Put the right cylinder at TDC and look through the plug hole. See if there is a hole in the top of the piston. When you mentioned before that you rode it quite hard for a while before this problem, and then later you said you had stock jetting, you might have been to lean. I assume you are running pods and free flow exhaust? That would make you run very lean and since the right cylinder runs hotter than the left, it burned first.