Yamaha YFM660RN Service Manual page 143

FRONT AND REAR BRAKES
3.Air bleed:
Brake system
Refer to "BLEEDING THE HYDRAULIC
BRAKE SYSTEM" in CHAPTER 3.
4.Check:
Brake fluid level
Brake fluid level is below the "LOWER" level
line → Add the recommended brake fluid to
the proper level.
Refer to "CHECKING THE BRAKE FLUID
LEVEL" in CHAPTER 3.
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CHAS