Page 4 of 610

INTRODUCTION
Congratulations on your purchase of a
Yamaha TT-R125/TT-R125E/TT-R125LW/
TT-R125LWE. This model is the culmination
of Yamaha’s vast experience in the produc-
tion of pacesetting racing machines. It repre-
sents the highest grade of craftsmanship and
reliability that have made Yamaha a leader.
This manual explains operation, inspection,
basic maintenance and tuning of your
machine. If you have any questions about this
manual or your machine, please contact your
Yamaha dealer.
NOTE:
As improvements are made on this model,
some data in this manual may become out-
dated. If you have any questions, please con-
sult your Yamaha dealer.
WARNING
READ THIS MANUAL CAREFULLY FOR
INSTRUCTIONS ON HOW TO PROPERLY
OPERATE THIS MACHINE.
ADULT INSTRUCTION AND SUPERVI-
SION ARE REQUIRED.
WEIGHT OF THE RIDER SHOULD NOT
EXCEED 68 kg (150 lb). (TT-R125/TT-R125E
ONLY)
ALWAYS WEAR A HELMET AND SUIT-
ABLE PROTECTIVE CLOTHING WHEN
RIDING.
DO NOT TOUCH ANY MOVING PARTS OR
HEATED AREAS.
ALWAYS PERFORM PRE-OPERATION
CHECKS. REFER TO PAGE 3-3.
THIS MACHINE IS DESIGNED TO CARRY
THE OPERATOR ONLY.
NO PASSENGERS.
THIS MACHINE IS DESIGNED OFF-ROAD
USE ONLY.
IT IS NOT SUITABLE FOR ON-ROAD USE.
Page 14 of 610
EC050000
TO THE NEW OWNER
This manual will provide you with a good basic
understanding of features, operation, and
basic maintenance and inspection items of this
machine. Please read this manual carefully
and completely before operating your new
machine. If you have any questions regarding
the operation or maintenance of your machine,
please consult your Yamaha dealer.
NOTE:
This manual should be considered a perma-
nent part of this machine and should remain
with it even if the machine is subsequently
sold.
EC060000
NOTICE
Some data in this manual may become out-
dated due to improvements made to this
model in the future. If there is any question
you have regarding this manual or your
machine, please consult your Yamaha
dealer.
Page 24 of 610

EC0A0000
CONTENTS
CHAPTER 1
GENERAL INFORMATION
DESCRIPTION ...........................................1-1
MACHINE IDENTIFICATION .....................1-2
IMPORTANT INFORMATION ....................1-3
CHECKING OF CONNECTION .................1-5
SPECIAL TOOLS ......................................1-6
CONTROL FUNCTIONS ............................1-9
FUEL ........................................................1-12
STARTING AND BREAK-IN ....................1-13
TORQUE-CHECK POINTS ......................1-16
TT-R125/TT-R125E ............................1-16
TT-R125LW/TT-R125LWE .................1-17
CLEANING AND STORAGE ...................1-18
CHAPTER 2
SPECIFICATIONS
GENERAL SPECIFICATIONS ...................2-1
TT-R125/TT-R125E...............................2-1
TT-R125LW/TT-R125LWE....................2-4
MAINTENANCE SPECIFICATIONS ..........2-7
ENGINE ...................................................2-7
CHASSIS ...............................................2-15
TT-R125/TT-R125E ............................2-15
TT-R125LW/TT-R125LWE .................2-19
ELECTRICAL ........................................2-23
TT-R125/TT-R125LW .........................2-23
TT-R125E/TT-R125LWE ....................2-24
GENERAL TORQUE
SPECIFICATIONS ...................................2-26
DEFINITION OF UNITS ...........................2-26
CABLE ROUTING DIAGRAM .................2-27
TT-R125/TT-R125LW .........................2-27
TT-R125E/TT-R125LWE ....................2-30
Page 26 of 610

