steering YAMAHA YZ450F 2016 User Guide

CHASSIS
3-36
5. Install:
• Upper bracket
Refer to “STEERING HEAD” on page 4-51.
• Handlebar
Refer to “HANDLEBAR” on page 4-32.
EASB111111LUBRICATING THE LEVERS
1. Lubricate the pivoting points and metal-to-
metal moving parts of the following parts.
• Brake lever
•Clutch lever
EASB111112LUBRICATING THE PEDAL
1. Lubricate the pivoting point and metal-to-
metal moving parts of the pedal.Recommended lubricant
Silicone grease
Recommended lubricant
Lithium-soap-based grease
Recommended lubricant
Lithium-soap-based grease

HANDLEBAR................................................................................................. 4-32
REMOVING THE HANDLEBAR............................................................... 4-34
CHECKING THE HANDLEBAR ............................................................... 4-34
INSTALLING THE HANDLEBAR ............................................................. 4-34
FRONT FORK................................................................................................. 4-38
REMOVING THE FRONT FORK LEGS ................................................... 4-40
DISASSEMBLING THE FRONT FORK LEGS ......................................... 4-40
CHECKING THE FRONT FORK LEGS ................................................... 4-41
ASSEMBLING THE FRONT FORK LEGS ............................................... 4-42
INSTALLING THE FRONT FORK LEGS ................................................. 4-48
STEERING HEAD........................................................................................... 4-51
REMOVING THE LOWER BRACKET...................................................... 4-52
CHECKING THE STEERING HEAD ........................................................ 4-52
INSTALLING THE STEERING HEAD ...................................................... 4-52
REAR SHOCK ABSORBER ASSEMBLY..................................................... 4-55
HANDLING THE REAR SHOCK ABSORBER ......................................... 4-58
DISPOSING OF A REAR SHOCK ABSORBER ...................................... 4-58
REMOVING THE REAR SHOCK ABSORBER ASSEMBLY.................... 4-58
REMOVING THE BEARING..................................................................... 4-59
CHECKING THE REAR SHOCK ABSORBER ASSEMBLY .................... 4-59
CHECKING THE CONNECTING ARM AND RELAY ARM ...................... 4-59
INSTALLING THE RELAY ARM............................................................... 4-59
INSTALLING THE REAR SHOCK ABSORBER ASSEMBLY .................. 4-60
SWINGARM.................................................................................................... 4-62
REMOVING THE SWINGARM................................................................. 4-63
REMOVING THE BEARING..................................................................... 4-63
CHECKING THE SWINGARM ................................................................. 4-63
INSTALLING THE SWINGARM ............................................................... 4-64
CHAIN DRIVE................................................................................................. 4-65
REMOVING THE DRIVE CHAIN.............................................................. 4-66
CHECKING THE DRIVE CHAIN .............................................................. 4-66
CHECKING THE DRIVE SPROCKET...................................................... 4-67
CHECKING THE REAR WHEEL SPROCKET ......................................... 4-67
INSTALLING THE DRIVE CHAIN ............................................................ 4-67

STEERING HEAD
4-51
EASB111170
STEERING HEAD
Removing the lower bracket
Order Part name Q’ty Remarks
Refer to “CHECKING AND ADJUSTING
THE STEERING HEAD” on page 3-35.
Use a suitable stand to raise the front wheel
off the ground.
Number plate Refer to “GENERAL CHASSIS” on page 4-1.
Handlebar Refer to “HANDLEBAR” on page 4-32.
1 Front fender 1
2 Steering stem nut 1
3 Front fork leg (s) 2 Refer to “FRONT FORK” on page 4-38.
4 Upper bracket 1
5 Steering ring nut 1
6 Lower bracket 1
7 Bearing race cover 1
8 Upper bearing 1
9 Bearing (lower side) 1
10 Bearing races 2
For installation, reverse the removal proce-
dure.
2
4
5
7
3
1
6
8
9
10
LS
T
.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
4-52
EASB111171REMOVING THE LOWER BRACKET
1. Use a suitable stand to raise the front wheel
off the ground.
EWA
WARNING
Securely support the vehicle so that there is
no danger of it falling over.
2. Remove:
• Rng nut “1”
TIP
Remove the ring nut with the steering nut
wrench “2”.
EWA
WARNING
Securely support the lower bracket so that
there is no danger of it falling.
EASB111172CHECKING 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.
ECA
NOTICE
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.
EASB111173INSTALLING THE STEERING HEAD
1. Install:
• Lower bearing “1”
TIP
Apply the lithium-soap-based grease on the
dust seal lip and bearing inner circumference. Steering nut wrench
90890-01403
Exhaust flange nut wrench
YU-A9472

