bolt pattern YAMAHA YZ250F 2002 Owners Manual

4 - 22
ENGCAMSHAFTS
REMOVAL POINTS
Camshaft
1. Remove:
Timing mark accessing screw 1
Crankshaft end accessing screw 2
2. Align:
T.D.C. mark
With align mark.
Checking steps:
Turn the crankshaft counterclockwise with
a wrench.
NOTE:
Squeezing the decompression lever allows
the crankshaft to be turned easily.
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.
NOTE:
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 camshaft must align with the cyl-
inder 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
NOTE:
Remove the bolts (camshaft cap) in a criss-
cross pattern, working from the outside in.
CAUTION:
The bolts (camshaft cap) must be removed
evenly to prevent damage to the cylinder
head, camshafts or camshaft caps.

4 - 24
ENGCAMSHAFTS
4. Measure:
Camshaft-to-cap clearance
Out of specification → Measure bearing
diameter (camshaft).
Camshaft-to-cap clearance:
0.020 ~ 0.054 mm
(0.0008 ~ 0.0021 in)
: 0.08 mm (0.003 in)
Measurement steps:
Install the camshaft onto the cylinder
head.
Position a strip of Plastigauge® 1 onto the
camshaft.
Install the clip, dowel pins and camshaft
caps.
T R..
Bolt (camshaft cap):
10 Nm (1.0 m • kg, 7.2 ft • lb)
NOTE:
Tighten the bolts (camshaft cap) in a criss-
cross pattern from innermost to outer
caps.
Do not turn the camshaft when measuring
clearance with the Plastigauge®.
Remove the camshaft caps and measure
the width of the Plastigauge
® 1.
5. Measure:
Camshaft outside diameter a
Out of specification → Replace the
camshaft.
Within specification → Replace cam-
shaft case and camshaft caps as a set.
Camshaft sprocket
1. Inspect:
Camshaft sprocket 1
Wear/damage → Replace the camshaft
assembly and timing chain as a set.
Camshaft outside diameter:
21.967 ~ 21.980 mm
(0.8648 ~ 0.8654 in)
1

4 - 26
ENGCAMSHAFTS
CAUTION:
Do not turn the crankshaft during the
camshaft installation. Damage or
improper valve timing will result.
Install the clips, camshaft caps 4 and
bolts (camshaft cap) 5.
T R..
Bolt (camshaft cap):
10 Nm (1.0 m • kg, 7.2 ft • lb)
NOTE:
Before removing the clips, cover the cylin-
der head with a clean rag to prevent the
clips from into the cylinder head cavity.
Apply the engine oil on the thread and con-
tact surface of the bolts (camshaft cap).
Tighten the bolts (camshaft cap) 5 in a
crisscross pattern.
CAUTION:
The bolts (camshaft cap) must be tight-
ened evenly, or damage to the cylinder
head, camshaft caps, and camshaft will
result.
2. Install:
Timing chain tensioner
Installation steps:
While pressing the tensioner rod lightly
with fingers, use a thin screwdriver and
wind the tensioner rod up fully clockwise.
With the rod fully wound and the chain
tensioner UP mark a facing upward,
install the gasket 1 and the timing chain
tensioner 2, and tighten the bolt 3 to the
specified torque.
T R..
Bolt (timing chain tensioner):
10 Nm (1.0 m • kg, 7.2 ft • lb)

4 - 55
ENGCLUTCH
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 1
Bolt (clutch spring) 2
NOTE:
Tighten the bolts in stage, using a crisscross
pattern.
T R..8 Nm (0.8 m · kg, 5.8 ft · lb)
10. Install:
Dowel pin 1
Gasket (clutch cover) 2
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)

4 - 61
ENG

OIL FILTER ELEMENT, WATER PUMP AND RIGHT
CRANKCASE COVER
2. Install:

Right crankcase cover
1


Bolt (right crankcase cover)
2

NOTE:


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.
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)

Kickstarter crank
1. Install:

Kickstarter crank
1


Washer
2


Bolt (kickstarter crank)
3

NOTE:

Install the kickstarter crank so that the kick-
starter crank is as vertical as possible with the
distance
a
between the kickstarter crank and
the frame being 8 mm (0.31 in) or more.
2. Install:

Oil hose
1


Bolt (oil hose)
2

T R..33 Nm (3.3 m · kg, 24 ft · lb)
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)

3. Install:

Copper washer
1


Oil delivery pipe
2


Union bolt (M8)
3


Union bolt (M10)
4

T R..18 Nm (1.8 m · kg, 13 ft · lb)
T R..20 Nm (2.0 m · kg, 14 ft · lb)

4 - 81
ENGCDI MAGNETO
4. Connect:
CDI magneto lead
Refer 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 breather
hose) 2
Bolt (left crankcase cover) 3
NOTE:
Tighten the bolts in stage, using a crisscross
pattern.
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)

4 - 95
ENGCRANKCASE AND CRANKSHAFT
6. Tighten:
Hose guide 1
Clutch cable holder 2
Bolt (crankcase) 3
NOTE:
Tighten the crankcase tightening bolts in
stage, using a crisscross pattern.
T R..12 Nm (1.2 m · kg, 8.7 ft · lb)
7. Install:
Oil delivery pipe 2 1
O-ring 2
Bolt (oil delivery pipe 2) 3
NOTE:
Apply the lithium soap base grease on the O-
rings.
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
8. Install:
Timing chain 1
Timing chain guide (intake side) 2
Bolt (timing chain guide) 3
9. Remove:
Sealant
Forced out on the cylinder mating sur-
face.
10. Apply:
Engine oil
To the crank pin, bearing and oil deliv-
ery hole.
11. Check:
Crankshaft and transmission operation.
Unsmooth operation → Repair.
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)

5 - 5
CHAS

FRONT WHEEL AND REAR WHEEL
EC595000
ASSEMBLY AND INSTALLATION
Front wheel
1. Install:

Bearing (left)
1


Spacer
2


Bearing (right)
3


Oil seal
4

NOTE:


Apply the lithium soap base grease on the
bearing and oil seal lip when installing.

Use a socket that matches the outside diam-
eter of the race of the bearing.

Left side of bearing shall be installed first.

Install the oil seal with its manufacture’s
marks or numbers facing outward.
ACHTUNG:CAUTION:

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
NOTE:
Tighten the bolts in stage, using a crisscross
pattern.
T R..12 Nm (1.2 m · kg, 8.7 ft · lb)
3. Install:
Collar 1
NOTE:
Apply the lithium soap base grease on the oil
seal lip.
Install the collars with their projections a
facing the wheel.
4. Install:
Wheel
NOTE:
Install the brake disc 1 between the brake
pads 2 correctly.

5 - 7
CHASFRONT WHEEL AND REAR WHEEL
9. Install:
Brake hose cover 1
Washer 2
Bolt [brake hose cover (M8)] 3
Bolt [brake hose cover (M6)] 4
T R..16 Nm (1.6 m · kg, 11 ft · lb)
T R..7 Nm (0.7 m · kg, 5.1 ft · lb)
Rear wheel
1. Install:
Bearing (right) 1
Circlip 2
Spacer 3
Bearing (left) 4
Oil seal 5
NOTE:
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 outside diam-
eter of the race of the bearing.
Right side of bearing shall be installed first.
Install the oil seal with its manufacture’s
marks or numbers facing outward.
ACHTUNG:CAUTION:
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
NOTE:
Tighten the bolts in stage, using a crisscross
pattern.
T R..14 Nm (1.4 m · kg, 10 ft · lb)

5 - 8
CHAS
3. Install:
Rear wheel sprocket 1
Bolt (rear wheel sprocket) 2
Washer (rear wheel sprocket) 3
Nut (rear wheel sprocket) 4
NOTE:
Tighten the nuts in stage, using a crisscross
pattern.
T R..42 Nm (4.2 m · kg, 30 ft · lb)
FRONT WHEEL AND REAR WHEEL
4. Install:
Collar 1
NOTE:
Apply the lithium soap base grease on the oil
seal lip.
5. Install:
Wheel
NOTE:
Install the brake disc 1 between the brake
pads 2 correctly.
6. Install:
Drive chain 1
NOTE:
Push the wheel 2 forward and install the drive
chain.
7. Install:
Left drive chain puller 1
Wheel axle 2
NOTE:
Install the left drive chain puller, and insert
the wheel axle from left side.
Apply the lithium soap base grease on the
wheel axle.