clutch YAMAHA WR 250F 2008 Owner's Guide

5-50
AC MAGNETO AND STARTER CLUTCH
REMOVING THE ROTOR
1. Remove:• Nut (rotor) "1"
• Washer
Use the sheave holder "2".
2. Remove: • Rotor "1"Use the rotor puller "2".
REMOVING THE STARTER
CLUTCH
1. Remove: • Starter clutch a ssembly cover "1"
Insert a thin screwdriver or the like
under the convexity "a" and remove
the starter clutch assembly cover by
prying it gently to void damage to the
cover.
2. Remove:
• Starter clutch "1"
Using a thin screwdriver or the like,
remove the plate "a" while prying it
upward little by little.
CHECKING THE AC MAGNETO
1. Inspect:
• Rotor inner surface "a"
• Stator outer surface "b"Damage →Inspect the crankshaft
runout and crankshaft bearing.
If necessary, replace AC magneto
and/or stator.
CHECKING THE WOODRUFF KEY
1. Inspect: • Woodruff key "1"
Damage →Replace.
CHECKING THE STARTER
CLUTCH
1. Check: • Starter clutchDamage/wear →Replace.
2. Check:
• Idle gear
• Starter clutch drive gearPitting/burrs/chips/roughness/
wear →Replace the defective
parts.
1. Check: • Starter clutch operation
a. Install the starter clutch drive gear "1" onto the starter clutch "2" and
hold the starter clutch.
b. When turning the starter clutch drive gear counterclockwise "B",
the starter clutch and the starter
clutch drive gear should engage.
If the starter clutch drive gear and
starter clutch do not engage, the
starter clutch is faulty and must be
replaced.
c. When turning the starter clutch
drive gear clockwise "A", it should
turn freely. If the starter clutch
drive gear does not turn freely, the
starter clutch is faulty and must be
replaced.
CHECKING THE TORQUE LIMITER
1. Check:• Torque limiterDamage/wear →Replace.
INSTALLING THE AC MAGNETO
AND STARTER CLUTCH
1. Install: • Stator "1"
• Bolt (stator) "2"
• Pickup coil "3"
• Bolt (pickup coil) "4"
Sheave holder:
YS-1880-A/90890-
01701
Rotor puller: YM-04141/90890-04141
Bolt (stator):
7 Nm (0.7 m•kg, 5.1
ft•lb)
Bolt (pickup coil): 10 Nm (1.0 m•kg, 7.2
ft•lb)

5-51
AC MAGNETO AND STARTER CLUTCH
2. Install:• Holder "1"
•Bolt "2"
Pass the pickup coil lead and
charging coil lead under the holder
while taking care not to allow these
leads to get caught with each oth-
er. Also take care to pass the leads
so that they do not become loose
at the bend of the holder "a" in or-
der to avoid their contacting the
starter clutch drive gear.
Apply the sealant to the grommet of
the AC magneto lead.
3. Install:• Idle gear 2 "1"
• Dowel pin "2"
Apply the engine oil on the idle gear
2.
4. Install:• Idle gear plate "1"
• Bolt (idle gear plate) "2" 5. Install:
• Washer "1"
•Bearing "2"
• Starter clutch drive gear "3"
• Washer "4"
Apply the engine oil on the washer,
bearing and starter clutch drive gear
inner circumference.
6. Install:• Starter clutch "1"To rotor "2".
• Install the starte r clutch with its
plate side upward.
• While installing the starter clutch, push in the projections "a" one by
one on the clutch circumference.
• Push in the starter clutch until it hits the rotor.
7. Install:• Starter clutch assembly cover "1"To rotor "2".
Install the starter clutch assembly
cover by fitting its pawls "a" into the
groove "b" in the rotor.
8. Install:
• Woodruff key "1"
• Rotor "2"
• Degrease the contact surfaces of the tapered portions of the crank-
shaft 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.
9. Install:• Washer (rotor)
• Nut (rotor) "1"
Use the sheave holder "2"
Tighten the rotor nut to 65 Nm (6.5
m•kg, 47 ft•lb), loosen and retighten
the rotor nut to 65 Nm (6.5 m•kg, 47
ft•lb).
10. Install:• Dowel pin
• Gasket [crankcase cover (left)]
• Crankcase cover (left) "1"
• Bolt [crankcase cover (left)] "2"
Bolt:
7 Nm (0.7 m•kg, 5.1
ft•lb)
YAMAHA Bond No. 1215
(ThreeBond
® No. 1215):
90890-85505
Bolt (idle gear plate): 10 Nm (1.0 m•kg, 7.2
ft•lb)
E
E
Nut (rotor):65 Nm (6.5 m•kg, 47
ft•lb)
Sheave holder: YS-1880-A/90890-
01701
Bolt [crankcase cover
(left)]: 10 Nm (1.0 m•kg, 7.2
ft•lb)

