Yamaha 2002 TW125 Manual

FOREWORD
This Supplementary Service Manual has been prepared to introduce new service and data for the
TW125 2002. For complete service information procedures it is necessary to use this Supplementary
Service Manual together with the following manual.
TW125 SERVICE MANUAL: 5EK1-AE1
TW125 2002
SUPPLEMENTARY
SERVICE MANUAL
E2001 by Yamaha Motor Co., Ltd.
First Edition, August 2001
Any reproduction or unauthorized use
without the written permission of
Yamaha Motor Co., Ltd. is expressly
prohibited.

NOTE:
WARNING
CAUTION:
EB001000
NOTICE
This manual was produced by the Yamaha Motor Company primarily for use by Yamaha dealers and
their 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 Yamaha
motorcycle has a basic understanding of the mechanical ideas and the procedures of motorcycle
repair. Repairs attempted by anyone without this knowledge are likely to render the motorcycle unsafe
and unfit for use.
Yamaha Motor Company, Ltd. is continually striving to improve all its models. Modifications and
significant changes in specifications or procedures will be forwarded to all authorized Yamaha dealers
and will appear in future editions of this manual where applicable.
Designs and specifications are subject to change without notice.
EAS00004
IMPORTANT INFORMATION
Particularly important information is distinguished in this manual by the following notations.
The Safety Alert Symbol means ATTENTION! BECOME ALERT! YOUR
SAFETY IS INVOLVED!
Failure to follow WARNING instructions could result in severe injury or death to
the motorcycle operator, a bystander or a person inspecting or repairing the
motorcycle.
A CAUTION indicates special precautions that must be taken to avoid damage
to the motorcycle.
NOTE: A NOTE provides key information to make procedures easier or clearer.

1
2
5
7
6
43
8
EAS00007
HOW TO USE THIS MANUAL
This manual is intended as a handy, easy-to-read reference book for the mechanic. Comprehensive
explanations of all installation, removal, disassembly, assembly, repair and inspection procedures are
laid out with the individual steps in sequential order.
1The manual is divided into chapters. An abbreviation and symbol in the upper right corner of each
page indicate the current chapter. Refer to “SYMBOLS” on the following page.
2Each 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 each
page, instead of the section title.)
3Sub-section titles appear in smaller print than the section title.
4To help identify parts and clarify procedure steps, there are exploded diagrams at the start of each
removal and disassembly section.
5Numbers are given in the order of the jobs in the exploded diagram. A circled number indicates a
disassembly step.
6Symbols indicate parts to be lubricated or replaced (see “SYMBOLS”).
7A job instruction chart accompanies the exploded diagram, providing the order of jobs, names of
parts, notes in jobs, etc.
8Jobs 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
GEN
INFO SPEC
ENG
CARB
ELEC
CHAS
CHK
ADJ
TRBL
SHTG
16
EAS00009
SYMBOLS
The following symbols are not relevant to every
vehicle.
Symbols 1to 9indicate the subject of each
chapter.
1General information
2Specifications
3Periodic checks and adjustments
4Engine
5Carburetor(-s)
6Chassis
7Electrical system
8Troubleshooting
Symbols 9to 16 indicate the following.
9Serviceable with engine mounted
10 Filling fluid
11 Lubricant
12 Special tool
13 Tightening torque
14 Wear limit, clearance
15 Engine speed
16 Electrical data
Symbols 17 to 22 in the exploded diagrams indi-
cate the types of lubricants and lubrication
points.
17 Engine oil
18 Gear oil
19 Molybdenum disulfide oil
20 Wheel bearing grease
21 Lithium soap base grease
22 Molybdenum disulfide grease
Symbols 23 to 24 in the exploded diagrams indi-
cate the following:
23 Apply locking agent (LOCTITER)
24 Replace the part

