2002 YAMAHA WR 250F length

3 - 33
INSP
ADJ
SPROCKETS INSPECTION/DRIVE CHAIN INSPECTION
SPROCKETS INSPECTION
1. Inspect:
Sprocket teeth a
Excessive wear → Replace.
NOTE:
Replace the drive sprocket, rear wheel
sprocket and drive chain as a set.
DRIVE CHAIN INSPECTION
1. Remove:
Drive chain 1
NOTE:
Remove the drive chain using a drive chain
cutter 2.
2. Clean:
Drive chain
Brush off as much dirt as possible.
Then clean the drive chain using the
chain cleaner.
CAUTION:
This machine has a drive chain with small
rubber O-rings 1 between the side plates.
Steam cleaning, high-pressure washes,
certain solvent and kerosene can damage
these O-rings.
1
3. Inspect:
O-ring 1 (drive chain)
Damage → Replace the drive chain.
Roller 2
Side plate 3
Damage/wear → Replace the drive
chain.
4. Measure:
Drive chain length (10 links) a
Out of specification → Replace.
Drive chain length (10 links):
: 150.1 mm (5.91 in)

3 - 39
INSP
ADJREAR SHOCK ABSORBER INSPECTION/REAR SHOCK
ABSORBER SPRING PRELOAD ADJUSTMENT
EC36K000
REAR SHOCK ABSORBER INSPECTION
1. Inspect:
Swingarm smooth action
Abnormal noise/unsmooth action →
Grease the pivoting points or repair the
pivoting points.
Damage/oil leakage → Replace.
EC36M013
REAR SHOCK ABSORBER SPRING
PRELOAD ADJUSTMENT
1. Elevate the rear wheel by placing the
suitable stand under the engine.
2. Remove:
Rear frame
3. Loosen:
Locknut 1
4. Adjust:
Spring preload
By turning the adjuster 2.
* For EUROPE
** For AUS, NZ and ZA
NOTE:
Be sure to remove all dirt and mud from
around the locknut and adjuster before
adjustment.
The length of the spring (installed) changes
1.5 mm (0.06 in) per turn of the adjuster.
CAUTION:
Never attempt to turn the adjuster beyond
the maximum or minimum setting.
5. Tighten:
Locknut
6. Install:
Rear frame Stiffer →Increase the spring preload.
(Turn the adjuster 2 in.)
Softer →Decrease the spring preload.
(Turn the adjuster 2 out.)
Spring length (installed) a:
Standard length Extent of adjustment
244 mm (9.61 in)
* 247 mm (9.72 in)
** 243.5 mm (9.59 in)240.5 ~ 258.5 mm
(9.47 ~ 10.18 in)
T R..29 Nm (2.9 m · kg, 21 ft · lb)

4 - 24
ENGCAMSHAFTS
5. Remove:
Exhaust camshaft 1
Intake camshaft 2
NOTE:
Attach a wire 3 to the timing chain to prevent
it from falling into the crankcase.
INSPECTION
Camshaft
1. Inspect:
Cam lobe
Pitting/scratches/blue discoloration →
Replace.
2. Measure:
Cam lobe length a and b
Out of specification → Replace.
Cam lobes length:
Intake:
a30.296 ~ 30.346 mm
(1.1923 ~ 1.1947 in)
: 30.196 mm
(1.1888 in)
b22.45 ~ 22.55 mm
(0.8839 ~ 0.8878 in)
: 22.35 mm
(0.8799 in)
Exhaust:
a30.399 ~ 30.499 mm
(1.1968 ~ 1.2007 in)
: 30.299 mm
(1.1929 in)
b22.45 ~ 22.55 mm
(0.8839 ~ 0.8878 in)
: 22.35 mm
(0.8799 in)
3. Measure:
Runout (camshaft)
Out of specification → Replace.
Runout (camshaft):
Less than 0.03 mm (0.0012 in)

4 - 40
ENGVALVES AND VALVE SPRINGS
Valve spring
1. Measure:
Valve spring free length a
Out of specification → Replace.
2. Measure:
Compressed spring force a
Out of specification → Replace.
bInstalled length
Free length (valve spring):
Intake:
37.81 mm (1.49 in)
: 35.9 mm (1.41 in)
Exhaust:
37.54 mm (1.48 in)
: 35.7 mm (1.41 in)
Compressed spring force:
Intake:
10.1 ~ 11.6 kg at 29.13 mm
(22.27 ~ 25.57 lb at 1.15 in)
Exhaust:
12.9 ~ 14.7 kg at 29.30 mm
(28.44 ~ 32.41 lb at 1.15 in)
3. Measure:
Spring tilt a
Out of specification → Replace.
Spring tilt limit:
Intake:
2.5˚/1.7 mm (0.067 in)
Exhaust:
2.5˚/1.6 mm (0.063 in)
Valve lifter
1. Inspect:
Valve lifter
Scratches/damage → Replace both lift-
ers and cylinder head.

