Yamaha SR125 Service Manual

4-20CYLINDER AND PISTONENGOrder Job name/Part name Q’ty Remarks123456789Cylinder and piston removalCylinder headTiming chain guide (exhaust side)Cylin

4-21CYLINDER AND PISTONENGNOTE:NOTE:***************************************NOTE:YP******PISTON AND PISTON RINGS REMOVAL1. Remove: Piston pin circlip

4-22CYLINDER AND PISTONENG***************************************Cylinder bore “C” 57.00 57.02 mmTaper limit “T” 0.05mmOut of round “R” 0.01mm“C” = M

4-23CYLINDER AND PISTONENGNOTE:NOTE:NOTE:EB402110PISTON RING INSPECTION1. Measure: Side clearanceOut of specification  Replace the pistonand the pis

4-24CYLINDER AND PISTONENG***************************************ba***************************************NOTE:EB402120PISTON PIN INSPECTION1. Inspect

4-25CYLINDER AND PISTONENGNewNOTE:NewNOTE:Engine oilNewNOTE:2. Install: Piston 1 Piston pin 2 Piston pin clip 3  Apply engine oil onto the piston

4-26CLUTCHENGOrder Job name/Part name Q’ty Remarks123456Crankcase cover (right) removalDrain the engine oilNutFoot rest (right)Clutch cableCrankcase c

4-27CLUTCHENGOrder Job name/Part name Q’ty Remarks123456789101141431/1111111/1Remove the parts in order.Refer to “ENGINE REMOVAL” section.Refer to “CL

4-28CLUTCHENGOrder Job name/Part name Q’ty Remarks12131415161718Push lever axleTorsion springCirclipOil sealNut/WasherPush rod #1/O-ringPush plate1111

4-29CLUTCHENGNOTE:SR401061CLUTCH REMOVAL1. Remove: Nut 1 (clutch boss) Lock washer 2 Clutch boss 3Straighten the lock washer tab 2.Loosen the clutc

1-1MOTORCYCLE IDENTIFICATIONGENINFONOTE:YP100000GENERAL INFORMATIONMOTORCYCLE IDENTIFICATIONSR100020FRAME SERIAL NUMBERThe frame serial number 1 is st

4-30CLUTCHENGNOTE:New12 Nm (1.2 mkg)NOTE:6. Measure: Free length (clutch spring) aOut of specification  Replace the clutchsprings as a set.Free len

4-31CLUTCHENGNew70 Nm (7.0 mkg)NOTE:NOTE:New6 Nm (0.6 mkg)NOTE:3. Install:Lock washer 1  Nut 2 (clutch boss)Install the clutch boss nut 2 while ho

4-32CLUTCHENG***************************************CAUTION:***************************************8 Nm (0.8 mkg)9. Check: Push lever positionPush t

4-33OIL PUMPENGOrder Job name/Part name Q’ty Remarks123456Oil pump removalClutchNutLock washerPrimary drive gearOil pump coverOil pump assemblyGasket

4-34OIL PUMPENGOrder Job name/Part name Q’ty RemarksOil pump disassemblyOil pump housingDowel pinOil pump driven gearDowel pinsInner rotorOuter rotorH

4-35OIL PUMPENGNOTE:NOTE:SR401070PRIMARY DRIVE GEAR REMOVALStraighten the lock washer tab.1. Remove: Nut (primary drive gear) 1 Lock washer 2 Prima

4-36OIL PUMPENGNew50 Nm (5.0 mkg)NOTE:SR404010OIL PUMP INSTALLATION1. Lubricate: Oil delivery passage (crankcase right) Oil pump assemblyRecommende

4-37BALANCER GEARENGOrder Job name/Part name Q’ty Remarks12345678910Balancer gear removalClutchPrimary drive gearNut/Lock washerBalancer driven gearWo

4-38BALANCER GEARENGNOTE:NOTE:NOTE:NOTE:SR******BALANCER DRIVEN GEAR REMOVALStraighten the lock washer tab.1. Remove: Nut (balancer driven gear) 1 L

4-39BALANCER GEARENGNOTE:New50 Nm (5.0 mkg)NOTE:SR******BALANCER GEAR INSTALLATION1. Install: Balancer driven gear 1Install the balancer driven gear

1-2IMPORTANT INFORMATIONGENINFOEB101000IMPORTANT INFORMATIONPREPARATION FOR REMOVAL PROCE-DURES1. Remove all dirt, mud, dust and foreign mate-rial bef

4-40SHIFT SHAFT AND SEGMENTENGOrder Job name/Part name Q’ty Remarks123456789Shift shaft and segment removalClutchShift pedalShift shaftPlate washerTor

4-41SHIFT SHAFT AND SEGMENTENGOrder Job name/Part name Q’ty Remarks10111213ScrewSegmentDowel pins (short length)Dowel pins (long length)1141Reverse th

4-42SHIFT SHAFT AND SEGMENTENGNOTE:NOTE:SR******SHIFT SHAFT REMOVAL1. Remove: Shift shaft assembly 1Push the shift lever arm 2 and the stopper lever3

4-43SHIFT SHAFT AND SEGMENTENGNOTE:12 Nm (1.2 mkg)******************************************************************************2. Install: Segment

4-44CDI MAGNETO AND STARTER CLUTCHENGOrder Job name/Part name Q’ty Remarks1234Crankcase cover (left) removalDrain the engine oilSide coverDrive sprock

4-45CDI MAGNETO AND STARTER CLUTCHENGOrder Job name/Part name Q’ty Remarks1234Pickup coil and stator coil removalClamp (stator coil)Clamp (pickup coil