CONTENTS
SPECIFICATIONS
GENERAL SPECIFICATIONS 1
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MAINTENANCE SPECIFICATIONS 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ENGINE 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CHASSIS 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ELECTRICAL 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CABLE ROUTING 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PERIODIC CHECKS AND ADJUSTMENTS
INTRODUCTION 16
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PERIODIC MAINTENANCE/LUBRICATION INTERVALS 16. . . . . . . . .
ENGINE 18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ADJUSTING THE ENGINE IDLING SPEED 18. . . . . . . . . . . . . . . . . . . . .
ADJUSTING THE THROTTLE CABLE FREE PLAY 19. . . . . . . . . . . .
ELECTRICAL SYSTEM 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CHECKING AND CHARGING THE BATTERY 21. . . . . . . . . . . . . . . . . .
REPLACING THE HEADLIGHT BULB 27. . . . . . . . . . . . . . . . . . . . . . . . . . .
ADJUSTING THE HEADLIGHT BEAM 28. . . . . . . . . . . . . . . . . . . . . . . . . . .
ENGINE
CLUTCH 29
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CARBURETOR
CARBURETOR 31
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CHECKING THE CARBURETOR 34. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ASSEMBLING THE CARBURETOR 36. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
INSTALLING THE CARBURETOR 37. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MEASURING AND ADJUSTING THE FUEL LEVEL 37. . . . . . . . . . . .
CHASSIS
FRONT WHEEL AHD BRAKE DISC 39
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
REAR WHEEL AND REAR BRAKE 40. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
REAR WHEEL 40. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
REAR BRAKE AND REAR WHEEL SPROCKET 42. . . . . . . . . . . . . . . .
FRONT FORK 44. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
HANDLEBAR 45. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
STEERING HEAD 47. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LOWER BRACKET 47. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ELECTRICAL SYSTEM
IGNITION SYSTEM 49
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CIRCUIT DIAGRAM 49. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CHECKING THE IGNITION SYSTEM 50. . . . . . . . . . . . . . . . . . . . . . . . . . . .
TW125 2002 WIRING DIAGRAM

GENERAL SPECIFICATIONS SPEC
SPECIFICATIONS
GENERAL SPECIFICATIONS
Model TW125
Model code: 5RS1, 5RS2
Dimensions:
Overall length
Overall width
Overall height
Seat height
Wheelbase
Minimum ground clearance
Minimum turning radius
2,135 mm
,820 mm
1,120 mm
,820 mm
1,350 mm
,255 mm
2,100 mm
Carburetor:
Type/quantity
Manufacturer
MV28/1
TEIKEI
Transmission:
Primary reduction system
Primary reduction ratio
Secondary reduction system
Secondary reduction ratio
Transmission type
Operation
Gear ratio 1st
2nd
3rd
4th
5th
Spur gear
74/20 (3.700)
Chain drive
51/14 (3.643)
Constant mesh 5 speed
Left foot operation
36/16 (2.250)
31/21 (1.476)
27/24 (1.125)
25/27 (0.926)
23/29 (0.793)
Chassis:
Frame type
Caster angle
Trail
Diamond
25_50’
93 mm
Tire:
Type
Size front
rear
Manufacture front
rear
Type front
rear
Tube type
130/80-18 66P
130/80-18 M/C 66P
180/80-14 M/C 78P
BRIDGESTONE
BRIDGESTONE
TW203
TW204
–1–

GENERAL SPECIFICATIONS SPEC
Model TW125
Wheel travel:
Front wheel travel
Rear wheel travel
150 mm
150 mm
Electrical:
Ignition system
Generator system
Battery type
Battery capacity
C.D.I.
A.C. magneto
GT6B-3
12 V 6 AH
Bulb wattage quantity:
Headlight
Auxiliary light
Tail/brake light
Turn signal light
Meter light
High beam indicator light
Neutral indicator light
Turn signal indicator light
12 V 60 W/55 W 1
12 V 4 W 1
12 V 5 W/21 W 1
12 V 21 W 4
12 V 3.4 W 1
12 V 3.4 W 1
12 V 3.4 W 1
12 V 3.4 W 1
–2–

