Front YAMAHA YZ450F 2014 Owner's Manual

CHASSIS
3-21
EAS1SL1089
CHASSIS
EAS1SL1090BLEEDING THE BRAKE SYSTEMEWA13100
WARNING
Bleed the brake system whenever:
• The system is disassembled.
• A brake hose is loosened, disconnected,
or replaced.
• The brake fluid level is very low.
• Brake operation is faulty.
1. Remove:
• Brake master cylinder cap
• Reservoir diaphragm
• Reservoir float (front brake)
• Protector (rear brake)
TIP
• Be careful not to spill any brake fluid or allow
the reservoir to overflow.
• Make sure that there is enough brake fluid be-
fore applying the brake. Ignoring this precau-
tion could allow air to enter the brake system,
considerably lengthening the bleeding proce
-
dure.
• If bleeding is difficult, it may be necessary to
let the brake fluid settle for a few hours. Re
-
peat the bleeding procedure when the tiny
bubbles in the hose have disappeared.
2. Bleed the brake system.
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a. Fill the reservoir to the proper level with the
recommended brake fluid.
b. Install the reservoir diaphragm.
c. Connect the plastic hose “1” to the bleed
screw “2” securely, and place a container
under the end of the plastic hose.
d. Slowly apply the brake several times.
e. Fully pull the brake lever or fully press down
the brake pedal and hold it in position.
f. Loosen the bleed screw.
TIP
Loosening the bleed screw will release the
pressure in the brake caliper and cause the
brake lever to contact the throttle grip or the
brake pedal to fully extend.
g. Tighten the bleed screw and then release
the brake lever or brake pedal.
h. Repeat steps (d) to (g) until all of the air bub-
bles have disappeared from the brake fluid
in the plastic hose.
TIP
During the procedure, keep adding brake fluid
to the reservoir.
ECA
NOTICE
Brake fluid may erode painted surfaces or
plastic parts. Always clean up spilled fluid
immediately.
i. Tighten the bleed screw.
j. Pour brake fluid to the reservoir up to the
specified level.
Refer to “CHECKING THE BRAKE FLUID
LEVEL” on page 3-26.EWA13110
WARNING
After bleeding, check the brake operation.
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EAS1SL1091
1 2
A
A. Front
B. Rear
Bleed screw
6 Nm (0.6 m·kgf, 4.3 ft·lbf)
2
1B
T R..

CHASSIS
3-22
CHECKING THE BRAKE HOSE
1. Check:
• Brake hose “1”
Cracks/damage/wear  Replace.
2. Check:
• Brake hose clamp
Loose Connection  Tighten the clamp bolt.
3. Stand the vehicle upright and apply the front
brake and the rear brake several times.
4. Check:
• Brake hoses
Brake fluid leaks  Replace the damaged
brake hose.
Refer to “FRONT BRAKE” on page 4-11.
Refer to “REAR BRAKE” on page 4-21.
EAS1SL1092ADJUSTING THE FRONT BRAKE
1. Check:
• Brake lever position “a”
2. Remove:
• Brake lever cover
3. Adjust:
• Brake lever position
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Loosen the locknut “1.”
b. Turn the adjusting bolt “2” in direction “a” or
“b” until the specified brake lever position is
obtained.
c. Tighten the locknut.
EWA13050
WARNING
A soft or spongy feeling in the brake lever
can indicate the presence of air in the brake
system. Before running, bleed the brake
system. Air in the brake system will cause
braking performance to be reduced.
ECA13490
NOTICE
After adjusting the brake lever position,
make sure that there is no brake drag.
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4. Install:
• Brake lever cover
A. Front
B. Rear
Brake lever position
95 mm (3.74 in)
Extent of adjustment
86–105 mm (3.39–4.13 in)
1
1
Direction “a”
Brake lever position is increased.
Direction “b”
Brake lever position is decreased.
Locknut
5 Nm (0.5 m·kgf, 3.6 ft·lbf)
a
b
T R..

