2002 YAMAHA WR 426F oil

4 - 48
ENG
2. Position:
Top ring
2nd ring
Oil ring
Offset the piston ring end gaps as
shown.
aTop ring end
b2nd ring end
cOil ring end (upper)
dOil ring
eOil ring end (lower)
45°
135°135°
a
b ced
3. Install:
Piston 1
Piston pin 2
Piston pin clips 3
NOTE:
Apply engine oil onto the piston pin and pis-
ton.
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.
Install the piston pin clips with their ends fac-
ing downward.
4. Lubricate:
Piston
Piston rings
Cylinder
NOTE:
Apply a liberal coating of engine oil.
Cylinder
1. Install:
Dowel pins
O-ring
Gasket 1
Cylinder 2
NOTE:
Install the cylinder with one hand while com-
pressing the piston rings with the other hand.
CAUTION:
Pass the timing chain 3 through the tim-
ing chain cavity.
Be careful not to damage the timing chain
guide 4 during installation.
New
3New
New
CYLINDER AND PISTON

ENG
4 - 49
CLUTCH (WR426F)
CLUTCH (WR426F)
CLUTCH
Extent of removal:1 Push rod and push lever removal2 Push pod 1 disassembly
3 Friction plate and clutch plate removal4 Clutch housing removal
Extent of removal Order Part name Q’ty Remarks
CLUTCH REMOVAL
Preparation for removal Drain the engine oil. Refer to “ENGINE OIL REPLACEMENT”
section in the CHAPTER 3.
Brake pedal Refer to “ENGINE REMOVAL” section.
Clutch cable Disconnect at engine side.
1 Clutch cover 1
2 Gasket 1
3 Dowel pin 2
4 Clutch spring 6
5 Pressure plate 1
6 Push rod 1 1
7 Circlip 1
8 Plain washer 1
9 Bearing 1
10 Ball 1
11Push rod 2
1
41
2
3
1

ENG
4 - 52
Reibscheiben
1. Messen:
Reibscheibenstärke
Unvorschriftsmäßig → Die
Reibscheiben im Satz
erneuern.
Die Reibscheiben an vier
Stellen messen.
Kupplungsscheiben
1. Messen:
Verzug der Kupplungsschei-
ben
Unvorschriftsmäßig →
Kupplungsscheiben im Satz
erneuern.
Eine Richtplatte 1 und eine
Fühlerlehre 2 verwenden.
Reibscheibenstärke
2,9–3,1 mm
2,7 mm
Verzugsgrenze
0,1 mm
Druckhebel
1. Kontrollieren:
Druckhebel 1
Verschleiß/Beschädigung →
Erneuern.
Druckstangen
1. Kontrollieren:
Druckstange 1 1
Lager 2
Beilagscheibe 3
Druckstange 2 4
Kugel 5
Verschleiß/Beschädigung/
Verbiegung → Erneuern. Disque de friction
1. Mesurer:
Epaisseur de disque de friction
Hors-spécification → Changer
tous les disques de friction.
Mesurer chaque disque en qua-
tre endroits.
Disque d’embrayage
1. Mesurer:
Voile de disque d’embrayage
Hors-spécification → Changer
tous les disques d’embrayage.
Utiliser une plaque à surfacer
1 et une jauge d’épaisseur 2.
Epaisseur de disque de
friction:
2,9 à 3,1 mm
(0,114 à 0,122 in)
:
2,7 mm (0,106 in)
Limite de déformation:
0,1 mm (0,004 in)
Levier de poussée
1. Contrôler:
Levier de poussée 1
Usure/endommagement →
Changer.
Tige de poussée
1. Contrôler:
Tige de poussée 1 1
Roulement 2
Rondelle ordinaire 3
Tige de poussée 2 4
Bille 5
Usure/endommagement/défor-
mation → Changer.Disco de fricción
1. Medir:
Espesor del disco de fricción
Fuera de especificaciones →
Reemplazar el disco de fricción
como un juego.
Medir en los cuatro puntos.
Discos de embrague
1. Medir:
Alabeo de los discos de embra-
gue
Fuera de especificaciones →
Reemplazar los discos de
embrague como un juego.
Utilice un mármol de ajustador
1 y un juego de galgas 2.
Espesor del disco de fric-
ción:
2,9 ~ 3,1 mm
(0,114 ~ 0,122 in)
:
2,7 mm (0,106 in)
Límite de alabeo:
0,1 mm (0,004 in)
Palanca de empuje
1. Inspeccionar:
Palanca de empuje 1
Desgaste/daños → Reempla-
zar.
Varilla de empuje
1. Inspeccionar:
Varilla de empuje 1 1
Cojinete 2
Arandela plana 3
Varilla de empuje 2 4
Bola 5
Desgaste/daños/deformacio-
nes → Reemplazar.
EMBRAYAGE (WR426F)
KUPPLUNG (WR426F)
EMBRAGUE (WR426F)

