Yamaha BIG BEAR PROFESSIONAL 400 YFM400FPT Owner's Manual page 316

Observe these precautions:
G
When checking the brake fluid level, make sure
the top of the brake fluid reservoir is level.
G
Use only the designated quality brake fluid, oth-
erwise, the rubber seals may deteriorate, caus-
ing leakage and poor brake performance.
Recommended brake fluid: DOT 4
G
Refill with the same type of brake fluid. Mixing
fluids may result in a harmful chemical reaction
and lead to poor brake performance.
G Be careful that water does not enter the brake
fluid reservoir when refilling. Water will signifi-
cantly lower the boiling point of the fluid and
may result in vapor lock.
G
Brake fluid may deteriorate painted surfaces or
plastic parts. Always clean up spilled fluid im-
mediately.
G
Have a Yamaha dealer check the cause if the
brake fluid level goes down.
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