4-46CDI MAGNETO AND STARTER CLUTCHENGOrder Job name/Part name Q’ty Remarks1234567891011CDI magneto and starter clutch removalCDI magnetoIdle shaft/col

4-47CDI MAGNETO AND STARTER CLUTCHENGNOTE:NOTE:******************************************************************************YP401081C.D.I. MAGNETO RE

4-48CDI MAGNETO AND STARTER CLUTCHENG30 Nm (3.0 mkg)NOTE:3. Inspect: Starter wheel gear(contacting surface)Pitting/Wear/Damage  Replace.SR******STA

4-49CDI MAGNETO AND STARTER CLUTCHENG50 Nm (5.0 mkg)NOTE:3. Tighten: CDI magneto assembly 1Tighten the bolt while holding the CDI magnetoassembly wi

1-3ORIMPORTANT INFORMATIONGENINFOCAUTION:EB101030LOCK WASHERS/PLATES AND COTTERPINS1. Replace all lock washers/plates and cotterpins after removal. Be

4-50CRANKCASE AND CRANK SHAFTENGOrder Job name/Part name Q’ty Remarks1Crankcase separationEngineCylinder headCylinder and pistonClutchPrimary drive ge

4-51CRANKCASE AND CRANK SHAFTENGOrder Job name/Part name Q’ty Remarks234Timing chainCrankcaseDowel pins112Refer to “CRANKCASE SEPARATION/INSTALLATION”

4-52CRANKCASE AND CRANK SHAFTENGOrder Job name/Part name Q’ty Remarks1234567Crankshaft and balancer weight removalBalancer weightCrankshaft assemblyDo

4-53CRANKCASE AND CRANK SHAFTENGNOTE:NOTE:CAUTION:NOTE:SR401132CRANKCASE SEPARATION1. Remove: Crankcase screws The numbers embossed on the crankcase

4-54CRANKCASE AND CRANK SHAFTENGNOTE:T******CRANKSHAFT INSPECTION1. Measure: Crankshaft runoutOut of specification  Replace crankshaftand/or bearing

4-55CRANKCASE AND CRANK SHAFTENGCAUTION:NOTE:7 Nm (0.7 mkg)NOTE:SR******PLUNGER SEAL INSTALLATION1. Install: Compression spring 1 Plunger seal 2 D

4-56TRANSMISSION SIFT CAM AND SHIFT FORKENGOrder Job name/Part name Q’ty Remarks12345678910Transmission, shift cam and shift fork removalCrankcase sep

4-57TRANSMISSION SIFT CAM AND SHIFT FORKENGOrder Job name/Part name Q’ty RemarksDrive axle and main axle disassemblySecond wheel gearFirst wheel gearF

4-58TRANSMISSION SIFT CAM AND SHIFT FORKENGWARNINGSR******TRANSMISSION, SHIFT CAM AND SHIFTFORK REMOVAL1. Install: O-Ring 1To the drive sprocket groo

4-59TRANSMISSION SIFT CAM AND SHIFT FORKENGNOTE:NOTE:NOTE:4. Check: Shift fork movement(on the guide bar)Unsmooth operation  Replace the shiftfork a

1-4CHECKING OF CONNECTIONSGENINFONOTE:NOTE:EB801000CHECKING OF CONNECTIONSDealing with stains, rust, moisture, etc. on theconnector.1. Disconnect: Co

ENG

CHAPTER 5.CARBURETIONCARBURETOR 5-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CARBURETOR ASSEMBLY

5-1CARBURETORCARBOrder Job name/Part name Q’ty Remarks1234Carburetor removalSide coverSeatFuel tankHeater unit leadCarburetor joint clamp screwAir fil

5-2CARBURETORCARBOrder Job name/Part name Q’ty RemarksCarburetor disassemblyThrottle cableThrottle valve assemblyThrottle valve springMixing chamber t

5-3CARBURETORCARBOrder Job name/Part name Q’ty RemarksPilot screw assemblyPilot jetThrottle stop screw assemblyStarter plunger assemblyScrew/gasketHea

5-4CARBURETORCARBCAUTION:NewSR******CARBURETOR ASSEMBLY Do not use a wire for cleaning. Before assembling, wash all parts in cleanpetroleum based so

5-5CARBURETORCARB******************************************************************************YP600060FUEL LEVEL ADJUSTMENT1. Measure: Fuel level aO

CARB

CHAPTER 6.CHASSISFRONT WHEEL AND BRAKE DISC 6-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . FRONT WHEEL DISASSEMBLY 6-3. . . . . . . . .

1-5HOW TO USE THE CONVERSION TABLEGENINFOEB201000HOW TO USE THE CONVERSION TABLEAll specification data in this manual are listed in Sl and METRIC UNIT

STEERING INSTALLATION 6-42. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . REAR SHOCK ABSORBER AND SWINGARM 6-43. . . . . . . . . .

