2008 YAMAHA YZ250F engine oil

4-29
CLUTCH
CLUTCH
REMOVING THE CLUTCHOrder Part name Q'ty Remarks Drain the engine oil. Refer to "CHANGING THE ENGINE OIL"
section in the CHAPTER 3.
Brake pedal Refer to "ENGINE REMOVAL" section.
Clutch cable Disconnect at engine side.
1 Clutch cover 1
2 Clutch spring 5
3 Pressure plate 1
4 Push rod 1 1
5 Circlip 1
6 Washer 1
7 Bearing 1
8Ball 1
9 Push rod 2 1
10 Friction plate 9
11 Clutch plate 8
12 Cushion spring 1
13 Seat plate 1

4-31
CLUTCH
REMOVING THE CLUTCH BOSS
1. Remove:•Nut "1"
• Lock washer "2"
• Clutch boss "3"
Straighten the lock washer tab and
use the clutch holding tool "4" to hold
the clutch boss.
A. For USA and CDN
B. Except for USA and CDN
CHECKING THE CLUTCH
HOUSING AND BOSS
1. Inspect: • Clutch housing "1"Cracks/wear/damage
→Replace.
• Clutch boss "2"
Scoring/wear/damage
→Re-
place.
CHECKING THE PRIMARY DRIVEN
GEAR
1. Check: • Circumferential playFree play exists
→Replace.
• Gear teeth "a"
Wear/damage
→Replace. CHECKING THE CLUTCH
SPRINGS
1. Measure:
• Clutch spring free length "a"
Out of specification
→Replace
springs as a set.
CHECKING THE FRICTION
PLATES
1. Measure: • Friction plate thicknessOut of specification
→Replace
friction plate as a set.
Measure at all four points.
CHECKING THE CLUTCH PLATES
1. Measure: • Clutch plate warpageOut of specification
→Replace
clutch plate as a set.
Use a surface plate "1" and thick-
ness gauge "2". CHECKING THE PUSH LEVER
SHAFT
1. Inspect:
• Push lever shaft "1"
Wear/damage
→Replace.
CHECKING THE PUSH ROD
1. Inspect: • Push rod 1 "1"
• Bearing "2"
• Washer "3"
• Push rod 2 "4"
• Ball "5"Wear/damage/bend
→Replace.
INSTALLING THE PUSH LEVER
SHAFT
1. Install: • Push lever shaft "1"
• Bolt (push lever shaft) "2"
• Apply the lithium soap base grease on the oil seal lip.
• Apply the engine oil on the push le-
ver shaft.
• Fit the seat plate "3" in the groove "a" of the push lever shaft and tight-
en the bolt (seat plate).
Clutch holding tool:
YM-91042/90890-04086
Clutch spring free
length:35.7 mm (1.41 in)
: 34.7 mm (1.37
in)
Friction plate thickness: 2.9–3.1 mm (0.114–
0.122 in)
: 2.8 mm (0.110
in)
Warp limit: 0.1 mm (0.004 in)
Bolt (push lever shaft):10 Nm (1.0 m•kg, 7.2
ft•lb)

4-32
CLUTCH
INSTALLING THE CLUTCH
1. Install:• Primary driven gear "1"
• Thrust washer "2"
• Clutch boss "3"
Apply the engine oil on the primary
driven gear inner circumference.
2. Install:• Lock washer "1"
• Nut (clutch boss) "2"
Use the clutch holding tool "3" to hold
the clutch boss.
A. For USA and CDN
B. Except for USA and CDN
3. Bend the lock washer "1" tab. 4. Install:
• Seat plate "1"
• Cushion spring "2"
• Install the seat plate with its cham-fered portion "a" facing the clutch
boss "3".
• Install the seat plate so that it is not caught on the step "b".
• Install the cushion spring with its concave surface "c" facing outward.
5. Install:• Friction plate "1"
• Clutch plate 1 "2"
• Clutch plate 2 "3"
• 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.
• Unlike the clutch plate 2, the clutch
plate 1 has no surface gloss. Use
the clutch plate 1 for the first while
paying attention to the difference in
surface gloss.
6. Install:• Bearing "1"
•Washer "2"
•Circlip "3" To push rod 1 "4".
Apply the engine oil on the bearing
and washer.
7. Install:• Push rod 2 "1"
• Ball "2"
• Push rod 1 "3"
Apply the engine oil on the push rod
1, 2 and ball.
8. Install:• Pressure plate "1"
9. Install: • Clutch spring "1"
• Bolt (clutch spring) "2"
Tighten the bolts in stage, using a
crisscross pattern.
10. Install:• Dowel pin "1"
• Gasket (clutch cover) "2"
Nut (clutch boss):
60 Nm (6.0 m•kg, 43
ft•lb)
Clutch holding tool: YM-91042/90890-04086
Bolt (clutch spring):
10 Nm (1.0 m•kg, 7.2
ft•lb)

