Well my Grizz began smoking when i rev it up, I asked on this site and someone told me to check valve adjustment as this could be the prob. Well valve seem to be adjusted properly. I'm going to put the tank back on tonight and warm it up to do a compression check. I'm afraid that it is the rings. That brings out the question about big bore. What goes with a big bore kit? If I understand correctly it is just a larger piston. Does anyone know what else I will have to do? rejet? clutch kit? anything? Will this kit alone give my Grizz more power? Or would it be better to stay with standard piston assuming cylinder is ok? Any info or advice would be helpfull. Thanks in advance.