2011 YAMAHA YZ450F lock

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.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
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.
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.
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:
355 cm
3 (12.5 Imp oz,
12.0 US oz)
Extent of adjustment:
300–365 cm
3
(10.6–12.8 Imp
oz,10.1–12.3 US oz)

5-30
STEERING
HANDLING NOTE
Support the machine securely so
there is no danger of it falling over.
REMOVING THE STEERING RING
NUT
1. Remove:
• Steering ring nut "1"
Use the steering nut wrench "2".
Support the steering stem so that
it may not fall down.
REMOVING THE LOWER
BEARING
1. Remove:
• Lower bearing "1"
Use the floor chisel "2".
Take care not to damage the steer-
ing shaft thread.
REMOVING THE BEARING RACE
1. Remove:
• Bearing race "1"
Remove the bearing race using
long rod "2" and the hammer.CHECKING THE STEERING STEM
1. Inspect:
• Steering stem "1"
Bend/damage→Replace.
CHECKING THE BEARING AND
BEARING RACE
1. Wash the bearings and bearing
races with a solvent.
2. Inspect:
•Bearing "1"
• Bearing race
Pitting/damage→Replace bear-
ings and bearing races as a set.
Install the bearing in the bearing
races. Spin the bearings by hand.
If the bearings hang up or are not
smooth in their operation in the
bearing races, replace bearings
and bearing races as a set.
INSTALLING THE LOWER
BRACKET
1. Install:
• Lower bearing "1"
Apply the lithium soap base grease
on the dust seal lip and bearing inner
circumference.
2. Install:
• Bearing race
• Upper bearing "1"
• Bearing race cover "2"
Apply the lithium soap base grease
on the bearing and bearing race cov-
er lip.
3. Install:
• Lower bracket "1"
Apply the lithium soap base grease
on the bearing, the portion "a" and
thread of the steering stem.
4. Install:
• Steering ring nut "1"
Install the steering nut with its
stepped side "a" facing downward.
Tighten the steering ring nut using
the steering nut wrench "2".
Refer to "CHECKING AND AD-
JUSTING THE STEERING
HEAD" section in the CHAPTER
3.
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. Steering nut wrench:
YU-33975/90890-01403
Steering ring nut:
7 Nm (0.7 m•kg, 5.1 ft•
lb)

5-37
REAR SHOCK ABSORBER
REAR SHOCK ABSORBER
REMOVING THE REAR SHOCK ABSORBER
Order Part name Q'ty Remarks
Hold the machine by placing the suitable stand
under the engine.Refer to "HANDLING NOTE".
Seat Refer to "SEAT AND SIDE COVERS" section
in the CHAPTER 4.
Silencer Refer to "EXHAUST PIPE AND SILENCER"
section in the CHAPTER 4.
1 Bolt (rear shock absorber-relay arm) 1 Hold the swingarm.
2 Bolt (rear shock absorber-frame) 1
3 Rear shock absorber 1
4 Locknut 1 Only loosening.
5 Adjuster 1 Only loosening.
6 Lower spring guide 1
7 Upper spring guide 1
8 Spring (rear shock absorber) 1
9 Bearing 2 Refer to removal section.

5-39
REAR SHOCK ABSORBER
2. Install:
• Stopper ring (upper bearing) "1"
After installing the stopper ring, push
back the bearing until it contacts the
stopper ring.
3. Install:
• Lower bearing "1"
Install the bearing by pressing it on
the side having the manufacture's
marks or numbers.
INSTALLING THE SPRING (REAR
SHOCK ABSORBER)
1. Install:
• Spring "1"
• Upper spring guide "2"
• Lower spring guide "3"
2. Tighten:
•Adjuster "1"3. Adjust:
• Spring length (installed)
Refer to "ADJUSTING THE
REAR SHOCK ABSORBER
SPRING PRELOAD" section in
the CHAPTER 3.
4. Tighten:
• Locknut "1"
INSTALLING THE REAR SHOCK
ABSORBER
1. Install:
• Dust seal "1"
• O-ring "2"
• Collar "3"
• Apply the molybdenum disulfide
grease on the dust seal lips and col-
lars.
• Apply the lithium soap base grease
on the O-rings.
2. Install:
• Bushing "1"
• Collar "2"
• Dust seal "3"
• Apply the molybdenum disulfide
grease on the bearing and dust seal
lips.
• Install the dust seals with their lips
facing inward.
3. Install:
• Rear shock absorber4. Install:
• Bolt (rear shock absorber-frame)
"1"
• Washer "2"
• Nut (rear shock absorber-frame)
"3"
Apply the molybdenum disulfide
grease on the bolt.
5. Install:
• Bolt (rear shock absorber-relay
arm) "1"
• Nut (rear shock absorber-relay
arm) "2"
Apply the molybdenum disulfide
grease on the bolt.
Installed depth of the
bearing "a":
4 mm (0.16 in)
Nut (rear shock absorb-
er-frame):
56 Nm (5.6 m•kg, 40
ft•lb)
Nut (rear shock absorb-
er-relay arm):
53 Nm (5.3 m•kg, 38
ft•lb)