6-1FRONT WHEEL AND BRAKE DISCCHASOrder Job name/Part name Q’ty Remarks1234567Front wheel and brake disc removalSpeedometer cableAxle pinch boltWheel a

6-2FRONT WHEEL AND BRAKE DISCCHASFront wheel disassemblyOil sealBearingSpacerSpacer flangeBearingOrder Job name/Part name Q’ty Remarks11111Disassemble

6-3FRONT WHEEL AND BRAKE DISCCHASCAUTION:WARNINGNOTE:NOTE:T******FRONT WHEEL DISASSEMBLY1. Remove: Bearings 1 SpacerRemove the bearings using a gene

6-4FRONT WHEEL AND BRAKE DISCCHASNOTE:5. Measure: Front wheel runoutOver the specified limits  Replace.Front wheel runout limits:Radial 1: 2.0 mmLat

6-5FRONT WHEEL AND BRAKE DISCCHASCAUTION:23 Nm (2.3 mkg)NOTE:NOTE:NOTE:Do not strike the inner race of balls of thebearing. Contact should be made on

6-6FRONT WHEEL AND BRAKE DISCCHAS59 Nm (5.9 m:kg)20 Nm (2.0 m:kg)CAUTION:WARNINGNOTE:*****************************************************************

6-7FRONT WHEEL AND BRAKE DISCCHAS***************************************NOTE:*************************************************************************

6-8FRONT BRAKECHASOrder Job name/Part name Q’ty Remarks123Brake pad removalBolt (caliper support bolt)Brake padsPad support121Remove the parts in orde

6-9FRONT BRAKECHASNOTE:NOTE:CAUTION:23 Nm (2.3 mkg)SR702010BRAKE PAD REPLACEMENTIt is not necessary to disassemble the brake cal-iper and brake hose

1-6SPECIAL TOOLSGENINFOEB102000SPECIAL TOOLSThe following special tools are necessary for complete and accurate tune-up and assembly. Use onlythe appr

6-10FRONT BRAKECHASOrder Job name/Part name Q’ty Remarks12345678Master cylinder removalDrain the brake fluidRear view mirror (right)Brake lever/compre

6-11FRONT BRAKECHASMaster cylinder disassemblyRubber bootsCirclipMaster cylinder kitSpringOrder Job name/Part name Q’ty Remarks111Disassemble the part

6-12FRONT BRAKECHASWARNINGYP702040MASTER CYLINDER INSPECTION1. Inspect: Master cylinder piston 1Wear/scratches  Replace the master cyl-inder kit. M

6-13FRONT BRAKECHASANew9 Nm (0.9 mkg)CAUTION:NewNew30 Nm (3.0 mkg)NOTE:CAUTION:2. Install: Circlip 1 Install the circlip securely into the master c

6-14FRONT BRAKECHASWARNING Use only designated quality brake fluid:Otherwise, the rubber seals may deterio-rate, causing leakage and poor brake per-f

6-15FRONT BRAKECHASOrder Job name/Part name Q’ty Remarks123456Caliper removalDrain teh brake fluidBrake hose holderUnion boltPlain washerBrake hoseCal

6-16FRONT BRAKECHASOrder Job name/Part name Q’ty RemarksCaliper disassemblyBrake padCaliper pistonDust sealPiston sealBleed screw/Cap2221Disassemble t

6-17FRONT BRAKECHASNOTE:***************************************WARNING***************************************WARNINGSR******BRAKE CALIPER DISASSEMBLYB

6-18FRONT BRAKECHASNewNewWARNING40 Nm (4.0 mkg)23 Nm (2.3 mkg)New30 Nm (3.0 mkg)CAUTION:CAUTION:1. Install: Piston seals 1  Dust seal 2 Always us

6-19FRONT BRAKECHASWARNING Use only the designated quality brakefluid: other brake fluids may deteriorate therubber seals, causing leakage and poorbr

1-7SPECIAL TOOLSGENINFOTool No. Tool name/Usage Illustration90890-03079 Thickness gaugeThis tool is used to measure the valveclearance.90890-030819089

6-20REAR WHEEL, REAR BRAKE AND DRIVE CHAINCHASOrder Job name/Part name Q’ty Remarks1234567891011Rear wheel and rear brake removalAdjusterBrake rodPinC

6-21REAR WHEEL REAR BRAKE AND DRIVE CHAINCHASOrder Job name/Part name Q’ty Remarks12131415161718Rear wheel assemblyCollarShoe plateNut (driven sprocke

6-22REAR WHEEL, REAR BRAKE AND DRIVE CHAINCHASOrder Job name/Part name Q’ty RemarksRear wheel disassemblyBearingCollarSpacerOil sealBearing11111Disass

6-23REAR WHEEL, REAR BRAKE AND DRIVE CHAINCHASOrder Job name/Part name Q’ty RemarksBrake shoe plate disassemblyBrake shoe kitTension springsCam leverI

6-24REAR WHEEL, REAR BRAKE AND DRIVE CHAINCHASOrder Job name/Part name Q’ty Remarks123456789Drive chain removalChain caseAxle nutShift pedalSprocket c

6-25REAR WHEEL, REAR BRAKE AND DRIVE CHAINCHASWARNINGT******REAR WHEEL DISASSEMBLY1. Remove: Bearings 1 Spacer 2 Collar 3Refer to “FRONT WHEEL”.SR7

6-26REAR WHEEL, REAR BRAKE AND DRIVE CHAINCHASNOTE:5. Inspect: Cam shaft faceT701020DRIVE CHAIN INSPECTION1. Inspect: Drive chain stiffnessStiffness

6-27REAR WHEEL, REAR BRAKE AND DRIVE CHAINCHAS******************************************************************************9 Nm (0.9 mkg)NOTE:NewNOT

6-28REAR WHEEL, REAR BRAKE AND DRIVE CHAINCHASNOTE:CAUTION:New40 Nm (4.0 mkg)NewCAUTION:SR******REAR WHEEL ASSEMBLY1. Install: Bearing 1 Spacer 2

6-29FRONT FORKCHASOrder Job name/Part name Q’ty Remarks12345678Front fork removalFront wheelBrake hose holderCaliperFront fenderCoverBolt/washerBolt (

