The hyper .21 is extremely tight when they are new. They are really too tight and not a very good fit. I ran 4 tanks through my hyper .21 8 port and never got over 190 degrees. When I took off the head to see how break in was going I noticed that at TDC the chrome on the sleeve had been stipped off and brass was showing through. OFNA is replacing the motor and they said that it was an incorrect piston and sleeve match. This is a common problem however with this motor. You could always try cracking the glow plug loose and getting it turned over that way. Also head the head and case of the motor with a hair dryer before trying to start. Good luck