2002 YAMAHA TTR125 engine

4 - 19
ENGCYLINDER HEAD
9. Check:
lValve clearance
Out of specification ® Adjust.
Refer to “VALVE CLEARANCE
INSPECTION AND ADJUSTMENT”
section in the CHAPTER 3.
10. Apply:
lEngine oil
On camshaft.
11. Install:
lTappet cover 1
lCylinder head side cover 2
T R..18 Nm (1.8 m · kg, 13 ft · lb)
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
12. Install:
lTiming mark accessing screw 1
lCrankshaft end accessing screw 2
T R..7 Nm (0.7 m · kg, 5.1 ft · lb)
T R..7 Nm (0.7 m · kg, 5.1 ft · lb)
13. Install:
lSpark plug
lEngine bracket
T R..13 Nm (1.3 m · kg, 9.4 ft · lb)
T R..40 Nm (4.0 m · kg, 29 ft · lb)

4 - 22
ENGCAMSHAFT AND ROCKER ARMS
Rocker arms and rocker arm shafts
1. Inspect:
lCam lobe contact surface a
lAdjuster surface 1
Wear/pitting/scratches/blue discolora-
tion ® Replace.
Measurement steps:
lMeasure the inside diameter a of the
rocker arm holes.
Out of specification ® Replace.
Inside diameter (rocker arm):
10.000 ~ 10.015 mm
(0.3937 ~ 0.3943 in)
: 10.03 mm (0.3949 in)
lMeasure the outside diameter b of the
rocker arm shafts.
Out of specification ® Replace.
Outside diameter
(rocker arm shaft):
9.981 ~ 9.991 mm
(0.3930 ~ 0.3933 in)
: 9.95 mm (0.3917 in)
ASSEMBLY AND INSTALLATION
1. Apply:
lMolybdenum disulfide oil
(onto the camshaft cam lobe and rocker
arm hole)
lEngine oil
(onto the camshaft bearing)
2. Install:
lRocker arms
lCamshaft 1
3. Apply:
lEngine oil
(onto the rocker arm shaft)
4. Install:
lRocker arm shaft

4 - 38
ENGCYLINDER AND PISTON
ASSEMBLY AND INSTALLATION
Piston ring and piston
1. Install:
lPiston rings
(onto the piston)
NOTE:
lBe sure to install the 2nd piston ring so that
the manufacturer’s mark or number are
located on the upper side of the ring.
lLubricate the piston and piston rings liberally
with engine oil.
2. Position:
lTop ring
l2nd ring
lOil ring
Offset the piston ring end gaps as
shown.
a: Top ring end
b: 2nd ring end
c: Oil ring end (upper)
d: Oil ring end (lower)
3. Install:
lPiston 1
lPiston pin 2
lPiston pin clips 3
NOTE:
lApply engine oil onto the piston pin, piston
rings and piston.
lBe sure that the arrow mark a on the piston
points to the exhaust side of the engine.
lBefore installing the piston pin clip, cover the
crankcase with a clean rag to prevent the
piston pin clip from falling into the crankcase.
lWhen removing the piston pin clip, pop it out
using the small opening b.
4. Lubricate:
lPiston
lPiston rings
lInside of cylinder
NOTE:
Apply a liberal coating of engine oil.
New

4 - 40
ENGCLUTCH AND PRIMARY DRIVEN GEAR
EC490000
CLUTCH AND PRIMARY DRIVEN GEAR
EC498000
CLUTCH PLATE AND FRICTION PLATE
Extent of removal:1 Clutch plate and friction plate removal
Extent of removal Order Part name Q’ty Remarks
CLUCTH PLATE AND FRIC-
TION PLATE REMOVAL
Preparation for removal Drain the engine oil. Refer to “ENGINE OIL REPLACEMENT”
section in the CHAPTER 3.
Engine skidplate Refer to “ENGINE REMOVAL” section.
1 Kickstarter crank 1
2 Right crankcase cover 1
3 Gasket 1
4 Dowel pin 2
5 Clutch spring 4
6 Pressure plate 1
7 Ball 1
8 Friction plate 5
9 Clutch plate 4
10 Nut/washer 1/1
11 Push rod 1 1
12 Push plate 1
1

