engine assembly YAMAHA TTR125 2005 User Guide

3 - 28
INSP
ADJ
STEERING HEAD INSPECTION AND ADJUSTMENT
2. Inspect:
Bearing free play
Exist play → Replace.
STEERING HEAD INSPECTION AND
ADJUSTMENT
1. Elevate the front wheel by placing a suit-
able stand under the engine.
2. Check:
Steering shaft
Grasp the bottom of the forks and gen-
tly rock the fork assembly back and
forth.
Free play → Adjust steering head.
3. Check:
Steering smooth action
Turn the handlebar lock to lock.
Unsmooth action → Adjust steering ring
nut.
4. Adjust:
TT-R125/TT-R125LW
Steering ring nut
Steering ring nut adjustment steps:
Remove the number plate and starter
knob.
Remove the handlebar and upper bracket.
Remove the special washer 1.
Remove the upper ring nut 2, and rubber
washer 3.
Loosen the lower ring nut 4 using the
steering nut wrench 5.
Steering nut wrench:
YU-33975/90890-01403

4 - 16
ENGCYLINDER HEAD
Warpage limit:
0.03 mm (0.0012 in)
If the warpage is out of specification,
resurface the cylinder head.
Place #400 ~ 600 grit wet sandpaper on
the surface plate, and re-surface the head
using a figure-eight sanding pattern.
NOTE:
Rotate the cylinder head several times to
avoid removing too much material from one
side.
ASSEMBLY AND INSTALLATION
Cylinder head
1. Install:
Dowel pin 1
Gasket 2 New
2. Install:
Cylinder head
Copper washer
Bolt (cylinder head)
NOTE:
Apply Quick gasket® (YAMAHA Bond
No.1215) on end of the cylinder head bolts
(M6), as shown.
Apply the engine oil on the contact surfaces of
the bolts (cylinder head) and copper washers.
Follow the numerical order shown in the illus-
tration. Tighten the bolts in two stages.
Quick gasket®:
ACC-QUICK-GS-KT
YAMAHA Bond No.1215:
90890-85505
T R..M8 22 Nm (2.2 m · kg, 16 ft · lb)
M6 10 Nm (1.0 m · kg, 7.2 ft · lb)

4 - 22
ENGCAMSHAFT AND ROCKER ARMS
Rocker arms and rocker arm shafts
1. Inspect:
Cam lobe contact surface a
Adjuster surface 1
Wear/pitting/scratches/blue discolora-
tion → Replace.
Measurement steps:
Measure 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)
Measure 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:
Molybdenum disulfide oil
(onto the camshaft cam lobe and rocker
arm hole)
Engine oil
(onto the camshaft bearing)
2. Install:
Rocker arms
Camshaft 1
3. Apply:
Engine oil
(onto the rocker arm shaft)
4. Install:
Rocker arm shaft

4 - 38
ENGCYLINDER AND PISTON
ASSEMBLY AND INSTALLATION
Piston ring and piston
1. Install:
Piston rings
(onto the piston)
NOTE:
Be sure to install the 2nd piston ring so that
the manufacturer’s mark or number are
located on the upper side of the ring.
Lubricate the piston and piston rings liberally
with engine oil.
2. Position:
Top ring
2nd ring
Oil 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:
Piston 1
Piston pin 2
Piston pin clips 3
NOTE:
Apply engine oil onto the piston pin, piston
rings and piston.
Be sure that the arrow mark a on the piston
points to the exhaust side of the engine.
Before installing the piston pin clip, cover the
crankcase with a clean rag to prevent the
piston pin clip from falling into the crankcase.
When removing the piston pin clip, pop it out
using the small opening b.
4. Lubricate:
Piston
Piston rings
Inside of cylinder
NOTE:
Apply a liberal coating of engine oil.
New

