Yamaha YZ450FA 2011 Owner's Service Manual page 208

Remove the brake caliper piston seals and
brake caliper piston dust seals by pushing them
with a finger.
Never attempt to pry out brake caliper pis-
ton seals and brake caliper piston dust
seals.
Replace the brake caliper piston seals and
brake caliper piston dust seals whenever a
caliper is disassembled.
A. Front
B. Rear
CHECKING THE BRAKE MASTER
CYLINDER
1. Inspect:
• Brake master cylinder inner surface "a"
Wear/scratches → Replace master cylinder
assembly.
Stains → Clean.
Use only new brake fluid.
FRONT BRAKE AND REAR BRAKE
A. Front
B. Rear
2. Inspect:
• Diaphragm "1"
Crack/damage → Replace.
A. Front
B. Rear
3. Inspect: (front brake only)
• Reservoir float "1"
Damage → Replace.
4. Inspect:
• Brake master cylinder piston "1"
• Brake master cylinder cup "2"
Wear/damage/score marks→Replace brake
master cylinder kit.
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