1-8SPECIAL TOOLSGENINFOTool No. Tool name/Usage Illustration90890-04101 Valve lapperThis tool is used for removing and installingthe lifter and for la

6-30FRONT FORKCHAS10Order Job name/Part name Q’ty RemarksFront fork disassemblyCap bolt/O-ringCollar/washerFork springDust coverRetaining clipWasher (

6-31FRONT FORKCHASCAUTION:***************************************CAUTION:***************************************WARNINGSR******FRONT FORK DISASSEMBLY1

6-32FRONT FORKCHASCAUTION:NOTE:NOTE:2. Measure: Fork spring aFront fork spring free length:326.1 mm<Wear limit>321 mmOver the specified limit 

6-33FRONT FORKCHASNewNewNOTE:CAUTION:NewNOTE:2. Install: Piston metal 1  Oil seal 2 Use the fork seal driver weight 3 and the at-tachment 4.Before i

6-34FRONT FORKCHASNOTE:NOTE:New65 Nm (6.5 mkg)NOTE:48 Nm (4.8 mkg)30 Nm (3.0 mkg)7. Measure: Oil level aOut of specification  Adjust.Oil level:16

6-35HANDLEBARCHASOrder Job name/Part name Q’ty Remarks12345678910Handlebar removalHeadlight assemblyHandlebar switch lead (left and right),front brake

6-36HANDLEBARCHASOrder Job name/Part name Q’ty Remarks1112131415Handlebar switch (left)Grip (left)Lever holder (left)Upper holderHandlebar11121Refer t

6-37HANDLEBARCHAS******************************************************************************WARNING20 Nm (2.0 mkg)NOTE:NOTE:WARNINGYP******HANDLEB

6-38HANDLEBARCHAS9 Nm (0.9 mkg)NOTE:3. Install: Master cylinder 1 Master cylinder bracket 2Install the master cylinder bracket with the “UP”mark fa

6-39STEERINGCHASOrder Job name/Part name Q’ty Remarks123456789Under bracket removalFront forkHandlebarFlasher light assembly (left)Flasher light assem

CHAPTER 2.SPECIFICATIONSGENERAL SPECIFICATIONS 2-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . MAINTENANCE SPECIFICATIONS 2-4

6-40STEERINGCHASOrder Job name/Part name Q’ty Remarks1011121314Ball race (upper)BallBallBall race (center)Ball race (lower)1221911Reverse the removal

6-41STEERINGCHASWARNINGWARNING******************************************************************************NOTE:CAUTION:YP704010STEERING REMOVAL Sec

6-42STEERINGCHAS7 Nm (0.7 mkg)EB704030STEERING INSTALLATIONReverse the “REMOVAL” procedure.Note the following points.1. Lubricate: Bearings (upper a

6-43REAR SHOCK ABSORBER AND SWINGARMCHASOrder Job name/Part name Q’ty Remarks123456789Rear shock absorber and swingarmremovalRear wheelChain caseDrive

6-44REAR SHOCK ABSORBER AND SWINGARMCHAST*****SWINGARM INSPECTION1. Inspect: Swingarm side playFree play exists  Check side clearance. Swingarm up

CHAPTER 7.ELECTRICALELECTRICAL COMPONENTS 7-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SWITCH INSPECTION 7-2. . . . . . . .

7-1ELECTRICAL COMPONENTSELEC15 C.D.I. unit8 Neutral relay9 Thermo switch10 Sidestand switch11 Rear brake switch12 Neutral switch13 Spark plug cap14 Ig

7-2SWITCH INSPECTIONELECNOTE:YP-NSWITCH INSPECTIONINSPECTION STEPSUsing pocket tester, check switches for continu-ity between their terminals to deter

7-31 Clutch switch2 Turn switch3 Dimmer switch4 Horn switch5 Main switch6 Front brake switch7 Engine stop switch8 Start switch9 Rear brake switch10 Ne

7-41 C.D.I. magneto6 Main switch10 Engine stop switch12 C.D.I. unit13 Ignition coil14 Spark plug15 Sidestand switchIGNITION SYSTEMELECEB802000IGNITION

7-5IGNITION SYSTEMELECNOTE:1. Spark plug Check the spark plug condition. Check the spark plug type. Check the spark plug gap.Refer to “SPARK PLUG

7-6IGNITION SYSTEMELECS Remove the spark plug cap.S Connect the pocket tester (Ω  1k) to thespark plug cap.S When removing the spark plug cap, do not

7-7IGNITION SYSTEMELECTester (+) lead Spark plug lead Tester (–) lead Orange TerminalS Disconnect the ignition coil connector fromthe wireharness.S

7-8Tester (+) lead White Terminal Tester (–) lead Red TerminalTester (+) lead Brown Terminal Tester (–) lead Green TerminalS Disconnect the pickup

7-9IGNITION SYSTEMELECRefer to “SWITCH INSPECTION” section.8. Engine stop switch:Replace the handlebar switch (right).NO CONTINUITYCONTINUITYRefer to

7-103 Starter relay4 Battery5 Fuse6 Main switch10 Engine stop switch11 Start switch15 Clutch switch16 Sidestand switch17 Neutral relay24 Neutral switc

7-11ELECTRICAL STARTING SYSTEMELECSR******STARTING CIRCUIT OPERATIONThe starting circuit on this model consists of thestarter motor, starter relay, an

7-12ELECTRICAL STARTING SYSTEMELECNOTE:1. FuseRefer to “SWITCH INSPECTION” section.CONTINUITYNO CONTINUITYReplace the fuse.2. Battery Check the batt