MAINTENANCE SPECIFICATIONS SPEC
MAINTENANCE SPECIFICATIONS
ENGINE
Item Standard Limit
Clutch:
Friction plate thickness
Quantity
Clutch plate thickness
Quantity
Clutch spring free length
Quantity
Push rod bending limit
2.9 X3.1 mm
5 pcs.
1.6 mm
4 pcs.
34.9 mm
4 pcs.
SSS
2.7 mm
SSS
0.05 mm
SSS
33.9 mm
SSS
0.2 mm
Carburetor:
Type
I.D. mark
Main jet (M.J)
Main air jet (M.A.J)
Jet needle (J.N)
Needle jet (N.J)
Pilot air jet 1 (P.A.J.1)
Pilot air jet 2 (P.A.J.2)
Pilot outlet (P.O)
Pilot jet (P.J)
Bypass 1 (B.P.1)
Bypass 2 (B.P.2)
Bypass 3 (B.P.3)
Bypass 4 (B.P.4)
Pilot screw (P.S)
Valve seat size (V.S)
Starter jet 1 (G.S.1)
Starter jet 2 (G.S.2)
Fuel level (F.L)
Engine idle speed
Intake vacuum
MV28
5RS1 00
#134
ø1.2
5A50-3/5
B1/60
#90
#120
0.8
#34
0.7
0.7
0.7
0.7
1-1/2
1.6
0.6
0.8
0 X2.0 mm
1,450 X1,650 r/min
190 X230 mmHg
SSS
SSS
SSS
SSS
SSS
SSS
SSS
SSS
SSS
SSS
SSS
SSS
SSS
SSS
SSS
SSS
SSS
SSS
SSS
SSS
TIGHTENING TORQUES
ENGINE
Part to be tightened Part name Thread
size
Q’ty
Tightening
torque Remarks
g
size
y
Nm mSkg
Cam sprocket cover
Oil filter cover
Crankcase (left and right)
Generator cover
Clutch cover
Clutch boss
Drive sprocket
Pick up coil
Stator coil
Screw
Screw
Screw
Screw
Screw
Nut
Bolt
Screw
Screw
M6
M6
M6
M6
M6
M14
M5
M6
M6
2
2
12
10
10
1
2
2
3
10
10
10
10
10
50
4
10
10
1.0
1.0
1.0
1.0
1.0
5.0
0.4
1.0
1.0
–3–

MAINTENANCE SPECIFICATIONS SPEC
CHASSIS
Item Standard Limit
Front suspension:
Front fork travel
Fork spring free length
Fitting length
Spring rate (K1)
Stroke (K1)
Oil capacity
Oil level
Oil grade
Inner tube vend limit
150 mm
330 mm
325 mm
4.9 N/mm (0.49 kg/mm)
0 X150 mm
0.259 L (259 cm3)
122 mm
Fork oil 10 WT or equivalent
SSS
SSS
323 mm
SSS
SSS
SSS
SSS
SSS
SSS
0.2 mm
Rear suspension:
Shock absorber stroke
Spring free length
Fitting length
Spring rate (K1)
Stroke (K1)
48 mm
190 mm
185 mm
127 N/mm (12.7 kg/mm)
0 X48 mm
SSS
171 mm
SSS
SSS
SSS
Drive chain:
Type/manufacturer
No. of links
Chain free play
Maximum ten-link section
428HD/DAIDO
125
35 X60 mm
129.5 mm
SSS
SSS
SSS
SSS
Rear brake:
Type
Drum inside diameter
Shoe thickness
Shoe spring free length
Leading, trailing
130 mm
4 mm
Cam side 52 mm
Pin side 48 mm
SSS
131 mm
2 mm
SSS
Brake lever:
Brake lever free play (at lever end) 5 X8 mm SSS
–4–