7-13
FUEL INJECTION SYSTEM
TROUBLESHOOTING DETAILS
This section describes the countermeasures per fault code number displayed on the FI diagnostic tool. Check and service
the items or components that are the probable cause of the malfunction following the order given. After the check and ser-
vice of the malfunctioning part have been completed, reset the FI diagnostic tool display according to the "Reinstatement
method".
Fault code No.
Fault code number displayed on the FI diagnostic tool when the engine failed to work normally. Refer to "FAULT CODE
TABLE".
Diagnostic code No.
Diagnostic code number to be used when the diagnostic mode is operated. Refer to "DIAGNOSTIC CODE TABLE".
Fault code No. 12
Symptom No normal signals are received from the crankshaft position sensor.
Fail-safe system Able to start
Able to drive
Diagnostic code No. —
FI diagnostic tool display —
Checking method —
Item Item/components and probable cause Check or maintenance job Checking method
1 Check the connection and locking condition of
the crankshaft position sensor coupler.
Disconnect the coupler and check the pins.
(bent or broken terminals and locking condition
of the pins)Poor connection → Properly con-
nect, repair, or replace.Crank the engine and
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item
2.
2 Check the connection and locking condition of
the wire harness ECU coupler.
Disconnect the coupler and check the pins.
(bent or broken terminals and locking condition
of the pins)Poor connection → Properly con-
nect, repair, or replace.Crank the engine and
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 3.
3 Continuity of harness Open or short circuit → Replace.
Between the crankshaft position
sensor coupler and ECU coupler.
(Gray–Gray)
(Black/Blue–Black/Blue)Crank the engine and
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 4.
4 Installed condition of sensor.
Check that the gap between the crankshaft po-
sition sensor and the rotor is 0.85 mm.Check that the sensor is installed
securely and that there are no
pinched leads.Check that the ECU
is installed securely and that there
are no pinched leads.
Incorrect installation → Reinstall
or repair.Crank the engine and
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item
5.

7-14
FUEL INJECTION SYSTEM
If fault code Nos. 13 and 14 are both displayed, perform the checks and maintenance jobs for fault code No. 13 first.
5 Defective crankshaft position sensor. Sensor malfunction → Replace.
Refer to "CHECKING THE AC
MAGNETO" section.Crank the engine and
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item
6.
6 Malfunction in ECU. Replace the ECU.
Fault code No. 13
Symptom Intake air pressure sensor signal is not received properly.
Fail-safe system Able to start
Able to drive
Diagnostic code No. D03
FI diagnostic tool display Intake air pressure
Checking method Crank the engine. (If the display value changes, the performance is OK.)
Item Item/components and probable cause Check or maintenance job Checking method
1 Check the connection and locking condition of
the intake air pressure sensor coupler.
Disconnect the coupler and check the pins.
(bent or broken terminals and locking condition
of the pins)Poor connection → Properly con-
nect, repair, or replace.Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 2.
2 Check the connection and locking condition of
the wire harness ECU coupler.
Disconnect the coupler and check the pins.
(bent or broken terminals and locking condition
of the pins)Poor connection → Properly con-
nect, repair, or replace.Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 3. Fault code No. 12
Symptom No normal signals are received from the crankshaft position sensor.
Fail-safe system Able to start
Able to drive
Diagnostic code No. —
FI diagnostic tool display —
Checking method —
Item Item/components and probable cause Check or maintenance job Checking method

7-17
FUEL INJECTION SYSTEM
Fault code No. 15
Symptom Throttle position sensor signal is not received properly.
Fail-safe system Able to start
Able to drive
Diagnostic code No. D01
FI diagnostic tool display • 15–19° (Fully closed position)
• 95–101° (Fully opened position)
Checking method• Check with throttle valves fully closed.
• Check with throttle valves fully open.
Item Item/components and probable cause Check or maintenance job Checking method
1 Check the connection and locking condition of
the throttle position sensor coupler.
Disconnect the coupler and check the pins.
(bent or broken terminals and locking condition
of the pins)Poor connection → Properly con-
nect, repair, or replace.Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 2.
2 Check the connection and locking condition of
the wire harness ECU coupler.
Disconnect the coupler and check the pins.
(bent or broken terminals and locking condition
of the pins)Poor connection → Properly con-
nect, repair, or replace.Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 3.
3 Continuity of harness Open or short circuit → Replace.
Between throttle position sensor
coupler and ECU coupler.
(Black/Blue–Black/Blue)
(Yellow–Yellow)
(Blue–Blue)Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 4.
4 Installed condition of sensor.
• Make sure that the installation position is cor-
rect.
• Make sure that there are no problems with the
installation.Check that the sensor is installed
securely and that there are no
pinched leads.Check that the ECU
is installed securely and that there
are no pinched leads.
Incorrect installation → Reinstall
or repair.
Incorrect installation position →
Properly install.Set the switch on the FI di-
agnostic tool sub-wire har-
ness to "ON", and then
check the fault code dis-
play.
Fault code number is not
displayed → Service is
finished.
Fault code number is dis-
played → Refer to item 5.