2005 YAMAHA TTR90 engine oil

3 - 13
INSP
ADJFRONT FORK INSPECTION/REAR SHOCK ABSORBER INSPECTION/
REAR SHOCK ABSORBER SPRING PRELOAD ADJUSTMENT
Tighten the wheel axle nut while pushing
down the drive chain.
T R..
Axle nut:
60 Nm (6.0 m • kg, 43 ft • lb)
Tighten the locknuts.
T R..
Locknut:
7 Nm (0.7 m • kg, 5.1 ft • lb)
EC36C000
FRONT FORK INSPECTION
1. Inspect:
Front fork smooth action
Operate the front brake and stroke the
front fork.
Unsmooth action/oil leakage → Repair
or replace.
EC36K000
REAR SHOCK ABSORBER INSPECTION
1. Inspect:
Swingarm smooth action
Abnormal noise/unsmooth action →
Grease the pivoting points or repair the
pivoting points.
Damage/oil leakage → Replace.
REAR SHOCK ABSORBER SPRING
PRELOAD ADJUSTMENT
1. Elevate the rear wheel by placing the
suitable stand under the engine.
2. Remove:
Rear shock absorber
Refer to “SWINGARM” section in the
CHAPTER 5.
3. Remove:
Spring guide 1
NOTE:
While compressing the spring, remove the
spring guide.

4 - 11
ENGCYLINDER HEAD
4. Remove:
Cylinder head
NOTE:
Loosen the bolts and nuts in their proper
loosening sequence.
Start by loosening each bolt and nut 1/2 turn
until all are loose.
ASSEMBLY AND INSTALLATION
1. Install:
Cylinder head
2. Tighten:
Nuts
Bolts
NOTE:
Apply the engine oil on the contact surfaces
of the nuts, bolts and copper washers.
Follow the numerical order shown in the illus-
tration. Tighten the bolts and nuts in two
stages.
T R..22 Nm (2.2 m · kg, 16 ft · lb)
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
3. Install:
Camshaft sprocket 1
Installation steps:
Turn the crankshaft counterclockwise until
the “I” mark a on the rotor is aligned with
the stationary pointer b on the crankcase
cover.
Align the “I” mark c on the camshaft
sprocket with the stationary pointer d on
the cylinder head.
Fit the timing chain 2 onto camshaft
sprocket and install the camshaft sprocket
on the camshaft.
NOTE:
When installing the camshaft sprocket, keep
the timing chain as tense as possible on the
exhaust side.

4 - 14
ENGCAMSHAFT AND ROCKER ARMS
REMOVAL POINTS
Rocker arm shaft
1. Remove:
Rocker arm shafts
NOTE:
Use a slide hammer bolt 1 and weight 2 to
slide out the rocker arm shafts.
Slide hammer set:
YU-1083-A
Slide hammer bolt:
90890-01085
Weight:
90890-01084
INSPECTION
Camshaft
1. Measure:
Cam lobes length a and b
Out of specification → Replace.
Cam lobes length limit:
Intake:
a 25.398 mm (0.9999 in)
b 21.004 mm (0.8269 in)
Exhaust:
a 25.256 mm (0.9943 in)
b 21.017 mm (0.8274 in)
ASSEMBLY AND INSTALLATION
1. Apply:
Molybdenum disulfide oil
(onto the camshaft cam lobe)
Engine oil
(onto the camshaft bearing)
2. Install:
Camshaft 1

4 - 25
ENGCYLINDER AND PISTON
Piston pin
1. Inspect:
Piston pin
Blue discoloration/grooves →
Replace, then inspect the lubrication
system.
2. Measure:
Piston pin outside diameter
Piston pin bore inside diameter
ASSEMBLY AND INSTALLATION
Piston
1. Install:
Piston rings
(onto the piston)
NOTE:
Be sure to install the piston rings so that the
manufacturer’s marks or numbers are
located on the upper side of the rings.
Lubricate the piston and piston rings liberally
with engine oil. Measurement steps:
Measure the piston pin outside diameter
a.
If out of specification, replace the piston
pin.
Outside diameter (piston pin):
12.996 ~ 13.000 mm
(0.5117 ~ 0.5118 in)
:12.976 mm (0.5109 in)
Measure the piston inside diameter b.
If out of specification, replace the piston.
Inside diameter (piston):
13.002 ~ 13.013 mm
(0.5119 ~ 0.5123 in)
: 13.045 mm (0.5136 in)

