2015 YAMAHA YZ450F Owners Manual

STEERING HEAD
4-51
2. Install:
• Bearing races
• Upper bearing “1”
• Bearing race cover “2”
TIP
Apply the lithium soap base grease on the
bearing and bearing race cover lip.
3. Install:
• Lower bracket “1”
TIP
Apply the lithium soap base grease on the
bearing, the portion “a” and thread of the steer-
ing stem.
4. Install:
• Steering ring nut “1”
TIP
Install the steering nut with its stepped side “a”
facing downward.
Tighten the steering ring nut with a steering
nut wrench “2”.
Refer to “CHECKING AND ADJUSTING
THE STEERING HEAD” on page 3-33.5. Check the steering stem by turning this lock
to lock. If there is any binding, remove the
steering stem and check the steering bear-
ing.
6. Install:
• Washer “1”
7. Install:
• Front fork “1”
• Upper bracket “2”
TIP
• Temporarily tighten the pinch bolts (lower
bracket).
• Do not tighten the pinch bolts (upper bracket)
yet. Steering ring nut
7 Nm (0.7 m·kgf, 5.1 ft·lbf)
LS
1 a
LSLS
T R..

STEERING HEAD
4-52
8. Install:
• Steering stem nut “1”
TIP
Apply the lithium soap base grease to the con-
tact surface of the steering stem nut when in-
stalling.
9. After tightening the nut, check the steering
for smooth movement. If not, adjust the
steering by loosening the steering ring nut
little by little.
10.Adjust:
• Front fork top end “a”11.Tighten:
• Pinch bolt (upper bracket) “1”
• Pinch bolt (lower bracket) “2”
EWA33DD049
WARNING
Tighten the lower bracket to specified
torque. If torqued too much, it may cause
the front fork to malfunction. Steering stem nut
145 Nm (14.5 m·kgf, 105 ft·lbf)
Front fork top end (standard) “a”
0 mm (0 in)T R..
a
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)
T R..
T R..
21

REAR SHOCK ABSORBER ASSEMBLY
4-53
EAS1SL5176
REAR SHOCK ABSORBER ASSEMBLY
Removing the rear shock absorber assembly
Order Part name Q’ty Remarks
Seat Refer to “GENERAL CHASSIS” on page 4-1.
Side cover (left / right) Refer to “GENERAL CHASSIS” on page 4-1.
Air scoop (left / right) Refer to “GENERAL CHASSIS” on page 4-1.
Fuel tank Refer to “FUEL TANK” on page 7-1.
1 Rear shock absorber assembly lower bolt 1
2 Rear shock absorber assembly upper bolt 1
3 Rear shock absorber assembly 1
4 Locknut 1
5 Adjusting nut 1
6 Lower spring guide 1
7 Upper spring guide 1
2
12
1615
1413
12
14
4
5
7
6
83
9
9 10
10 11
1
New
New
13New
LS
LS
M
M
M
M
M

REAR SHOCK ABSORBER ASSEMBLY
4-54
Removing the rear shock absorber assembly
Order Part name Q’ty Remarks
8Spring 1
9 Dust seal 2
10 Collars 2
11 Bushing 1
12 Collars 2
13 O-ring 2
14 Dust seal 2
15 Stopper ring 1
16 Bearing 1
For installation, reverse the removal proce-
dure.
2
12
1615
1413
12
14
4
5
7
6
83
9
9 10
10 11
1
New
New
13New
LS
LS
M
M
M
M
M

REAR SHOCK ABSORBER ASSEMBLY
4-55
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

REAR SHOCK ABSORBER ASSEMBLY
4-56
EAS1SL5177HANDLING THE REAR SHOCK ABSORBEREWA13740
WARNING
This rear shock absorber contains highly
compressed nitrogen gas. Before handling
the rear shock absorber, read and make
sure that you understand the following in-
formation. The manufacturer cannot be held
responsible for property damage or person-
al injury that may result from improper han-
dling of the rear shock absorber.
• Do not tamper or attempt to open the rear
shock absorber.
• Do not subject the rear shock absorber to
an open flame or any other source of high
heat. High heat can cause an explosion
due to excessive gas pressure.
• Do not deform or damage the rear shock
absorber in any way. Rear shock absorber
damage will result in poor damping perfor-
mance.
TIP
A break-in is required up to about 50 km of run-
ning.
EAS1SL5178DISPOSING OF A REAR SHOCK ABSORB-
ER
Before disposing the rear shock absorber, be
sure to extract the nitrogen gas from valve “1”.
EWA33DD052
WARNING
• Wear protective glasses to prevent your
eyes from damage due to possible gas or
metal chips scattered.
• To dispose of a damaged or a worn-out
rear shock absorber, take the unit to your
Yamaha dealer for this disposal proce-
dure.
EAS1SL5179REMOVING THE REAR SHOCK ABSORBER
ASSEMBLY
1. Use a suitable stand to raise the rear wheel
off the ground.
EWA13120
WARNING
Securely support the vehicle so that there is
no danger of it falling over.
2. Remove:
• Rear shock absorber assembly lower bolt
“1”
TIP
While removing the rear shock absorber as-
sembly lower bolt, hold the swingarm so that it
does not drop down.
3. Remove:
• Rear shock absorber assembly upper bolt
• Rear shock absorber assembly
EAS1SL5180REMOVING THE BEARING
1. Remove:
• Stopper ring (upper bearing) “1”
TIP
Press in the bearing while pressing its outer
race and remove the stopper ring.
1
1

