2015 YAMAHA YZ450F Owners Manual

REAR BRAKE
4-27
EAS1SL5156INSTALLING THE BRAKE CALIPER PISTON
1. Clean:
• Brake caliper
• Brake caliper piston seal
• Brake caliper piston dust seal
• Brake caliper piston
Use brake fluid for cleaning.
2. Install:
• Brake caliper piston seals “1”
• Brake caliper piston dust seal “2”
EWA33DD033
WARNING
Always use new brake caliper piston seal
and brake caliper piston dust seal.
TIP
• Apply the silicone grease on the brake caliper
piston seal and brake caliper piston dust seal.
• Fit the brake caliper piston seals and brake
caliper piston dust seals onto the slot on
brake caliper correctly.
3. Install:
• Brake caliper piston “1”
TIP
Apply the brake fluid on the piston outer sur-
face.
ECA33DD047
NOTICE
• Install the piston with its side “a” facing
the brake caliper.
• Never force to insert.
EAS1SL5157
INSTALLING THE REAR BRAKE CALIPER
1. Install:
• Rear brake caliper
• Rear brake caliper bracket
2. Install:
• Rear wheel
Refer to “REAR WHEEL” on page 4-7.
• Copper washers
• Brake hose
• Union bolt
EWA13530
WARNING
Proper brake hose routing is essential to in-
sure safe vehicle operation.
ECA14170
NOTICE
Make sure that a bend in its pipe portion “a”
is directed as shown and the brake hose
touches the projection “b” on the brake cal-
iper.
3. Install:
• Brake pad springs
• Brake pads
• Brake pad pin
• Brake pad pin plug
Refer to “CHECKING THE REAR BRAKE
PADS” on page 3-25.
4. Pour brake fluid to the brake fluid reservoir
up to the specified level.
EWA13090
New
New
2
1
1
a1
Brake hose union bolt
30 Nm (3.0 m·kgf, 22 ft·lbf)
Brake pad pin
17 Nm (1.7 m·kgf, 12 ft·lbf)
Brake pad pin plug
2.5 Nm (0.25 m·kgf, 1.8 ft·lbf)
Recommended brake fluid
DOT 4
New
T R..
b
b
a
T R..

REAR BRAKE
4-28
WARNING
• Use only the designated brake fluid. Other
brake fluids may cause the rubber seals to
deteriorate, causing leakage and poor
brake performance.
• Refill with the same type of brake fluid that
is already in the system. Mixing brake flu-
ids may result in a harmful chemical reac-
tion, leading to poor brake performance.
• When refilling, be careful that water does
not enter the brake fluid reservoir. Water
will significantly lower the boiling point of
the brake fluid and could cause vapor
lock.
ECA13540
NOTICE
Brake fluid may damage painted surfaces
and plastic parts. Therefore, always clean
up any spilt brake fluid immediately.
5. Bleed:
• Brake system
Refer to “BLEEDING THE BRAKE SYS-
TEM” on page 3-21.
6. Check:
• Brake fluid level
The minimum level mark “a” or below 
Add.
Refer to “CHECKING THE BRAKE FLUID
LEVEL” on page 3-26.
7. Check:
• Brake pedal operation
A softy or spongy feeling  Bleed the brake
system.
Refer to “BLEEDING THE BRAKE SYS-
TEM” on page 3-21.
EAS1SL5158
REMOVING THE REAR BRAKE MASTER
CYLINDER
TIP
Before removing the rear brake master cylin-
der, drain the brake fluid from the entire brake
system.
1. Remove:
• Union bolt
• Copper washers
• Brake hose
TIP
To drain any remaining brake fluid, place a con-
tainer under the master cylinder and the end of
the brake hose.
EAS1SL5159CHECKING THE REAR BRAKE MASTER
CYLINDER
1. Check:
• Brake master cylinder “1”
Damage/scratches/wear  Replace.
• Brake fluid delivery passages “2”
(brake master cylinder body)
Obstruction  Blow out with compressed
air.
2. Check:
• Brake master cylinder kit
Damage/wear  Replace.
3. Check:
• Master cylinder reservoir cap
Crack/damage  Replace.
• Brake master cylinder reservoir diaphragm
holder
• Brake master cylinder reservoir diaphragm
Crack/damage  Replace.
4. Check:
• Brake hoses
Cracks/damage/wear  Replace.
a
1
2

REAR BRAKE
4-29
EAS1SL5160ASSEMBLING THE REAR BRAKE MASTER
CYLINDER
EWA13520
WARNING
• Before installation, all internal brake com-
ponents should be cleaned and lubricated
with clean or new brake fluid.
• Never use solvents on internal brake com-
ponents.
1. Wash the brake master cylinder and the
brake master cylinder kit with brake fluid.
2. Install:
• Primary cylinder cup “1”
• Secondary cylinder cup “2”
Install to the brake master cylinder piston
“3”.
EWA13520
WARNING
Apply brake fluid to the cylinder cups and
install them as shown. Wrong orientation in
installation causes poor braking perfor-
mance.
3. Install:
• Spring “1”
Install to the brake master cylinder piston
“2”.
TIP
Install the spring with a smaller inside diameter
to the brake master cylinder piston.4. Install:
• Master cylinder kit “1”
• Push rod “2”
• Circlip “3”
• Dust boot “4”
TIP
• Before installation, apply brake fluid to the
brake master cylinder kit.
• Before installation, apply silicone grease to
the push rod end.
• Use circlip pliers to install the circlip.
EAS1SL5161INSTALLING THE REAR BRAKE MASTER
CYLINDER
1. Install:
• Copper washers
• Brake hose
• Union bolt
EWA13530
WARNING
Proper brake hose routing is essential to in-
sure safe vehicle operation.
ECA1DX1008
NOTICE
Make sure that the pipe portion of the brake
hose touches the projection “a” on the
brake caliper. Recommended brake fluid
DOT 4
2
3
1
2
3
1Brake hose union bolt
30 Nm (3.0 m·kgf, 22 ft·lbf)
12
New
New
13
4
2NewNew
New
T R..

