2000 Yamaha YFM400FWA(M) Factory Service workshop Manual, Page 284Get this manual
FRONT AND REAR BRAKES CHAS
Be careful that water does not enter the brake master cylinder when refillingWater will significantly lower the boiling point of the brake fluid and may result in vapor lock
4.Air bleed: Brake system Refer to "AIR BLEEDING (HYDRAULIC BRAKE SYSTEM)" in CHAPTER 35.Inspect: Brake fluid level Brake fluid level is under the "LOWER" level line Fill upRefer to "BRAKE FLUID LEVEL INSPECTION" in CHAPTER 3