7-13ELECTRICAL STARTING SYSTEMELECS Connect the battery positive terminal and starter motor cable using a jumperlead *.S Check the starter motor ope

2-1GENERAL SPECIFICATIONSSPECSPECIFICATIONSGENERAL SPECIFICATIONSModel SR125Model code: 3MW6Dimensions:Overall lengthOverall widthOverall heightSeat h

7-14ELECTRICAL STARTING SYSTEMELEC:1:2345. Neutral relayS Remove the relay from the frame.S Connect the pocket tester (Ω  100) to theBattery and the

7-15ELECTRICAL STARTING SYSTEMELEC:10.Clutch switchRefer to “SWITCH INSPECTION” section.CONTINUITYNO CONTINUITYReplace the clutch switch.11.Start swit

7-16Order Job name/Part name Q’ty Remarks123Starter motor removalDrain the engine oilCrankcase cover (right)Starter motor leadStarter motorO-ring111Re

7-17ELECTRICAL STARTING SYSTEMELECNOTE:ABYP803034Inspection and repair1. Inspect: CommutatorDirt  Clean it with #600 grit sandpaper.2. Measure: Com

7-18ELECTRICAL STARTING SYSTEMELECNOTE:New3 Nm (0.3 mkg)NOTE:6. Measure: Brush spring forceFatigue/out of specification  Replace as aset.Brush spri

7-191 C.D.I. magneto2 Rectifier/Regulator4 Battery5 FuseCHARGING SYSTEMELECYP804000CHARGING SYSTEMCIRCUIT DIAGRAM

7-20CHARGING SYSTEMELECNOTE:1. FuseRefer to “SWITCH INSPECTION” section.CONTINUITYNO CONTINUITYReplace the fuse.2. Battery Check the battery conditi

7-21CHARGING SYSTEMELECTester (+) lead Battery (+) terminal Tester (–) lead Battery (–) terminal:12:3. Charging voltageS Connect the engine tachomet

7-225. Wiring connectionCheck the entire charging system for connec-tions.Refer to “CIRCUIT DIAGRAM” section.CORRECTReplace the rectifier/regulator.P

7-234 Battery5 Fuse6 Main switch22 High beam indicator light23 Meter light26 Tail/Brake light30 Auxiliary light34 Lights switch36 Dimmer switch39 Head

2-2GENERAL SPECIFICATIONSSPECModel SR125Carburetor:Type/quantityManufacturerY24P/1TEIKEISpark plug:TypeManufacturerSpark plug gapDR8EANGK0.6 X 0.7 mmC

7-24LIGHTING SYSTEMELECNOTE:1. FuseRefer to “SWITCH INSPECTION” section.CONTINUITYNO CONTINUITYReplace the fuse.2. Battery Check the battery conditi

7-25Headlight:Tester (+) lead  Green or Yellow leadTester negative (–) lead  Black leadHigh beam indicator light:Tester (+) lead  Yellow le

7-26LIGHTING SYSTEMELECTester (+) lead Blue terminal Tester (–) lead Black terminal:S Turn the main switch to on position.S Turn the lights switch t

7-27Tester (+) lead Blue/Red terminal Tester (–) lead Black terminal2Tester (+) lead Blue terminal Tester (–) lead Black terminal1211. Bulb and bu

7-284 Battery5 Fuse6 Main switch7 Thermo switch8 Heater unit19 Neutral indicator light20 Turn indicator light (left)21 Turn indicator light (right)24

7-29SIGNAL SYSTEMELECNOTE::1. FuseRefer to “SWITCH INSPECTION” section.CONTINUITYNO CONTINUITYReplace the fuse.2. BatteryS Check the battery condition

7-30SIGNAL SYSTEMELEC:4. WireharnessS Check the connections of the entire signalsystem.Refer to “CIRCUIT SYSTEM WIRING DIA-GRAM” section.CORRECTCheck

7-31Tester (+) lead  Pink terminalTester (–) lead  Frame groundTester (+) lead  Brown terminal Tester (–) lead  Frame ground111. Horn switchRefe

7-32Tester (+) lead  Yellow terminal Tester (–) lead  Black terminal121. Bulb and bulb socketRefer to “SWITCH INSPECTION” section.CONTINUITY2. Brake

7-33Tester (+) lead  Brown/White terminal Tester (–) lead  Frame groundTester (+) lead  Brown terminal Tester (–) lead  Frame ground11:1. Bulb and

2-3GENERAL SPECIFICATIONSSPECModel SR125Brake:Front brake typeoperationRear brake typeoperationSingle disc brakeRight hand operationDrum brakeRight

7-34At flasher light (right)Tester (+) lead  Dark green lead Tester (–) lead  Black terminalAt flasher light (left)Tester (+) lead  Chocolate lead

7-35Tester (+) lead  Black terminal Tester (–) lead  Black terminal:1212:COOL DOWNHEAT UPAB3. VoltageS Connect the pocket tester (DC20V) to thefuel

7-36SIGNAL SYSTEMELECTester (+) lead  Terminal Tester (–) lead  Terminal:122. Heater unit resistanceS Remove the heater unit from the carburetor.S C

CHAPTER 8.TROUBLE SHOOTINGSTARTING FAILURE/HARD STARING 8-1. . . . . . . . . . . . . . . . . . . . . . . . . . . POOR IDLE SPEED PERFORMANCE 8-2. . .