STEERING HEAD
4-53
2. Install:
• Bearing races
• Upper bearing “1”
• Bearing race cover “2”
TIP
Apply the lithium-soap-based grease on the
bearing and bearing race cover lip.
3. Install:
• Lower bracket “1”
TIP
Apply the lithium-soap-based 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 3-35.5. 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
4-54
8. Install:
• Steering stem nut “1”
TIP
Apply the lithium-soap-based grease to 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 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

TROUBLESHOOTING
9-3
Fuel system
1. Throttle body
• Damaged or loose throttle body joint
2. Air filter
• Clogged air filter element
Chassis
1. Brake(s)
• Dragging brake
Electrical system
1. Spark plug
• Incorrect spark plug gap
• Incorrect spark plug heat range
2. Ignition system
• Faulty ECU
• Faulty coolant temperature sensor
EASB111359OVERCOOLING
Cooling system
1. Coolant temperature sensor
• Faulty coolant temperature sensor
EASB111360POOR BRAKING PERFORMANCE
Chassis
1. Brake(s)
• Worn brake pad
• Worn brake disc
• Air in hydraulic brake system
• Leaking brake fluid
• Defective master cylinder kit
• Faulty brake caliper kit
• Faulty brake caliper seal
• Loose union bolt
• Damaged brake hose
• Oil or grease on the brake disc
• Oil or grease on the brake pad
• Incorrect brake fluid level
EASB111361FRONT FORK OIL LEAKING
Chassis
1. Front fork
• Bent, damaged, or rusty inner tube
• Cracked or damaged outer tube
• Improperly installed oil seal
• Damaged oil seal lip
• Incorrect oil level (high)
• Loose damper rod assembly bolt
• Damaged damper rod assembly bolt copper
washer
• Cracked or damaged cap bolt O-ring
EASB111362FAULTY FRONT FORK LEGS
Chassis
1. Front fork
• Bent or damaged inner tube
• Bent or damaged outer tube
• Broken fork spring
• Bent or damaged damper rod
• Incorrect oil viscosity
• Incorrect oil level
EASB111363UNSTABLE HANDLING
Chassis
1. Handlebar
• Bent or improperly installed handlebar
2. Steering head components
• Improperly installed upper bracket
• Improperly installed lower bracket
(improperly tightened ring nut)
• Bent steering stem
• Damaged ball bearing or bearing race
3. Front fork leg (s)
• Uneven oil levels (both front fork legs)
• Unevenly tensioned fork spring (both front
fork legs)
• Broken fork spring
• Bent or damaged inner tube
• Bent or damaged outer tube
4. Swingarm
• Worn bearing or bushing
• Bent or damaged swingarm
5. Rear shock absorber assembly (-ies)
• Faulty rear shock absorber spring
• Leaking oil or gas
6. Tire (s)
• Uneven tire pressures (front and rear)
• Incorrect tire pressure
• Uneven tire wear
7. Wheel (s)
• Incorrect wheel balance
• Broken or loose spoke
• Damaged wheel bearing
• Bent or loose wheel axle
• Excessive wheel runout
8. Frame
• Bent frame
• Damaged steering head pipe
• Improperly installed bearing race