CHASSIS
3-23
EAS1SL1093ADJUSTING THE REAR BRAKE
1. Check:
• Brake pedal position “a”
(distance from the top of the rider footrest to
the top of the brake pedal)
Out of specification  Regulate.
2. Adjust:
• Brake pedal position
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Loosen the locknut “1.”
b. Turn the adjusting bolt “2” in direction “a” or
“b” until the specified brake pedal position is
obtained.
c. Tighten the locknut.
EWA1DX1001
WARNING
A soft or spongy feeling in the brake pedal
can indicate the presence of air in the brake
system. Before running, bleed the brake
system. Air in the brake system will cause
braking performance to be reduced.
ECA13510
NOTICE
After adjusting the brake pedal position,
make sure that there is no brake drag.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
EAS1SL1094CHECKING THE FRONT BRAKE PADS
1. Measure:
• Brake pad thickness “a”
Out of specification  Replace as a set.
TIP
The pads worn up to the indicator “b” grooves
mean that the brake pad thickness limit is
reached.
2. Replace:
• Brake pads
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a. Remove the pad pin plug “1.”
Brake pedal position
0.0 mm (0.00 in)
Direction “a”
Brake pedal is raised.
Direction “b”
Brake pedal is lowered.
Locknut
6 Nm (0.6 m·kgf, 4.3 ft·lbf)
1 2
a
b
T R..
Brake pad lining thickness (inner)
4.4 mm (0.17 in)
Limit
1.0 mm (0.04 in)
Brake pad lining thickness (outer)
4.4 mm (0.17 in)
Limit
1.0 mm (0.04 in)
a
b
a
1

CHASSIS
3-24
b. Loosen the pad pin “2.”
c. Remove the brake caliper “3” from the front
fork.
d. Remove the pad pin and brake pads “4.”
e. Connect the plastic hose “5” to the bleed
screw “6” and place a container under the
end of the plastic hose.
f. Loosen the bleed screw and push the brake
caliper piston in.
EWA@
WARNING
Do not reuse the drained brake fluid.
g. Tighten the bleed screw.
h. Install the brake pads “7” and the pad pin.
TIP
• Install the brake pads with their projections “a”
into the brake caliper recesses “b”.
• Temporarily tighten the pad pin at this point.
i. Install the brake caliper “8” and tighten the
pad pin “9”.
j. Install the pad pin plug “10.”
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3. Check:
• Brake fluid level
Refer to “CHECKING THE BRAKE FLUID
LEVEL” on page 3-26.
4. Check:
• Brake lever operation
A softy or spongy feeling  Bleed the brake
system.
Refer to “BLEEDING THE BRAKE SYS-
TEM” on page 3-21.
Bleed screw
6 Nm (0.6 m·kgf, 4.3 ft·lbf)
3
2
4
6
5
T R..
Bolt (brake caliper)
28 Nm (2.8 m·kgf, 20 ft·lbf)
Pad pin
17 Nm (1.7 m·kgf, 12 ft·lbf)
Pad pin plug
2.5 Nm (0.25 m·kgf, 1.8 ft·lbf)
7
a b
T R..
8
9
T R..
10

CHASSIS
3-26
i. Install the brake caliper “12” and the rear
wheel “13.”
Refer to “REAR WHEEL” on page 4-7.
j. Tighten the pad pin “14.”
k. Install the pad pin plug “15” and the protector
“16.”
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3. Check:
• Brake fluid level
Refer to “CHECKING THE BRAKE FLUID
LEVEL” on page 3-26.
4. Check:
• Brake pedal operation
A softy or spongy feeling  Bleed the brake
system.
Refer to “BLEEDING THE BRAKE SYS-
TEM” on page 3-21.
EAS1SL1096CHECKING THE REAR BRAKE PAD INSU-
LATOR
1. Remove:
• Brake pads
Refer to “REAR BRAKE” on page 4-21.
2. Check:
• Rear brake pad insulator “1”
Damage  Replace.
EAS1SL1097CHECKING THE BRAKE FLUID LEVEL
1. Stand the vehicle upright on a level surface.
TIP
In order to ensure a correct reading of the brake
fluid level, make sure that the top of the brake
fluid reservoir is horizontal.
2. Check:
• Brake fluid level
The minimum level mark “a” or below 
Add.
EWA13090
Pad pin
17 Nm (1.7 m·kgf, 12 ft·lbf)
Pad pin plug
2.5 Nm (0.25 m·kgf, 1.8 ft·lbf)
Bolt (protector)
7 Nm (0.7 m·kgf, 5.1 ft·lbf)
10 11
a
b
T R..
13
14
12
T R..
15
16Recommended brake fluid
DOT 4
A. Front brake
B. Rear brake