4 - 53
ENGCLUTCH (WR426F)
EC4A5000
ASSEMBLY AND INSTALLATION
Push lever
1. Install:
Push lever 1
Bolt (push lever)
NOTE:
Apply the lithium soap base grease on the oil
seal lip.
Apply the engine oil on the push lever.
Fit the seat plate 2 in the groove a of the
push lever 1 and tighten the bolt (seat
plate).
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
Clutch
1. Install:
Primary driven gear 1
Thrust washer 2
Clutch boss 3
NOTE:
Apply the engine oil on the primary driven gear
inner circumference.
2. Install:
Lock washer 1
Nut (clutch boss) 2
NOTE:
Use the clutch holding tool 3 to hold the clutch
boss.
Å
For USA and CDN
ıExcept for USA and CDN
Clutch holding tool:
YM-91042/90890-04086
New
T R..75 Nm (7.5 m · kg, 54 ft · lb)
Å
ı

4 - 54
ENGCLUTCH (WR426F)
3. Bend the lock washer 1 tab.
4. Install:
Seat plate 1
Clutch damper spring 2
NOTE:
Install the seat plate with its chamfered por-
tion a facing the clutch boss 3.
Install the seat plate so that it is not caught
on the step b.
Install the clutch damper spring with the
“OUT SIDE” mark c facing out.
5. Install:
Friction plate 1 [d = ø128 mm (5.04 in)]
1
Clutch plate 2
Friction plate 2 [d = ø119 mm (4.69 in)]
3
NOTE:
Install the clutch plates and friction plates
alternately on the clutch boss, starting with a
friction plate and ending with a friction plate.
Use the friction plate 1 for the first while pay-
ing attention to the difference in inner diame-
ter.
1
2
c
3
a
b
6. Install:
Bearing 1
Plain washer 2
Circlip 3
To push rod 1 4.
NOTE:
Apply the engine oil on the bearing and plain
washer.
New

4 - 55
ENGCLUTCH (WR426F)
7. Install:
Push rod 2 1
Ball 2
Push rod 1 3
NOTE:
Apply the engine oil on the push rod 1, 2 and
ball.
8. Install:
Pressure plate 1
9. Install:
Clutch spring
Bolt (clutch spring)
NOTE:
Tighten the bolts in stage, using a crisscross
pattern.
T R..8 Nm (0.8 m · kg, 5.8 ft · lb)
10. Install:
Gasket (clutch cover) 1
Dowel pin 2
New
11. Install:
Clutch cover 1
Bolt (clutch cover)
NOTE:
Tighten the bolts in stage, using a crisscross
pattern.
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)

ENG
4 - 56
CLUTCH (WR400F)
CLUTCH (WR400F)
CLUTCH
Extent of removal:1 Push rod and push lever removal2 Push rod 1 disassembly
3 Friction plate and clutch plate removal4 Clutch housing removal
Extent of removal Order Part name Q’ty Remarks
CLUTCH REMOVAL
Preparation for removal Drain the engine oil. Refer to “ENGINE OIL REPLACEMENT”
section in the CHAPTER 3.
Brake pedal Refer to “ENGINE REMOVAL” section.
Clutch cable Disconnect at engine side.
1 Clutch cover 1
2 Gasket 1
3 Dowel pin 2
4 Clutch spring 5
5 Pressure plate 1
6 Push rod 1 1
7 Circlip 1
8 Plain washer 1
9 Bearing 1
10Push rod 2
1
4
1
1
2
3