MAINTENANCE SPECIFICATIONS SPEC
NOTE:
TIGHTENING TORQUES
CHASSIS
Part to be tightened Thread size
Tightening
torque Remarks
g
Nm mSkg
Headlight and headlight stay
Handle crown and steering shaft
Steering ring nut
Brake hose union bolt (front brake)
Swingarm pivot shaft
Footrest (left)
(right)
Rear footrest
Brake caliper and front fork
Rear wheel sprocket and hub
M8
M22
M25
M10
M12
M12
M10
M8
M10
M8
16
110
4
30
83
88
48
16
40
43
1.6
11.0
0.4
3.0
8.3
8.8
4.8
1.6
4.0
4.3
Refer to NOTE
1. When tighten the ring nut, should be steady the ball bearings and the steering shaft moving smooth-
ly.
2. First, tighten the ring nut approximately 38 Nm (3.8 mSkg) by using the torque wrench, then loosen
the ring nut one turn and retighten the ring nut to specification.
ELECTRICAL
Item Standard Limit
Charging system:
Type
Model/manufacturer
Standard output
Stator coil resistance/color
C.D.I. magneto
F5BT/YAMAHA
14 V 170 W/5,000 r/min
0.48 X0.72 Ωat 20_C/
White –White
SSS
SSS
SSS
SSS
SSS
Battery:
Specific gravity 1.320 SSS
Electric starter system:
Type
Starter motor:
Model/manufacturer
Output
Armature coil resistance
Brush overall length
Brush spring pressure
Commutator diameter
Mica undercut (depth)
Constant mesh type
5RS/YAMAHA
0.4 kW
0.0126 X0.0154 Ωat 20_C
10 mm
5.52 X8.28 N (552 X828 g)
22 mm
1.5 mm
SSS
SSS
SSS
SSS
3.5 mm
SSS
21 mm
SSS
–5–

CABLE ROUTING SPEC
12 Wire harness
13 Front turn signal light lead (right)
14 Indicator lead
1Brake hose
2Throttle cables
3Front brake light switch lead
4Right handlebar switch lead
5Main switch lead
6Clutch cable
7Clutch switch lead
8Speedometer cable
9Left handlebar switch lead
10 Front turn signal light lead (left)
11 Meter lead
A Clamp the grommet of brake
hose with the band. After
completion of clamping, cut the
surplus part and point it to the
backward.
B No positioning for the headlight
body is specified.
C To the headlight
CABLE ROUTING
–6–

A After clamping the wire harness,
point the surplus part to the
downward. Clamp the part im-
mediately before the junction to
the C.D.I. unit and relay.
B Cut it to be 10 mm or less.
C Handlebar switch lead (right)
and front brake light switch lead
should not be twined around.
1Battery positive lead
2Starter relay
3Starter motor lead
4Clamp
5Ignition coil
6Throttle cable (pull side)
7Throttle cable (return side)
8Throttle cable holder
9Horn lead
10 Spark plug lead
11 Relay (White)
12 C.D.I. unit
CABLE ROUTING SPEC
13 Diode
14 Resister lead
15 Turn signal relay
–7–

CABLE ROUTING SPEC
I Pass the throttle cables through
the engine bracket hole. Point
the surplus part to the downward
and cut the end.
J Pass the carburetor heater lead
in front of the seat pillar tube so
that it is not caught between the
side cover flange and seat pillar
tube frame.
K Point the rear brake switch lead
wire to the rear side of frame.
switch lead, main switch lead,
resonator hose and starter
cable.
F Clamp the ignition coil lead and
the ignition coil grand lead horn
lead.
G Route the wire harness, handle-
bar switch lead (right) and front
brake light switch lead through
the guide.
H Do not bend the lead sharply just
after the terminal connection.
D Clamp the wire harness, handle
bar switch lead (right), front
brake light switch lead, clutch
switch lead and main switch
lead. After clamping, point the
surplus part to the downward
and then cut it. Do not clamp the
resonator hose and starter
cable.
E Clamp the wire harness, handle-
bar switch lead (right), front
brake light switch lead, clutch
–8–

CABLE ROUTING SPEC
O Clamp the wire harness and
diode. Point the surplus part to
the downward.
L Clamp the rear brake switch lead
connector and turn signal relay
lead with the band and point the
surplus part to the inner side,
then cut it. Secure the connector
at the front part of frame.
M Push the wire harness in be-
tween frame and box.
N Place the C.D.I. unit on the
mounting port for the left side
relay.
–9–

