Piston ring compressed like it was supposed to but tolerances to tight on one side of ring and would not decompress . Found it out when my new honed cylinder and new little red barn piston/ring had weak compression and the saw didnt even run. Pulled cylinder off and only half the piston ring sprung out and other half stuck in piston. Wall had a deep grove put in it from this. Should have to be a pro engine builder to freshen up top end of a chainsaw engine!
Piston ring issues 