4-34
OIL FILTER ELEMENT AND WATER PUMP
OIL FILTER ELEMENT AND WATER PUMP
REMOVING THE OIL FILTER ELEMENT AND WATER PUMPOrder Part name Q'ty Remarks Drain the engine oil. Refer to "CHANGING THE ENGINE OIL"
section in the CHAPTER 3.
Drain the coolant. Refer to "CHANGING THE COOLANT" sec-
tion in the CHAPTER 3.
Radiator hose 3 Disconnect at water pump side.
Exhaust pipe Refer to "EXHAUST PIPE AND SILENCER"
section.
Brake pedal Refer to "ENGINE REMOVAL" section.
Right engine guard
1 Oil filter element cover 1
2 Oil filter element 1
3 Water pump housing 1
4 Oil delivery pipe 1
5 Bolt (oil hose) 1
6 Kickstarter crank 1
7 Right crankcase cover 1
8 Impeller 1 Refer to removal section.

4-37
OIL FILTER ELEMENT AND WATER PUMP
INSTALLING THE RIGHT
CRANKCASE COVER
1. Install:• Dowel pin "1"
• O-ring "2"
•Collar "3"
•Gasket "4"
Apply the lithium soap base grease
on the O-ring.
2. Install:• Right crankcase cover "1"
• Bolt (right crankcase cover) "2"
• Apply the engine oil on the impeller
shaft end.
• Mesh the impeller shaft gear "3"
with primary drive gear "4".
• Tighten the bolts in stage, using a crisscross pattern.
INSTALLING THE KICKSTARTER
CRANK
1. Install:
• Kickstarter crank "1" •Washer
• Bolt (kickstarter crank)
Install so that there is a clearance "a"
of 5 mm (0.20 in) or more between
the kickstarter and frame and that the
kickstarter does not contact the
crankcase cover when it is pulled.
2. Install:
• Oil hose "1"
• Bolt (oil hose) "2"
3. Install: • Copper washer "1"
• Oil delivery pipe "2"
• Union bolt (M8) "3"
• Union bolt (M10) "4"
INSTALLING THE WATER PUMP
HOUSING
1. Install: • Dowel pin "1"
• O-ring "2"
Apply the lithium soap base grease
on the O-ring.
2. Install:• Water pump housing "1"
• Bolt (water pump housing) "2"
INSTALLING THE OIL FILTER
ELEMENT
1. Install: • Oil filter element "1"
• O-ring "2"
• Oil filter element cover "3"
• Bolt (oil filter element cover)
Apply the lithium soap base grease
on the O-ring.
Bolt (right crankcase
cover): 10 Nm (1.0 m•kg, 7.2
ft•lb)
Bolt (kickstarter crank):
33 Nm (3.3 m•kg, 24
ft•lb)
Bolt (oil hose): 8 Nm (0.8 m•kg, 5.8
ft•lb)
Union bolt (M8): 18 Nm (1.8 m•kg, 13
ft•lb)
Union bolt (M10): 20 Nm (2.0 m•kg, 14
ft•lb)
Bolt (water pump hous-
ing):10 Nm (1.0 m•kg, 7.2
ft•lb)
Bolt (oil filter element
cover): 10 Nm (1.0 m•kg, 7.2
ft•lb)