4 - 45
ENGCLUTCH AND PRIMARY DRIVEN GEAR
Push rod
1. Inspect:
Push rod 1 1
Ball 2
Wear/damage/bend → Replace.
Primary drive gear
1. Inspect:
Primary drive gear
Wear/damage → Replace.
EC495000
ASSEMBLY AND INSTALLATION
Push lever
1. Install:
Push lever 1
NOTE:
Apply the lithium soap base grease on the oil
seal lip.
Apply the engine oil on the push lever.
Primary drive gear
1. Install:
Straight key
Primary drive gear 1
Washer 2
Nut (primary drive gear) 3
Primary driven gear 4
NOTE:
Install the primary drive gear with the stamp
a facing out.
Place 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 - 47
ENGCLUTCH AND PRIMARY DRIVEN GEAR
5. Install:
Ball
NOTE:
Apply the engine oil on the ball.
6. Install:
Push rod 1 1
Push plate 2
Washer 3
Nut (push rod 1) 4
7. Install:
Pressure plate 1
Clutch spring 2
Bolt (clutch spring) 3
NOTE:
Align the arrow mark a on the pressure
plate with the punched mark b on the clutch
boss.
Tighten the bolts in stage, using a crisscross
pattern.
T R..6 Nm (0.6 m · kg, 4.3 ft · lb)
8. Check:
Push 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 strainer1. Inspect:
●Oil strainer
Cracks/damage → Replace.
Contamination → Clean the flushing oil.
ASSEMBLY AND INSTALLATION
Oil pump
1. Install:
●Oil pump housing 1
●Outer rotor 2
●Inner rotor 3
●Pin 4
●Oil pump shaft 5
●Pin 6
●Oil pump cover 7
●Washer 8
●Circlip 9
●Conical spring washer 0
●Oil pump driven gear A
●Circlip B
●Screws C
NOTE:
●Apply engine oil onto the outer rotor, inner
rotor and oil pump shaft.
●Install the conical spring washer in the direc-
tion as shown.
2. Install:
●Oil strainer
●Gasket
●Oil pump assembly
●Screws (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)
NOTE:
● Install the oil pump drive gear with its groove
a facing the engine.
●Install the rotary filter with the dog b facing
out.
●Align the rotary filter dog b with groove c of
the crankshaft.
3. Install:
● Washer 1
● Oil pump drive gear 2
● Rotary filter 3
● Install the washer with stamped "H" for the
side of the engine.

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ENGKICK AXLE AND SHIFT SHAFT
KICK AXLE AND SHIFT SHAFT
KICK AXLE AND SHIFT SHAFT
Extent of removal:1 Kick axle removal2 Shift shaft removal
Extent of removal Order Part name Q’ty Remarks
KICK AXLE AND SHIFT SHAFT
REMOVAL
Preparation for removal Shift pedal link Refer to “ENGINE REMOVAL” section.
Clutch Refer to “CLUTCH AND PRIMARY
DRIVEN GEAR” section.
1 Kick axle assembly 1 Refer to “REMOVAL POINTS”.
2 Circlip 1
3 Washer 1
4 Kick idle gear 1
5 Washer 1
6 Circlip 1
7 Shift shaft 1
8 Circlip 1
9 Torsion spring 1
10 Bolt (stopper lever) 1
11 Stopper lever 1
12 Spring 1
13 Segment 1 Refer to “REMOVAL POINTS”.
1
2

4 - 56
ENGKICK AXLE AND SHIFT SHAFT
Shift shaft
1. Install:
Shift shaft 1
NOTE:
Apply the lithium soap base grease on the oil
seal lip of the left crankcase side.
Hook the spring ends onto the stopper 2.
Kick axle assembly
1. Install:
Kickstarter segment gear 1
Plain washer 2
Torsion spring 3
On kick axle 4.
NOTE:
Make sure the stopper a of the torsion spring
fits into the hole b on the kick axle.
2. Install:
Spring guide 1
NOTE:
Slide the spring guide into the kick axle, make
sure the groove a in the spring guide fits on
the stopper of the torsion spring.
3. Install:
Kick axle assembly 1
NOTE:
Apply the engine oil on the kick axle.
Slide the kick axle assembly into the crank-
case, make sure the clip 2 and kick axle
stopper b fit into their home positions a, c.
4. Hook:
Torsion spring 1
NOTE:
Turn the torsion spring clockwise and hook
into the proper hole a in the crankcase.

4 - 63
ENG
CDI MAGNETO AND STARTER CLUTCH
(TT-R125E/TT-R125LWE)
3. Check:
Starter clutch operation
Install the starter clutch drive gear 1 onto
the starter clutch 2 and hold the starter
clutch.
When turning the starter clutch drive gear
counterclockwise ı, the starter clutch and
the starter clutch drive gear should
engage. If the starter clutch drive gear and
starter clutch do not engage, the starter
clutch is faulty and must be replaced.
When turning the starter clutch drive gear
clockwise Å, it should turn freely.
If the starter clutch drive gear does not
turn freely, the starter clutch is faulty and
must be replaced.
Å
ı
1
2
EC4L5000
ASSEMBLY AND INSTALLATION
CDI magneto
1. Install:
Stator 1
Bolt (stator)
Lead guide
Screw (lead guide) 2
Pickup coil 3
Bolt (pickup coil)
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)LT
T R..7 Nm (0.7 m · kg, 5.1 ft · lb)LT
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)LT
2. Install:
Stater idle gear 1
Plate 2
Bolt 3
Washer 4
NOTE:
Apply the engine oil on the starter idle gear
inner circumference.
4
1
2
3
ET R..7 Nm (0.7 m · kg, 5.1 ft · lb)