fuel YAMAHA TTR125 2003 Owner's Manual

3 - 1
INSP
ADJ

MAINTENANCE INTERVALS
EC300000
REGULAR INSPECTION AND ADJUSTMENTS
MAINTENANCE INTERVALS
The following schedule is intended as a general guide to maintenance and lubrication. Bear in mind
that such factors as weather, terrain, geographical location, and individual usage will alter the
required maintenance and lubrication intervals. If you are a doubt as to what intervals to follow in
maintaining and lubricating your machine, consult your Yamaha dealer.
Dealer
NoteItem Checks and maintenance jobsInitial Every
10 hours
(1 month)60 hours
(6 months)120 hours
(12 months)
*
Fuel lineCheck fuel hoses for cracks or damage.
Replace if necessary.
Spark plugCheck condition.
Clean, regap or replace if necessary.
*
ValvesCheck valve clearance.
Adjust if necessary.
Air filter Clean or replace element if necessary.
*
CarburetorCheck engine idling speed and starter operation.
Adjust if necessary.
Exhaust systemsCheck for leakage.
Retighten if necessary.
Replace gasket if necessary.
Engine oilCheck oil level and vehicle for oil leakage.
Correct if necessary.
Change. (Warm engine before draining.)
ClutchCheck operation.
Adjust or replace cable.
*
Front brakeCheck operation.
Adjust brake lever free play.
Check fluid level and leakage. (TT-R125LWE only)Every ride
*
Rear brakeCheck operation.
Adjust brake pedal free play and replace brake
shoes if necessary.Every ride
*
WheelsCheck balance, runout, spoke tightness and for
damage.
Tighten spokes and rebalance, replace if
necessary.
*
TiresCheck tread depth and for damage.
Replace if necessary.
Check air pressure.
Correct if necessary.
*
Wheel bearingsCheck bearing for looseness or damage.
Replace if necessary.
*
SwingarmCheck swingarm pivoting point for play.
Correct if necessary.
Lubricate with molybdenum disulfide grease.
Drive chainCheck chain slack.
Adjust if necessary. Make sure that the rear wheel
is properly aligned.
Clean and lubricate.Every ride
*
Steering bearingsCheck bearing play and steering for roughness.
Correct accordingly.
Lubricate with lithium soap base grease every 120
hours.
SidestandCheck operation.
Lubricate and repair if necessary.

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INSP
ADJ

PRE-OPERATION INSPECTION AND MAINTENANCE
PRE-OPERATION INSPECTION AND MAINTENANCE
Before riding for break-in operation or practice, make sure the machine is in good operating condi-
tion.
Before using this machine, check the following points.
GENERAL INSPECTION AND MAINTENANCE
Item Routine Page
FuelCheck that a fresh gasoline is filled in the fuel tank. Check the
fuel line for leakage.P.1-12
Engine oilCheck that the oil level is correct. Check the crankcase for leak-
age.P.3-7 ~ 10
Gear shifter and clutchCheck that gears can be shifted correctly in order and that the
clutch operates smoothly.P.3-4
Throttle grip/housingCheck that the throttle grip operation and free play are correctly
adjusted. Lubricate the throttle grip and housing, if necessary.P.3-4 ~ 5
BrakesCheck the play of front and rear brake and effect of front and
rear brake.
Check fluid level and leakage. (TT-R125LWE only)P.3-15 ~ 20
Drive chainCheck chain slack and alignment. Check that the chain is lubri-
cated properly.P.3-21 ~ 22
WheelsCheck for excessive wear and tire pressure. Check for loose
spokes and have no excessive play.P.3-27 ~ 28
SteeringCheck that the handlebar can be turned smoothly and have no
excessive play.P.3-28 ~ 30
Front forks and rear shock
absorber assemblyCheck that they operate smoothly and there is no oil leakage. P.3-23 ~ 26
Cables (wires)Check that the clutch and throttle cables move smoothly. Check
that they are not caught when the handlebars are turned or
when the front forks travel up and down.—
Muffler Check that the muffler is tightly mounted and has no cracks. P.4-2
Sprocket Check that the driven sprocket tightening nut is not loose. P.3-20
Lubrication Check for smooth operation. Lubricate if necessary. P.3-31
Bolts and nuts Check the chassis and engine for loose bolts and nuts. —
Lead connectorsCheck that the CDI magneto, CDI unit, and ignition coil are con-
nected tightly.P.1-5

