oil YAMAHA TTR90 2000 Owner's Guide

4 - 15
ENGCAMSHAFT AND ROCKER ARMS
3. Apply:
lMolybdenum disulfide oil
(onto the rocker arm and rocker arm
shaft)
4. Install:
lRocker arm 1
lRocker arm shaft 2

4 - 19
ENGVALVES AND VALVE SPRINGS
2. Lap:
lValve face
lValve seat
NOTE:
After refacing the valve seat or replacing the
valve and valve guide, the valve seat and
valve face should be lapped.
Lapping steps:
lApply a coarse lapping compound to the
valve face.
lApply molybdenum disulfide oil to the
valve stem.
lInstall the valve into the cylinder head.
lTurn the valve until the valve face and
valve seat are evenly polished, then clean
off all of the compound.
lApply a fine lapping compound to the
valve face and repeat the above steps.
lApply Mechanic’s blueing dye (Dykem) to
the valve face.
lInstall the valve into the cylinder head.
lPress the valve through the valve guide
and onto the valve seat to make a clear
pattern.
lMeasure the valve seat width again. If the
valve seat width is out of specification,
reface and relap the valve seat.
CAUTION:
Do not let the compound enter the gap
between the valve stem and the guide.
NOTE:
For best lapping results, lightly tap the valve
seat while rotating the valve back and forth
between your hands.
NOTE:
After every lapping operation be sure to
clean off all of the compound from the valve
face and valve seat.

4 - 20
ENG

VALVES AND VALVE SPRINGS
ASSEMBLY AND INSTALLATION
1. Apply:
l
Molybdenum disulfide oil
(onto the valve stem and valve stem
seal)
2. Install:
l
Valve spring seats
l
Valves
l
Valve springs
l
Valve spring retainers
NOTE:

l
Make sure that each valve is installed in its
original place, also referring to the embossed
mark as follows.
Intake: “G”
Exhaust “L”
l
Install the valve springs with the larger pitch
a
facing upwards.
b
Smaller pitch
New

3. Install:
l
Valve cotters
NOTE:

While compressing the valve spring with a
valve spring compressor and attachment
1
install the valve cotters.
Valve spring compressor:
YM-01253/90890-01253
4. To secure the valve cotters onto the
valve stem, lightly tap the valve tip with a
piece of wood.
CAUTION:

Hitting the valve tip with excessive force
could damage the valve.

4 - 24
ENGCYLINDER AND PISTON
Piston ring
1. Measure:
lRing side clearance
Use a feeler gauge 1.
Out of specification ® Replace the pis-
ton and rings as a set.
NOTE:
Clean carbon from the piston ring grooves and
rings before measuring the side clearance.
2. Position:
lPiston ring
(in cylinder)
NOTE:
Insert a ring into the cylinder and push it
approximately 5 mm (0.20 in) into the cylinder.
Push the ring with the piston crown so that the
ring will be at a right angle to the cylinder bore.
a5 mm (0.20 in)
3. Measure:
lRing end gap
Out of specification ® Replace.
NOTE:
You cannot measure the end gap on the
expander spacer of the oil control ring. If the oil
control ring rails show excessive gap, replace
all three rings.
Side clearance
Standard Limit
Top
ring0.030 ~ 0.065 mm
(0.0012 ~ 0.0026 in)0.12 mm
(0.005 in)
2nd
ring0.020 ~ 0.055 mm
(0.0008 ~ 0.0022 in)0.12 mm
(0.005 in)
End gap
Standard Limit
Top
ring0.10 ~ 0.25 mm
(0.004 ~ 0.010 in)0.4 mm
(0.016 in)
2nd
ring0.10 ~ 0.25 mm
(0.004 ~ 0.010 in)0.4 mm
(0.016 in)
Oil
ring0.2 ~ 0.7 mm
(0.01 ~ 0.03 in)—

4 - 25
ENGCYLINDER AND PISTON
Piston pin
1. Inspect:
lPiston pin
Blue discoloration/grooves ®
Replace, then inspect the lubrication
system.
2. Measure:
lPiston pin-to-piston clearance
Measurement steps:
lMeasure 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)
lMeasure the piston inside diameter b.
lCalculate the piston pin-to-piston clear-
ance with the following formula.
Piston pin-to-piston clearance =
Bore size (piston pin) b –
Outside diameter (piston pin) a
lIf out of specification, replace the piston.
Piston pin-to-piston clearance:
0.002 ~ 0.017 mm
(0.00008 ~ 0.00067 in)
: 0.07 mm (0.003 in)
ASSEMBLY AND INSTALLATION
Piston
1. Install:
lPiston rings
(onto the piston)
NOTE:
lBe sure to install the piston rings so that the
manufacturer’s marks or numbers are
located on the upper side of the rings.
lLubricate the piston and piston rings liberally
with engine oil.

