lock YAMAHA YZ250F 2010 Owner's Guide

4-54
ENGINE REMOVAL
INSTALLING THE DRIVE
SPROCKET
1. Install:• Drive sprocket "1"
• Drive chain "2"
Install the drive sprocket together
with the drive chain.
2. Install:
• Lock washer "1"
• Nut (drive sprocket) "2"
Tighten the nut while applying the
rear brake.
3. Bend the lock washer tab to lock the nut.
4. Install:
• Drive chain sprocket guide "1"
• Drive chain sp rocket cover "2"
• Bolt (drive chain sprocket cover)
"3" INSTALLING THE NEUTRAL
SWITCH
1. Install:
• Spring "1"
•Pin "2"
• O-ring "3"
• Neutral switch "4"
• Screw (neutral switch) "5"
Apply the lithium soap base grease
on the O-ring.
2. Install:• Hose guide (cylinder head breath-
er hose) "1"
• Bolt (hose guide) "2"
Nut (drive sprocket):
75 Nm (7.5 m•kg, 54
ft•lb)
Bolt (drive chain sprock-
et cover): 7 Nm (0.7 m•kg, 5.1
ft•lb)
Screw (neutral switch):4 Nm (0.4 m•kg, 2.9
ft•lb)
Bolt (hose guide): 10 Nm (1.0 m•kg, 7.2
ft•lb)

5-5
FRONT WHEEL AND REAR WHEEL
4. Install:•Collar "1"
Apply the lithium soap base grease
on the oil seal lip.
5. Install:• Wheel
Install the brake disc "1" between the
brake pads "2" correctly.
6. Install:• Drive chain "1"
Push the wheel "2" forward and install
the drive chain.
7. Install:• Left drive chain puller "1"
• Wheel axle "2"
• Install the left drive chain puller, and
insert the wheel axle from left side.
• Apply the lithium soap base grease on the wheel axle.
8. Install:
• Right drive chain puller "1"
• Washer "2"
• Nut (wheel axle) "3"
Temporarily tighten the nut (wheel
axle) at this point.
9. Adjust:• Drive chain slack "a"
Refer to "ADJUSTING THE
DRIVE CHAIN SLACK" section in
the CHAPTER 3.
10. Tighten: • Nut (wheel axle) "1"
• Locknut "2"
Drive chain slack: 50–60 mm (2.0–2.4 in)
Nut (wheel axle): 135 Nm (13.5 m•kg, 98
ft•lb)
Locknut: 21 Nm (2.1 m•kg, 15
ft•lb)

5-10
FRONT BRAKE AND REAR BRAKE
HANDLING NOTE
Support the machine securely so
there is no danger of it falling over.
DRAINING THE BRAKE FLUID
1. Remove:• Brake master cylinder cap "1"
• Protector (rear brake)
Do not remove the diaphragm.
A. Front
B. Rear
2. Connect the transparent hose "2" to the bleed screw "1" and place a
suitable container under its end.
A. Front
B. Rear
3. Loosen the bleed screw and drain the brake fluid while pulling the le-
ver in or pushing down on the
pedal.
• Do not reuse the drained brake
fluid.
• Brake fluid may erode painted surfaces or plastic parts. Always
clean up spilled fluid immediate-
ly.
REMOVING THE BRAKE CALIPER
PISTON
1. Remove: • Brake caliper piston
Use compressed air and proceed
carefully.
• Cover piston with rag and use ex-treme caution when expelling
piston from cylinder.
• Never attempt to pry out piston.
Caliper piston removal steps:
a. Insert a piece of rag into the brake
caliper to lock one brake caliper.
b. Carefully force the piston out of
the brake caliper cylinder with
compressed air.
A. Front
B. Rear
REMOVING THE BRAKE CALIPER
PISTON SEAL KIT
1. Remove:• Brake caliper piston dust seal "1"
• Brake caliper piston seal "2"
Remove the brake caliper piston
seals and brake caliper piston dust
seals by pushing them with a finger.
Never attempt to pry out brake cal-
iper piston seals and brake caliper
piston dust seals.
Replace the brake caliper piston
seals and brake caliper piston dust
seals whenever a caliper is disas-
sembled.
A. Front
B. Rear
CHECKING THE BRAKE MASTER
CYLINDER
1. Inspect: • Brake master cylinder inner sur-
face "a"
Wear/scratches → Replace mas-
ter cylinder assembly.
Stains →Clean.
Use only new brake fluid.
A. Front
B. Rear
2. Inspect: • Diaphragm "1"
Crack/damage →Replace.
A. Front
B. Rear