3 - 10
INSP
ADJOIL PRESSURE INSPECTION/PILOT AIR SCREW
ADJUSTMENT/ENGINE IDLING SPEED ADJUSTMENT
OIL PRESSURE INSPECTION
1. Check:
Oil pressure
Checking steps:
Slightly loosen the oil pressure check bolt
1.
Start the engine and keep it idling until oil
starts to seep from the oil pressure check
bolt. If no oil comes out after one minute,
turn the engine off so it will not seize.
Check oil passages and oil pump for dam-
age or leakage.
Start the engine after solving the prob-
lem(s) and recheck the oil pressure.
Tighten the oil pressure check bolt.
T R..
Oil pressure check bolt:
7 Nm (0.7 m • kg, 5.1 ft • lb)
PILOT AIR SCREW ADJUSTMENT
1. Adjust:
Pilot air screw 1
Adjustment steps:
NOTE:
To optimize the fuel flow at a smaller throttle
opening, each machine’s pilot air screw has
been individually set at the factory. Before
adjusting the pilot air screw, turn it in fully
and count the number of turns. Record this
number as the factory-set number of turns
out.
Screw in the pilot air screw until it is lightly
seated.
Back out by the specified number of turns.
Pilot air screw:
2-1/2 ~ 3-1/2 turns out (example)
ENGINE IDLING SPEED ADJUSTMENT
1. Start the engine and thoroughly warm it
up.
2. Attach:
Inductive tachometer
To spark plug lead.
3. Adjust:
Engine idling speed

3 - 11
INSP
ADJ
VALVE CLEARANCE INSPECTION AND ADJUSTMENT
VALVE CLEARANCE INSPECTION AND
ADJUSTMENT
NOTE:
The valve clearance should be adjusted
when the engine is cool to the touch.
The piston must be at Top Dead Center
(T.D.C.) on compression stroke to check or
adjust the valve clearance.
1. Remove:
Seat
Fuel tank
Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section in the CHAPTER 4. Adjustment steps:
Adjust the pilot air screw.
Refer to “PILOT AIR SCREW ADJUST-
MENT” section.
Turn the throttle stop screw 1 until the
specified engine idling speed.
To increase idling speed →
Turn the throttle stop screw 1 in a.
To decrease idling speed →
Turn the throttle stop screw 1 out b.
Inductive tachometer:
YU-8036-B/90890-03113
Engine idling speed:
1,300 ~ 1,500 r/min
2. Remove:
Spark plug
Intake tappet cover 1
Exhaust tappet cover 2
O-ring
3. Remove:
Timing mark accessing screw 1
Crankshaft end accessing screw 2
O-ring

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INSP
ADJ
VALVE CLEARANCE INSPECTION AND ADJUSTMENT
Measure the valve clearance.
If the clearance is incorrect, repeat above
steps until specified clearance is obtained.
6. Install:
O-ring 1
Crankshaft end accessing screw 2
Timing mark accessing screw 3
NOTE:
Apply the lithium soap base grease on the O-
rings.
New
T R..7 Nm (0.7 m · kg, 5.1 ft · lb)
T R..7 Nm (0.7 m · kg, 5.1 ft · lb)
7. Install:
O-ring 1
Exhaust tappet cover 2
Intake tappet cover 3
NOTE:
Apply the lithium soap base grease on the O-
rings.
8. Install:
Spark plug
Fuel tank
Seat
Refer to “SEAT, FUEL TANK AND
SIDE COVERS” section in the CHAP-
TER 4.
New
T R..18 Nm (1.8 m · kg, 13 ft · lb)
T R..18 Nm (1.8 m · kg, 13 ft · lb)
T R..13 Nm (1.3 m · kg, 9.4 ft · lb)
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
T R..7 Nm (0.7 m · kg, 5.1 ft · lb)

