Just picked up a barely used 2006 z400. The pads in the rear looked thin, so I went to change them. I can seem to get the piston on the rear caliper to compress all the way to get the new pads in. What am I missing...must be to tired as its 11:30 pm EST.

 

Update: Found that the parking brake that bolts on the rear brake cylinder was all gunked up. Once I took it apart, cleaned and lubed, all was well and the cylinder was easily compressed back into place.