My 51 Pacemaker has a brand new engine in it. I started it back in the spring when I put the engine in and did not start it all summer. I tried to start it last week and it would not start. I realized it had no compression. I took the tappet cover off and the exhaust valve was stuck open no. I did not want to disturb the head so I just got a needle nose pliers and played around with it and it popped down and the bike started right up. I must ride my bikes more.