5-52
AC MAGNETO AND STARTER CLUTCH
• Bolt [crankcase cover (left)] "3"
Tighten the bolts in stage, using a
crisscross pattern.
11. Install:• Washer "1"
• Torque limiter "2"
• Washer "3"
Apply the engine oil to the shaft and
washers.
12. Install:• O-ring
• Cover (idle gear 1) "1"
•Bolt "2"
• Apply the lithium soap base grease on the O-ring.
• Install the cover (idle gear 1) with its
mark "a" facing upward.
13. Connect:• AC magneto leadRefer to "CABLE ROUTING DIA-
GRAM" section in the CHAPTER
2.
14. Install: • Shift pedal "1"
• Bolt (shift pedal)
When installing the shift pedal onto
the shift shaft, be sure that the center
of the shift pedal is about 1.4 mm
(0.06 in) "a" above the top of the foot-
rest.
Bolt [crankcase cover
(left)]: 12 Nm (1.2 m•kg, 8.7
ft•lb)
Bolt: 10 Nm (1.0 m•kg, 7.2
ft•lb)
E
Bolt (shift pedal):
12 Nm (1.2 m•kg, 8.7
ft•lb)

5-53
ENGINE REMOVAL
ENGINE REMOVAL
REMOVING THE ENGINEOrder Part name Q'ty Remarks Hold the machine by placing the suitable stand
under the frame. Refer to "HANDLING NOTE".
Drain the engine oil. Refer to "CHANGING THE ENGINE OIL"
section in the CHAPTER 3.
Seat and fuel tank Refer to "REMOVING THE SEAT, FUEL
TANK AND SIDE COVERS" section in the
CHAPTER 3.
Carburetor Refer to "CARBURETOR" section.
Exhaust pipe and silencer Refer to "REMOVING THE EXHAUST PIPE
AND SILENCER" section in the CHAPTER 3.
Air cut-off valve assembly Refer to "AIR INDUCTION SYSTEM" section.
Clutch cable Disconnect at the engine side.
Radiator Refer to "RADIATOR" section.
Shift pedal Refer to "AC MAGNETO AND STARTER
CLUTCH" section.
Cylinder head breather hose Refer to "CAMSHAFTS" section.
Oil hose and oil tank breather ho seRefer to "OIL PUMP" section.
Ignition coil

5-57
CRANKCASE AND CRANKSHAFT
CRANKCASE AND CRANKSHAFT
REMOVING THE CRANKSHAFTOrder Part name Q'ty Remarks Engie Refer to "ENGINE REMOVAL" section.
Piston Refer to "CYLINDE R AND PISTON" section.
Kick shaft assembly Refer to "KICK SHAFT AND SHIFT SHAFT"
section.
Segment Refer to "KICK SHAFT AND SHIFT SHAFT"
section.
Stator Refer to "AC MAGNETO AND STARTER
CLUTCH" section.
Balancer shaft Refer to "BALANCER" section.
1 Timing chain guide (intake side) 1
2 Timing chain 1
3 Oil delivery pipe 2 1
4 Bolt [L = 45 mm (1.77 in)] 5 Refer to removal section.
5 Bolt [L = 55 mm (2.17 in)] 1 Refer to removal section.
6 Bolt [L = 70 mm (2.76 in)] 3 Refer to removal section.
7 Hose guide 1 Refer to removal section.
8 Clutch cable holder 1 Refer to removal section.

