FOREWORD

This Supplementary Service Manual has been prepared to introduce new service and data for theTW125 2003. For complete service information procedures it is necessary to use this SupplementaryService Manual together with the following manual.

TW125 SERVICE MANUAL: 5EK1-AE1TW125 SUPPLEMENTARY SERVICE MANUAL : 5EK1-AE2

TW125 2003SUPPLEMENTARYSERVICE MANUAL

2002 by Yamaha Motor Co., Ltd.First Edition, October 2002

Any reproduction or unauthorized usewithout the written permission of

Yamaha Motor Co., Ltd. is expresslyprohibited.

NOTE:

WARNING

CAUTION:

EB001000

NOTICEThis manual was produced by the Yamaha Motor Company primarily for use by Yamaha dealers andtheir qualified mechanics. It is not possible to include all the knowledge of a mechanic in one manual,so it is assumed that anyone who uses this book to perform maintenance and repairs on Yamahamotorcycle has a basic understanding of the mechanical ideas and the procedures of motorcyclerepair. Repairs attempted by anyone without this knowledge are likely to render the motorcycle unsafeand unfit for use.

Yamaha Motor Company, Ltd. is continually striving to improve all its models. Modifications andsignificant changes in specifications or procedures will be forwarded to all authorized Yamaha dealersand will appear in future editions of this manual where applicable.

Designs and specifications are subject to change without notice.

EAS00004

IMPORTANT INFORMATIONParticularly important information is distinguished in this manual by the following notations.

The Safety Alert Symbol means ATTENTION! BECOME ALERT! YOURSAFETY IS INVOLVED!

Failure to follow WARNING instructions could result in severe injury or death tothe motorcycle operator, a bystander or a person inspecting or repairing themotorcycle.

A CAUTION indicates special precautions that must be taken to avoid damageto the motorcycle.

NOTE: A NOTE provides key information to make procedures easier or clearer.

12

5

7

6

4 3

8

EAS00007

HOW TO USE THIS MANUALThis manual is intended as a handy, easy-to-read reference book for the mechanic. Comprehensiveexplanations of all installation, removal, disassembly, assembly, repair and inspection procedures arelaid out with the individual steps in sequential order.

1 The manual is divided into chapters. An abbreviation and symbol in the upper right corner of eachpage indicate the current chapter. Refer to “SYMBOLS” on the following page.

2 Each chapter is divided into sections. The current section title is shown at the top of each page,except in Chapter 3 (“Periodic Inspections and Adjustments”), where the sub-section title(-s) appear.

(In Chapter 3, “Periodic Inspections and Adjustments”, the sub-section title appears at the top of eachpage, instead of the section title.)

3 Sub-section titles appear in smaller print than the section title.

4 To help identify parts and clarify procedure steps, there are exploded diagrams at the start of eachremoval and disassembly section.

5 Numbers are given in the order of the jobs in the exploded diagram. A circled number indicates adisassembly step.

6 Symbols indicate parts to be lubricated or replaced (see “SYMBOLS”).

7 A job instruction chart accompanies the exploded diagram, providing the order of jobs, names ofparts, notes in jobs, etc.

8 Jobs requiring more information (such as special tools and technical data) are described sequen-tially.

21

1

3

5

7

9

2

4

8

6

23 24

2220

18 1917

15

1413

11 12

10

GENINFO SPEC

ENG

CARB

ELEC

CHAS

CHKADJ

TRBLSHTG

16

EAS00009

SYMBOLSThe following symbols are not relevant to everyvehicle.Symbols 1 to 8 indicate the subject of eachchapter.1 General information2 Specifications3 Periodic checks and adjustments4 Engine5 Carburetor(-s)6 Chassis7 Electrical system8 Troubleshooting

Symbols 9 to 16 indicate the following.9 Serviceable with engine mounted10 Filling fluid11 Lubricant12 Special tool13 Tightening torque14 Wear limit, clearance15 Engine speed16 Electrical data

Symbols 17 to 22 in the exploded diagrams indi-cate the types of lubricants and lubricationpoints.17 Engine oil18 Gear oil19 Molybdenum disulfide oil20 Wheel bearing grease21 Lithium soap base grease22 Molybdenum disulfide grease

Symbols 23 to 24 in the exploded diagrams indi-cate the following:23 Apply locking agent (LOCTITE)24 Replace the part