REAR SHOCK ABSORBER ASSEMBLY
4-57
2. Remove:
• Upper bearing “1”
TIP
Remove the bearing by pressing its outer race.
3. Remove:
• Lower bearing “1”
TIP
Remove the bearing by pressing its outer race.
EAS1SL5181CHECKING THE REAR SHOCK ABSORBER
ASSEMBLY
1. Check:
• Rear shock absorber rod
Bends/damage  Replace the rear shock
absorber assembly.
• Rear shock absorber
Gas leaks/oil leaks  Replace the rear
shock absorber assembly.
•Spring
Damage/wear  Replace.
• Spring guide
Damage/wear  Replace.
• Bearing
Damage/wear  Replace.
•Bolts
Bends/damage/wear  Replace.
EAS1SL5182
CHECKING THE CONNECTING ARM AND
RELAY ARM
1. Check:
• Connecting arm
• Relay arm
Damage/wear  Replace.
2. Check:
• Bearing
• Spacers
Damage/pitting/scratches  Replace the
bearings and spacers as a set.
3. Check:
• Oil seals
Damage/pitting  Replace.
EAS1SL5183INSTALLING THE RELAY ARM
1. Lubricate:
• Oil seals
• Bearing
• Spacers
• Washers
•Collars
2. Install:
• Bearing “1”
• Washer “2”
• Oil seals “3”
(to relay arm “4”)
3. Install:
• Bearing “1”
• Oil seals “2”
(to connecting arm “3”)
1
Recommended lubricant
Molybdenum disulfide grease
Installed depth “a”
0 mm (0 in)
Installed depth “a”
0 mm (0 in)
New
3 3
43
2 2
22
a
1
11
New

REAR SHOCK ABSORBER ASSEMBLY
4-58
EAS1SL5184INSTALLING THE REAR SHOCK ABSORB-
ER ASSEMBLY
1. Lubricate:
• Bearing (lower side)
•Dust seal
•Collars
• Bushing
ECA1DX1012
NOTICE
Do not apply the grease to the bearing outer
race because it will wear the rear shock ab-
sorber surface on which the bearing is
press fitted.
2. Lubricate:
• O-ring
3. Install:
• Bearing
• Stopper ring
(to rear shock absorber assembly (upper
side))
TIP
• Install the bearing parallel until the stopper
ring groove appears by pressing its outer
race.
• After installing the stopper ring, push back the
bearing unit it contacts the stopper ring.
4. Install:
• Bearing “1”
• Bushing “2”
• Collar “3”
• Dust seal “4”
(to rear shock absorber assembly (lower
side))
TIP
Install the dust seals with their lips facing in-
ward.
5. Lubricate:
• Connecting arm and frame bolt
• Relay arm and connecting arm bolt
• Relay arm and swingarm bolt
(circumference and threaded portion)
• Rear shock absorber assembly upper bolt
• Rear shock absorber assembly lower bolt
6. Install:
• Rear shock absorber assembly
TIP
• When installing the rear shock absorber as-
sembly, lift up the swingarm.
• Install the rear shock absorber assembly up-
per bolt, and connecting arm bolt (frame side)
from the right.
• Install the rear shock absorber assembly low-
er bolts, connecting arm bolt (relay arm side),
and relay arm bolt (swingarm side) from the
left.
7. Tighten:
• Rear shock absorber assembly upper bolt
• Connecting arm bolt (frame side) Recommended lubricant
Molybdenum disulfide grease
Recommended lubricant
Molybdenum disulfide grease
3
a 1
12
a
2
New
Installed depth “a”
4.25 mm (0.17 in)
Recommended lubricant
Molybdenum disulfide grease
Rear shock absorber assembly
upper bolt
56 Nm (5.6 m·kgf, 41 ft·lbf)
Connecting arm bolt (frame side)
80 Nm (8.0 m·kgf, 58 ft·lbf)
T R..
T R..