5-60
CRANKCASE AND CRANKSHAFT
DISASSEMBLING THE
CRANKCASE
1. Separate:• Right crankcase
• Left crankcase
Separation steps:
a. Remove the crankcase bolts "1", hose guide "2" and clutch cable
holder "3".
Loosen each bolt 1/4 of a turn at a
time and after all the bolts are loos-
ened, remove them.
b. Remove the right crankcase "4".
• Place the crankcase with its left
side downward and split it by insert-
ing a screwdriver tip into the split-
ting slit "a" in the crankcase.
• Lift the right crankcase horizontally while lightly patting the case split-
ting slit and engine mounting boss
using a soft hammer, and leave the
crankshaft and transmission with
the left crankcase.
Use soft hammer to tap on the
case half. Tap only on reinforced
portions of case. Do not tap on
gasket mating surface. Work slow-
ly and carefully. Make sure the
case halves separate evenly. If the
cases do not separate, check for a
remaining case bolt or fitting. Do
not force.
c. Remove the dowel pins and O-
ring.
REMOVING THE CRANKSHAFT
1. Remove:• Crankshaft "1"
Use the crankcase separating
tool "2".
Do not use a hammer to drive out
the crankshaft.
REMOVING THE CRANKCASE
BEARING
1. Remove:•Bearing "1"
• Remove the bearing from the crankcase by pressing its inner
race.
• Do not use the removed bearing.
CHECKING THE TIMING CHAIN
AND TIMING CHAIN GUIDE
1. Inspect: • Timing chain
Cracks/stiff →Replace the timing
chain and camshaft sprocket as a
set.
2. Inspect: • Timing chain guideWear/damage →Replace. CHECKING THE CRANKCASE
1. Inspect:
• Contacting surface "a"Scratches →Replace.
• Engine mounting boss "b", crank- case
Cracks/damage →Replace.
2. Inspect: • BearingRotate inner race with a finger.
Rough spot/seizure →Replace.
3. Inspect: • Oil sealDamage →Replace.
CHECKING THE CRANKSHAFT
1. Measure: • Runout limit "a"
• Small end free play limit "b"
• Connecting rod big end side clearance "c"
• Crank width "d" Out of specification →Replace.
Use the dial gauge and a thick-
ness gauge.
Crankcase separating
tool: YU-1135-A/90890-
01135
Dial gauge and stand: YU-3097/90890-01252
Standard
Runo
ut lim-
it: 0.03 mm (0.0012
in) 0.05
mm
(0.002 in)
Small
end
free
play: 0.4–1.0 mm
(0.016–0.039 in) 2.0 mm
(0.08 in)
Side
clear-
ance: 0.15–0.45 mm
(0.0059–0.0177 in) 0.50
mm
(0.02 in)
Crack
width: 55.95–56.00
mm (2.203–
2.205 in) —

5-62
CRANKCASE AND CRANKSHAFT
5. Install:• Dowel pin "1"
• O-ring "2"
• Right crankcaseTo left crankcase.
• Apply the lithium soap base grease
on the O-ring.
• Fit the right crankcase onto the left crankcase. Tap lightly on the case
with soft hammer.
• When installing the crankcase, the connecting rod should be posi-
tioned at TDC (top dead center).
6. Tighten:
• Hose guide "1"
• Clutch cable holder "2"
• Bolt (crankcase) "3"
Tighten the crankcase tightening
bolts in stage, using a crisscross pat-
tern.
7. Install:• Oil delivery pipe 2 "1"
• O-ring "2"
• Bolt (oil delivery pipe 2) "3"
Apply the lithium soap base grease
on the Orings.
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
surface.
10. Apply:
• Engine oilTo the crank pin, bearing and oil
delivery hole.
11. Check: • Crankshaft and transmission op-eration.
Unsmooth operation →Repair.
Bolt (crankcase):
12 Nm (1.2 m•kg, 8.7
ft•lb)
Bolt (oil delivery pipe 2): 10 Nm (1.0 m•kg, 7.2
ft•lb)
Bolt (timing chain guide):10 Nm (1.0 m•kg, 7.2
ft•lb)

