2008 YAMAHA YZ250F bolt pattern

4-16
CAMSHAFTS
REMOVING THE CAMSHAFT
1. Remove:• Timing mark accessing screw "1"
• Crankshaft end accessing screw "2"
2. Align: • T.D.C. mark
With align mark.
Checking steps:
a. Turn the crankshaft counterclock- wise with a wrench.
b. Align the T.D.C. mark "a" on the rotor with the align mark "b" on the
crankcase cover when piston is at
T.D.C. on compression stroke.
In order to be sure that the piston is at
Top Dead Center, the punch mark "c"
on the exhaust camshaft and the
punch mark "d" on the intake cam-
shaft must align with the cylinder
head surface, as shown in the illustra-
tion.
3. Remove:• Timing chain tensioner cap bolt
"1"
• Timing chain tensioner "2"
•Gasket 4. Remove:
• Bolt (camshaft cap) "1"
• Camshaft cap "2"
•Clip
Remove the bolts (camshaft cap) in a
crisscross pattern, working from the
outside in.
The bolts (camshaft cap) must be
removed evenly to prevent dam-
age to the cylinder head, cam-
shafts or camshaft caps.
5. Remove:• Exhaust camshaft "1"
• Intake camshaft "2"
Attach a wire "3" to the timing chain to
prevent it from falling into the crank-
case.
CHECKING THE CAMSHAFT
1. Inspect:• Cam lobe
Pitting/scratches/blue discolora-
tion
→Replace.
2. Measure:
• Cam lobe length "a" and "b" Out of specification
→Replace.
3. Measure: • Runout (camshaft)Out of specification
→Replace.
Cam lobes length: Intake "a":30.246–30.346 mm
(1.1908–1.1947 in)
: 30.146 mm (1.1869 in)
Intake "b":
22.45–22.55 mm
(0.8839–0.8878 in)
:
22.35 mm (0.8799 in)
Exhaust "a": 30.399–30.499 mm
(1.1968–1.2007 in)
: 30.299 mm (1.1929 in)
Exhaust "b": 22.45–22.55 mm
(0.8839–0.8878 in)
: 22.35 mm (0.8799 in)
Runout (camshaft): Less than 0.03 mm
(0.0012 in)

4-17
CAMSHAFTS
4. Measure:• Camshaft-to-cap clearanceOut of specification
→Measure
camshaft outside diameter.
Measurement steps:
a. Install the camshaft onto the cylin-
der head.
b. Position a strip of Plastigauge
®
"1" onto the camshaft.
c. Install the clip, dowel pins and camshaft caps.
• Tighten the bolts (camshaft cap) in a crisscross pattern from innermost
to outer caps.
• Do not turn the camshaft when measuring clearance with the Plas-
tigauge
®.
d. Remove the camshaft caps and measure the width of the Plasti-
gauge
® "1".
5. Measure:• Camshaft outside diameter "a"Out of specification
→Replace
the camshaft.
Within specification
→Replace
camshaft case and camshaft
caps as a set. CHECKING THE CAMSHAFT
SPROCKET
1. Inspect:
• Camshaft sprocket "1"
Wear/damage
→Replace the
camshaft assembly and timing
chain as a set.
CHECKING THE
DECOMPRESSION SYSTEM
1. Check: • Decompression system
Checking steps:
a. Check that the decompression mechanism cam "1" moves
smoothly.
b. Check that the decompression
mechanism cam lever pin "2"
projects from the camshaft.
CHECKING THE TIMING CHAIN
TENSIONER
1. Check:• While pressing the tensioner rod
lightly with fingers, use a thin
screwdriver "1" and wind the ten-
sioner rod up fully clockwise.
• When releasing the screwdriver by pressing lightly with fingers,
make sure that the tensioner rod
will come out smoothly.
• If not, replace the tensioner as- sembly. INSTALLING THE CAMSHAFT
1. Install:
• Exhaust camshaft "1"
• Intake camshaft "2"
Installation steps:
a. Turn the crankshaft counterclock- wise with a wrench.
• Apply the molybdenum disulfide oil
on the camshafts.
• Apply the engine oil on the decom- pression system.
• Squeezing the decompression le- ver allows the crankshaft to be
turned easily.
b. Align the T.D.C. mark "a" on the rotor with the align mark "b" on the
crankcase cover when piston is at
T.D.C. on compression stroke.
Camshaft-to-cap clear-
ance:
0.028–0.062 mm
(0.0011–0.0024 in)
:0.08 mm (0.003
in)
Bolt (camshaft cap): 10 Nm (1.0 m•kg, 7.2
ft•lb)
Camshaft outside diame-
ter: 21.959–21.972 mm
(0.8645–0.8650 in)

