2016 YAMAHA YZ450F oil

FRONT FORK
4-41
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5. Remove:
• Base valve “1”
(from the damper assembly)
TIP
Hold the damper assembly with the cap bolt
ring wrench “2” and use the cap bolt wrench “3”
to remove the base valve.
EASB111167CHECKING THE FRONT FORK LEGS
1. Check:
• Inner tube
Scratches  Repair or replace.
Use #1000 grit wet sandpaper.
Damaged oil lock piece  Replace.
• Outer tube
Out of specification  Replace.
Use the dial gauge “1”.
TIP
The bending value is shown by one half of the
dial gauge reading.
EWA13650
WARNING
Do not attempt to straighten a bent inner
tube as this may dangerously weaken it.
2. Check:
• Outer tube
Scratches/wear/damage  Replace.
3. Measure:
• Fork spring free length “a”
Out of specification  Replace.
4. Check:
• Damper rod “1”
Bend/damage  Replace.
• Damper rod “2”
Wear/damage  Replace.
ECA1DX1010
NOTICE
• The front fork leg has a built-in damper ad-
justing rod and a very sophisticated inter-
nal construction, which are particularly
sensitive to foreign material.
• When disassembling and assembling the
front fork leg, do not allow any foreign ma-
terial to enter the front fork. Cap bolt wrench
90890-01500
YM-01500
Cap bolt ring wrench
90890-01501
YM-01501
Inner tube bending limit
0.2 mm (0.01 in)
1 23
Fork spring free length
497.0 mm (19.57 in)
Limit
492.0 mm (19.37 in)

FRONT FORK
4-42
5. Check:
• Base valve “1”
Wear/damage  Replace.
Contamination  Clean.
• O-rings “2”
Wear/damage  Replace.
• Base valve bushing “3”
Wear/damage  Replace.
• Spring “4”
Damage/fatigue  Replace the base valve.
• Air bleed screw “5”
Wear/damage  Replace.
6. Check:
• Contacting surface “a”
Wear/damage  Replace.
7. Check:
• Adjuster “1”
• O-rings “2”
Wear/damage  Replace.EASB111168ASSEMBLING THE FRONT FORK LEGSEWA13660
WARNING
• Make sure the oil levels in both front fork
legs are equal.
• Uneven oil levels can result in poor han-
dling and a loss of stability.
TIP
• When assembling the front fork leg, be sure to
replace the following parts:
• Inner tube bushing
• Outer tube bushing
• Oil seals
• Copper washers
• Before assembling the front fork leg, make
sure that all of the components are clean.
1. Stretch the damper assembly fully.
2. Fill:
• Damper assembly
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, take care not to allow any
foreign material to enter the front fork.
3. After filling, pump the damper assembly “1”
slowly up and down (about 200 mm (7.9 in)
stroke) several times to bleed the damper
assembly of air.
TIP
Avoid excessive full stroke. A stroke of 200 mm
(7.9 in) or more will cause air to enter. In this
case, repeat the steps 1 to 3.
21
New
New
New
2
21 543
a
New
Recommended oil
Suspension oil S1
Standard oil amount
204 cm
3 (6.90 US oz, 7.20
Imp.oz)
New
1
2

FRONT FORK
4-43
4. Measure:
• Oil level (left and right) “a”
Out of specification  Regulate.
5. Tighten:
• Locknut “1”
TIP
Fully finger tighten the locknut onto the damper
assembly.6. Loosen:
• Compression 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.
7. Install:
• Base valve “1”
(to the damper assembly “2”)
TIP
First bring the damper rod pressure to a maxi-
mum. Then install the base valve while releas-
ing the damper rod pressure.
8. Check:
• Damper assembly
Not fully stretched  Repeat the steps 1 to
7. Standard oil level
145–148 mm (5.71–5.83 in)
From top of fully stretched
damper assembly.
1
a1
1
2

FRONT FORK
4-44
9. Tighten:
• Base valve “1”
TIP
Hold the damper assembly with the cap bolt
ring wrench “2” and use the cap bolt wrench “3”
to tighten the base valve.
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. Base valve
28 Nm (2.8 m·kgf, 20 ft·lbf)
Cap bolt wrench
90890-01500
YM-01500
Cap bolt ring wrench
90890-01501
YM-01501
T R..
1 23
1
1
a
New
New
New

FRONT FORK
4-45
TIP
• Apply the lithium-soap-based 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.
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.
LS
New
Fork seal driver
90890-01502
YM-A0948
Fork seal driver
90890-01502
YM-A0948
New

FRONT FORK
4-46
19.Install:
• Oil seal clip “1”
TIP
Fit the oil seal clip correctly in the groove in the
outer tube.
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.
New
Distance “a”
16 mm (0.63 in) or more
Between the damper assembly
“1” bottom and locknut “2” bot-
tom.
1 2a
12
3
a

FRONT FORK
4-48
29.Install:
• Adjuster “1”
(to the inner tube)
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”
EASB111169INSTALLING 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. Adjuster
55 Nm (5.5 m·kgf, 40 ft·lbf)
LOCTITE®
Recommended oil
Suspension oil S1
Standard oil amount
315 cm
3 (10.65 US oz, 11.11 lmp
oz)
Extent of adjustment
300–365 cm
3 (10.14–12.34 US
oz, 10.58–12.87 lmp oz)
T R..
1LT
1

REAR SHOCK ABSORBER ASSEMBLY
4-57
Disassembling the relay arm
Order Part name Q’ty Remarks
1 Relay arm 1
2 Connecting arm 1
3Collars 3
4Oil seals 6
5Washers 8
6 Bearing 6
For assembly, reverse the disassemble pro-
cedure.
5
3
5
6
165
4
5
5
4
5
6
6
5
4
3
2
4
6
6
3
4
4
T.R.80 Nm (8.0 mlbf) kgf, 58 ft
M
M
M
M
M MM