2002 YAMAHA YZ250F clock

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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 - 27
ENG
Release the screwdriver, check the ten-
sioner rod to come out and tighten the
gasket 4 and the cap bolt 5 to the speci-
fied torque.
T R..
Tensioner cap bolt:
7 Nm (0.7 m • kg, 5.1 ft • lb)
3. Turn:
Crankshaft
Counterclockwise several turns.
4. Check:
Rotor T.D.C. mark
Align with the crankcase align mark.
Camshaft match marks
Align with the cylinder head surface.
Out of alignment → Adjust.
5. Install:
Timing mark accessing screw 1
Crankshaft end accessing screw 2
6. Install:
Timing chain guide (top side) 1
Cylinder head cover gasket 2
Cylinder head cover 3
Bolt (cylinder head cover) 4
NOTE:
Apply the sealant on the cylinder head cover
gasket.
Quick gasket®:
ACC-QUICK-GS-KT
YAMAHA Bond No. 1215:
90890-85505
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
CAMSHAFTS

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ENGKICK SHAFT AND SHIFT SHAFT
REMOVAL POINTS
Kick shaft assembly
1. Remove:
Kick shaft assembly 1
NOTE:
Unhook the torsion spring 2 from the hole a
in the crankcase.
EC4C3101
Shift guide and shift lever assembly
1. Remove:
Bolt (shift guide)
Shift guide 1
Shift lever assembly 2
NOTE:
The shift lever assembly is disassembled at
the same time as the shift guide.
EC4N3100
Segment
1. Remove:
Bolt (segment) 1
Segment 2
NOTE:
Turn the segment counterclockwise until it
stops and loosen the bolt.
INSPECTION
Kick shaft and ratchet wheel
1. Check:
Ratchet wheel 1 smooth movement
Unsmooth movement → Replace.
Kick shaft 2
Wear/damage → Replace.
Spring 3
Broken → Replace.
EC4C4300
Kick gear, kick idle gear and ratchet wheel
1. Inspect:
Kick gear 1
Kick idle gear 2
Ratchet wheel 3
Gear teeth a
Ratchet teeth b
Wear/damage → Replace.

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ENGKICK SHAFT AND SHIFT SHAFT
3. Install:
Spring guide 1
NOTE:
Slide the spring guide into the kick shaft, make
sure the groove a in the spring guide fits on
the stopper of the torsion spring.
4. Install:
Kick shaft assembly 1
Washer 2
NOTE:
Apply the molybdenum disulfide grease on
the contacting surfaces of the kick shaft stop-
per a and stopper plate 3.
Apply the engine oil on the kick shaft.
Slide the kick shaft assembly into the crank-
case and make sure the kick shaft stopper a
fits into the stopper plate.
5. Hook:
Torsion spring 1
NOTE:
Turn the torsion spring clockwise and hook
into the proper hole a in the crankcase.
Kick idle gear
1. Install:
Kick idle gear 1
Washer 2
Circlip 3
NOTE:
Apply the engine oil on the kick idle gear
inner circumference.
Install the kick idle gear with its depressed
side a toward you.

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ENGCDI MAGNETO
EC4L3000
REMOVAL POINTS
Rotor
1. Remove:
Nut (rotor) 1
Washer 2
Use the rotor holding tool 3.
2. Remove:
Rotor 1
Use the flywheel puller 2.
NOTE:
When installing the flywheel puller, turn it
counterclockwise.
Rotor holding tool:
YU-1235/90890-01235
Flywheel puller:
YM-1189/90890-01189
EC4L4000
INSPECTION
EC4L4101
CDI magneto
1. Inspect:
Rotor inner surface a
Stator outer surface b
Damage → Inspect the crankshaft
runout and crankshaft bearing.
If necessary, replace CDI magneto and/
or stator.
EC4L4200
Woodruff key
1. Inspect:
Woodruff key 1
Damage → Replace.

