oil YAMAHA WR 450F 2003 Repair Manual

4 - 45
ENGCYLINDER AND PISTON
Piston ring
1. Measure:
Ring 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:
Piston ring
(in cylinder)
NOTE:
Insert a ring into the cylinder and push it
approximately 10 mm (0.39 in) into the cylin-
der. Push the ring with the piston crown so that
the ring will be at a right angle to the cylinder
bore.
a10 mm (0.39 in)
Side clearance:
Standard
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)
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.
End gap:
Standard
Top ring0.20 ~ 0.30 mm
(0.008 ~ 0.012 in)0.55 mm
(0.022 in)
2nd ring0.35 ~ 0.50 mm
(0.014 ~ 0.020 in)0.85 mm
(0.033 in)
Oil ring0.20 ~ 0.50 mm
(0.01 ~ 0.02 in)—

4 - 46
ENGCYLINDER AND PISTON
Piston pin
1. Inspect:
Piston pin
Blue discoloration/grooves → Replace,
then inspect the lubrication system.
2. Measure:
Piston pin-to-piston clearance
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 outside diameter (piston pin)
a.
If out of specification, replace the piston
pin.
Outside diameter (piston pin):
17.991 ~ 18.000 mm
(0.7083 ~ 0.7087 in)
Measure the inside diameter (piston) b.
Inside diameter (piston):
18.004 ~ 18.015 mm
(0.7088 ~ 0.7093 in)
Calculate the piston pin-to-piston clear-
ance with the following formula.
Piston pin-to-piston clearance =
Inside diameter (piston) b –
Outside diameter (piston pin) a
If out of specification, replace the piston.
Piston pin-to-piston clearance:
0.004 ~ 0.024 mm
(0.00016 ~ 0.00094 in)
: 0.07 mm (0.003 in)

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

ENG
4 - 51 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
2,92–3,08 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 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:
2,92 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/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:
2,92 ~ 3,08 mm
(0,115 ~ 0,121 in)
:
2,8 mm (0,110 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
KUPPLUNG
EMBRAGUE

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.
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.
7. Install:
Pressure plate 1

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 Kickstarter 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.