CABLE ROUTING SPEC
A Clamp between the positioning
belts of resonator hose. Do not
pinch the resonator hose.
B Starter cable, clutch switch lead
and main switch lead should not
be twined around.
C Clamp at the point ahead of the
part where resonator hose pro-
tector is torn. Do not pinch the
resonator hose.
D Place the coupler below the res-
onator hose.
1Resonator hose
2Fuel hose
3Rectifier/regulator lead
4Thermo switch lead
5Sidestand switch lead
6Air filter case
7Breather hose
8Battery negative lead
9C.D.I. magneto leads
10 Over flow hose
11 Air vent hose
12 Clutch cable
13 Clutch cable guide
14 Brake hose
15 Speedometer cable
16 Handlebar switch lead (left)
17 Clamp
18 Flange bolt
19 Brake hose holder
–10–

CABLE ROUTING SPEC
tween engine and swingarm.
M Route the neutral switch lead be-
tween engine and swingarm.
N Route the air vent hose and over
flow hose through the engine
guide.
O To the fuel cock.
P Route the horn lead through in-
side the clutch cable.
Q Insert the starter cable to the
clamp.
side, then cut it.
H Clamp the sidestand switch
lead.
I Clamp the air vent hose, over
flow hose, starter motor lead and
neutral switch lead.
J Hold down the side stand switch
lead using the special washer.
K Route the air vent hose and over
flow hose between engine and
swingarm.
L Route the starter motor lead be-
E Clamp the rectifier/regulator
lead and resonator hose. Point
the surplus part toward the inner
side. Clamp within a range
where the resonator hose pro-
tector is torn. Do not pinch the
resonator hose.
F Place the air vent hose in the in-
ner side of the main pipe.
G Clamp the C.D.I. magneto lead
at the frame pipe bend and point
the surplus part to the inner
–11–

CABLE ROUTING SPEC
V Place the speedometer cable in
the inner side.
W After tightening screws, insert
the hose in the screw section.
X Distortion should be within this
range toward the traveling direc-
tion of vehicle.
Y Place the brake hose in the outer
side.
R Clamp the brake hose and
speedometer cable. Align the
clamping position with the center
of white paint mark on the brake
hose.
S Clamp the brake hose and
speedometer cable with a hold-
er.
T Point the speedometer cable
cap to the backward.
U Make sure to push in the boot ful-
ly.
–12–

CABLE ROUTING SPEC
24 C.D.I. magneto leads, neutral
switch lead
1Handlebar switch lead (right)
2Front brake light switch lead
3Brake hose
4Throttle cable (return side)
5Throttle cable (pull side)
6Starter motor lead
7Battery positive lead
8Wire harness
9Clamp (wire harness)
10 Thermo switch lead
11 Sidestand switch lead
12 Negative lead
13 Battery negative lead
14 Grommet
15 Rectifier/regulator
16 Clamp (rectifier/regulator lead)
17 Handlebar switch lead (left)
18 Clutch switch lead
19 Clutch cable
20 Master cylinder
21 Starter cable
22 Rear turn signal light lead
23 Turn signal light stay
–13–

CABLE ROUTING SPEC
H Pass the rear turn signal light
lead (right) between the rear
frame and license bracket,
avoiding to be caught.
I Pass the rear turn signal light
lead (left) between the rear
frame and license bracket,
avoiding to be caught.
J Clamp the rear turn signal light
lead (left). After clamping, point
the surplus part to the inner side.
D Clamp the wire harness and rear
turn signal light lead (right). Point
the surplus part to the inner side.
E Cover the naked part of rear turn
signal light lead (right) with the
hose.
F Cover the naked part of rear turn
signal light lead (left) with the
hose.
G Clamp the wire harness and rear
turn signal lead (right).
A Clamp the handlebar switch lead
and front brake light switch lead
with a band.
B Clamp the throttle cables.
C Clamp the C.D.I. magneto lead
(2 leads), starter motor lead,
neutral switch lead, battery neg-
ative lead and pass them
through the frame gusset hole,
then point the surplus part to the
inner side.
–14–