I have a 2002 Arctic Cat ZR 500, Last season I burnt a piston and the whole cylinder was replaced by a dealer. This year after about 800 miles, I burnt another piston, when i took the plugs out the left cylinder(The one which was replaced) the gap on the plug was completely gone. The end was pinched shut. Does anyone know what could cause this and if it was the cause for the piston burning up? Thanks for any help!