5-14
FRONT BRAKE AND REAR BRAKE
Install the brake hose so that its
pipe portion "a" directs as shown
and lightly touches the projection
"b" on the brake caliper.
2. Install:• Brake hose holder "1"
• Bolt (brake hose holder) "2"
Align the top "a" of the brake hose
holder with the paint "b" of the brake
hose.
3. Pass the brake hose through the cable guide "1".
4. Install: • Copper washer "1"
• Brake hose "2"
• Union bolt "3"
Always use new copper washers.
Install the brake hose so that its
pipe portion "a" directs as shown
and lightly touches the projection
"b" on the brake master cylinder.
INSTALLING THE REAR BRAKE
HOSE
1. Install:• Copper washer "1"
• Brake hose "2"
• Union bolt "3"
Always use new copper washers.
Install the brake hose so that its
pipe portion "a" directs as shown
and lightly touches the projection
"b" on the brake caliper.
2. Install:• Brake hose holder "1"
• Screw (brake hose holder) "2"
After installing the brake hose
holders, make sure the brake hose
does not contact the spring (rear
shock absorber). If it does, correct
its twist.
FILLING THE BRAKE FLUID
1. Fill:• Brake fluid
Until the fluid level reaches
"LOWER" level line "a".
• Use only the designated quality brake fluid:
otherwise, the rubber seals may
deteriorate, causi ng leakage and
poor brake performance.
• Refill with the same type of brake
fluid;
mixing fluids may result in a
harmful chemical reaction and
lead to poor performance.
• Be careful that water does not enter the master cylinder when
refilling. Water will significantly
lower the boiling point of the flu-
id and may result in vapor lock.
Brake fluid may erode painted sur-
faces or plastic parts. Always
clean up spilled fluid immediately.
Bolt (brake hose holder):
8 Nm (0.8 m•kg, 5.8 ft
•lb)
Union bolt: 30 Nm (3.0 m•kg, 22
ft•lb)
Union bolt:
30 Nm (3.0 m•kg, 22
ft•lb)
Screw (brake hose hold-
er): 3 Nm (0.3 m•kg, 2.2
ft•lb)
Recommended brake flu-
id:
DOT #4

5-18
FRONT FORK
HANDLING NOTE
Support the machine securely so
there is no danger of it falling over.
The front fork requires careful atten-
tion. So it is recommended that the
front fork be maintained at the deal-
ers.
To prevent an accidental explosion
of air, the following instructions
should be observed:
• The front fork with a built-in pis-ton rod has a very sophisticated
internal construction and is par-
ticularly sensitive to foreign ma-
terial. Use enough care not to
allow any foreign material to
come in when the oil is replaced
or when the front fork is disas-
sembled and reassembled.
• Before removing the base valves or front forks, be sure to extract
the air from the air chamber com-
pletely.
REMOVING THE DAMPER
ASSEMBLY
1. Loosen:
• Damper assembly "1"
Before removing the front fork from
the machine, loosen the damper as-
sembly with the cap bolt ring wrench
"2".
REMOVING THE ADJUSTER
1. Drain the outer tube of its front fork oil at its top.
2. Loosen:
•Adjuster "1"
3. Remove: •Adjuster "1"
• While compressing the inner tube "2", set the cap bolt ring wrench "4"
between the inner tube and locknut
"3".
• Hold the locknut and remove the
adjuster.
Do not remove the locknut as the
damper rod may go into the damp-
er assembly and not be taken out.
REMOVING THE INNER TUBE
1. Remove:• Dust seal "1"
• Stopper ring "2"Using slotted-head screwdriver.
Take care not to scratch the inner
tube.
2. Remove:
• Inner tube "1"
Oil seal removal steps:
a. Push in slowly "a" the inner tube just before it bottoms out and then
pull it back quickly "b".
b. Repeat this step until the inner tube can be pulled out from the
outer tube.
REMOVING THE BASE VALVE
1. Remove:• Base valve "1"From damper assembly "2".
Hold the damper assembly with the
cap bolt ring wrench "3" and use the
cap bolt wrench "4" to remove the
base valve.
Cap bolt ring wrench:
YM-01501/90890-01501
Cap bolt ring wrench:YM-01501/90890-01501
Cap bolt wrench: YM-01500/90890-01500
Cap bolt ring wrench: YM-01501/90890-01501

