2005 YAMAHA TTR90 oil

4 - 24
ENGCYLINDER AND PISTON
Piston ring
1. Measure:
Ring side clearance
Use a feeler gauge.
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:
Piston 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:
Ring 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:
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 - 31
ENG
EMBRAYAGE
KUPPLUNG
Kupplungsscheiben
1. Messen:
Verzug der Kupplungsscheiben
Unvorschriftsmäßig → Kupplungsschei-
ben im Satz erneuern.
Eine Richtplatte 1 und eine Fühlerleh-
re 2 verwenden.
Kupplungsfeder
1. Messen:
Ungespannte Länge der Kupplungsfe-
der a
Unvorschriftsmäßig → Die Feder im
Satz erneuern.
Druckstange
1. Messen:
Verzug (Druckstange Nr. 2)
Unvorschriftsmäßig → Erneuern.
Grenzwert:
0,2 mm (0,008 in)
Ungespannte Länge der Kupp-
lungsfeder
Standard Grenzwert
26,2 mm (1,03 in) 24,2 mm (0,95 in)
Druckstangen-Verzugsgrenze:
0,5 mm (0,02 in)
Primärkupplung
1. Messen:
Primärkupplungsgehäuse-Innendurch-
messer
Unvorschriftsmäßig → Erneuern.
Primärkupplungsgehäuse-Innen-
durchmesser:
105 mm (4,13 in)
: 106 mm (4,17 in)
2. Messen:
Tiefe a der Kupplungsbelag-Nut
Unvorschriftsmäßig → Erneuern.
Tiefe der Kupplungsbelag-Nut:
1,0–1,3 mm (0,039–0,051 in)
: 0,1 mm (0,004 in)
Disques d’embrayage
1. Mesurer:
Voile 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:
Longueur libre de ressort d’embrayage a
Hors spécification → Changer tous les res-
sorts.
Tige de commande
1. Mesurer:
Déformation (tige de commande n˚2)
Hors spécifications → Remplacer.
Limite de déformation:
0,2 mm (0,008 in)
Longueur libre de ressort
d’embrayage
Standard Limite
26,2 mm
(1,03 in)24,2 mm
(0,95 in)
Limite de déformation:
0,5 mm (0,02 in)
Embrayage primaire
1. Mesurer:
Diamètre 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)
2. Mesurer:
Profondeur de gorge de garniture d’embra-
yage a
Hors spécifications → Remplacer.
Profondeur de gorge de garniture
d’embrayage:
1,0 à 1,3 mm (0,039 à 0,051 in)
: 0,1 mm (0,004 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

4 - 38
ENGOIL PUMP
INSPECTION
Oil pump
1. Measure:
Tip clearance a
(between the inner rotor 1 and the
outer rotor 2)
Side clearance b
(between the outer rotor 2 and the
rotor housing 3)
Out of specification → Replace the oil
pump assembly.
Rotor housing and rotor clearance c
(between the rotor housing 3 and the
rotors 1 2)
Out of specification → Replace the oil
pump assembly.
Tip clearance a:
0.15 mm (0.0059 in)
: 0.2 mm (0.0079 in)
Side clearance b:
0.13 ~ 0.18 mm
(0.0051 ~ 0.0071 in)
: 0.23 mm (0.0091 in)
Rotor housing and rotor clear-
ance c:
0.06 ~ 0.10 mm
(0.0024 ~ 0.0039 in)
: 0.15 mm (0.006 in)
Rotary filter and oil strainer
1. Inspect:
Rotary filter 1
Oil strainer 2
Damage → Replace.
3Upper side
4Lower side
ASSEMBLY AND INSTALLATION
Rotary filter
1. Install:
Rotary filter 1
NOTE:
When installing the rotary filter, align the match
mark a on the rotary filter with the hole b of
the crankshaft.