4 - 45
ENGCLUTCH AND PRIMARY DRIVEN GEAR
Push rod
1. Inspect:
lPush rod 1 1
lBall 2
Wear/damage/bend ® Replace.
Primary drive gear
1. Inspect:
lPrimary drive gear
Wear/damage ® Replace.
EC495000
ASSEMBLY AND INSTALLATION
Push lever
1. Install:
lPush lever 1
NOTE:
lApply the lithium soap base grease on the oil
seal lip.
lApply the engine oil on the push lever.
Primary drive gear
1. Install:
lStraight key
lPrimary drive gear 1
lWasher 2
lNut (primary drive gear) 3
lPrimary driven gear 4
NOTE:
lInstall the primary drive gear with the stamp
a facing out.
lPlace a folded rag or aluminum plate 5
between the teeth of the primary drive gear
and primary driven gear.
T R..70 Nm (7.0 m · kg, 50 ft · lb)

4 - 46
ENGCLUTCH AND PRIMARY DRIVEN GEAR
Clutch
1. Install:
lConical spring washer 1
lThrust plate 2
lPrimary driven gear 3
lThrust plate 4
lClutch boss 5
2. Install:
lLock washer
lNut (clutch boss) 1
NOTE:
Use the clutch holding tool 2 to hold the clutch
boss.
For USA and CDN
õExcept for USA and CDN
3. Bend:
lLock washer tab
Clutch holding tool:
YM-91042/90890-04086
New
T R..60 Nm (6.0 m · kg, 43 ft · lb)

õ
4. Install:
lFriction plate 1
lClutch plate 2
NOTE:
lInstall the clutch plates and friction plates
alternately on the clutch boss, starting with a
friction plate and ending with a friction plate.
lApply the engine oil on the friction plates and
clutch plates.
lBe sure to install a clutch plate with projec-
tion a offset approximately 90˚ from previ-
ous plates projection. Continue this
procedure in a clockwise direction until all
clutch plates are installed.

4 - 47
ENGCLUTCH AND PRIMARY DRIVEN GEAR
5. Install:
lBall
NOTE:
Apply the engine oil on the ball.
6. Install:
lPush rod 1 1
lPush plate 2
lWasher 3
lNut (push rod 1) 4
7. Install:
lPressure plate 1
lClutch spring 2
lBolt (clutch spring) 3
NOTE:
lAlign the arrow mark a on the pressure
plate with the punched mark b on the clutch
boss.
lTighten the bolts in stage, using a crisscross
pattern.
T R..6 Nm (0.6 m · kg, 4.3 ft · lb)
8. Check:
lPush lever position
Push the push lever assembly in the
arrow direction and make sure that the
mach mark are aligned ® adjust.
aMatch mark on the push lever assembly
bMatch mark on the crankcase

4 - 52
ENGOIL PUMP
Oil strainer
1. Inspect:
lOil strainer
Cracks/damage ® Replace.
Contamination ® Clean the flushing oil.
ASSEMBLY AND INSTALLATION
Oil pump
1. Install:
lOil pump housing 1
lOuter rotor 2
lInner rotor 3
lPin 4
lOil pump shaft 5
lPin 6
lOil pump cover 7
lWasher 8
lCirclip 9
lConical spring washer 0
lOil pump driven gear A
lCirclip B
lScrews C
NOTE:
lApply engine oil onto the outer rotor, inner
rotor and oil pump shaft.
lInstall the conical spring washer in the direc-
tion as shown.
2. Install:
lOil strainer
lGasket
lOil pump assembly
lScrews (oil pump assembly)
NOTE:
Apply engine oil onto the crankcase oil pas-
sage and oil pump assembly.
New
New
T R..5 Nm (0.5 m · kg, 3.6 ft · lb)
New
T R..7 Nm (0.7 m · kg, 5.1 ft · lb)
3. Install:
lOil pump drive gear 1
lRotary filter 2
NOTE:
lInstall the oil pump drive gear with its groove
a facing the engine.
lInstall the rotary filter with the dog b facing
out.
lAlign the rotary filter dog b with groove c of
the crankshaft.