5-19
FRONT FORK
CHECKING THE DAMPER
ASSEMBLY
1. Inspect:• Damper assembly "1"
Bend/damage → Replace.
• O-ring "2" Wear/damage → Replace.
The front fork with a built-in piston
rod has a very sophisticated inter-
nal construction and is particularly
sensitive to foreign material.
Use enough care not to allow any
foreign material to come in when
the oil is replaced or when the
front fork is disassembled and re-
assembled.
CHECKING THE BASE VALVE
1. Inspect: • Base valve "1"
Wear/damage →Replace.
Contamination →Clean.
• O-ring "2"
Wear/damage →Replace.
• Piston metal "3" Wear/damage →Replace.
• Spring "4" Damage/fatigue →Replace base
valve.
• Air bleed screw "5" Wear/damage →Replace.
CHECKING THE COLLAR
1. Inspect: • Piston metal "1"Wear/damage →Replace. CHECKING THE FORK SPRING
1. Measure:
• Fork spring free length "a"Out of specification →Replace.
CHECKING THE INNER TUBE
1. Inspect: • Inner tube surface "a"Score marks →Repair or replace.
Use #1,000 grit wet sandpaper.
Damaged oil lock piece →Re-
place.
• Inner tube bends Out of specification →Replace.
Use the dial gauge "1".
The bending value is shown by one
half of the dial gauge reading.
Do not attempt to straighten a bent
inner tube as this may dangerous-
ly weaken the tube.
CHECKING THE OUTER TUBE
1. Inspect:
• Outer tube "1"Score marks/wear/damage →Re-
place. CHECKING THE ADJUSTER
1. Inspect:
•Adjuster "1"
• O-ring "2"
Wear/damage →Replace.
ASSEMBLING THE FRONT FORK
1. Wash the all parts in a clean sol- vent.
2. Stretch the damper assembly ful- ly.
3. Fill:
• Front fork oil "1"To damper assembly.
• Be sure to use recommended fork oil. If other oils are used,
they may have an excessively ad-
verse effect on the front fork per-
formance.
• Never allow foreign materials to
enter the front fork.
4. After filling, pump the damper as- sembly "1" slowly up and down
(about 200 mm (7.9 in) stroke)
several times to bleed the damper
assembly of air.
Be careful not to ex cessive full stroke.
A stroke of 200 mm (7.9 in) or more
will cause air to enter. In this case, re-
peat the steps 2 to 4.
Fork spring free length: 454 mm (17.9 in)
: 449 mm (17.7
in)
Inner tube bending limit: 0.2 mm (0.008 in)
Recommended oil: Suspension oil "S1"
Oil capacity: 199 cm
3 (7.00 Imp oz,
6.73 US oz)

5-20
FRONT FORK
5. Measure:• Oil level (left and right) "a"Out of specification → Adjust.
6. Tighten: • Locknut "1"
Fully finger tighten the locknut onto
the damper assembly.
7. Loosen:• Compression damping adjuster "1"
• Loosen the compression damping
adjuster finger tight.
• Record the set position of the ad- juster (the amount of turning out the
fully turned in position).
8. Install:
• Base valve "1"To damper assembly "2".
First bring the damper rod pressure to
a maximum. Then install the base
valve while releasing the damper rod
pressure.
9. Check:
• Damper assemblyNot fully stretched → Repeat the
steps 2 to 8.
10. Tighten: • Base valve "1"
Hold the damper assembly with the
cap bolt ring wrench "2" and use the
cap bolt wrench "3" to tighten the
base valve with specified torque.
11. After filling, pump the damper as-
sembly "1" slowly up and down
more than 10 times to distribute
the fork oil. 12. While protecting the damper as-
sembly "1" with a rag and com-
pressing fully, al low excessive oil
to overflow on the base valve
side.
Take care not to damage the damp-
er assembly.
13. Allow the overflowing oil to es- cape at the hole "a" in the damper
assembly.
14. Check: • Damper assembly smooth move-ment
Tightness/binding/rough spots →
Repeat the steps 2 to 13.
15. Install: • Dust seal "1"
• Stopper ring "2"
• Oil seal "3"
• Oil seal washer "4"
• Slide metal "5" To inner tube "6".
• Apply the fork oil on the inner tube.
• When installing the oil seal, use vi-nyl seat "a" with fork oil applied to
protect the oil seal lip.
• Install the oil seal with its manufac-
ture's marks or number facing the
axle holder side.
Standard oil level: 145-148 mm (5.71-5.83
in)
From top of fully
stretched damper as-
sembly.
Base valve:29 Nm (2.9 m•kg, 21 ft•
lb)
Cap bolt wrench: YM-01500/90890-01500
Cap bolt ring wrench:
YM-01501/90890-01501