CONTENTS

SPECIFICATIONSGENERAL SPECIFICATIONS 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CHASSIS SPECIFICATIONS 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ELECTRICAL SPECIFICATIONS 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CABLE ROUTING 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ELECTRICALCHECKING THE SWITCHES 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LIGHTING SYSTEM 14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

CIRCUIT DIAGRAM 14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . TROUBLESHOOTING 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

TROUBLESHOOTINGFAULTY LIGHTING SYSTEM 17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

HEADLIGHT DOES NOT COME ON 17. . . . . . . . . . . . . . . . . . . . . . . . . . HEADLIGHT BULB BURNT OUT 17. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

TW125 2003 WIRING DIAGRAM

–1–

GENERAL SPECIFICATIONS/CHASSIS SPECIFICATIONS SPEC

SPECIFICATIONS

GENERAL SPECIFICATIONS

Item Standard Limit

Model code 5RS3, 5RS4

CHASSIS SPECIFICATIONS

Item Standard Limit

FrameFrame typeCaster angleTrail

Diamond2583’93 mm

Tire pressure (cold tire)Maximum load-except motorcycleLoading condition A*

frontrear

Loading condition B*frontrear

Off road ridingfrontrear

High speed ridingfrontrear

180 kg0 90 kg150 kPa (1.5 kg/cm2, 1.5 bar)150 kPa (1.5 kg/cm2, 1.5 bar)90 180 kg150 kPa (1.5 kg/cm2, 1.5 bar)175 kPa (1.75 kg/cm2, 1.75 bar)

125 kPa (1.25 kg/cm2, 1.25 bar)125 kPa (1.25 kg/cm2, 1.25 bar)

150 kPa (1.5 kg/cm2, 1.5 bar)175 kPa (1.75 kg/cm2, 1.75 bar)

*Load is the total weight of cargo, rider, passenger, and accessories.

–2–

CHASSIS SPECIFICATIONS/ELECTRICAL SPECIFICATIONS SPEC

Item Standard Limit

Front suspensionFront fork travelFork spring free lengthFitting lengthSpring rate (K1)Stroke (K1)Oil capacityOil levelOil gradeInner tube vend limit

150 mm330.4 mm325.4 mm4.9 N/mm (0.5 kg/mm)0 150 mm0.259 L (259 cm3)122 mmFork oil 10 WT or equivalent

324 mm

0.2 mm

Rear suspensionShock absorber strokeSpring free lengthFitting lengthSpring rate (K1)

(K2)Stroke (K1)

(K2)

48 mm190 mm185 mm127.5 N/mm (12.8 kg/mm)186.4 N/mm (18.6 kg/mm)0 32 mm32 48 mm

173 mm

Drive chainType/manufacturerNo. of linksChain free play

428HD/DAIDO12635 60 mm

Rear brakeTypeDrum inside diameterShoe thicknessShoe spring free length

Leading, trailing130 mm4 mm52 mm

131 mm2 mm

ELECTRICAL SPECIFICATIONS

Item Standard Limit

C.D.I.Pickup coil resistance/color

Source coil resistance/color

C.D.I. unit model/manufacturer

656 984 Ω at 20C/Red – White624 936 Ω at 20C/Brown – Green5BT/YAMAHA

Headlight relayModel/manufacturerCoil resistance

G8MS-1A48T-L2-F28/OMRON90 110 Ω

–3–

12 Wire harness13 Front turn signal light lead (right)14 Indicator lead

1 Brake hose2 Throttle cables3 Front brake light switch lead4 Right handlebar switch lead5 Main switch lead6 Clutch cable7 Clutch switch lead8 Speedometer cable9 Left handlebar switch lead10 Meter lead11 Front turn signal light lead (left)

CABLE ROUTING SPEC

A Clamp the grommet of brakehose with the band. Aftercompletion of clamping, cut thesurplus part and point it to thebackward.

B No positioning for the headlightbody is specified.

C To the headlightD Clamp the left handle bar switch

lead and the meter lead.

CABLE ROUTING

–4–

1 Battery positive lead2 Starter relay3 Starter motor lead4 Ignition coil5 Throttle cable (pull side)6 Throttle cable (return side)7 Throttle cable holder8 Horn lead9 Throttle cable guide10 Spark plug lead11 Headlight relay (Black)12 Relay (White)

CABLE ROUTING SPEC

13 C.D.I. unit14 Diode15 Turn signal relay

A Point the surplus part of theclamp of the wire harness to thedownward. Clamp the immedi-ate front part of the junction sec-tion to the C.D.I. unit relay.