7 - 21
TUNSETTING
EC72H002
Suspension setting
Front fork
NOTE:
If any of the following symptoms is experienced with the standard position as the base, make
resetting by reference to the adjustment procedure given in the same chart.
Before any change, set the rear shock absorber sunken length to the standard figure 90 ~
100 mm (3.5 ~ 3.9 in).
SymptomSection
Check Adjust
JumpLarge
gapMedium
gapSmall
gap
Stiff over entire range

Compression damping
Oil level (oil amount)
SpringTurn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Decrease oil level by about 5 ~ 10 mm (0.2 ~ 0.4 in).
Replace with soft spring.
Unsmooth movement
over entire range

Outer tube
Inner tube
Under bracket tightening
torqueCheck for any bends, dents, and other noticeable
scars, etc. If any, replace affected parts.
Retighten to specified torque.
Poor initial
movement

Rebound damping
Oil sealTurn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Apply grease in oil seal wall.
Soft over entire range,
bottoming out

Compression damping
Oil level (oil amount)
SpringTurn adjuster clockwise (about 2 clicks) to increase
damping.
Increase oil level by about 5 ~ 10 mm (0.2 ~ 0.4 in).
Replace with stiff spring.
Stiff toward stroke end
Oil level (oil amount) Decrease oil level by about 5 mm (0.2 in).
Soft toward stroke end,
bottoming out
Oil level (oil amount) Increase oil level by about 5 mm (0.2 in).
Stiff initial movement
Compression dampingTurn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Low front, tending to
lower front posture

Compression damping
Rebound damping
Balance with rear end
Oil level (oil amount)Turn adjuster clockwise (about 2 clicks) to increase
damping.
Turn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Set sunken length for 95 ~ 100 mm (3.7 ~ 3.9 in) when
one passenger is astride seat (lower rear posture).
Increase oil level by about 5 mm (0.2 in).
“Obtrusive” front, tend-
ing to upper front pos-
ture

Compression damping
Balance with rear end
Spring
Oil lever (oil amount)Turn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Set sunken length for 90 ~ 95 mm (3.5 ~ 3.7 in) when
one passenger is astride seat (upper rear posture).
Replace with soft spring.
Decrease oil level by about 5 ~ 10 mm (0.2 ~ 0.4 in).

7 - 22
TUNSETTING
Rear shock absorber
NOTE:
If any of the following symptoms is experienced with the standard position as the base, make
resetting by reference to the adjustment procedure given in the same chart.
Adjust the rebound damping in 2-click increments or decrements.
Adjust the low compression damping in 1-click increments or decrements.
Adjust the high compression damping in 1/6 turn increments or decrements.
SymptomSection
Check Adjust
JumpLarge
gapMedium
gapSmall
gap
Stiff, tending to sink

Rebound damping
Spring set lengthTurn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Set sunken length for 90 ~ 100 mm (3.5 ~ 3.9 in) when
one passenger is astride seat.
Spongy and unstable

Rebound damping
Low compression damping
SpringTurn adjuster clockwise (about 2 clicks) to increase
damping.
Turn adjuster clockwise (about 1 click) to increase
damping.
Replace with stiff spring.
Heavy and dragging

Rebound damping
SpringTurn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Replace with soft spring.
Poor road gripping

Rebound damping
Low compression damping
High compression damp-
ing
Spring set length
SpringTurn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Turn adjuster clockwise (about 1 clicks) to increase
damping.
Turn adjuster clockwise (about 1/6 clicks) to increase
damping.
Set sunken length for 90 ~ 100 mm (3.5 ~ 3.9 in) when
one passenger is astride seat.
Replace with soft spring.
Bottoming out

High compression damp-
ing
Spring set length
SpringTurn adjuster clockwise (about 1/6 turn) to increase
damping.
Set sunken length for 90 ~ 100 mm (3.5 ~ 3.9 in) when
one passenger in astride seat.
Replace with stiff spring.
Bouncing

Rebound damping
SpringTurn adjuster clockwise (about 2 clicks) to increase
damping.
Replace with soft spring.
Stiff travel

High compression damp-
ing
Spring set length
SpringTurn adjuster counterclockwise (about 1/6 turn) to
decrease damping.
Set sunken length for 90 ~ 100 mm (3.5 ~ 3.9 in) when
one passenger is astride seat.
Replace with soft spring.