARTER MAGNETIC SWITCH INSPECTION Disconnect the negative battery cable from the battery hetero proceeding. Remove the magnetic switch. Test the primary windings tor continuity. Also test for shorts from either primary lead to the case. Replace the magnetic swrtch it the primary coil has an open circuit, or is shorted to the case. Connect 12-Volt source across primary leads. Magnetic swrtch should make an audibleclick. Test for contlnuity across the large termi- nals when the magnetlc switch is energized. If there is any resistance, the relay mast be replaced. STARTER CLUTCH (A.C. GENERATOR ROTOR) INSPECTION Remove the generator cover, Remove the AC. generator rotor and start- ing clutch gear. (Page 15—4) Rotor puller 0793373000000 Check to make sure that the clutch rollers operate smoothly. STARTER REDUCTION GEAR INSPECTION Remove the generator cover. Check gears for wear or damage. ELECTRIC STARTER HONDA c3750 Owe 17-4 Date of Issue :Dec.,I977 @HONDA MOTOR CO.,LTD. “39's? 18. LIGHTS/ SWITCHES SERVICE INFORMATION 18—1 LIGHTS 18—2 SWITCHES 13—3 . I HORN 18—6 . SERVICE INFORMATION WORKING PRACTICE All electrical wires and connectors are color-coded When two or more dillerent colored wrres are connected, 3 colored tube that matches the malor color 0' the other wire appears on the wire near the connector. Observe the color codes belore disconnecting any wrres, All plastic plugs that have locking tabs must be released belore disconnecting, and must be aligned when reconnecting. The color codes used on the motorcycle are Indicated throughout this section and on the wirlng dlagram by the lollowing abbreviations: . B , Blue Le v nght Green Bk , Black 0 , Orange Br ~ Brown F' : Plnk G , Green R : Red Gr 7 Grey w ,7 White LB : nghtBlue Y ' Yellow Date of Issue 1Dec..1977 C HONDA MOTOR CO.,LTD. 18'1 HONDA c3750 LIGHTS/SWITCHES LI G HTS HEADLIGHT Headlight Specification 12V 50 HOW NOTE Adjust the lamp alter reassembling to conform to applicable state laws. TAILLIGHT/STOPLIGHT Remove the lens to remove the bulb. Bulb Specification 12V 32/30P CA U TION Do not overliénten the lens mounting screws. TURN SIGNALS Remove the lens to remove the bulb. (FRONT) 12V 3213C? (HEARD 12V 32 CP CAUTION Do not ave/tighten the lens mounting screws. TURN SIGNAL FLASHER AND BUZZER Flasher should flash 60 to 120 times per minute. ll flasher does not work or flasher lrequency l5 incorrect, check the components and connections shown in the circuit belore re- placing flasherv 18-2 Date uf Issue :Dec..1977 DHONDA MOTOR C0..LTD. HONDA CB7 50 LIGHTS/SWITCH ES SWITCHES HANDLEBAR SWITCHES The handlebar cluster switches (lights. turn signals, horn, siart, and stop) must be replaced as assemblies. Continuity tests for the components of the handlebar clutster switches are as follows: Continuity should exist between color coded wires indicated by interconnected circles on each chart. DIMMER SWICH HORN PASSING SWITCH swncn :COLOR Bi B SWITCH COLOR Elk LG 8 -‘ ‘ 'w H0 ‘32ng rm IE (kfi —a> on (F REE! STARTER BUTTON 779959” an ‘ v/n TURN SlGNALSWITCHfi 7 ')——4\ 5W6? CT 5: LEM/a 0,1" LB . l ’ I "“' ’T "‘ ENGINE STOP swrrcn E94: SWITCH COLOR Bk Bk/w I t AWN if Q ”I 0,745.) I l l P4 I Date of Issue :Dec.,1977 LC HONDA MOTOR CO.,LTD. 1 8'3 LIGHTS/SWITCHES % C3750 IGNITION SWITCH SWITCNOLOR R g grlw an 572 & LOCK it C OFF Dun 3 0N ) A [In- I? 1; l l l é FRONT BRAKE STOPLIGHT SWITCH Continuity should exist when the front brake . STOF’LIGHT SWITCH lever IS operated REAR BRAKE STOPLIGHT SWITCH The switch should be adjusted so that the rear brake stoplight comes on just when brake pressure is applied. 