REAR BRAKE
4-30
2. Pour brake fluid to the brake fluid reservoir
up to the specified level.
EWA13090
WARNING
• Use only the designated brake fluid. Other
brake fluids may cause the rubber seals to
deteriorate, causing leakage and poor
brake performance.
• Refill with the same type of brake fluid that
is already in the system. Mixing brake flu-
ids may result in a harmful chemical reac-
tion, leading to poor brake performance.
• When refilling, be careful that water does
not enter the brake fluid reservoir. Water
will significantly lower the boiling point of
the brake fluid and could cause vapor
lock.
ECA13540
NOTICE
Brake fluid may damage painted surfaces
and plastic parts. Therefore, always clean
up any spilt brake fluid immediately.
3. Bleed:
• Brake system
Refer to “BLEEDING THE BRAKE SYS-
TEM” on page 3-21.
4. Check:
• Brake fluid level
The minimum level mark “a” or below 
Add.
Refer to “CHECKING THE BRAKE FLUID
LEVEL” on page 3-26.5. Check:
• Brake pedal operation
A softy or spongy feeling  Bleed the brake
system.
Refer to “BLEEDING THE BRAKE SYS-
TEM” on page 3-21. Recommended brake fluid
DOT 4
a
a

HANDLEBAR
4-31
EAS1SL5162
HANDLEBAR
Removing the handlebar
Order Part name Q’ty Remarks
Number plate Remove the band only.
1 Clutch cable 1 Disconnect.
2 Clutch lever holder 1
3 Engine stop switch 1
4 Brake master cylinder 1
5 Throttle cable cap 1
6 Throttle cable (pull) 1 Disconnect.
7 Throttle cable (return) 1 Disconnect.
8 Right grip 1
9 Tube guide 1
10 Collars 1
11 Left grip 1
12 Handlebar upper holder 2
13 Handlebar 1
14 Handlebar lower holder 2
15 Damper 4

HANDLEBAR
4-32
For installation, reverse the removal proce-
dure.
Removing the handlebar
Order Part name Q’ty Remarks

HANDLEBAR
4-33
EAS1SL5163REMOVING THE HANDLEBAR
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. Remove:
• Grip “1”
TIP
Blow in compressed air between the handlebar
or tube guide and the grip. Then remove the
grip which has become loose.
EAS1SL5164CHECKING THE HANDLEBAR
1. Check:
• Handlebar
Bends/cracks/damage  Replace.
EWA13690
WARNING
Do not attempt to straighten a bent handle-
bar as this may dangerously weaken it.
EAS1SL5165INSTALLING THE HANDLEBAR
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. Install:
• Damper “1”
• Lower handlebar holders “2” (temporarily)
• Handlebar “3”
• Upper handlebar holders “4”
TIP
• Install the lower handlebar holders with them
side having the greater distance “a” from the
mounting bolt center facing forward.
• Installing the lower handlebar holders in the
reverse direction allow the front-to-rear offset
amount of the handlebar position to be
changed.
• The upper handlebar holders should be in-
stalled with the punch marks “b” facing for-
ward.
• When installing the handlebar, make sure that
right and left marks “c” are in place identically
on both sides.
• Install the handlebar so that the projection “d”
of the upper handlebar holders is positioned
at the mark on the handlebar as shown.
ECA14250
NOTICE
• First, tighten the bolts on the front side of
the upper handlebar holder, and then on
the rear side.
• Turn the handlebar all the way to the left
and right. If there is any contact with the
fuel tank, adjust the handlebar position.
Upper handlebar holder bolt
28 Nm (2.8 m·kgf, 20 ft·lbf)
T R..
2
1
1
a

HANDLEBAR
4-34
3. Tighten:
• Lower handlebar holder nut4. Install:
• Handlebar grip “1”
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Slightly coat the handlebar left end with a
rubber adhesive.
b. Install the handlebar grip on the handlebar
by pressing the grip from the left side.
c. Wipe off any excess adhesive with a clean
cloth.
EWA13120
WARNING
Securely support the vehicle so that there is
no danger of it falling over.
TIP
Install the handlebar grip to the handlebar so
that the line “a” between the two arrow marks
faces straight upward.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
5. Install:
• Engine stop switch “1”
• Clutch lever “2”
• Clutch lever holder “3”
•Clamp “4”
TIP
• The engine stop switch, the clutch lever, and
the clutch lever holder should be installed ac-
cording to the dimensions shown.
• Pass the engine stop switch lead through the
middle of the clutch lever holder. Lower handlebar holder nut
40 Nm (4.0 m·kgf, 29 ft·lbf)
3
4
T R..
Engine stop switch screw
0.5 Nm (0.05 m·kgf, 0.36 ft·lbf)
Clutch lever holder bolt
5 Nm (0.5 m·kgf, 3.6 ft·lbf)
T R..