2003 YAMAHA TTR125 fuel

IMPORTANT NOTICE
This machine is designed for off-road use only
by young operators under adult instruction and
supervision. It is illegal for this machine to be
operated on any public street, road, or high-
way.
Off-road use on public lands may be illegal.
Please check local regulations before riding.
1. GASOLINE IS HIGHLY FLAMMABLE:
* Always turn off the engine when
refueling.
* Take care not to spill on the engine
or exhaust pipe/muffler, when refu-
eling.
* Never refuel while smoking or in
the vicinity of an open flame.
2. If you should swallow some gasoline
or inhale a lot of gasoline vapor, or
allow some gasoline to get in your
eye(s), see your doctor immediately.
If any gasoline spills on your skin or
clothing, immediately wash it with
soap and water, and change your
clothes.
3. Always turn off the engine before
leaving the machine unattended.
When parking the machine, note the
following:
* The engine and exhaust pipe(s)/
muffler(s) may be hot. Park the
machine in a place where pedestri-
ans or children are not likely to
touch the machine.
* Do not park the machine on a slope
or soft ground; the machine may
overturn.
SAFETY INFORMATION

4. When transporting the machine in
another vehicle, be sure is kept
upright and that the fuel cock is
turned to the “OFF”. If it should lean
over, gasoline may leak out of the car-
buretor or fuel tank.
5. Never start your engine or let it run for
any length of time in a closed area.
The exhaust fumes are poisonous and
may cause loss of consciousness and
death within a short time. Always
operate your machine in an area with
adequate ventilation.
6. Always wear a helmet, gloves, boots,
trousers, and jacket for motocross
riding.

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
..................... 1-15
TT-R125
.............................................. 1-15
TT-R125LW
........................................ 1-16
CLEANING AND STORAGE
.................. 1-17
CHAPTER 2
SPECIFICATIONS
GENERAL SPECIFICATIONS
................... 2-1
TT-R125
................................................ 2-1
TT-R125LW
.......................................... 2-4
MAINTENANCE SPECIFICATIONS
......... 2-7
ENGINE
................................................... 2-7
CHASSIS
............................................... 2-15
TT-R125
.............................................. 2-15
TT-R125LW
........................................ 2-19
ELECTRICAL
........................................ 2-23
GENERAL TORQUE
SPECIFICATIONS
.................................. 2-24
DEFINITION OF UNITS
.......................... 2-24
CABLE ROUTING DIAGRAM
................ 2-25
CHAPTER 3
REGULAR INSPECTION AND
ADJUSTMENTS
MAINTENANCE INTERVALS
................... 3-1
PRE-OPERATION INSPECTION
AND MAINTENANCE
............................... 3-3
ENGINE
..................................................... 3-4
CHASSIS
................................................. 3-15
ELECTRICAL
.......................................... 3-29

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
....................................... 4-58
ENGINE REMOVAL
................................ 4-61
CRANKCASE, CRANKSHAFT
AND BALANCER
.................................... 4-65
TRANSMISSION, SHIFT CAM
AND SHIFT FORK
.................................. 4-73
CHAPTER 5
CHASSIS
FRONT WHEEL AND FRONT BRAKE
(TT-R125)
.................................................. 5-1
FRONT WHEEL (TT-R125LW)
................. 5-8
FRONT BRAKE (TT-R125LW)
............... 5-12
REAR WHEEL AND REAR BRAKE
....... 5-24
FRONT FORK
......................................... 5-32
HANDLEBAR
.......................................... 5-41
STEERING
.............................................. 5-49
SWINGARM
............................................ 5-55
REAR SHOCK ABSORBER
ASSEMBLY
............................................. 5-62
CHAPTER 6
ELECTRICAL
ELECTRICAL COMPONENTS
AND WIRING DIAGRAM
.......................... 6-1
IGNITION SYSTEM
................................... 6-2

1 - 1
GEN
INFO

DESCRIPTION
EC100000
GENERAL INFORMATION
EC110000
DESCRIPTION
1
Clutch lever
2
Engine stop switch
3
Starter knob
4
Front brake lever
5
Throttle grip
6
Fuel tank cap
7
Air filter
8
Kickstarter crank
9
Fuel tank
0
Dipstick
A
Rear brake pedal
B
Fuel cock
C
Drive chain
D
Shift pedal
E
Front fork
*The illustration shows the TT-R125LW.
NOTE:


The machine you have purchased may differ
slightly from those shown in the following.

Designs and specifications are subject to
change without notice.

1 - 7
GEN
INFO
SPECIAL TOOLS
YM-1312-A, 90890-01312Fuel level gauge
This gauge is used to measure the fuel level in the
float chamber.YM-1312-A 90890-01312
YU-33270-B, 90890-01362 Flywheel puller
This tool is used to remove the rotor.YU-33270-B 90890-01362
YM-33963, 90890-01367
YM-33281, 90890-01400Fork seal driver weight
Fork seal driver attachment
These tools are used to installing the fork oil seal.YM-33963
YM-3328190890-01367
90890-01400
YU-33975, 90890-01403 Steering nut wrench
This tool is used when tighten the steering ring nut to
specification.YU-33975 90890-01403
YS-1880-A, 90890-01701 Sheave holder
This tool is used for when loosening or tightening the
flywheel magneto securing nut.YS-1880-A 90890-01701
YU-3112-C, 90890-03112 Pocket tester
Use this tool to inspect the coil resistance, output
voltage and amperage.YU-3112-C 90890-03112
YU-8036-B
90890-03113Inductive tachometer
Engine tachometer
This tool is needed for observing engine rpm.YU-8036-B 90890-03113
YM-4019, 90890-04019 Valve spring compressor
This tool is needed to remove and install the valve
assemblies.YM-4019 90890-04019
YM-91042, 90890-04086 Clutch holding tool
This tool is used to hold the clutch when removing or
installing the clutch boss securing nut.YM-91042 90890-04086
Part number Tool name/How to use Illustration

1 - 10
GEN
INFO
CONTROL FUNCTIONS
EC156000
FRONT BRAKE LEVER
The front brake lever 1 is located on the right
handlebar. Pull it toward the handlebar to acti-
vate the front brake.
EC157000
REAR BRAKE PEDAL
The rear brake pedal 1 is located on the right
side of the machine. Press down on the brake
pedal to activate the rear brake.
EC158010
FUEL COCK
The fuel cock supplies fuel from the tank to
carburetor while filtering the fuel. The fuel cock
has the three positions:
OFF: With the lever in this position, fuel will
not flow. Always return the lever to this
position when the engine is not running.
ON: With the lever in this position, fuel flows
to the carburetor. Normal riding is done
with the lever in this position.
RES: This indicates reserve. If you run out of
fuel while riding, move the lever to this
position. FILL THE TANK AT THE
FIRST OPPORTUNITY. BE SURE TO
SET THE LEVER TO “ON” AFTER
REFUELING.
EC159000
STARTER KNOB (CHOKE)
When cold, the engine requires a richer air-fuel
mixture for starting. A separate starter circuit,
which is controlled by the starter knob 1, sup-
plies this mixture. Pull the starter knob out to
open the circuit for starting. When the engine
has warmed up, push it in to close the circuit.

1 - 11
GEN
INFO
CONTROL FUNCTIONS
FUEL TANK CAP
Remove the fuel tank cap 1 by turning coun-
terclockwise.
WARNING
Do not overfill the fuel tank. Avoid spilling
fuel on the hot engine.
SIDESTAND
This sidestand 1 is used to support only the
machine when standing or transporting it.
WARNING
Never apply additional force to the side-
stand.
Hold up the sidestand before starting out.