6-23
HANDLEBAR
HANDLEBAR
REMOVING THE HANDLEBAROrder Part name Q'ty Remarks Headlight
1 Hot starter cable 1 Disconnect at the lever side.
2 Hot starter lever holder 1
3 Clutch cable 1 Disconnect at the lever side.
4 Clutch lever holder 1 Disconnect the clutch switch lead.
5 Engine stop switch 1 Disconnect the engine stop switch lead.
6 Brake master cylinder 1 Refer to removal section.
7 Start switch 1 Disconnect the start switch lead.
8 Throttle cable cap 1
9 Throttle cable #1 (pulled) 1 Disconnect at the throttle side.
10 Throttle cable #2 (pushed) 1 Disconnect at the throttle side.
11 Right grip 1 Refer to removal section.
12 Tube guide 1
13 Left grip 1 Refer to removal section.
14 Handlebar upper holder 2
15 Handlebar 1
16 Handlebar lower holder 2

6-25
HANDLEBAR
5. Install:• Right grip "1"
•Collar "2"Apply the adhesive on the tube
guide "3".
• Before applying the adhesive, wipe off grease or oil on the tube guide
surface "a" with a lacquer thinner.
• Install the grip to the tube guide so that the grip match mark "b" and
tube guide slot "c" form the angle as
shown.
6. Install:• Grip cap cover "1"
• Throttle grip "2"
Apply the lithium soap base grease
on the throttle grip sliding surface.
7. Install:
• Throttle cables "1"To tube guide "2".
Apply the lithium soap base grease
on the throttle cable end and tube
guide cable winding portion.
8. Install:
• Throttle cable cap "1"
• Screw (throttle cable cap) "2"
After tightening the screws, check
that the throttle grip "3" moves
smoothly. If it does not, retighten
the bolts for adjustment.
9. Install:• Grip cap cover "1"
• Cover (throttle cable cap) "2"
10. Install: • Start switch "1"
• Brake master cylinder "2"
• Brake master cylinder bracket "3"
• Bolt (brake master cylinder brack-
et) "4"
•Clamp "5"
• The start switch and brake master
cylinder bracket should be installed
according to the dimensions
shown.
• Install the bracket so that the arrow
mark "a" faces upward.
• First tighten the bolt on the upper side of the brake master cylinder
bracket, and then tighten the bolt on
the lower side.
11. Install:
• Engine stop switch "1"
• Clutch lever holder "2"
• Bolt (clutch lever holder) "3"
• Hot starter lever holder "4"
• Bolt (hot starter lever holder) "5"
• Clamp "6"
• The engine stop switch, clutch lever holder and clamp should be in-
stalled according to the dimensions
shown.
• Pass the engine stop switch lead in
the middle of the clutch lever hold-
er.
Screw (throttle cable
cap): 4 Nm (0.4 m•kg, 2.9
ft•lb)
Bolt (brake master cylin-
der bracket): 9 Nm (0.9 m•kg, 6.5
ft•lb)
Bolt (clutch lever holder): 4 Nm (0.4 m•kg, 2.9
ft•lb)
Bolt (hot starter lever
holder): 4 Nm (0.4 m•kg, 2.9
ft•lb)

6-26
HANDLEBAR
12. Install:• Clutch cable "1"
• Hot starter cable "2"
Apply the lithium soap base grease
on the clutch cable end and hot start-
er cable end.
13. Adjust:• Clutch lever free play
Refer to "ADJUSTING THE
CLUTCH CABLE FREE PLAY"
section in the CHAPTER 3.
• Hot starter lever free play Refer to "ADJUSTING THE HOT
STARTER LEVER FREE PLAY"
section in the CHAPTER 3.