ENG
4 - 59
Reibscheiben
1. Messen:
Reibscheibenstärke
Unvorschriftsmäßig → Die
Reibscheiben im Satz
erneuern.
Die Reibscheiben an vier
Stellen messen.
Reibscheibenstärke
Reibscheibe 1
[ø112 mm]
2,72–2,88 mm
2,52 mm
Reibscheibe 2
[ø116 mm]
2,92–3,08 mm

2,72 mm
Kupplungsscheiben
1. Messen:
Verzug der Kupplungsschei-
ben
Unvorschriftsmäßig →
Kupplungsscheiben im Satz
erneuern.
Eine Richtplatte 1 und eine
Fühlerlehre 2 verwenden.
Verzugsgrenze
0,1 mm
Druckhebel
1. Kontrollieren:
Druckhebel 1
Verschleiß/Beschädigung →
Erneuern.
Druckstangen
1. Kontrollieren:
Druckstange 1 1
Lager 2
Beilagscheibe 3
Druckstange 2 4
Verschleiß/Beschädigung/
Verbiegung → Erneuern. Disque de friction
1. Mesurer:
Epaisseur de disque de friction
Hors-spécification → Changer
tous les disques de friction.
Mesurer chaque disque en qua-
tre endroits.
Epaisseur de disque de
friction:
Disque de friction 1
[ø112 mm (4,41 in)]:
2,72 à 2,88 mm
(0,107 à 0,113 in)
:
2,52 mm (0,099 in)
Disque de friction 2
[ø116 mm (4,57 in)]:
2,92 à 3,08 mm
(0,115 à 0,121 in)
:
2,72 mm (0,107 in)
Disque d’embrayage
1. Mesurer:
Voile de disque d’embrayage
Hors-spécification → Changer
tous les disques d’embrayage.
Utiliser une plaque à surfacer
1 et une jauge d’épaisseur 2.
Limite de déformation:
0,1 mm (0,004 in)
Levier de poussée
1. Contrôler:
Levier de poussée 1
Usure/endommagement →
Changer.
Tige de poussée
1. Contrôler:
Tige de poussée 1 1
Roulement 2
Rondelle ordinaire 3
Tige de poussée 2 4
Usure/endommagement/défor-
mation → Changer.Disco de fricción
1. Medir:
Espesor del disco de fricción
Fuera de especificaciones →
Reemplazar el disco de fricción
como un juego.
Medir en los cuatro puntos.
Espesor del disco de fric-
ción:
Disco de fricción 1
[ø112 mm (4,41 in)]:
2,72 ~ 2,88 mm
(0,107 ~ 0,113 in)
:
2,52 mm (0,099 in)
Disco de fricción 2
[ø116 mm (4,57 in)]:
2,92 ~ 3,08 mm
(0,115 ~ 0,121 in)
:
2,72 mm (0,107 in)
Discos de embrague
1. Medir:
Alabeo de los discos de embra-
gue
Fuera de especificaciones →
Reemplazar los discos de
embrague como un juego.
Utilice un mármol de ajustador
1 y un juego de galgas 2.
Límite de alabeo:
0,1 mm (0,004 in)
Palanca de empuje
1. Inspeccionar:
Palanca de empuje 1
Desgaste/daños → Reempla-
zar.
Varilla de empuje
1. Inspeccionar:
Varilla de empuje 1 1
Cojinete 2
Arandela plana 3
Varilla de empuje 2 4
Desgaste/daños/deformacio-
nes → Reemplazar.
EMBRAYAGE (WR400F)
KUPPLUNG (WR400F)
EMBRAGUE (WR400F)