CHAPTER 3
REGULAR INSPECTION
AND ADJUSTMENTS
MAINTENANCE INTERVALS ...................3-1
PRE-OPERATION INSPECTION
AND MAINTENANCE ................................3-3
ENGINE ......................................................3-4
CHASSIS .................................................3-15
ELECTRICAL ...........................................3-34
CHAPTER 4
ENGINE
SEAT, FUEL TANK
AND SIDE COVERS ..................................4-1
MUFFLER ..................................................4-2
CARBURETOR ..........................................4-3
CYLINDER HEAD ....................................4-12
CAMSHAFT AND ROCKER ARMS ........4-20
VALVES AND VALVE SPRINGS ............4-24
CYLINDER AND PISTON ........................4-32
CLUTCH AND PRIMARY DRIVEN
GEAR .......................................................4-40
OIL PUMP ................................................4-49
KICK AXLE AND SHIFT SHAFT .............4-53
CDI MAGNETO
(TT-R125/TT-R125LW) ............................4-58
CDI MAGNETO AND STARTER
CLUTCH (TT-R125E/TT-R125LWE) .......4-61
ENGINE REMOVAL .................................4-66
CRANKCASE, CRANKSHAFT
AND BALANCER ....................................4-70
TRANSMISSION, SHIFT CAM
AND SHIFT FORK ...................................4-78
Page 62 of 610
1 - 15
GEN
INFO
STARTING AND BREAK-IN
BREAKING IN AFTER REPLACEMENT
After a part is replaced with a new one, it is
necessary to break it in as in a new machine.
This is required especially when the following
engine-related parts are replaced.
Cylinder
Piston
Piston ring
Valve
Camshaft
Crankshaft
Clutch
Transmission gear
Shift fork
* For warming up and inspection during
break-in, refer to “GENERAL INSPECTION
AND MAINTENANCE” section in the
CHAPTER 3 and if there is any problem,
stop the engine immediately and check.
Page 64 of 610
1 - 16
GEN
INFO
TORQUE-CHECK POINTS
TORQUE-CHECK POINTS
TT-R125/TT-R125E
Engine mounting
Muffler
Steering Steering stem to
handlebar
Suspension Front Steering stem to
front fork
Rear For link type
Rear Installation of shock
absorber
Rear Installation of swing-
arm
Wheel Installation of wheel Front
Rear
Brake Front
Rear
Fuel systemFrame to engine
Frame to engine bracket
Engine bracket to engine
Muffler to cylinder head
Muffler to rear fender bracket
Muffler to seat pillar tube
Steering stem to upper bracket
Upper bracket to handlebar
Front fork to upper bracket
Front fork to lower bracket
Assembly of links
Link to frame
Link to shock absorber
Link to swingarm
Shock absorber to frame
Tightening of pivot shaft
Tightening of wheel axle
Tightening of wheel axle
Wheel to sprocket
Camshaft lever to camshaft
Camshaft lever to camshaft
Fuel tank to fuel cock
NOTE:
Concerning the tightening torque, refer to
“MAINTENANCE SPECIFICATIONS” section
in the CHAPTER 2.
Page 65 of 610

1 - 17
GEN
INFO
TORQUE-CHECK POINTS
TT-R125LW/TT-R125LWE
Engine mounting
Muffler
Steering Steering stem to
handlebar
Suspension Front Steering stem to
front fork
Rear For link type
Rear Installation of shock
absorber
Rear Installation of swing-
arm
Wheel Installation of wheel Front
Rear
Brake Front
Rear
Fuel systemFrame to engine
Frame to engine bracket
Engine bracket to engine
Muffler to cylinder head
Muffler to rear fender bracket
Muffler to seat pillar tube
Steering stem to upper bracket
Upper bracket to handlebar
Front fork to upper bracket
Front fork to lower bracket
Assembly of links
Link to frame
Link to shock absorber
Link to swingarm
Shock absorber to frame
Tightening of pivot shaft
Tightening of wheel axle
Tightening of wheel axle
Wheel to sprocket
Brake caliper to front fork
Brake disc to wheel
Tightening of union bolt
Brake master cylinder to joint
Brake hose to joint
Brake master cylinder to handlebar
Tightening of bleed screw
Brake camshaft lever to brake camshaft
Fuel tank to fuel cock
NOTE:
Concerning the tightening torque, refer to
“MAINTENANCE SPECIFICATIONS” section
in the CHAPTER 2.
Page 80 of 610
SPEC
2 - 7
MAINTENANCE SPECIFICATIONS
EC212000
MAINTENANCE SPECIFICATIONS
EC212100
ENGINE
Item Standard Limit
Cylinder head:
Warp limit ---- 0.03 mm
(0.0012 in)
Cylinder:
Bore size 54.000 ~ 54.019 mm
(2.1260 ~ 2.1267 in)----
Out of round limit ---- 0.05 mm
(0.0020 in)
Camshaft:
Drive method Chain drive (left) ----
Cam dimensions
Intake“A”25.881 ~ 25.981 mm
(1.0189 ~ 1.0229 in)25.851 mm
(1.0178 in)
“B”21.195 ~ 21.295 mm
(0.8344 ~ 0.8384 in)21.165 mm
(0.8333 in)
Exhaust“A”25.841 ~ 25.941 mm
(1.0174 ~ 1.0213 in)25.811 mm
(1.0162 in)
“B”21.050 ~ 21.150 mm
(0.8287 ~ 0.8327 in)21.020 mm
(0.8276 in)
Camshaft runout limit ---- 0.03 mm
(0.0012 in)