4 - 52
ENG

CLUTCH
EC4A3000
REMOVAL POINTS
Clutch boss
1. Remove:

Nut
1


Lock washer
2


Clutch boss
3

NOTE:

Straighten the lock washer tab and use the
clutch holding tool
4
to hold the clutch boss.
Å
For USA and CDN
ı
Except for USA and CDN
Clutch holding tool:
YM-91042/90890-04086
Å
ı

EC4A4000
INSPECTION
EC484100
Clutch housing and boss
1. Inspect:

Clutch housing
1

Cracks/wear/damage
→
Replace.

Clutch boss
2

Scoring/wear/damage
→
Replace.
EC484201
Primary driven gear
1. Check:

Circumferential play
Free play exists
→
Replace.

Gear teeth
a

Wear/damage
→
Replace.
Clutch spring
1. Measure:

Clutch spring free length
a

Out of specification
→
Replace springs
as a set.
Clutch spring free length:
37.0 mm (1.46 in)
: 36.0 mm (1.42 in)

5 - 32
CHAS

EC554200
Base valve
1. Inspect:

Valve assembly
1

Wear/damage
→
Replace.

O-ring
2

Damage
→
Replace.
EC554400
Fork spring
1. Measure:

Fork spring free length
a

Out of specification
→
Replace.
EC554502
Inner tube
1. Inspect:

Inner tube surface
a

Score marks
→
Repair or replace.
Use #1,000 grit wet sandpaper.
Damaged oil lock piece
→
Replace.

Inner tube bends
Out of specification
→
Replace.
Use the dial gauge
1
.
NOTE:

The bending value is shown by one half of the
dial gauge reading.
WARNING

Do not attempt to straighten a bent inner
tube as this may dangerously weaken the
tube.
EC554600
Outer tube
1. Inspect:

Outer tube
1

Score marks/wear/damage
→
Replace.
Fork spring free length:
460 mm (18.1 in)
: 455 mm (17.9 in)
Inner tube bending limit:
0.2 mm (0.008 in)
FRONT FORK

5 - 65
CHASREAR SHOCK ABSORBER
2. Tighten:
Adjuster 1
3. Adjust:
Spring length (installed) a
* For EUROPE
** For AUS, NZ and ZA
NOTE:
The length of the spring (installed) changes
1.5 mm (0.06 in) per turn of the adjuster.
CAUTION:
Never attempt to turn the adjuster beyond
the maximum or minimum setting.
4. Tighten:
Locknut 1
Rear shock absorber
1. Install:
Dust seal 1
O-ring 2
Collar 3
NOTE:
Apply the molybdenum disulfide grease on
the bearing.
Apply the lithium soap base grease on the
dust seals, O-rings and collars.
Spring length (installed) a:
Standard
lengthExtent of
adjustment
244 mm (9.61 in)
* 247 mm (9.72 in)
** 243.5 mm (9.59 in)240.5 ~ 258.5 mm
(9.47 ~ 10.18 in)

7 - 18
TUN
EC72B000
Rear suspension setting
The rear suspension setting should be made
depending on the rider’s feeling of an actual
run and the circuit conditions.
The rear suspension setting includes the fol-
lowing two factors:
1. Setting of spring preload
Change the set length of the spring.
Change the spring.
2. Setting of damping force
Change the rebound damping.
Change the compression damping.
EC72C001
Choosing set length
1. Place a stand or block under the engine
to put the rear wheel above the floor, and
measure the length a between the rear
wheel axle center and the rear fender
holding bolt.
2. Remove the stand or block from the
engine and with a rider astride the seat,
measure the sunken length b between
the rear wheel axle center and the rear
fender holding bolt.
3. Loosen the locknut 1 and make adjust-
ment by turning the spring adjuster 2 to
achieve the standard figure from the sub-
traction of the length b from the length
a.
Standard figure:
90 ~ 100 mm (3.5 ~ 3.9 in)
SETTING