1977 kz1000 stock brake refresh

I some rare cases i cooked the calipers in hot oil to get the pistons free, heat is your friend sometimes.....

I managed to get the pistons to move by heating the caliper body with a heat gun and then applying brake cleaner spray to the middle of the piston surface to cool it relative to the caliper bore.  It's probably not seized to the caliper bore surface, but held tight by the seal inside.  Penetrating oil like PB Blaster and some heat can help.