engine YAMAHA WR 250F 2008 Repair Manual

5-41
OIL PUMP
REMOVING THE OIL TANKOrder Part name Q'ty Remarks Drain the engine oil. Refer to "CHANGING THE ENGINE OIL"
section in the CHAPTER 3.
1 Oil hose 2 1
2 Oil hose 1 1
3 Dowel pin 2
4 Oil tank breather hose 1
5 Oil tank 1
6 Oil strainer 1

5-42
OIL PUMP
CHECKING THE OIL PUMP
1. Inspect:• Oil pump drive gear "1"
• Oil pump drive shaft "2"
• Rotor housing "3"
• Oil pump cover "4"Cracks/wear/damage →Replace.
2. Measure: • Tip clearance "a"(between the inner rotor "1" and
outer rotor "2")
• Side clearance "b" (between the outer rotor "2" and
rotor housing "3")
• Housing and rotor clearance "c" (between the rotor housing "3"
and rotors "1" "2")
Out of specification →Replace the
oil pump assembly. 3. Check:
• Unsmooth →Repeat steps #1 and
#2 or replace the defective parts.
INSTALLING THE OIL PUMP
1. Install: • Oil pump drive shaft "1"
• Washer "2"
• Dowel pin "3"
• Inner rotor 1 "4"
• Apply the engine oil on the oil pump drive shaft and inner rotor 1.
• Fit the dowel pin into the groove in
the inner rotor 1.
2. Install:• Outer rotor 1 "1"
Apply the engine oil on the outer rotor
1.
3. Install:• Oil pump cover "1"
• Screw (oil pump cover) "2"
• Dowel pin "3"
• Inner rotor 2 "4"
• Circlip "5"
• Apply the engine oil on the inner ro-tor 2.
• Fit the dowel pin into the groove in
the inner rotor 2.
4. Install:• Outer rotor 2 "1"
• Dowel pin "2"
• Oil pump assembly "3"
• Bolt (oil pump assembly)
[L = 25 mm (0.94 in)] "4"
• Bolt (oil pump assembly) [L = 30 mm (1.18 in)] "5"
Apply the engine oil on the outer rotor
2.
5. Install:
• Oil pump drive gear "1"
• Washer "2"
• Circlip "3"
Apply the engine oil on the oil pump
drive gear inner circumference.
Tip clearance "a": 0.12 mm or less (0.0047
in or less)
: 0.20 mm
(0.008 in)
Side clearance "b": 0.09–0.17 mm (0.0035–
0.0067 in)
: 0.24 mm
(0.009 in)
Housing and rotor clear-
ance "c": 0.03–0.10 mm (0.0012–
0.0039 in)
: 0.17 mm
(0.0067 in)
Screw (oil pump cover):2 Nm (0.2 m•kg, 1.4
ft•lb)
Bolt (oil pump assem-
bly): 10 Nm (1.0 m•kg, 7.2
ft•lb)
Bolt (oil pump assem-
bly): 10 Nm (1.0 m•kg, 7.2
ft•lb)

5-46
KICK SHAFT AND SHIFT SHAFT
INSTALLING THE SHIFT GUIDE
AND SHIFT LEVER ASSEMBLY
1. Install:• Spring "1"
• Pawl pin "2"
•Pawl "3"To shift lever "4".
Apply the engine oil on the spring,
pawl pin and pawl.
2. Install:• Shift lever assembly "1"
To shift guide "2".
3. Install: • Shift lever assembly "1"
• Shift guide "2"
• The shift lever assembly is installed at the same time as the shift guide.
• Apply the engine oil on the bolt
(segment) shaft.
4. Install:• Bolt (shift guide) "1" INSTALLING TH
E SHIFT SHAFT
1. Install: • Roller "1"
• Collar "2"
• Torsion spring "3"
• Shift shaft "4"
Apply the engine oil on the roller and
shift shaft.
2. Install:• Shift pedalRefer to "AC MAGNETO AND
STARTER CLUTCH" section.
INSTALLING THE KICK SHAFT
ASSEMBLY
1. Install: • Kick gear "1"
• Washer "2"
• Circlip "3"
• Ratchet wheel "4"
• Spring "5"
• Washer "6"
• Circlip "7" To kick shaft "8".
• Apply the molybdenum disulfide oil on the inner circumferences of the
kick gear and ratchet wheel.
• Align the punch mark "a" on the ratchet wheel with the punch mark
"b" on the kick shaft.
2. Install:• Torsion spring "1"
To kick shaft "2".
Make sure the stopper "a" of the tor-
sion spring fits into the hole "b" on the
kick shaft.
3. Install:• Spring guide "1"
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"
• Apply the molybdenum disulfide
grease on the contacting surfaces
of the kick shaft stopper "a" and kick
shaft ratchet wheel guide "3".
• Apply the engine oil on the kick shaft.
• Slide the kick shaft assembly into the crankcase and make sure the
kick shaft stopper "a" fits into the
kick shaft ratchet wheel guide.
5. Hook:• Torsion spring "1"
Turn the torsion spring clockwise and
hook into the proper hole "a" in the
crankcase.Bolt (shift guide):
10 Nm (1.0 m•kg, 7.2
ft•lb)