CHASSIS
3-28
EAS1SL1099CHECKING THE FRONT FORK LEGS
1. Stand the vehicle upright on a level surface.EWA13120
WARNING
Securely support the vehicle so that there is
no danger of it falling over.
2. Check:
• Inner tube
Damage/scratches  Replace.
• Front fork leg (s)
Oil leaks between inner tube and outer tube
 Replace the oil seal.
3. Hold the vehicle upright and apply the front
brake.
4. Check:
• Front fork operation
Push down hard on the handlebar several
times and check if the front fork rebounds
smoothly.
Unsmooth operation  Correct or replace.
Refer to “FRONT FORK” on page 4-37.
EAS1SL1100CHECKING THE FRONT FORK PROTEC-
TOR GUIDE
1. Check:
• Protector guide “1”
Out of specification  Replace.
TIP
The protector guide reaches the limit of its use
when it is worn down to the same height “a” as
of the outer tube circumference.
EAS1SL1101
CLEANING THE FRONT FORK OIL SEAL
AND DUST SEAL
1. Remove:
•Protector
• Dust seal “1”ECA?
NOTICE
Be careful not to damage the dust seal and
the inner tube by a driver.
2. Clean:
• Dust seal “a”
• Oil seal “b”
TIP
• Clean the dust seal and oil seal after every
run.
• Apply lithium-soap-based grease on the inner
tube.
EAS1SL1102AIR BLEEDING FROM FRONT FORK
TIP
If the front fork initial movement feels stiff dur-
ing a run, relieve the front fork internal pres-
sure.
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 the air bleed screw “1” and release
the internal pressure from the front fork.
1
a
1
LS
a
b

CHASSIS
3-29
3. Tighten:
• Air bleed screw
EAS1SL1103ADJUSTING THE FRONT FORK LEGSEWA32D1006
WARNING
• Always adjust the left and right front forks
evenly. If this is not done, the vehicle may
have poor stability.
• Securely support the vehicle so that there
is no danger of it falling over.
Rebound damping forceECA13590
NOTICE
Do not turn the adjuster forcibly beyond its
adjusting range.
1. Adjust:
• Rebound damping force
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Turn the adjuster “1” in the direction of “a” or
“b” to make an adjustment.
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Compression damping forceECA13590
NOTICE
Do not turn the adjuster forcibly beyond its
adjusting range.
1. Adjust:
• Compression damping force
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Turn the adjuster “1” in the direction of “a” or
“b” to make an adjustment.
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EAS1SL1104
Air bleed screw
1.3 Nm (0.13 m·kgf, 0.94 ft·lbf)
Direction “a”
Rebound damping force is increased
(suspension is harder).
Direction “b”
Rebound damping force is decreased
(suspension is softer).
Rebound damping force
Maximum
Turn it in finger-tight.
STD
Turn it out by 8 clicks.*
Minimum
Turn it out by 20 clicks.*
* With the adjuster fully turned in
T R..
1
Direction “a”
Compression damping force is in-
creased (suspension is harder).
Direction “b”
Compression damping force is de-
creased (suspension is softer).
Compression damping force
Maximum
Turn it in finger-tight.
STD
Turn it out by 9 clicks.*
(USA)(CAN)
Turn it out by 8 clicks.*
(EUR)(JPN)(AUS)(NZL)(ZAF)
Minimum
Turn it out by 20 clicks.*
* With the adjuster fully turned in
1
a
b
a b
1

CHASSIS
3-33
2. Tighten:
• Spokes
Use a spoke nipple wrench “1” for tighten-
ing.
TIP
• Do not give a half turn (180°) or more for one
tightening.
• Make sure that tightening after a break-in is
done until the initial looseness in nipples dis
-
appears.
• Make sure that tightening is done in stages,
not at a time.
EAS1SL1109CHECKING THE WHEELS
1. Check:
• Wheel (s)
Damage/out-of-round  Replace.EWA13260
WARNING
Never attempt to make any repairs to the
wheel.
TIP
After replacing a tire or a wheel, always bal-
ance the wheel.
EAS1SL1110CHECKING THE WHEEL BEARINGS
1. Check:
• Wheel bearings
“CHECKING THE FRONT WHEEL” on page
4-4and “CHECKING THE REAR WHEEL”
on page 4-8.
EAS1SL1111
CHECKING AND ADJUSTING THE STEER-
ING HEAD
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. Check:
• Steering head
Grasp the bottom of the front fork legs and
gently rock the front fork.
Blinding/looseness  Adjust the steering
head.
3. Remove:
• Handlebar
Refer to “HANDLEBAR” on page 4-31.
• Upper bracket
Refer to “STEERING HEAD” on page 4-49.
4. Adjust:
• Steering head
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Remove the washer “1.”
b. After loosening the ring nut “2” with a steer-
ing nut wrench “3,” tighten it to the specified
torque.
TIP
• Set the torque wrench at a right angle to the
steering nut wrench.
• Move the steering to the left and right a couple
of times to check that it moves smoothly.
Spoke nipple wrench (6–7)
90890-01521
YM-01521
Spokes
2.5 Nm (0.25 m·kgf, 1.8 ft·lbf)
1
T R..
1