4 - 26
ENGCYLINDER AND PISTON
2. Position:
lTop ring
l2nd ring
lOil ring
Offset the piston ring end gaps as
shown.
aTop ring end
bOil ring end (lower)
cOil ring end (upper)
d2nd ring end
3. Install:
lPiston 1
lPiston pin 2
lPiston pin clips 3
NOTE:
lApply engine oil onto the piston pin, piston
ring 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.
4. Lubricate:
lPiston
lPiston rings
lCylinder
NOTE:
Apply a liberal coating of engine oil.
New
Cylinder
1. Install:
lCylinder 1
NOTE:
Install the cylinder with one hand while com-
pressing the piston rings with the other hand.
CAUTION:
lBe careful not to damage the timing chain
damper during installation.
lPass the timing chain through the timing
chain cavity.

4 - 27
ENGCLUTCH
CLUTCH
CRANKCASE COVER (LEFT AND RIGHT)
Extent of removal:1 Crankcase cover (left) removal2 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

ENG
4 - 31
EMBRAYAGE
KUPPLUNG
Kupplungsscheiben
1. Messen:
lVerzug der Kupplungsscheiben
Unvorschriftsmäßig ® Kupplungsschei-
ben im Satz erneuern.
Eine Richtplatte 1 und eine Fühlerleh-
re 2 verwenden.
Kupplungsfeder
1. Messen:
lUngespannte Länge der Kupplungsfe-
der a
Unvorschriftsmäßig ® Die Feder im
Satz erneuern.
Grenzwert
0,05 mm
Ungespannte Länge der Kupp-
lungsfeder
Standard Grenzwert
26,2 mm 24,2 mm
Druckstange
1. Messen:
lVerzug (Druckstange Nr. 2)
Unvorschriftsmäßig ® Erneuern.
Druckstangen-Verzugsgrenze
0,5 mm
Primärkupplung
1. Messen:
lPrimärkupplungsgehäuse-Innendurch-
messer
Unvorschriftsmäßig ® Erneuern.
Primärkupplungsgehäuse-Innen-
durchmesser
105 mm
106 mm
Disques d’embrayage
1. Mesurer:
lVoile de disque d’embrayage
Hors-spécification ® Changer tous les dis-
ques d’embrayage.
Utiliser une plaque à surfacer 1 et une
jauge d’épaisseur 2.
Ressorts d’embrayage
1. Mesurer:
lLongueur libre de ressort d’embrayage a
Hors spécification ® Changer tous les res-
sorts.
Limite de déformation:
0,05 mm (0,002 in)
Longueur libre de ressort
d’embrayage
Standard Limite
26,2 mm
(1,03 in)24,2 mm
(0,95 in)
Tige de commande
1. Mesurer:
lDéformation (tige de commande n˚2)
Hors spécifications ® Remplacer.
Limite de déformation:
0,5 mm (0,02 in)
Embrayage primaire
1. Mesurer:
lDiamètre intérieur de cloche d’embrayage
primaire
Hors spécifications ® Remplacer.
Diamètre intérieur de cloche
d’embrayage primaire:
105 mm (4,13 in)
: 106 mm (4,17 in)

4 - 36
ENGOIL PUMP
OIL PUMP
Extent of removal:1 Oil pump removal2 Oil strainer removal
3 Oil pump disassembly
Extent of removal Order Part name Q’ty Remarks
OIL PUMP REMOVAL AND DIS-
ASSEMBLY
Preparation for removal Clutch housing and clutch carrier Refer to “CLUTCH” section.
Shift shaft Refer to “SHIFT SHAFT” section.
1 Rotary filter 1
2 Oil pump assembly 1
3 Gasket 1
4 Oil pump drive gear 1
5 Oil strainer 1
6 Circlip 1
7 Oil pump driven gear 1
8 Spring washer 1
9 Circlip 1
10 Washer 1
1
2
3

4 - 37
ENGOIL PUMP
Extent of removal Order Part name Q’ty Remarks
11 Oil pump cover 1
12 Dowel pin 2
13 Oil pump drive shaft 1
14 Pin 1
15 Inner rotor 1
16 Outer rotor 1
17 Rotor housing 1
3