I had the same problem last spring. Bad gas will cause your valves to stick. I bent two push rods on mine. Pulled the head off and the intake smelled just like varnish. Best thing to do is to take the head off and to a machine shop if you can't get the vavles unstuck yourself. But before you put it back on drain out all of the old gas. If you can get your tank out, I recomend cleaning it real good. Heads up, you will proably have to rebuild your carb also. After I had everything cleaned and the head put back on and new gas in the tank, the carb stuck because the previous gas had varnished it up also. This year, before I put my truck in storage for the winter, I am going to put some stabul in the gas and hope it keeps it from going bad.