8-1STARTING FAILURE/HARD STARTINGTRBLSHTGNOTE:EB90000TROUBLESHOOTINGThe following troubleshooting does not cover all the possible causes of trouble. I

8-2POOR IDLE SPEED PERFORMANCETRBLSHTGIGNITION SYSTEMBattery Improperly charged battery Faulty batteryFuse Burnt out, improper connectionSpark plug

8-3POOR MEDIUM AND HIGH SPEED PERFORMANCETRBLSHTGEB902000POOR MEDIUM AND HIGH SPEED PERFORMANCEPOOR MEDIUM AND HIGH SPEED PERFORMANCERefer to “STARTIN

8-4FAULTY CLUTCH/FAULTY GEAR SHIFTINGTRBLSHTGEB904000CLUTCH SLIPPING/DRAGGINGCLUTCH SLIPPINGClutch Improperly adjusted clutch cable Loose clutch spr

8-5OVER HEATING/FAULTY BRAKETRBLSHTGSR905000OVER HEATING OR OVER-COOL-INGOVER HEATINGIgnition system Improper spark plug gap Improper spark plug hea

2-4MAINTENANCE SPECIFICATIONSSPECHead Dia. Face Width Seat Width Margin ThicknessMAINTENANCE SPECIFICATIONSENGINEItemStandard LimitCylinder head:Warp

8-6FRONT FORK MALFUNCTION/INSTABLE HANDLINGTRBLSHTGSR907000FRONT FORK MALFUNCTIONOIL LEAKAGE Bent, damaged or rusty inner tube Damaged or cracked ou

8-7STARTER MOTOR DOES NOT OPERATETRBLSHTGSR******STARTER MOTOR DOES NOT OPERATESTARTER MOTOR DOES NOT OPERATEBattery Insufficient battery capacity F

8-8FAULTY SIGNAL AND LIGHTING SYSTEMTRBLSHTGYP909000FAULTY SIGNAL AND LIGHTING SYSTEMHEADLIGHT DARK Improper bulb Too many electric accessories Har

COLOR CODEB Black. . . . . Br Brown. . . . Ch Chocolate. . . Dg Dark green. . . G Green. . . . L Blue. . . . . O Orange. . . . Sb Sky blue. . . . P Pi

2-5MAINTENANCE SPECIFICATIONSSPECItem Standard LimitGuide inside diameter INEXStem-to-guide clearance INEXStem runout limitValve seat width INEX6.000

2-6MAINTENANCE SPECIFICATIONSSPECItem Standard LimitCrankshaft:Crank width “A”Runout limit “C”Big end side clearance “D”Big end radial clearanceSmall

2-7MAINTENANCE SPECIFICATIONSSPECTIGHTENING TORQUESENGINETh dTighteningPart to be tightened Part nameThreadsizeQ’tyggtorqueRemarksgsizeyNmmSkgCylinder

2-8MAINTENANCE SPECIFICATIONSSPECPart to be tightened Part nameThreadsizeQ’tyTighteningtorqueRemarksgsizeyNm mSkgDrive sprocketShift cam (Segment)Shif

2-9MAINTENANCE SPECIFICATIONSSPECTightening sequenceCylinder headCrankcaseItem Standard Limit

EB000000SR125SERVICE MANUAL1996 by Yamaha Motor Co., Ltd.1st Edition, September 1996All rights reserved. Any reprinting orunauthorized use without th

2-10MAINTENANCE SPECIFICATIONSSPECCHASSISItemStandard LimitSteering system:Steering bearing typeNo./size of steel balls (upper)(lower)Ball bearing22

2-11MAINTENANCE SPECIFICATIONSSPECItem Standard LimitFront brake:TypeDisc outside diameterDisc thicknessPad thickness (inner)(outer)Master cylinder in

2-12MAINTENANCE SPECIFICATIONSSPECNOTE:TIGHTENING TORQUESCHASSISPart to be tightenedThread sizeTighteningtorqueRemarksgNmmSkgHandle crown and front fo

2-13MAINTENANCE SPECIFICATIONSSPECELECTRICALItemStandard LimitIgnition timing:Ignition timing (B.T.D.C.)Advanced timingAdvanced type9_ at 1,300 r/min2

2-14MAINTENANCE SPECIFICATIONSSPECItem Standard LimitStarter relay:Model/manufacturerAmperage ratingCoil winding resistanceMS5D-191/JIDECO100 A3.9 X 4

2-15GENERAL TORQUE SPECIFICATIONSSPECGENERAL TORQUE SPECIFICATIONSThis chart specifies torque for standard fasten-ers with standard I.S.O. pitch threa

2-16LUBRICATION POINT AND GRADE OF LUBRICANTSPECLUBRICATION POINT AND GRADE OF LUBRICANTENGINELubrication PointSymbolOil seal lips (all)Bearing retain

2-17LUBRICATION POINT AND GRADE OF LUBRICANTSPECCHASSISLubrication PointSymbolSteering head pipe bearing (upper/lower)Front wheel oil seal lips (left/

2-181 Rocker arm (IN)2 Rocker shaft3 Rocker arm (EX)4 Camshaft5 Oil pump6 Push leverLUBRICATION DIAGRAMSPECLUBRICATION DIAGRAM

2-191 Oil pump2 Oil filter3 Crankshaft4 Main axle5 Drive axle6 Oil strainerLUBRICATION DIAGRAMSPEC

NOTE:WARNINGCAUTION:EB001000NOTICEThis manual was produced by the Yamaha Motor Company primarily for use by Yamaha dealers andtheir qualified mechanic

2-20A Clamp the handlebar switchlead, (left and right), front brakeswitch lead, clutch switch lead tothe handlebar.B Do not contact the horn and wire-