B Handlebar switch lead (right)and front brake light switch leadshould not be twined around.

–5–

C Clamp the wire harness, handle-bar switch lead (right), frontbrake light switch lead, clutchswitch lead, main switch lead,resonator hose and startercable.

D Clamp the ignition coil lead andthe ignition coil grand lead hornlead.

E Route the wire harness, handle-bar switch lead (right) and frontbrake light switch lead throughthe guide.

CABLE ROUTING SPEC

F Do not bend the lead sharply justafter the terminal connection.

G Point the rear brake light switchlead to the rear side of the ve-hicle.

H Route the lead by the front sideof the sheet pillar tube so that it isnot be caught between the sidecover flange and the frame sheetpillar tube.

I Secure the rear brake switch,knob-shape part of the lead, car-buretor heater lead and turn sig-nal relay lead. At this time, makesure to secure the turn signalrelay lead at the outmost posi-tion. Next, point the surplus partof the band to the inner side andthen cut it.

J Relay lead can be routed eitherthe front or the rear side of therelay.

–6–

CABLE ROUTING SPEC

K Push the wire harness in be-tween frame and box.

L Place the C.D.I. unit on the at-taching section of the left siderelay.

M Route the carburetor heater leadin the inner side of the turn signalrelay.

N Clamp the wire harness anddiode. Point the surplus part tothe downward.

O Point the surplus part of theclamp for the wire harness andthe diode to the inner side.Place the diode section betweenthe pipes of the frame.

–7–

1 Resonator hose2 Fuel hose3 Rectifier / regulator lead4 Thermo switch lead5 Sidestand switch lead6 Air filter case7 Breather hose8 Battery negative lead9 C.D.I. magneto two leads10 Over flow hose11 Air vent hose12 Clutch cable13 Horn lead clamp

CABLE ROUTING SPEC

14 Clutch cable guide15 Brake hose16 Speedometer cable17 Horn18 Horn lead19 Flange bolt20 Brake hose holder21 Meter lead22 Handlebar switch lead (left)

A Clamp between the positioningbelts of resonator hose. Do notpinch the resonator hose.

B Starter cable, clutch switch leadand main switch lead should notbe twined around.

C Clamp at the point ahead of thepart where resonator hose pro-tector is torn. Do not pinch theresonator hose.

D Place the coupler below the res-onator hose.

–8–

G Clamp the C.D.I. magneto leadat the frame pipe bend and pointthe surplus part to the inner side,then cut it.

H Clamp the sidestand switchlead.

I Clamp the air vent hose, overflow hosed and neutral switchlead.

J Hold down the side stand switchlead using the special washer.

CABLE ROUTING SPEC

E Clamp the rectifier / regulatorlead and resonator hose. Pointthe surplus part toward the innerside. Clamp within a rangewhere the resonator hose pro-tector is torn. Do not pinch theresonator hose.

F Point the surplus part of theclamp to the rear side. Clamp theC.D.I. magnet leads (2 pieces),starter motor lead, neutral switchlead and battery negative lead.

K Route the air vent hose and overflow hose between engine andswingarm.

L Route the neutral switch lead be-tween engine and swingarm.

M Pass the air vent hose and over-flow hose through the engineguide.

N To the fuel cock.O Insert the starter cable to the

clamp.

–9–

T Place the speedometer cable inthe inner side.

U After tightening screws, insertthe hose in the screw section.

V Distortion should be within thisrange toward the traveling direc-tion of vehicle.

W Place the brake hose in the outerside.

X Cut the surplus part of the clampfor the left handle bar switch leadand the meter lead.

P Clamp the brake hose andspeedometer cable. Align theclamping position with the centerof white paint mark on the brakehose.

Q Clamp the brake hose andspeedometer cable with a hold-er.

R Point the speedometer cablecap to the backward.

S Make sure to push in the boot ful-ly.

