I have a 2003 KX85 and the back brakes don't stop the bike very well. Fronts work fantastically but the back brakes don't really have any stopping power, just slows it a little. I rebuilt the rear master cylinder and bled the brakes and the pedal has good pressure and there aren't any leaks. The pads have about 3 mm of pad life left. Does anyone have any ideas of what I can do to bring the rear brakes back to life again?