Yamaha YZ125 2021 - Bleeding the Hydraulic Brake System; Checking the Brake Operation; Checking the Front Brake Hose; Checking the Rear Brake Hose

CHASSIS
3-15
EAM30232
CHECKING THE REAR BRAKE PADS
The following procedure applies to all of the
brake pads.
1. Operate the brake.
2. Check:
• Rear brake pad
Wear indicator grooves “1” almost disap-
peared  Replace the brake pads as a set.
Refer to “REAR BRAKE” on page 4-22.
EAM30478
CHECKING THE FRONT BRAKE HOSE
1. Check:
• Brake hose
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 several times.
4. Check:
• Brake hose
Brake fluid leaks  Replace the damaged
brake hose.
Refer to “FRONT BRAKE” on page 4-11.
EAM30498
CHECKING THE REAR BRAKE HOSE
1. Check:
• Brake hose
Cracks/damage/wear  Replace.
2. Check:
• Brake hose holder
Loose connection  Tighten the holder bolt.
3. Hold the vehicle upright and apply the rear
brake several times.
4. Check:
• Brake hose
Brake fluid leakage  Replace the damaged
hose.
Refer to “REAR BRAKE” on page 4-22.
EAM30499
CHECKING THE BRAKE OPERATION
1. Check:
• Brake operation
Brake not working properly  Check the
brake system.
Refer to “FRONT BRAKE” on page 4-11 and
“REAR BRAKE” on page 4-22.
TIP
Drive on the dry road, operate the front and rear
brakes separately and check to see if the brakes
are operating properly.
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BLEEDING THE HYDRAULIC BRAKE
SYSTEM
WARNING
EWA19140
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. Repeat
the bleeding procedure when the tiny bubbles
in the hose have disappeared.
2. Bleed the brake system.
a. Fill the reservoir to the proper level with
the recommended brake fluid.
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