18-4 Date of Issue :Dec,,l977 @HONDA MOTOR COHLTD. HONDA C3750 LIGHTS/SWITCHES NEUTRAL SWITCH Continuity with the transmission in neutral (steel ball released). No continuity with the transmission in other than neutral (steel ball depressedlt OIL PRESSURE SWITCH Before testing, check the oil level in the engine oil pan. No continuity with the engine running Continuity with the engine stopped DIODES Continuity must exist only in the arrow di- rection. Diodes must be replaced if there is COI’INI’IUI- ty in the reverse direction. NEUTRAL: CONTINUITY IN ANY GEAFI NO CONTINUITY Date of Issue :Dec.,1977 ©HONDA MOTOR C0..LTD. 18-5 CLUTCH SWITCH Check continuity of clutch lever switch with clutch released and applied, Replace if there is no continuity where clutch is released. HORN Check continuity oi horn by connecting to a 12 V source Adjust ham to desired tone with the adjusting screw located on rear oi the horn. Replace the nor it it can not be adjusted correctly. LIGHTS/SWITCHES ADJUSTING SCREW BATI'ERY 18-6 Date of Issue :DecHIB’l? QHONDA MOTOR C0.,LTD. HONDA CB750 19. TROUBLESHOOTING . CENGINE DOES NOT START OR IS HARD TO START SYMPTOM CHECK . fiiecfifiiTeiTsEIciEngclfl ‘ ’’’’’’’’’ 1 huretor by loosening drain 1 SDYEW ‘ 777777777 J . F ,_ ,l:_..._ 'F . Fuel reaching carburetor "9' "0‘ "am"! l carburetor "EirIelsFaEH-EGJTO + 777777777 i try spark test J O 7 ii a W K, , Good spark Weak or no spark 7, ”if, H , 7,, "WfiASl ‘V 7 Ti l Test cylinder compression i l V 1“ 7777777777 l by operating kick pedal l fifeifi_ ,, , ,, Compression normal ‘ Loss or compression >¥r e, , 77,7777, , e, ,7 a _ , , c e i , s I ’1 l Start by following normal e; 7 fifififififi WV . , '0 L m T 71,—1 es l . . i Engine does not fire ‘ [ Engine me: but 1 stops H , fl, 1 7 777a '_ . ,_ ”7 ,fi ’ 4 ' 'r‘ ' " ' **"'* 777i Remove spark plugs l ,,,, rife " ,1 , Dry spark mug j [Tm spark plug F" 777i," -7, 77”, ee_,,,,,,, 7*, ~77 , 77,—. fl {m 7 T iiiiiiiiii 1 Restart with choke applied i t ,,,,,,,,,,,,,, . 0 ENGINE LACKS POWER SYMPTOM CHECK O ‘ low L— W, ,7 is W 777777 Try rapid acceleration from ‘ L44::3‘444fi lymMmm J [*7 . 77777777777 i Engine speed not changed when clutch is released Engine speed lowered when clutch is released PROBABLE CAUSE Fill No fuel in fuel tanl: l2 ) Clogged luel tube or fuel filter *l3) Clogged carburetor jets 7(4) Clogged ruel tank can breather hole [(1) Faulty spark plug (2) Fouled spark plug >(3l Fouled contact breaker points *(4) lrnproper breaker point sap Faulty condenser *lE) Broken or shorted high tension cord *0) Broken or shorted ignition coil 7(8) Defective main switch _(9) improper ignition timing * (1) Valve clearance too small >(2l Valve stuck open l3l Warn cylinder and piston rings *(Il