CABLE ROUTING SPEC

–10–

13 Rectifier / regulator14 Clamp (rectifier / regulator lead)15 Handlebar switch lead (left)16 Clutch switch lead17 Clutch cable18 Starter cable19 Neutral switch lead20 Connect cover21 C.D.I. magneto leads

CABLE ROUTING SPEC

1 Brake hose2 Throttle cable (return side)3 Throttle cable (pull side)4 Front brake light switch lead5 Handlebar switch lead (right)6 Starter motor lead7 Battery positive lead8 Wire harness9 Clamp (wire harness)10 Thermo switch lead11 Sidestand switch lead12 Grommet

A Clamp the handlebar switch leadand front brake light switch leadwith a band.

B Pass the C.D.I. magnet leads (3pieces), neutral switch leadthrough the cover connector.

C Clamp the wire harness and rearturn signal light lead (right). Pointthe surplus part to the inner side.

D Cover the naked part of rear turnsignal light lead (right) with thehose.

–11–

E Cover the naked part of rear turnsignal light lead (left) with thehose.

F Clamp the wire harness and rearturn signal lead (right).

G Pass the rear turn signal lightlead (right) between the rearframe and license bracket,avoiding to be caught.

H Rout the lead by the outside ofthe frame so that it does not con-tact with the tip of the bolt asshown in the illustration.

CABLE ROUTING SPEC

I Pass the rear turn signal lightlead (left) between the rearframe and license bracket,avoiding to be caught.

J Clamp the rear turn signal lightlead (left). After clamping, pointthe surplus part to the inner side.

K Clamp the thermo switch leadcoupler. After clamping, pointthe surplus part to the inner side.

L Battery negative lead to be con-nected with the ground.

M Route the battery negative leadabove the side stand switch leadand thermo switch lead.

N No special order is set for theC.D.I. magneto lead (2 leads),neutral switch lead, starter motorlead and battery negative lead.

O Clamp the handlebar switch lead(left) and clutch switch lead.

P Route the thermo switch lead un-der the cover connector.

Q Route the starter motor lead un-der the cover connector.

–12–

CABLE ROUTING SPEC

R Route the sidestand switch leadunder the cover connector.

S Assemble so that the couplerand the lead are positioned low-er than the battery’s top face.

–13–

1 Turn signal switch2 Dimmer switch3 Horn switch4 Clutch switch5 Front brake switch

6 Engine stop switch7 Start switch8 Main switch9 Neutral switch10 Sidestand switch

11 Rear brake switch12 Fuse13 Thermo switch

CHECKING THE SWITCHES ELEC

EAS00731

ELECTRICALCHECKING THE SWITCHESCheck each switch for damage or wear, proper connections, and also for continuity between the termi-nals. Refer to “CHECKING SWITCH CONTINUITY” in chapter 7 (Manual No.: 5EK1-AE1)

Damage/wear Repair or replace the switch.Improperly connected Properly connect.Incorrect continuity reading Replace the switch.

–14–

1 C.D.I magneto3 Rectifier/Regulator4 Battery5 Main fuse11 Main switch16 C.D.I unit21 Meter light24 Hi-beam indicator light29 Tail/Brake light30 Diode B31 Headlight relay37 Dimmer switch42 Headlight43 Auxiliary light

LIGHTING SYSTEM ELEC

EB804000

LIGHTING SYSTEMCIRCUIT DIAGRAM

–15–

2. Battery

Check the condition of the battery.Refer to “CHECKING AND CHARGING THEBATTERY” in chapter 3. (Manual No. :5EK1-AE2)

Minimum open-circuit voltage12.8 V more at 20 C

Is the battery OK?

YES

Clean the batteryterminals.

Recharge or replace the battery.

NO

EAS00749

Check the main switch for continuity.Refer to “CHECKING THE SWITCHES” inP13.

Is the main switch OK?

YES

Replace the mainswitch.

NO

3. Main switch

EAS00760

Disconnect the diode B from the wire har-ness.

Connect the pocket tester (Ω 1) to thediode B terminals as shown.

Measure the diode B for continuity as follows.

4. Diode B

LIGHTING SYSTEM ELEC

NOTE:

YES NO

Replace the fuse(-s).

1. Fuse

Check the fuse for continuity.Refer to “CHECKING THE FUSES” in chap-ter 3. (Manual No. : 5EK1-AE1)

Is the fuse OK?

EAS00781

TROUBLESHOOTING

Any of the following fail to light: headlight, high beam indicator light, taillight,auxiliary light or meter light.

