I was changing the rear pads on my Honda 400 EX that I recently bought used and I was trying like crazy to make the piston go all the way in to make room for the pads. I tried and tried -- thank god I didn't break anything.

HINT

I figured out how much trouble the parking brake has been on the 400 EX model (after reading this forum) and deducted that as the brake pads wear down, people tighten the parking brake screw on the rear caliper for the brake to catch. As you tighten the screw, it pushes the brake piston forward (on wore down brake pads). If you have the screw in too much you have to screw it out in order to allow the piston to be pushed all the way in to make room for new pads.

IF YOU DO THIS FIRST... I swear it will save lots and lots of time. It took my friend and I nearly 4 hours and a half case of beer before we got it.

 

...and don't forget to use brake cleaner on the pads and rotor! =)