2004 Official factory service manual for Yamaha YFZ450S ATV Quad., Page 256Get this manual
FRONT AND REAR BRAKESEBS00413
CHECKING THE MASTER CYLINDERS 1Check: brake master cylinder Wearscratches Replace the brake master cylinder assembly brake master cylinder body Cracksdamage Replace brake fluid delivery passage (brake master cylinder body) Blockage Blow out with compressed air Front Rear