4-39
BALANCER
REMOVING THE BALANCER
1. Straighten the lock washer tab.
2. Loosen:• Nut (primary drive gear) "1"
• Nut (balancer shaft driven gear)
"2"
Place an aluminum plate "a" between
the teeth of the balancer shaft drive
gear "3" and driven gear "4".
3. Remove:• Balancer shaft "1"
When removing the balancer shaft,
align the center "a" of the balancer
shaft weight along the line connecting
the centers of the crankshaft and bal-
ancer shaft.
CHECKING THE PRIMARY DRIVE
GEAR, BALANCER SHAFT DRIVE
GEAR AND BALANCER SHAFT
DRIVEN GEAR
1. Inspect:
• Primary drive gear "1"
• Balancer shaft drive gear "2"
• Balancer shaft driven gear "3"Wear/damage
→Replace. CHECKING THE BALANCER
SHAFT
1. Inspect:
• Balancer shaft
Cracks/damage
→Replace.
INSTALLING THE BALANCER
1. Install: • Balancer shaft "1"
• Apply the engine oil on the bearing.
• When installing the balancer shaft, align the center "a" of the balancer
shaft weight along the line connect-
ing the centers of the crankshaft
and balancer shaft.
2. Install:
• Balancer shaft driven gear "1"
Install the balancer shaft driven gear
onto the balancer shaft while aligning
the punch mark "a" on the balancer
shaft driven gear with the lower spline
"b" on the balancer shaft end.
3. Install:• Balancer shaft drive gear "1"
• Align the punched mark "a" on the balancer shaft drive gear with the
punched mark "b" on the balancer
shaft driven gear "2".
• Align the punched mark "c" on the
balancer shaft drive gear with the
lower spline "d" on the crankshaft
end.
4. Install:• Lock washer "1"
• Nut (balancer shaft driven gear) "2"
• Primary drive gear "3"
• Lock washer "4"
• Nut (primary drive gear) "5"
• Install the primary drive gear with its stepped side "a" facing the engine.
• Place an aluminum plate "b" be- tween the teeth of the balancer
shaft drive gear "6" and driven gear
"7".
5. Bend the lock washer tab.
Nut (balancer shaft driv-
en gear): 50 Nm (5.0 m•kg, 36
ft•lb)
Nut (primary drive gear): 75 Nm (7.5 m•kg, 54
ft•lb)

4-42
OIL PUMP
REMOVING THE OIL TANKOrder Part name Q'ty Remarks Drain the engine oil. Refer to "CHANGING THE ENGINE OIL"
section in the CHAPTER 3.
1Oil hose 2 1
2Oil hose 1 1
3 Dowel pin 2
4 Oil tank breather hose 1
5 Oil tank 1
6 Oil strainer 1

4-43
OIL PUMP
CHECKING THE OIL PUMP
1. Inspect:• Oil pump drive gear "1"
• Oil pump drive shaft "2"
• Rotor housing "3"
• Oil pump cover "4"Cracks/wear/damage
→Replace.
2. Measure: • Tip clearance "a"(between the inner rotor "1" and
outer rotor "2")
• Side clearance "b" (between the outer rotor "2" and
rotor housing "3")
• Housing and rotor clearance "c" (between the rotor housing "3"
and rotors "1" "2")
Out of specification
→Replace
the oil pump assembly.
3. Check: • Unsmooth
→Repeat steps #1 and
#2 or replace the defective parts. INSTALLING THE OIL PUMP
1. Install:
• Oil pump drive shaft "1"
•Washer "2"
• Dowel pin "3"
• Inner rotor 1 "4"
• Apply the engine oil on the oil pump drive shaft and inner rotor 1.
• Fit the dowel pin into the groove in the inner rotor 1.
2. Install:• Outer rotor 1 "1"
Apply the engine oil on the outer rotor
1.
3. Install:• Oil pump cover "1"
• Screw (oil pump cover) "2"
• Dowel pin "3"
• Inner rotor 2 "4"
•Circlip "5"
• Apply the engine oil on the inner ro-tor 2.
• Fit the dowel pin into the groove in
the inner rotor 2.
4. Install:• Outer rotor 2 "1"
• Dowel pin "2"
• Oil pump assembly "3"
• Bolt (oil pump assembly)[L = 25 mm (0.94 in)] "4"
• Bolt (oil pump assembly) [L = 30 mm (1.18 in)] "5"
Apply the engine oil on the outer rotor
2.
5. Install:• Oil pump drive gear "1"
• Washer "2"
• Circlip "3"
Apply the engine oil on the oil pump
drive gear inner circumference.
Tip clearance "a": 0.12 mm or less (0.0047
in or less)
: 0.20 mm
(0.008 in)
Side clearance "b": 0.09–0.17 mm (0.0035–
0.0067 in)
: 0.24 mm
(0.009 in)
Housing and rotor clear-
ance "c": 0.03–0.10 mm (0.0012–
0.0039 in)
: 0.17 mm
(0.0067 in)
Screw (oil pump cover):2 Nm (0.2 m•kg, 1.4
ft•lb)
Bolt (oil pump assem-
bly):
10 Nm (1.0 m•kg, 7.2
ft•lb)
Bolt (oil pump assem-
bly): 10 Nm (1.0 m•kg, 7.2
ft•lb)