Yamaha YZ450FP 2023, Owner'S Service Manual

Page: 140 / 388

FRONT BRAKE
4-24
5. Bleed:
• Brake system
Refer to “BLEEDING THE HYDRAULIC
BRAKE SYSTEM” on page 3-26.
6. Check:
• Brake fluid level
The minimum level mark or below

Add.
Refer to “CHECKING THE BRAKE FLUID
LEVEL” on page 3-24.
7. Check:
•
Brake lever operation
A softy or spongy feeling

Bleed the brake
system.
Refer to “BLEEDING THE HYDRAULIC
BRAKE SYSTEM” on page 3-26.
EAM30036
REMOVING THE FRONT BRAKE MASTER
CYLINDER
TIP
Before removing the front brake master cylinder,
drain the brake fluid from the entire brake sys-
tem.
1. Remove:
•
Union bolt
• Copper washer
•
Brake hose
TIP
To drain any remaining brake fluid, place a con-
tainer under the master cylinder and the end of
the brake hose.
EAM30037
CHECKING THE FRONT BRAKE MASTER
CYLINDER
1. Check:
•
Brake master cylinder “1”
Damage/scratches/wear

Replace the
brake master cylinder assembly.
• Brake fluid delivery passages “2”
(brake master cylinder body)
Obstruction

Blow out with compressed air.
2. Check:
• Brake master cylinder reservoir cap
Damage/scratches/wear

Replace.
3. Check:
•
Brake hose
Cracks/damage/wear

Replace.
•
Protector “1”
Out of specification

Replace.
TIP
The protector reaches the limit of its use when it
is worn down to the same height “a” as of the
plastic locking tie circumference.
EAM30038
ASSEMBLING THE FRONT BRAKE MASTER
CYLINDER
WARNING
EWA13520
• 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 with brake
fluid.
2. Install:
•
Primary cylinder cup “1”
• Secondary cylinder cup “2”
(to the brake master cylinder piston “3”)
WARNING
EWA20240
Apply brake fluid to the cylinder cups and in-
stall them as shown. Wrong orientation in in-
stallation causes poor braking performance.
1
2
Specified brake fluid
DOT 4
a a a
1 1