I would like to, but as i mentioned earlier, the newer piston is shorter, at TDC the exhaust port opens (shorter piston skirt). if you look close at the the two cylinders the newer version ports are 1/8" higher. I'm new to conversions but not new to all forms of two strokes, and was hoping one of the conversion experts new these Ryobi's like the back of their hand. I might save the old one for EI or glow. Maybe the whole flywheel is out of balance. It does vibrate at two or three levels when i run it up.