I Took the rear wheel of my 2004 R6 to change the sproket. Everything went well, untill my friend decided to spread the brake pads apart so they would fit back over the rotor. Well since than I have had nothing but hell trying to get the brakes to work. I have replaced the Master Cylinder. I put my finger over the whole of the master cylinder and pumped it up and it had enough pressure to blow my finger off the whole. So I know the master cylinder is good. Than I attached the hose back to the M/C and closed my fingers over the end of the hose closest to the caliper. And it also built enough pressure to blow fluid past my fingers. So after the process of elimanation I realized that it was the caliper all along. But I bought a new repair kit for the caliper. Which included two O-Rings for the piston in the caliper. Needless to say it still doesnt grab the rotor like it should. It will barely stop the bike, but it wont lock up the rear tire. Is there any special way to clean the caliper or can any one give me an idea on something I might have over looked? Oh yea also its not air in the lines because thats what I thought so I bought a MityVac to vacum the line.