2014 YAMAHA YZ450F Owners Manual

FRONT FORK
4-43
10.After filling, pump the damper assembly “1”
slowly up and down more than 10 times to
distribute the fork oil.
11.While protecting the damper assembly “1”
with a cloth and compressing fully, allow ex
-
cessive oil to overflow on the base valve
side.
ECA32D1010
NOTICE
Take care not to damage the damper assem-
bly.
12.Allow the overflowing oil to escape at the
hole “a” in the damper assembly.
TIP
The overflow measures about 8 cm3 (0.27 US
oz, 0.28 lmp oz).
13.Check:
• Damper assembly smooth movement
Tightness/binding/rough spots  Repeat
the steps 1 to 12.
14.Install:
• Dust seal “1”
• Oil seal clip “2”
• Oil seals “3”
• Washer “4”
• Outer tube bushing “5”
(to the inner tube “6”)ECA32D1010
NOTICE
Make sure that the numbered side of the oil
seal faces bottom side.
TIP
• Apply the lithium soap base grease on the
dust seal lip and oil seal lip.
• Apply the fork oil on the inner tube.
• When installing the oil seal, use vinyl seat “a”
with fork oil applied to protect the oil seal lip.
Cap bolt wrench
90890-01500
YM-01500
Cap bolt ring wrench
90890-01501
YM-01501
1 23
1
1
a
New
New
New
LS

FRONT FORK
4-44
15.Install:
• Inner tube bushing “1”
TIP
Install the inner tube bushing onto the slot on
inner tube.
16.Install:
• Outer tube “1”
(to the inner tube “2”)
17.Install:
• Inner tube bushing “1”
• Washer “2”
(to the outer tube)
TIP
Press the inner tube bushing into the outer tube
with fork seal driver “3”.
18.Install:
• Oil seals “1”
TIP
Using a fork seal driver “2,” press the oil seal in
until the stopper ring groove fully appears.
19.Install:
• Oil seal clip “1”
TIP
Fit the oil seal clip correctly in the groove in the
outer tube.
Fork seal driver
90890-01502
YM-A0948
New
Fork seal driver
90890-01502
YM-A0948
New

FRONT FORK
4-45
20.Install:
• Dust seal “1”
TIP
Apply lithium-soap-based grease on the inner
tube.
21.Check:
• Inner tube smooth movement
Tightness/binding/rough spots  Repeat
the steps 14 to 20.
22.Measure:
• Distance “a”
Out of specification  Turn into the locknut.
23.Install:
• Collar “1”
• Fork spring “2”
(to the damper assembly “3”)
TIP
Install the collar with its larger dia. end “a” fac-
ing the fork spring.
24.Install:
• Damper assembly “1”
(to the inner tube “2”)ECA32D1010
NOTICE
Allow the damper assembly to slide slowly
down the inner tube until it contacts the bot
-
tom of the inner tube. Be careful not to dam-
age the inner tube.
Distance “a”
16 mm (0.63 in) or more
Between the damper assembly
“1” bottom and locknut “2” bot
-
tom.
New
1 2a
12
3
a
1
2

FRONT FORK
4-46
25.Loosen:
• Rebound damping force adjuster “1”
TIP
• Before loosening the damping force adjuster,
record the setting position.
• Unless the damping force adjuster is fully
loosened, correct damping characteristic can
-
not be obtained after installation.
26.Install:
• Damper adjusting rod “1”
• Copper washer “2”
• Adjuster “3”
(to the damper assembly “4”)
TIP
• 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.
27.Measure:
• Gap “a” between the adjuster “1” and the
locknut “2”
Out of specification  Retighten and read-
just the locknut.
TIP
If it is installed with a gap out of specification,
correct damping force cannot be obtained.
28.Tighten:
• Adjuster (locknut) “1”
TIP
Hold the locknut “2” and tighten the adjuster.
29.Install:
• Adjuster “1”
(to the inner tube)
Cap bolt ring wrench
90890-01501
YM-01501
1
New
Gap “a” between the adjuster and
the locknut
0.5-1.0 mm (0.02-0.04 in)
Adjuster (locknut)
29 Nm (2.9 m·kgf, 21 ft·lbf)
Adjuster
55 Nm (5.5 m·kgf, 40 ft·lbf)
LOCTITE®
1
2a
T R..
T R..
1LT