Damaged cylinder head gasket *l5) Improper valve timing _ ‘l1l Misuse of choke *lZl Carburetor pilot screw excessively closed ~l3l Air leaking past manifold Carburetor overflooded 7(2) Carburetor choke excessively closed *(3) Throttle valve excessively opened PROBABLE CAUSE {l1 ) Punctured tire (Z) Faulty tire valve H Clutch slipping Worn clutch disc Clutch disr: warped Date of Issue :Dec..1977 ©HONDA MOTOR C0,.LTD. 19-1 TROUBLESHOOTING lacnutua C3750 #% Engine speed increased Engine speed not in- l'l1) creased sufficiently l Checkignition timing II " iiiiiiiiii 1 test lamp ' fi—fi Ignition timing is correct Improper ignition Valve clearance is normal *(2) —, —l3l -(4l 7(5) Valve clearance is not correct 1 fist cy der compression l Lusing compression gauge Compression is normal I 7777777777 —-—: by operating kick pedal l l l Compression is low fl ‘ i " " ‘ ‘ *i“*‘lr‘ check carburetor for clogg- l l l lhki¥fi "Lg_e,,_eifi_,ed Carburetor is not clogged Carburetor it clogged , f 1 1°2°12W5Ee$tfij Spark plug is not fouled or or discolored r Spark plug is fouled or diwolored ' ,__,,~_.,,, es ,ee- 4|; Oil pressure normal , Remove all level gauge and L check oil level and _fouling Li Oil level is not correct - eeeeeeeee Normal oil pressure Low oil pressure : """ Engine is not overheated E ngine overheats [g i Accelerate or run at high I speed ,,,,,,,,,,,,, u ——l Engine does not knock 7(1) ’(3) Engine knocks A ’(4) ’(5) Carburetor choke closed Clogged air cleaner Restricted fuel flow Clogged fuel tank breather can hole Clogged muffler Improper ignition timing Improper valve clearance Worn valve seat Valve stuck open Worn cylinder and piston rings Leaking cylinder head gasket Flaws in cylinder hand Improper valve timing Fuel filter not serviced frequently enough use of low quality fuel Plugs not serviced frequently . enough Use of plug with improper heat range Oil level too high Oil level too low Contaminated oil Clogged oil passage Poor oil pump delivery Excessive carbon build-up on combustion chamber wall Use of low quality fuel Clutch slipping Fuel»air mixture too lean Worn plston and cylinder ’ Fuel air mixture too lean Use of low quality fuel Excessive carbon build-up in combustion chamber Ignition timing too early 19-2 Date of Issue :Decr,1977 CHONDA MOTOR CoqLTD. HONDA. C8750 TROUBLESHOOTING. . 'POOR PERFORMANCE AT LOW AND IDLE SPEEDS SYMPTOM CHECK PROBABLE CAUSE O fi*~* i77f77#7“ ‘ 777777777777 , Check ignition tlmmg and ijliefliarjmi 77777 J (1) Improper va|ve clearance . Normal Incorrect Improper ignition timing ,,,,,,,,,,, f Ergo? 3.3.7.397 El}? "7 Li's”,afli:=:'":"_‘ _____ J . T "4" 7A1 7; (1) (Fue| air mixture too |e)an or ncorrect >——( T t, t ma Futlngrrfncixtfr'StVOZUrich (To correct, screw in) Dateriorated imulator Loose carburetor l f”Wifimr'r’a’sgat's: ' ' 17*" 7. 