5-21
FRONT FORK
16. Install:• Piston metal "1"
Install the piston metal onto the slot
on inner tube.
17. Install:• Outer tube "1"
To inner tube "2".
18. Install: • Slide metal "1"
• Oil seal washer "2"
To outer tube slot.
Press the slide metal into the outer
tube with fork seal driver "3".
19. Install:• Oil seal "1"
Press the oil seal into the outer tube
with fork seal driver "2".
20. Install:• Stopper ring "1"
Fit the stopper ring correctly in the
groove in the outer tube.
21. Install:• Dust seal "1"
Apply the lithium soap base grease
on the inner tube.
22. Check:• Inner tube smooth movement
Tightness/binding/rough spots →
Repeat the steps 15 to 21. 23. Measure:
• Distance "a"
Out of specification → Turn into
the locknut.
24. Install: •Collar "1"
• Fork spring "2"To damper assembly "3".
Install the collar with its larger dia.
end "a" facing the fork spring.
25. Install:• Damper assembly "1"To inner tube "2".
To install the damper assembly
into the inner tube, hold the inner
tube aslant. If the inner tube is held
vertically, the damper assembly
may fall into it, damaging the valve
inside.
Fork seal driver: YM-A0948/90890-01502
Fork seal driver:
YM-A0948/90890-01502
Distance "a": 16 mm (0.63 in) or more
Between the damper
assembly "1" bottom
and locknut "2" bot-
tom.

5-22
FRONT FORK
26. Loosen:• Rebound damping adjuster "1"
• Loosen the rebound damping ad-juster finger tight.
• Record the set position of the ad-
juster (the amount of turning out the
fully turned in position).
27. Install:• Push rod "1"
• Copper washer "2"
• Adjuster "3" To damper assembly "4".
• While compressing the inner tube "5", set the cap bolt ring wrench "7"
between the inner tube and locknut
"6".
• Fully finger tighten the adjuster onto the damper assembly.
28. Inspect:• Gap "a" between the adjuster "1" and locknut "2".
Out of specification → Retighten
and readjust the locknut.
If the adjuster is installed out of spec-
ification, proper damping force can-
not be obtained.
29. Tighten: • Adjuster (locknut) "1"
Hold the locknut "2" and tighten the
adjuster with specified torque.
30. Install:• Adjuster "1"
To inner tube.
31. Fill: • Front fork oil "1"From outer tube top.
Never fail to make the oil amount
adjustment between the maximum
and minimum amount and always
adjust each front fork to the same
setting. Uneven adjustment can
cause poor handling and loss of
stability.
• Be sure to use recommended
fork oil. If other oils are used,
they may have an excessively ad-
verse effect on the front fork per-
formance.
• Never allow foreign materials to
enter the front fork.
32. Install:• Damper assembly "1"
To outer tube.
Temporarily tighten the damper as-
sembly.
33. Install:• Protector guide "1"
Cap bolt ring wrench:
YM-01501/90890-01501
Gap "a" between the ad-
juster and locknut: 0.5–1.0 mm (0.02–0.04
in)
Adjuster (locknut):29 Nm (2.9 m•kg, 21
ft•lb)
Adjuster: 55 Nm (5.5 m•kg, 40
ft•lb)
Recommended oil: Suspension oil "S1"
Standard oil amount: 350 cm
3 (12.3 Imp oz,
11.8 US oz)
*337 cm
3 (11.9 Imp oz,
11.4 US oz)
Extent of adjustment:
300–375 cm
3
(10.6–13.2 Imp
oz,10.1–12.7 US oz)
* Except for USA & CDN

5-30
STEERING
5. Check the steering stem by turn-ing it lock to lock. If there is any
binding, remove the steering stem
assembly and inspect the steer-
ing bearings.
6. Install: • Washer "1"
7. Install: • Front fork "1"
• Upper bracket "2"
• Temporarily tighten the pinch bolts (lower bracket).
• Do not tighten the pinch bolts (up- per bracket) yet.
8. Install:
• Steering stem nut "1"
Apply the lithium soap base grease
on the contact surface of the steering
stem nut when installing.
9. After tightening the nut, check the steering for smooth movement. If
not, adjust the steering by loosen-
ing the steering ring nut little by lit-
tle.
10. Adjust: • Front fork top end "a"
11. Tighten: • Pinch bolt (upper bracket) "1"
• Pinch bolt (lower bracket) "2"
Tighten the lower bracket to speci-
fied torque. If to rqued too much, it
may cause the front fork to mal-
function.
Steering stem nut: 145 Nm (14.5 m•kg, 105
ft•lb)
Front fork top end (stan-
dard) "a":5 mm (0.20 in)
Pinch bolt (upper brack-
et): 21 Nm (2.1 m•kg, 15
ft•lb)
Pinch bolt (lower brack-
et): 21 Nm (2.1 m•kg, 15
ft•lb)