5-47
KICK SHAFT AND SHIFT SHAFT
INSTALLING THE KICK IDLE
GEAR
1. Install:• Kick idle gear "1"
• Washer "2"
• Circlip "3"
• Apply the engine oil on the kick idle gear inner circumference.
• Install the kick idle gear with its de- pressed side "a " toward you.

5-48
AC MAGNETO AND STARTER CLUTCH
AC MAGNETO AND STARTER CLUTCH
REMOVING THE AC MAGNETO AND STARTER CLUTCHOrder Part name Q'ty Remarks 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.
Disconnect the AC magneto lead.
1 Shift pedal 1
2 Cover (torque limiter) 1
3 Torque limiter 1 Do not disassemble.
4 Crankcase cover (left) 1
5 Gasket 1
6 Dowel pin 2
7* Nut (rotor) 1 Refer to NOTE.
8 Rotor 1 Refer to removal section.
9 Woodruff key 1
10 Starter clutch drive gear 1
11 Starter clutch assembly cover 1

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

5-54
ENGINE REMOVAL
Disconnect the AC magneto lead.
Negative battery lead Disconnect at the engine side.
1 Engine guard 1
2 Neutral switch 1
3 Drive chain sprocket cover 1
4 Nut (drive sprocket) 1 Refer to removal section.
5 Lock washer 1 Refer to removal section.
6 Drive sprocket 1 Refer to removal section.
7Clip 1
8 Bolt (brake pedal) 1
9 Brake pedal 1
10 Upper engine bracket 2
11 Lower engine bracket 2
12 Engine mounting bolt 3
13 Pivot shaft 1 Refer to removal section.
14 Engine 1 Refer to removal section.
Order
Part name Q'tyRemarks

5-55
ENGINE REMOVAL
HANDLING NOTE
Support the machine securely so
there is no danger of it falling over.
REMOVING THE DRIVE
SPROCKET
1. Remove:• Nut (drive sprocket) "1"
• Lock washer "2"
• Straighten the lock washer tab.
• Loosen the nut while applying the rear brake.
2. Remove:• Drive sprocket "1"
• Drive chain "2"
Remove the drive sprocket together
with the drive chain.
REMOVING THE ENGINE
1. Remove:• Pivot shaft "1"
If the pivot shaft is pulled all the way
out, the swingarm will come loose. If
possible, insert a sh aft of similar di-
ameter into the other side of the swin-
garm to support it.
2. Remove:
• Engine "1"From right side.
Make sure that the couplers, hoses
and cables are disconnected.
INSTALLING THE ENGINE
1. Install:
• Engine "1"Install the engine from right side.
• Pivot shaft "2"
• Engine mounting bolt (lower) "3"
• Lower engine bracket "4"
• Bolt (lower engine bracket) "5"
• Patch "6"
• Engine mounting bolt (front) "7"
• Upper engine bracket "8"
• Bolt (upper engine bracket) "9"
• Engine mounting bolt (upper) "10"
• Lower engine guard "11"
• Bolt (lower engine guard) "12"
• Apply the molybdenum disulfide grease on the pivot shaft.
• Install the patch with the claw "a"
facing outside the chassis.
INSTALLING THE BRAKE PEDAL
1. Install:• Spring "1"
• Brake pedal "2"
• O-ring "3"
• Bolt (brake pedal) "4"
• Clip "5"
Apply the lithium soap base grease
on the bolt, O-rings and brake pedal
bracket.
INSTALLING THE DRIVE
SPROCKET
1. Install:• Drive sprocket "1"
• Drive chain "2"
Install the drive sprocket together
with the drive chain.
Pivot shaft:
85 Nm (8.5 m•kg, 61
ft•lb)
Engine mounting bolt
(lower): 53Nm (5.3 m•kg, 38
ft•lb)
Bolt (lower engine brack-
et): 34 Nm (3.4 m•kg, 24
ft•lb)
Engine mounting bolt
(front): 53 Nm (5.3 m•kg, 38
ft•lb)
Bolt (upper engine brack-
et): 34 Nm (3.4 m•kg, 24
ft•lb)
Engine mounting bolt
(upper): 55 Nm (5.5 m•kg, 40
ft•lb)
Bolt (lower engine
guard): 7 Nm (0.7 m•kg, 5.1
ft•lb)
Bolt (brake pedal): 26 Nm (2.6 m•kg, 19
ft•lb)