2-21A Align the clamp to the white tapeon the wireharnessB Pass the clutch cable throughthe outside of the throttle cable.C Pass the brake hose and th

2-22A Clamp the speedometer cable tothe steering bracket and passthe cable to the cable holder.B Pass the brake hose through thebrake hose holder.14 R

2-23CABLE ROUTINGSPEC1 Air filter case2 Battery3 Swingarm4 Battery breather pipe5 Lid6 Air filter case drain pipeA Pass the air filter case drain pipe

SPEC

CHAPTER 3.PERIODIC INSPECTIONSAND ADJUSTMENTSINTRODUCTION 3-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3-1INTRODUCTION/PERIODIC MAINTENANCE/LUBRICATION INTERVALSINSPADJ1011121314151617EB300000PERIODIC INSPECTIONS AND ADJUSTMENTSINTRODUCTIONThis chapter

3-2PERIODIC MAINTENANCE/LUBRICATION INTERVALSINSPADJ18192021NOTE:EVERYNO. ITEM ROUTINEBRAKE-IN1,000 KM6,000 kmor6 months12,000 kmor12 monthsDrive chai

3-3Order Job name/Part name Q’ty Remarks12345Side cover, seat and fuel tankremovalSide cover (left)Side cover (right)SeatFuel pipeFuel tank11111Remove

12676438YP002000HOW TO USE THIS MANUALMANUAL ORGANIZATIONThis manual consists of chapters for the main categories of subjects. (See “Illustrated symbo

3-4VALVE CLEARANCE ADJUSTMENTINSPADJNOTE:******************************************************************************SR03004ENGINEVALVE CLEARANCE AD

3-5A BVALVE CLEARANCE ADJUSTMENT/IDLING SPEED ADJUSTMENTINSPADJ***************************************14 Nm (1.4 mkg)********************************

3-6IDLING SPEED ADJUSTMENT/THROTTLE CABLE ADJUSTMENTINSPADJ******************************************************************************NOTE:********

3-7THROTTLE CABLE ADJUSTMENT/SPARK PLUG INSPECTIONINSPADJWARNING***************************************CAUTION: Loosen the locknut 1 on the throttle

3-8SPARK PLUG INSPECTION/IGNITION TIMING CHECKINSPADJ18 Nm (1.8 mkg)NOTE:NOTE:***********************************************************************

3-9COMPRESSION PRESSURE MEASUREMENTINSPADJNOTE:CAUTION:SR303060COMPRESSION PRESSURE MEASUREMENTInsufficient compression pressure will result inperform

3-10COMPRESSION PRESSURE MEASUREMENT/ENGINE OIL LEVEL INSPECTIONINSPADJ***************************************WARNING18 Nm (1.8 mkg)NOTE:Compression

3-11ENGINE OIL LEVEL INSPECTION/ENGINE OIL REPLACEMENTINSPADJCAUTION:NOTE:****************************************************************************

3-12ENGINE OIL REPLACEMENTINSPADJ43 Nm (4.3 mSkg)NOTE:CAUTION:******************************************************************************6. Install

3-13TIMING CHAINE TENSIONER ADJUSTMENT/CLUTCH ADJUSTMENTINSPADJ******************************************************************************5 Nm (0.5

2113579248623 24222018 191715141311 1210GENINFOSPECENGCARBELECCHASINSPADJTRBLSHTG16EB003000ILLUSTRATED SYMBOLSIllustrated symbols 1 to 9 are designed

3-14CLUTCH ADJUSTMENT/AIR FILTER CLEANINGINSPADJ***************************************NOTE:***************************************CAUTION:2. Adjust:S

3-15AIR FILTER CLEANING/EXHAUST SYSTEM INSPECTIONINSPADJNOTE:CAUTION:WARNING2. Inspect:S Air filter element 1Damage  Replace.3. Clean:S Air filter el

3-16EXHAUST SYSTEM INSPECTIONINSPADJ122. Check:S Tightening torqueBolt :12 Nm (1.2 mSkg)Nut :20 Nm (2.0 mSkg)

3-17FRONT BRAKE ADJUST MENT/REAR BRAKE ADJUSTMENTINSPADJ***************************************CAUTION:WARNING***************************************E

3-18REAR BRAKE ADJUSTMENTINSPADJ*********************************************************************************************************************C

3-19BRAKE FLUID LEVEL INSPECTIONINSPADJNOTE:NOTE:CAUTION:WARNINGEB304020BRAKE FLUID LEVEL INSPECTION1. Stand the motorcycle on a level surface.S Make

3-20BRAKE PAD INSPECTION/BRAKE SHOE INSPECTION/BRAKE LIGHT SWITCH ADJUSTMENTINSPADJNOTE:**************************************************************

3-21AIR BLEEDINGINSPADJWARNING***************************************NOTE:EB304070AIR BLEEDING(HYDRAULIC BRAKE SYSTEM)Bleed the brake system whenever:

3-22AIR BLEEDING/DRIVE CHAIN SLACK ADJUSTMENTINSPADJNOTE:WARNING***************************************NOTE:CAUTION:WARNINGj. Tighten the bleed screw.