4 - 26
ENG

CYLINDER AND PISTON
2. Position:

Top ring

2nd ring

Oil ring
Offset the piston ring end gaps as
shown.
a
Top ring end
b
Oil ring end (lower)
c
Oil ring end (upper)
d
2nd ring end
3. Install:

Piston
1


Piston pin
2


Piston pin clips
3

NOTE:


Apply engine oil onto the piston pin, piston
ring 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.
4. Lubricate:

Piston

Piston rings

Cylinder
NOTE:

Apply a liberal coating of engine oil.
New

Cylinder
1. Install:

Dowel pins

Gasket

Cylinder
1

NOTE:

Install the cylinder with one hand while com-
pressing the piston rings with the other hand.
CAUTION:


Be careful not to damage the timing chain
damper during installation.

Pass the timing chain through the timing
chain cavity.
New

4 - 27
ENG

CLUTCH
CLUTCH
CRANKCASE COVER (LEFT AND RIGHT)
Extent of removal:
1
Crankcase cover (left) removal
2
Crankcase cover (right) removal
Extent of removal Order Part name Q’ty Remarks
CRANKCASE COVER (LEFT
AND RIGHT) REMOVAL
Preparation for removal Drain the engine oil. Refer to “ENGINE OIL REPLACEMENT”
section in the CHAPTER 3.
1 Shift pedal 1
2 Drive sprocket cover 1
3 Crankcase cover (left) 1
4 Gasket 1
5 Dowel pin 2
6 Clutch adjusting screw 1
7 Kick crank 1
8 Crankcase cover (right) 1
9 Gasket 1
10 Dowel pin 2
1
2

4 - 44
ENGCDI MAGNETO AND STARTER CLUTCH (TT-R90E)
3. Install:
Spring 1
Spring cap 2
Pin 3
4. Install:
Shim 1
Starter wheel gear 2
Starter idle gear 3
Shaft 4
NOTE:
Apply the molybdenum disulfide oil on the
starter wheel gear inner circumference.
Apply the engine oil on the starter idle gear
inner circumference and on the shaft outer
circumference.
12
3
123
5. Install:
Woodruff key 1
Rotor 2
NOTE:
Clean the tapered portion of the crankshaft
and the magneto hub.
When installing the magneto rotor, make
sure the woodruff key is properly seated in
the key way of the crankshaft.
6. Tighten:
Nut (magneto) 1
NOTE:
Tighten the nut (magneto) 1 while holding the
magneto 2 with a sheave holder 3.
7. Install:
Crankcase cover (left)
NOTE:
Pass the starter motor lead 1 and neutral
switch lead 2 into the crankcase cover
groove as shown.
Fasten the starter motor lead with the clamp 3.
Sheave holder:
YS-1880-A/90890-01701
T R..48 Nm (4.8 m · kg, 35 ft · lb)
2
1
1
3

4 - 45
ENGCRANKCASE AND CRANKSHAFT
CRANKCASE AND CRANKSHAFT
Extent of removal Order Part name Q’ty Remarks
CRANKCASE SEPARATION
AND CRANKSHAFT REMOVAL
Preparation for removal Seat, fuel tank and rear fender
Exhaust pipe
Air filter case
Carburetor Refer to “CARBURETOR” section.
Drain the engine oil Refer to “ENGINE OIL REPLACEMENT”
section in the CHAPTER 3.
Engine guard and drive sprocket
Engine assembly From the chassis.
Cylinder head Refer to “CYLINDER HEAD” section.
Cylinder and piston Refer to “CYLINDER AND PISTON” sec-
tion.
Clutch housing and clutch carrier Refer to “CLUTCH” section.
Kick axle assembly Refer to “KICK AXLE” section.