FRONT FORK
4-47
30.Fill:
• Front fork leg
ECA14210
NOTICE
• Be sure to use the recommended oil. Other
oils may have an adverse effect on front
fork performance.
• When disassembling and assembling the
front fork leg, do not allow any foreign ma
-
terial to enter the front fork.
31.Install:
• Damper assembly “1”
(to the outer tube)
TIP
Temporarily tighten the damper assembly.
32.Install:
• Protector guide “1”
EAS1SL1170INSTALLING THE FRONT FORK LEGS
1. Install:
• Front fork “1”
TIP
• Temporarily tighten the pinch bolts (lower
bracket).
• Do not tighten the pinch bolts (upper bracket)
yet.
2. Tighten:
• Damper assembly “1”
TIP
Use the cap bolt ring wrench “2” to tighten the
damper assembly.
Recommended oil
Suspension oil S1
Standard oil amount
335 cm3 (11.33 US oz, 11.82 lmp
oz)
355 cm3 (12.00 US oz, 12.52 lmp
oz)
Extent of adjustment
300–365 cm3 (10.14–12.34 US
oz, 10.58–12.87 lmp oz)
Damper assembly
30 Nm (3.0 m·kgf, 22 ft·lbf)
Cap bolt ring wrench
90890-01501
YM-01501
1
T R..
2
1

FRONT FORK
4-48
3. Adjust:
• Front fork top end “a”
4. Tighten:
• Pinch bolt (upper bracket) “1”
• Pinch bolt (lower bracket) “2”
EWA33DD044
WARNING
Tighten the lower bracket to specified
torque. If torqued too much, it may cause
the front fork to malfunction.
5. Install:
• Protector “1”
• Bolt (protector) “2”
6. Adjust:
• Rebound damping force
TIP
Turn in the damping adjuster “1” finger-tight
and then turn out to the originally set position.
7. Adjust:
• Compression damping force
TIP
Turn in the damping adjuster “1” finger-tight
and then turn out to the originally set position.
Front fork top end (standard) “a”
0 mm (0 in)
Upper bracket pinch bolts
21 Nm (2.1 m·kgf, 15 ft·lbf)
Lower bracket pinch bolts
21 Nm (2.1 m·kgf, 15 ft·lbf)
Bolt (protector)
5 Nm (0.5 m·kgf, 3.6 ft·lbf)
a
T R..
T R..
21
T R..
1
2
1
1

STEERING HEAD
4-49
EAS1SL1171
STEERING HEAD
Removing the lower bracket
OrderPart nameQ’tyRemarks
Use a suitable stand to raise the front wheel
off the ground.
Number plateRefer to “GENERAL CHASSIS” on page 4-1.
HandlebarRefer to “HANDLEBAR” on page 4-31.
1Front fender1
2Steering stem nut1
3Front fork leg (s)2Refer to “FRONT FORK” on page 4-37.
4Upper bracket1
5Steering ring nut1
6Lower bracket1
7Bearing race cover1
8Upper bearing1
9Bearing (lower side)1
10Bearing races2
For installation, reverse the removal proce-dure.
2
4
5
7
3
1
6
8
9
10
LS
1st
2ndT.R.
LS
LS
T.R.21 Nm (2.1 mlbf) kgf, 15 ft
T.R.9 Nm (0.9 mlbf) kgf, 6.5 ft
T.R.21 Nm (2.1 mlbf) kgf, 15 ft
T.R.10 Nm (1.0 mlbf) kgf, 7.2 ft
T.R.145 Nm (14.5 mlbf) kgf, 105 ft
38 Nm (3.8 m
lbf) kgf, 27 ft
7 Nm (0.7 m
lbf) kgf, 5.1 ft

STEERING HEAD
4-50
EAS1SL1172REMOVING THE LOWER BRACKET
1. Use a suitable stand to raise the front wheel
off the ground.
EWA13120
WARNING
Securely support the vehicle so that there is
no danger of it falling over.
2. Remove:
• Ring nut “1”
TIP
Remove the ring nut with the steering nut
wrench “2”.
EWA13730
WARNING
Securely support the lower bracket so that
there is no danger of it falling.
EAS1SL1173CHECKING THE STEERING HEAD
1. Wash with kerosene:
• Bearing
• Bearing races
2. Check:
• Bearing
• Bearing races
Damage/pitting  Replace.
3. Replace:
• Bearing
• Bearing races
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Remove the bearing race from the steering
head pipe with a long rod “1” and a hammer.
b. Remove the bearing race from the lower
bracket with a chisel “2” and a hammer.
c. Install a new bearing race.ECA14270
NOTICE
• Take care not to damage the steering shaft
thread.
• If the bearing race is not installed properly,
the steering head pipe could be damaged.
TIP
Always replace the bearing and the bearing
race as a set.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
4. Check:
• Upper bracket
• Lower bracket
(along with the steering stem)
Bends/cracks/damage  Replace.
EAS1SL1174INSTALLING THE STEERING HEAD
1. Install:
• Lower bearing “1”
TIP
Apply the lithium soap base grease on the dust
seal lip and bearing inner circumference.
Steering nut wrench
90890-01403
Exhaust flange nut wrench
YU-A9472