CHASSIS
3-34
c. Turn the front fork to the right and left a few
times, and make sure that the steering ro
-
tates smoothly. If it does not turn smoothly,
remove the lower bracket and check the up
-
per and lower bearings.
Refer to “STEERING HEAD” on page 4-49.
d. Loosen the ring nut fully turn and then tight-
en it to specification with a steering nut
wrench.
EWA13140
WARNING
Do not overtighten the ring nut beyond the
specified torque. Otherwise, the steering
may malfunction.
e. Check the steering head for looseness or
binding by turning the front fork all the way in
both directions. If any binding is felt, remove
the lower bracket and check the upper and
lower bearings.
Refer to “STEERING HEAD” on page 4-49.
f. Install the washer “1”.
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5. Install:
• Upper bracket
Refer to “STEERING HEAD” on page 4-49.
• Handlebar
Refer to “HANDLEBAR” on page 4-31.
EAS1SL1112LUBRICATING THE LEVERS
1. Lubricate the pivoting points and metal-to-
metal moving parts of the following parts.
•Brake lever
• Clutch lever
EAS1SL1113LUBRICATING THE PEDAL
1. Lubricate the pivoting point and metal-to-
metal moving parts of the pedal.
Steering nut wrench
90890-01403
Exhaust flange nut wrench
YU-A9472
Ring nut (initial tightening torque)
38 Nm (3.8 m·kgf, 27 ft·lbf)
Ring nut (final tightening torque)
7 Nm (0.7 m·kgf, 5.1 ft·lbf)
3
2
T R..
T R..
1
Recommended lubricant
Silicone grease
Recommended lubricant
Lithium-soap-based grease
Recommended lubricant
Lithium-soap-based grease

4
CHASSIS
GENERAL CHASSIS........................................................................................ 4-1
REMOVING THE LEFT SIDE COVER ....................................................... 4-2
REMOVING THE SEAT ............................................................................. 4-2
REMOVING THE NUMBER PLATE ........................................................... 4-2
FRONT WHEEL................................................................................................ 4-3
REMOVING THE FRONT WHEEL............................................................. 4-4
CHECKING THE FRONT WHEEL ............................................................. 4-4
DISASSEMBLING THE FRONT WHEEL ................................................... 4-5
ASSEMBLING THE FRONT WHEEL ......................................................... 4-5
INSTALLING THE FRONT WHEEL ........................................................... 4-6
REAR WHEEL.................................................................................................. 4-7
REMOVING THE REAR WHEEL ............................................................... 4-8
CHECKING THE REAR WHEEL................................................................ 4-8
DISASSEMBLING THE REAR WHEEL ..................................................... 4-8
CHECKING AND REPLACING THE REAR WHEEL SPROCKET ............ 4-8
ASSEMBLING THE REAR WHEEL ........................................................... 4-9
INSTALLING THE REAR WHEEL.............................................................. 4-9
FRONT BRAKE.............................................................................................. 4-11
INTRODUCTION ...................................................................................... 4-15
CHECKING THE FRONT BRAKE DISC .................................................. 4-15
REMOVING THE FRONT BRAKE CALIPER ........................................... 4-15
DISASSEMBLING THE FRONT BRAKE CALIPER................................. 4-15
CHECKING THE FRONT BRAKE CALIPER ........................................... 4-16
ASSEMBLING THE FRONT BRAKE CALIPER ....................................... 4-16
INSTALLING THE BRAKE CALIPER PISTON ........................................ 4-16
INSTALLING THE FRONT BRAKE CALIPER ......................................... 4-17
REMOVING THE FRONT BRAKE MASTER CYLINDER ........................ 4-18
CHECKING THE FRONT BRAKE MASTER CYLINDER......................... 4-18
ASSEMBLING THE FRONT BRAKE MASTER CYLINDER .................... 4-18
INSTALLING THE FRONT BRAKE MASTER CYLINDER....................... 4-19
REAR BRAKE................................................................................................ 4-21
INTRODUCTION ...................................................................................... 4-25
CHECKING THE REAR BRAKE DISC..................................................... 4-25
REMOVING THE REAR BRAKE CALIPER ............................................. 4-26
DISASSEMBLING THE REAR BRAKE CALIPER ................................... 4-26
CHECKING THE REAR BRAKE CALIPER .............................................. 4-26
ASSEMBLING THE REAR BRAKE CALIPER ......................................... 4-26
INSTALLING THE BRAKE CALIPER PISTON ........................................ 4-27
INSTALLING THE REAR BRAKE CALIPER ............................................ 4-27
REMOVING THE REAR BRAKE MASTER CYLINDER .......................... 4-28
CHECKING THE REAR BRAKE MASTER CYLINDER ........................... 4-28
ASSEMBLING THE REAR BRAKE MASTER CYLINDER....................... 4-29
INSTALLING THE REAR BRAKE MASTER CYLINDER ......................... 4-29