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STEERING HEAD INSPECTION AND ADJUSTMENT
Tighten the lower ring nut 6 using steer-
ing nut wrench 7 and turn the steering
right and left a few times.
Steering nut wrench:
YU-33975/90890-01403
T R..
Lower ring nut (initial tightening):
38 Nm (3.8 m • kg, 27 ft • lb)
Loosen the lower ring nut one turn.
Retighten the lower ring nut using the
steering nut wrench.
T R..
Ring nut (final tightening):
20 Nm (2.0 m • kg, 14 ft • lb)
Check the steering stem by turning it lock
to lock. If there is any binding, remove the
steering stem assembly and inspect the
steering bearings.
Install the rubber washer 8, upper ring
nut 9 and special washer 0.
NOTE:
Tighten the upper ring nut until it contacts
the rubber washer.
Insert the special washer pawls into the
slots. If the slots are not aligned, tighten
the upper ring nut for alignment.
Install the upper bracket A, steering stem
nut B, cap C, handlebar D, upper han-
dlebar holder E, main switch F, starter
knob nut G and number plate H.
NOTE:
The upper handlebar holder should be
installed with the punched mark a for-
ward.
Insert the end of fuel breather hose I into
the hose clamp.
NOTE:
Set the torque wrench to the steering nut
wrench so that they form a right angle.
WARNING
Avoid over-tightening.
H
DF
B
C
I
A

4 - 1
ENG

EC400000
ENGINE
EC4R0000
SEAT, FUEL TANK AND SIDE COVERS
Extent of removal:
1
Seat removal
2
Fuel tank removal
3
Side covers removal
4
Number plate removal
Extent of removal Order Part name Q’ty Remarks
Preparation for removal
SEAT, FUEL TANK AND SIDE
COVERS REMOVAL
Turn the fuel cock to “OFF”.
1 Seat 1
2 Air scoop (left and right) 2
3 Fuel hose 1 Remove on fuel tank side.
4 Fitting band 1
5 Bolt (fuel tank) 2
6 Fuel tank 1
7 Left side cover 1
8 Right side cover 1
9Number plate
1
13
4
2
3

SEAT, FUEL TANK AND SIDE COVERS

4 - 2
ENG

MUFFLER
MUFFLER
Extent of removal:
1
Muffler removal
Extent of removal Order Part name Q’ty Remarks
MUFFLER REMOVAL
Preparation for removal Right side cover Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section.
1 Bolt (spark arrester) 3
2 Spark arrester 1
3 Nut (muffler) 2
4 Bolt (muffler) 1
5Muffler
1
1

4 - 3
ENG

CARBURETOR
CARBURETOR
Extent of removal:
1
Carburetor removal
Extent of removal Order Part name Q’ty Remarks
CARBURETOR REMOVAL
Preparation for removal Fuel tank
Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section.
Number plate
1 Fuel hose 1
2 Over flow hose 1
3 Air vent hose 2
4 Starter plunger/starter knob 1
5 Carburetor top cover 1
6 Clamp (air cleaner joint) 1 Loosen the screw (air cleaner joint).
7 Clamp (carburetor joint) 1 Loosen the screws (carburetor joint).
8Carburetor
1
1

4 - 5
ENG

CARBURETOR
HANDLING NOTE
At high altitudes, the atmospheric pressure is
lower. This can make the fuel mixture too rich,
leading to such problems as fouled.
Spark plugs and slow response at high engine
speeds. A special part, High Altitude Main Jet
1
#102.5 (620-1423A-71-A0) is available to
correct this.
EC463000
REMOVAL POINTS
Throttle valve
1. Remove:

Throttle valve
1


Spring (throttle valve)
2


Carburetor top cover
3


Throttle cable
4

NOTE:

While compressing the spring (throttle valve),
disconnect the throttle cable.
Pilot air screw
1. Remove:

Pilot air screw
1

NOTE:

To optimize the fuel flow at a smaller throttle
opening, each machine’s pilot air screw has
been individually set at the factory. Before
removing the pilot air screw, turn it in fully and
count the number of turns. Record this number
as the factory-set number of turns out.