2004 Official factory service manual for Yamaha YFZ450S ATV Quad., Page 259Get this manual
FRONT AND REAR BRAKES WARNING
Use only the designated quality brake fluid: other brake fluids may deteriorate the rubber seals, causing leakage and poor brake performance Refill with the same type of brake fluid: mixing brake fluids may result in harmful reaction and lead to poor brake performance 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 lock4Air bleed: brake system Refer to "BLEEDING THE HYDRAULIC BRAKE SYSTEM" in chapter 35Check: brake fluid level Brake fluid level is under the "LOWER" level line Add the recommended brake fluid to the proper levelRefer to "CHECKING THE BRAKE FLUID LEVEL" in chapter 3