4-20
CYLINDER HEAD
CHECKING THE CYLINDER HEAD
1. Eliminate:• Carbon deposits (from the com-bustion chambers)
Use a rounded scraper.
Do not use a sharp instrument to
avoid damaging or scratching:
• Spark plug threads
•Valve seats
2. Inspect:
• Cylinder headScratches/damage
→Replace.
3. Measure: • Cylinder head warpageOut of specification
→Resurface.
Warpage measurement and resur-
facing steps:
a. Place a straightedge and a feeler
gauge across the cylinder head.
b. Use a feeler gauge to measure
the warpage.
c. If the warpage is out of specifica- tion, resurface the cylinder head.
d. Place a 400–600 grit wet sandpa- per on the surface plate, and re-
surface the head using a figure-
eight sanding pattern.
To ensure an even surface rotate the
cylinder head several times.
INSTALLING THE CYLINDER
HEAD
1. Install:• Dowel pin "1"
• Cylinder head gasket "2"
• Timing chain guide (exhaust side) "3"
• Cylinder head "4"
While pulling up the timing chain, in-
stall the timing chain guide (exhaust
side) and cylinder head.
2. Install: •Washer "1"
• Cable guide "2"
• Bolts [L = 145 mm (5.71 in)] "3"
• Bolts [L = 135 mm (5.31 in)] "4"
•Nuts "5"
• Apply the molybdenum disulfide grease on the thread and contact
surface of the bolts.
• Follow the numerical order shown in the illustration. Tighten the bolts
and nuts in two stages.
3. Install:• Copper washer "1"
• Oil delivery pipe "2"
• Union bolt (M8) "3"
• Union bolt (M10) "4"
4. Install: • Radiator pipe "1"
• Bolt (radiator pipe) "2"
Cylinder head warpage:
Less than 0.05 mm
(0.002 in)
Bolts [L = 145 mm (5.71
in)]:38 Nm (3.8 m•kg, 27
ft•lb)
Bolts [L = 135 mm (5.31
in)]: 38 Nm (3.8 m•kg, 27
ft•lb)
Nuts: 10 Nm (1.0 m•kg, 7.2
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 (radiator pipe): 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)

4-33
CLUTCH
11. Install:•Clutch cover "1"
• Bolt (clutch cover)
Tighten the bolts in stage, using a
crisscross pattern.
Bolt (clutch cover): 10 Nm (1.0 m•kg, 7.2
ft•lb)

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)

4-50
CDI MAGNETO
REMOVING THE ROTOR
1. Remove:• Nut (rotor) "1"
• Washer "2"Use the rotor holding tool "3".
2. Remove: • Rotor "1"Use the flywheel puller "2".
When installing the flywheel puller,
turn it counterclockwise.
CHECKING THE CDI MAGNETO
1. Inspect:• Rotor inner surface "a"
• Stator outer surface "b"
Damage
→Inspect the crankshaft
runout and crankshaft bearing.
If necessary, replace CDI magne-
to and/or stator.
CHECKING THE WOODRUFF KEY
1. Inspect: • Woodruff key "1"Damage
→Replace. INSTALLING THE CDI MAGNETO
1. Install:
•Stator "1"
• Screw (stator) "2"
• Apply the sealant on the grommet of the CDI magneto lead.
• Tighten the screws using the T30 bit.
2. Install:
• Woodruff key "1"
•Rotor "2"
• Clean the tapered portions of the crankshaft and rotor.
• When installing the woodruff key, make sure that its flat surface "a" is
in parallel with the crankshaft center
line "b".
• When installing the rotor, align the keyway "c" of the rotor with the
woodruff key.
3. Install:•Washer "1"
• Nut (rotor) "2"
Use the rotor holding tool "3". 4. Connect:
• CDI magneto leadRefer to "CABLE ROUTING DIA-
GRAM" section in the CHAPTER
2.
5. Install: • Dowel pin
• Gasket (left crankcase cover)
• Left crankcase cover "1"
• Hose guide (cylinder head breath-er hose) "2"
• Bolt (left crankcase cover)
Tighten the bolts in stage, using a
crisscross pattern.
Rotor holding tool:
YU-1235/90890-01235
Flywheel puller: YM-1189/90890-01189
Screw (stator):
10 Nm (1.0 m•kg,
7.2ft•lb)
YAMAHA Bond No. 1215
(ThreeBond
® No. 1215):
90890-85505
Nut (rotor): 56 Nm (5.6 m•kg, 40
ft•lb)
Rotor holding tool: YU-1235/90890-01235
Bolt (left crankcase cov-
er):10 Nm (1.0 m•kg, 7.2
ft•lb)

5-4
FRONT WHEEL AND REAR WHEEL
• Bolt (brake disc) "2"
Tighten the bolts in stage, using a
crisscross pattern.
3. Install:•Collar "1"
• Apply the lithium soap base grease on the oil seal lip.
• Install the collars with their projec- tions "a" facing the wheel.
4. Install:• Wheel
• Install the brake disc "1" between
the brake pads "2" correctly.
5. Install:• Wheel axle "1"
Apply the lithium soap base grease
on the wheel axle.
6. Install:• Nut (wheel axle) "1" 7. Tighten:
• Bolt (axle holder) "1"
Before tightening the bolt, fit the
wheel axle to the axle holder by strok-
ing the front fork several times with
the front brake applied.
INSTALLING THE REAR WHEEL
1. Install:
• Bearing (right) "1"
•Circlip "2"
•Spacer "3"
• Bearing (left) "4"
• Oil seal "5"
• Apply the lithium soap base grease on the bearing and oil seal lip when
installing.
• Install the bearing with seal facing
outward.
• Use a socket that matches the out- side diameter of the race of the
bearing.
• Right side of bearing shall be in- stalled first.
• Install the oil seal with its manufac- ture's marks or numbers facing out-
ward.
Do not strike the inner race of the
bearing. Contact should be made
only with the outer race.
2. Install:• Brake disc "1"
• Bolt (brake disc) "2"
Tighten the bolts in stage, using a
crisscross pattern.
3. Install:• Rear wheel sprocket "1"
• Bolt (rear wheel sprocket) "2"
• Washer (rear wheel sprocket) "3"
• Nut (rear wheel sprocket) "4"
Tighten the nuts in stage, using a
crisscross pattern.
Bolt (brake disc): 12 Nm (1.2 m•kg, 8.7
ft•lb)Nut (wheel axle):105 Nm (10.5 m•kg, 75
ft•lb)
Bolt (axle holder): 21 Nm (2.1 m•kg, 15
ft•lb)
Bolt (brake disc):14 Nm (1.4 m•kg, 10
ft•lb)
Nut (rear wheel sprock-
et): 42 Nm (4.2 m•kg, 30
ft•lb)