oil YAMAHA YZ450F 2003 Repair Manual

4 - 47
ENGCYLINDER AND PISTON
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)
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.
2. Install:
Bolt (cylinder)
45°
135°135°
a
b ced
3New
New
New
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)

4 - 48
ENGCLUTCH
CLUTCH
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

4 - 51
ENG
EMBRAYAGE
KUPPLUNG
Reibscheiben
1. Messen:
Reibscheibenstärke
Unvorschriftsmäßig → Die Reibschei-
ben im Satz erneuern.
Die Reibscheiben an vier Stellen mes-
sen.
Kupplungsscheiben
1. Messen:
Verzug der Kupplungsscheiben
Unvorschriftsmäßig → Kupplungsschei-
ben im Satz erneuern.
Eine Richtplatte 1 und eine Fühlerleh-
re 2 verwenden.
Reibscheibenstärke
2,92–3,08 mm
2,8 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 dis-
ques de friction.
Mesurer chaque disque en quatre endroits.
Disque 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.
Epaisseur de disque de friction:
2,92 à 3,08 mm (0,115 à 0,121 in)
: 2,8 mm (0,110 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/déformation →
Changer.

4 - 52
ENGCLUTCH
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 and tighten the bolt (seat plate).
2
1a
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.
ÅFor 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)
Åı

4 - 53
ENGCLUTCH
3. Bend the lock washer 1 tab.
4. Install:
Friction plate 1
Clutch plate 2
NOTE:
Install the clutch plates and friction plates
alternately on the clutch boss, starting with a
friction plate and ending with a friction plate.
Apply the engine oil on the friction plates and
clutch plates.
2 1
E
5. 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
6. Install:
Push rod 2 1
Ball 2
Push rod 1 3
NOTE:
Apply the engine oil on the push rod 1, 2 and
ball.

4 - 55
ENG
OIL FILTER, WATER PUMP AND CRANKCASE COVER
(RIGHT)
OIL FILTER, WATER PUMP AND CRANKCASE COVER (RIGHT)
OIL FILTER, WATER PUMP AND CRANKCASE COVER (RIGHT)
Extent of removal:1 Oil filter removal2 Water pump removal
3 Crankcase cover (right) removal
Extent of removal Order Part name Q’ty Remarks
OIL FILTER, WATER PUMP
AND CRANKCASE COVER
(RIGHT) REMOVAL
Preparation for removal Drain the engine oil. Refer to “ENGINE OIL REPLACEMENT”
section in the CHAPTER 3.
Drain the coolant. Refer to “COOLANT REPLACEMENT”
section in the CHAPTER 3.
Exhaust pipe Refer to “EXHAUST PIPE AND
SILENCER” section.
Brake pedal Refer to “ENGINE REMOVAL” section.
Clutch cover Refer to “CLUTCH” section.
1 Oil filter cover 1
2 Oil filter 1
3 Coolant pipe 2 1
4 Water pump housing 1
5 Pin 2
6 Oil delivery pipe 1
1
2
3

4 - 56
ENG
OIL FILTER, WATER PUMP AND CRANKCASE COVER
(RIGHT)
Extent of removal Order Part name Q’ty Remarks
7 Oil hose 1
8 Kick starter 1
9 Crankcase cover (right) 1
10 Gasket 1
11 Dowel pin/O-ring 4/2
12 Impeller 1
Refer to “REMOVAL POINTS”. 13 Plain washer 1
14 Impeller shaft 1
15 Oil seal 1 1
16 Oil seal 2 1
17 Bearing 1
2
3
2

4 - 57
ENG
OIL FILTER, WATER PUMP AND CRANKCASE COVER
(RIGHT)
REMOVAL POINTS
EC4G3110
Impeller shaft
1. Remove:
Impeller 1
Plain washer 2
Impeller shaft 3
NOTE:
Hold the impeller shaft on its width across the
flats a with spanners, etc. and remove the
impeller.
EC4G3210
Oil seal
NOTE:
It is not necessary to disassemble the water
pump, unless there is an abnormality such as
excessive change in coolant level, discolora-
tion of coolant, or milky transmission oil.
1. Remove:
Bearing 1
Oil seal 2
INSPECTION
EC444200
Impeller shaft
1. Inspect:
Impeller shaft 1
Bend/wear/damage → Replace.
Fur deposits → Clean.

4 - 58
ENG
OIL FILTER, WATER PUMP AND CRANKCASE COVER
(RIGHT)
EC4H4600
Bearing
1. Inspect:
Bearing
Rotate inner race with a finger.
Rough spot/seizure → Replace.
EC444400
Oil seal
1. Inspect:
Oil seal
Wear/damage → Replace.
ASSEMBLY AND INSTALLATION
EC4G5110
Oil seal
1. Install:
Oil seal 1
NOTE:
Apply the lithium soap base grease on the oil
seal lip.
Install the oil seal with its manufacture’s
marks or numbers facing inward.
Bearing
1. Install:
Bearing 1
NOTE:
Install the bearing by pressing its outer race
parallel.
New

4 - 59
ENG
OIL FILTER, WATER PUMP AND CRANKCASE COVER
(RIGHT)
EC4G5220
Impeller shaft
1. Install:
Impeller shaft 1
Plain washer 2
Impeller 3
NOTE:
Take care so that the oil seal lip is not dam-
aged or the spring does not slip off its posi-
tion.
When installing the impeller shaft, apply the
engine oil on the oil seal lip, bearing and
impeller shaft. And install the shaft while
turning it.
Hold the impeller shaft on its width across
the flats a with spanners, etc. and install the
impeller.
T R..14 Nm (1.4 m · kg, 10 ft · lb)
Crankcase cover (right)
1. Install:
Dowel pin 1
O-ring 2
Collar 3
Gasket 4 New
2. Install:
Crankcase cover (right) 1
Bolt
NOTE:
Apply the engine oil on the impeller shaft
end.
When installing the crankcase cover onto the
crankcase, be sure that the impeller shaft
end 2 aligns with the balancer end slot 3.
Tighten the bolts in stage, using a crisscross
pattern.
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)