3-23A BDRIVE CHAIN SLACK ADJUSTMENTINSPADJ***************************************NOTE:***************************************CAUTION:1. Check:S Drive

GENERAL INFORMATIONSPECIFICATIONSPERIODIC INSPECTION ANDADJUSTMENTENGINE OVERHAULCARBURATIONCHASSISELECTRICALTROUBLESHOOTINGGENINFO1SPEC23ENG4CARB5CHA

3-24STEERING HEAD INSPECTIONINSPADJWARNINGNOTE:***************************************NOTE:***************************************SR304130STEERING HEA

3-25FRONT FORK INSPECTION/REAR SHOCK ABSORBER ADJUSTMENTINSPADJWARNINGWARNING***************************************abEB304140FRONT FORK INSPECTIONSec

3-26REAR SHOCK ABSORBER ADJUSTMENT/TIRE INSPECTIONINSPADJCAUTION:***************************************WARNINGAdjustment numbers:Standard 1Minimum 1M

3-27TIRE INSPECTIONINSPADJWARNINGWARNING2. Inspect: Tire surfacesWear/damage  Replace.Minimum tire tread depth(front and rear): 1.6 mm1Tread depth2S

3-28SPOKE INSPECTION AND TIGHTENING/WHEEL INSPECTIONINSPADJNOTE:NOTE:WARNINGEB304190SPOKE INSPECTION AND TIGHTENING1. Inspect:S Spokes 1Bending/damage

3-29BATTERY INSPECTIONINSPADJCAUTION:NOTE:CAUTION:EB305001ELECTRICALBATTERY INSPECTION1. Remove:S Side covers (left and right)Refer to “SIDE COVER, SE

3-30BATTERY INSPECTIONINSPADJ******************************************************************************CAUTION:WARNINGReplace the battery if:S Bat

3-31BATTERY INSPECTION/FUSE INSPECTIONINSPADJCAUTION:CAUTION:***************************************NOTE:***************************************7. Ins

3-32FUSE INSPECTION/HEADLIGHT BEAM ADJUSTMENTINSPADJ***************************************WARNING***************************************3. Replace:S

CHAPTER 4.ENGINE OVERHAULENGINE REMOVAL 4-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . EXHAUST PIPE, START

BALANCER GEAR 4-37. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . BALANCER DRIVEN GEAR REMOVAL 4-38. . . . . .

4-1Order Job name/Part name Q’ty Remarks1234567Exhaust pipe, starting motor andwire read removalSide cover, seat and fuel tankRear foot rest (right)Ex

4-2ENGINE REMOVALENGOrder Job name/Part name Q’ty Remarks1234567Carburetor, clutch cable and drivechain removalCarburetorClutch cableCrankcase breathe

4-3ENGINE REMOVALENGOrder Job name/Part name Q’ty Remarks12345Engine removalEngine stay (top)Front engine stayEngine mount bolt (rear upper)Engine mou

4-4CYLINDER HEADENGOrder Job name/Part name Q’ty Remarks1234567Cam sprocket cover removalSide cover, seat and fuel tankExhaust pipe assemblyCarburetor

4-5CYLINDER HEADENGOrder Job name/Part name Q’ty Remarks12345678Cylinder head removalTiming chain tensioner cap/O-ringTiming chain tensioner assemblyC

4-6CYLINDER HEADENGNOTE:NOTE:T401030CYLINDER HEAD REMOVAL1. Align: Slit a on the magneto(with stationary pointer b on the crank casecover)Turn the cr

4-7CYLINDER HEADENGNOTE:NOTE:***************************************NOTE:***************************************5. Remove: Cylinder head Loosen the

4-8CYLINDER HEADENGNewNew22 Nm (2.2 mkg)M8 (1  4)20 Nm (2.2 mkg)M8 (5  6NOTE:***************************************NOTE:CAUTION:*****************

4-9CYLINDER HEADENG60 Nm (6.0 mkg)NOTE:4. Install: Plate washer Bolt (timing chain) Timing chain tensioner assembly5. Tighten: Bolt (timing chain

CHAPTER 1.GENERAL INFORMATIONMOTORCYCLE IDENTIFICATION 1-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . FRAME SERIAL NUMBER 1-1. . . .

4-10CAM SHAFT AND ROCKER ARMSENGOrder Job name/Part name Q’ty Remarks123456789Cam shaft and rocker arm removalCylinder headLock washerPlateCollarCam s

4-11CAM SHAFT AND ROCKER ARMSENGNOTE:NOTE:SR******ROCKER ARM AND ROCKER ARM SHAFTREMOVAL1. Remove: Camshaft 1 Collar (camshaft) 2Use 10 mm bolt 3 to

4-12CAM SHAFT AND ROCKER ARMSENG******************************************************************************YP402060ROCKER ARMS AND ROCKER ARMSHAFTS

4-13ENGCAM SHAFT AND ROCKER ARMSNOTE:CAUTION:NOTE:New8 Nm (0.8 mkg)NOTE:2. Apply: Molybdenum disulfide oil(onto the rocker arm and rocker arm shaft)

4-14Order Job name/Part name Q’ty Remarks12345678Valves and valve springs removalCylinder headRocker arm, CamshaftValve cottersSpring retainerValve sp

4-15VALVES AND VALVE SPRINGSENGNOTE:CAUTION:ab***************************************NOTE:YP401150VALVES AND VALVE SPRINGS REMOVAL1. Remove: Valve co

4-16VALVES AND VALVE SPRINGSENGNOTE:***************************************NOTE: Install the new valve guide using a valve guideinstaller 2 and valve

4-17VALVES AND VALVE SPRINGSENG*********************************************************************************************************************NO

4-18VALVES AND VALVE SPRINGSENGNOTE:NOTE:*************************************** Apply molybdenum disulfide oil to the valvestem. Install the valve

4-19VALVES AND VALVE SPRINGSENGMolybdenum disulfide oilNewNOTE:NOTE:CAUTION:2. Apply: Molybdenum disulfide oil(onto the valve stem 3 and oil seal 2)3