7 ii 1 (1) Daiective, carbon or j [ $27:°““‘°'“'""‘t (2) ::::::::.:::::::::a L 4 (3) Condenser shorted . [ (4) Low battery \ j Dale of Issue :Dec..1977 _ C HONDA MOTOR C0..LTD. 19 3 TROUBLESHOOTING HONDA C3750 0 ENGINE LACKS HIGH SPEED PERFORMANCE SYMPTOM CHECK g Timing and clearance Timing and clearance . (1) normal Improper ‘ ‘ L 1 Check in: clogging by dis- 1 F" ””””” 7: connecting Iuel tube at I carburetor ‘ V” '7’ "’fl , L V") Not clogged gagged 7 g; ’ ’ ’ ’ r7 7 1 L7 , "_ ‘77 A ¥ ,, ,,,_.A_1 Remove nrburetor and 1 7(4) l inspect jets \ L 7 , , ,,,,, , E ,1 I Q E , l I Fuel flows out freely Fuel Ilow restricted r 77 7 7 7 --— (1) i is r , J l 777777 . , 7“ l l 77 «7 a 7 7 , A A 7 7 Replace carburetor lets ; L ,. k, , W1 _ 1:, 7 J" *1 , [(1] Condition aggravated Condition improved 1* ' ' ' i ’7' (z) i ,, . I 7,,” *1 , ,,,,, ‘ L777 < W 7 e 77777 7‘ Check valve timing l L ,,,,,,,,,,,,,, i [' m r j , Timing normal l Engine out of time I» 7 7 7 7 7 7(1) 7e , 7E J ,7 4 r 7777777777777 j ‘ i [7 7 fi‘ 7 7 7 , ,_, 7 7 W71 Test valve spring tension Ff, ,, ,7; j Tension normal beak or broken spring *7 I1) j PROBABLE CAUSE Improper adjustment Lack of fuel in luel tank Fuel tube clogged Fuel tank cap breather hole clogged Fuel filter clogged Clean Main jet size too small ll improved with smaller size jet: a) Air cleaner clogged bl Choke valve not opened fully Cam sprocket aligning marks not aligned Faulty valve spring 19-4 Date of Issue :Dec..1977 CHONDA MOTOR C0.,LTD. HONDA C3750 TROUBLESHOOTING .. SMOKY EXHAUST SYMPTOM ,— l‘ll . F # :2; 7 3 Smoke disappeared [Smoky exhaust 7L7 7 7 7 7 7 l4) 7 7y 7 7 , 7 7 7 7 7 7—. close rnrorue grip quickly l L (5) 7,4 ,7 (i No white exhaust White smoke amined immediaiely after closing g_rip , r ~ 777777777777 r 7 *********** 4LT” low—spud run ng J lllgsrnokef 7 wine smoke #7 7 7 77m iiim fl r:(2l . fi‘j (3) A 0 FAULTY CLUTCH OPERATION SYMPYOM ~7 7 , 7 4—7 Adjust clutch properly L,,,,___,,,#_J F Cluich slipping L7 7 7 , e" e, , # 7 l1) 7 , , ,7, in) L 77 7 7(3) ‘ ~ in Mntnlcycle creeps with if ,7 i—Elzl . ‘ clutch disengaged rensron PROBABLE CAUSE Wnrn cylinder and pismn rings Cranknase oil level too high Piston rings installed upside down Scored or scuffed piston or cylinder wall Flaws in cylinder head Worn inlet valve guide or stem Valve guide Owing not seated properly Worn exhaust valve stem and guide Exhauss valve guide poorly pressed in Worn exhaust valve slam seal PROBABLE CAUSE Weak clutch spring Worn or warped clutch plate Worn or warped clutch disc Plates or discs warped Uneven clutch spring Date of Issue :Dec.,1977 © HONDA MOTOR COHLTD. 19-5 TROUBLESHOOTING 0 FAULTY TRANSMISSION OPERATION SYMPTOM O <- ——————— (Clutch operates properly) % Hard to shift into gear —I Gearshift pedal not returned 7 4,, I. Transmission inrnps out of gear 0 ENGINE NOISE Q SYMPTOM Valve noise Piston slap Cam chain noise Clutch noise A PROBABLE CAUSE I—(Z) ,—m I (2) —(3) Gearshift arm spring broken Shift folks bent Shift drum and shift fork binding Gear dogs broken or worn Excessively Shift arm pawl out of engagement with shift drum pin Drum stopper plate and drum stopper improperly set Shift return spring broken Gearshift spindle interfering with crankcase or left cover Shift guide fork pin worn Shift forks bent or worn Shift drum stopper spring broken or weak PROBABLE CAUSE Ii (1) 7 (2) ,—i1) 7- ,i i inkgg (2) Lie) (1) 7—92. (3) 1—”) \__(2) Drive and driven gear noise 4 I" ~— (2) Excessive valve clearance Worn valve Cylinder or piston worn Carbon deposits in combustion chamber Worn piston pin or connecting rod small end Worn camshaft Worn camshaft sprocket teeth Excessive chain slack HONDA C3750 Excessive clearance between clutch plate and clutch outer teeth Weak clutch damper spring Worn or deteriorated driven gear damper Worn drive and ,driven gears I 19-6 Date of Issue :Dec.,1977 ©HONDA MOTOR CO..LTD. / HONDA C3750 éé TROUBLESHOOTING . 