Check:1. fuse2. battery3. main switch4. diode B5. headlight relay6. dimmer switch7. wiring

(of the entire charging system)

Before troubleshooting, remove the followingpart(-s):

1) side covers (left and right)2) seat3) fuel tankTroubleshoot with the following specialtool(-s).

Pocket tester90890-03112

EAS00738

–16–

LIGHTING SYSTEM ELEC

Tester positive probe brown/white

Tester negative probe white

1

2

Tester positive probe brown/white

Tester negative probe blue/black

1

3

Continuity

YES

Replace the diode B.

NO

NOTE:When you switch the tester’s positive andnegative probes, the readings in the abovechart will be reversed.

Are the testing readings correct?

Tester positive probe white

Tester negative probe brown/white

2

1

Tester positive probe blue/black

Tester negative probe brown/white

3

1

No continuity

5. Headlight relay

Disconnect the headlight relay from the wireharness.

Connect the pocket tester (Ω 1) and bat-tery (12 V) to the headlight relay terminal asshown.

Check the headlight relay for continuity.

YES

Replace the head-light relay.

NO

Battery positive terminal brown/whiteBattery negative terminal skyblue

Does the headlight relay have continuity be-tween brown and blue/black?

Tester positive probe brown Tester negative probe blue/black

12

Check the dimmer switch for continuity.Refer to “CHECKING THE SWITCHES” inP13.

Is the dimmer switch OK?

YES

The dimmer switch isfaulty. Replace theleft handlebar switch.

NO

6. Dimmer switch

Check the entire lighting system’s wiring.Refer to “CIRCUIT DIAGRAM”.

Is the lighting system’s wiring properly con-nected and without defects?

YES

Properly connect orrepair the lightingsystem’s wiring.

NO

7. Wiring

Check the conditionof each of the lightingsystem’s circuits.Refer to “CHECKINGTHE LIGHTINGSYSTEM”. (ManualNo. : 5EK1-AE1)

–17–

FAULTY LIGHTING SYSTEMTRBLSHTG

EAS00866

TROUBLESHOOTINGFAULTY LIGHTING SYSTEMHEADLIGHT DOES NOT COME ONWrong headlight bulbToo many electrical accessoriesHard charging Incorrect connection Improperly grounded circuitPoor contacts (main or dimmer switch)Headlight relayBurnt-out headlight bulb

HEADLIGHT BULB BURNT OUTWrong headlight bulbFaulty batteryFaulty rectifier/regulator Improperly grounded circuitFaulty main switchFaulty dimmer switchFaulty headlight relayHeadlight bulb life expired

1 C.D.I. magneto2 Neutral switch3 Rectifier /Regulator4 Battery5 Main fuse6 Starter relay7 Starter motor8 Right handlebar switch9 Start switch10 Engine stop switch11 Main switch12 Diode A13 Clutch switch14 Sidestand switch15 Neutral relay16 C.D.I. unit17 Ignition coil18 Spark plug19 Speedometer20 Reed switch21 Meter light22 Neutral indicator light23 Turn signal indicator light24 Hi-beam indicator light25 Thermo switch26 Carburetor heater27 Rear brake light switch28 Front brake light switch29 Tail /Brake light30 Diode B31 Headlight relay32 Turn signal relay33 Horn34 Left handlebar switch35 Horn switch36 Turn signal switch37 Dimmer switch38 Rear turn signal light (right)39 Front turn signal light (right)40 Front turn signal light (left)41 Rear turn signal light (left)42 Headlight43 Auxiliary light

COLOR CODEB Black. . . . . . . Br Brown. . . . . . Ch Chocolate. . . . . Dg Dark green. . . . . G Green. . . . . . L Blue. . . . . . . O Orange. . . . . . Sb Sky blue. . . . . . P Pink. . . . . . . R Red. . . . . . . Y Yellow. . . . . . . W White. . . . . . B/R Black/Red. . . .

B/W Black/White. . . . B/Y Black/Yellow. . . . Br/W Brown/White. . . G/W Green/White. . . . G/Y Green/Yellow. . . . L/B Blue/Black. . . . . L/W Blue/White. . . . L/Y Blue/Yellow. . . . . R/L Red/Blue. . . . R/W Red/White. . . . W/B White/Black. . . . W/L White/Blue. . . . W/R White/Red. . . .

TW125 2003 WIRING DIAGRAM