I heard a skiping in my brakes, i took off the right side calipers, found one of the pistons, is not compressing as fast as the others, the brakes still fuunction properly, but i hear the noise, the fluid seames fine, any ideas?

 

Are you sure you're hearing a skipping? Maybe it's just normal vented rotor noise.

First thing I'd do is give the rotors and calipers a good scrubdown with brake cleaner. If that didn't work I'd flush/fill the brake fluid to make sure it's not just old fluid or air in the lines. If you haven't changed the fluid lately I'd do a flush and fill first.

Lastly, you can rebuild the calipers.

I don't know if the pistons need to really compress at the same speed...

 

the brake disks are free floating rotors, they are made that way to make up for the pistons not compressing at the same speed/rate/time. when one goes in faster than the other it pushes the rotor toward the other brake pad to compensate for the time difference. If you mean what i think you mean thats the explination for that.

As for the skipping i would go with Ajohn and do a good scrubbing with "brake quite" or brake silencer or something along those lines and see if it still makes the noise.