0 STEERS TO ONE SIDE OR DOES NOT TRACK STRAIGHT SYMPTOM PROBABLE CAUSE 4» ,, 7 , 7 777777777 77(Both tire pressures normal) . 7, brewing heavy } 7 *1“ u l Steering cone racas excessively tignteneu "7 7 77 '7 7 (2) Damaged sreering steel balls Frorit or rear wheel' IS excessively 7 7(1) Excessive ”me in Wm”, bearing wobbling , r—m Distortad rim ‘ 4 4 '4 7 (3) Improperly installed wheel hub . 44) Swing arm pivot bushing excessively worn (5) Ben! frame (6) Improper drive chain tension 0! adjustment 7 7Lpuiis to one side 17 7 7 (1) Unbalanced shack absorbers (right and left/(mm and rear) 7 , J J 777 # (2) From and rear wheels not aligned (3) Barn from fork ‘ (4) Bern swing arm A 0 IMPROPER FRONT/REAR SHOCK ABSORBER S VMPTOM ‘1 i __ yg Son suspension j}* «E 7 Hard xus ension 7 i ~ 77" 7 7 C i ‘77,:xcessive or abnormal noise 7* 7 4: i , PROBABLE CAUSE A 4Tire pressure normal) (1) (2) (3) Weak spring Excassive load incorrect Weight oil in iron: forks (1) (2) From/rear shock absorbzr damper valve run of operation Incorrect WEIghl oil in frum forks (1) (Z) Damaged stopper rubber lncorrecl weigh! oil in forks Date of Issu? ‘Dec.,1977 MOTOR C0.,LTD. C, HONDA 19-7 gonna CB-750K 559K ”Not even an open sports car lets you ’feel’ the scenery the way these bikes do.” Choke knob is located with instruments below /” speedometer. X Resettable tripmeter in ‘ speedometer/odometer unit. lgnition switch in center of instrument cluster also locks forks conveniently. Smooth, molded neoprene hand grips.— ’~- ”~HF’H‘ Contoured two-stage saddle. Sofl expanded vinyl covers soft foam on top with firm, dense foam Handlebars designed for proper rider positionin; underneatht \ \ for long-haul comfort. Five gallon fuel tank with chained cap under ‘ .. I. locking lid. \ :New Hawk type FVQ shocks with true two-stage dampening. Sleek and clean free-valve forks and ,1 long-stroke shocks provide quick, efficient dampening. Hydraulic disc brake on the front wheel. Five-step pre-load adjustment on shock springs.“‘> Heavy-dot ' 34 inch pitch 630 c ain with O-ring lubricant retention for less ‘maintenance, longer life. ‘ Four chrome, / seamless reverse- / cone mega hone style muf ers. Four lean jetted 28mm Wide profile tires on carburetors with accelerator \\\ wide steel rims for a pump for quick acceleration. wide tire footprint on the road. ”These two CB road bikes do everything well. Last weekend we took a trip up to Yosemite and for the first time we really sensed the tri .Any bike seems to let me and my lady eel, hear, smell—almost touch what we’re riding thmu h.There’s an exhilaration that these two ikes ive us that no car or other bike ever did. his is only a Sunda afternoon ride u in the hills, and Ionig t we’ll be riding t rough the city to the movies. ”Whether we’re touring or city ridv ing, the 750K and 550K make motorcy- clin something very s ecial.Can’t really exp ain it.Y0u have to eel it to under- stand. ! I917 minim“ wmmumrmo': Km. cmsox FRONTiLa ligm and [um signa mmnin Wide contoured bus lm (om on. r.- fullvlinlchcad- cassox ENGINE—Smooth, precision made, qukk-revving medium dis- lacemon! fourrcylinder engine and eed gear box. A dived dcsu‘mt a Grand I’rix world champion. C8750K TOURING SADDLEnBOdy contoured nwo-smgc saddle is designed for long haul comiorl. Twu-sugc mn- slmdion of soft and dense loam rom- bined. CBSSOK INSTRUMENTS~Easy-lo- read inslmmcmalion. Choke hzndlc is conveniently lacalcd next to speedome- lcr. Ccnler mounted ignition switch also locks forks. CB7SDK CDNTROLS—Moldt‘d neo- pmnc gri s {or comfnn, Double-table or smnnlhnoss and sah‘lyi Convonicnl olcrlvir slarlor blllHHL C5750K REAR—Wide 4.50H17A min lire on wide sine] rim {m wide lomprini on [he mad. Four reverse-rune mega- phone style seamless mumcn. SPECIFICATIONS 1978 CB-750K Engine: Type ......... r... 4-stroke, 4-cylinder OHC Displacement . . . ............... 736cc Bore and Stroke . a 61mm x 63mm Compression Ratio . ........... 9.2:] Transmission Cear Ratios: ‘lst .......... 2.50011 4th ............ l‘l33:l 2nd .. .i 1108:] 5th ............ 0969:] 3rd“. .i l.333:l Clutch ........ .. Manual (wet, mulIi-platel Oil Capacity , H .................... 37 qt. Carburetion iiiiiiiiii ... Four 28mm Keihins Ignition System ...... Starting System .. Exhaust System . iiiii Battery ignition ...... Electric and kick starter ........ Four mufflers Dimensions and Capacitie. Wheelbase .......................... 58.9 in, Seat Height .......................... 3L9 in. Overall Length ...................... 898 in. Ground Clearance .................... 5.9 in, Overall Width .......... .3411 in. Dry Weight .................. . . 508 lb. Tire Size iiiiii Front, 3.50Hl9. Rear, 4.50H17A Fuel Ca pacity r Colors .......... .i 5.1 gal. (1.1 gal. reserve) iiiiiiiiiii Black and Red 1978 CB-SSOK Engine: Type iiiiii . r 4-stroke, 4-cylinder OHC Displacement . . . .............. 544cc Bore and Stroke. ... .i 58‘5mm x 50.6mm Compression Ratio ..................... 9.0:] Transmission Gear Ratios: lst .......... 2.353:1 4th .. 1.0362] 2nd ......... 1.636;] 5th.. ...0.900:1 3rd ,,,,,,,,,, 1.269;] Clutch ............... Manual (wet, nIulti-platel Oil Capacity ............................ 3.4 qt. Carburetion ,,,,,,, ..r Four 22mm Keihins Ignition System ... Starling System . . . Exhaust System .. . ..... Battery ignition ”a Electric and kick starter ........ Four mufflers Dimensions and Capacitie, Wheelbase Him Scatlleighti....................r.r..31.5inr Overall Length ...................... 84.6 in. Ground Clearance .r 6.3 in. Overall Width .. . 32.5 in Dry Weight . . 427 lb. Tire Size ... Front, 3.25519, Rear, 3.75518 Fuel Capacity ........ 4.2 gal. (1.1 gal. reserve] Colors ........................ Black and Red coma mono! Honda believes m saloly msi Always wear a helm: and eye prolecllon when "ding Honda Is constantly striving lo improve as products. and reserves the right to change specilxcallons without notice. Prlnted m u s A