What he said. This is so true. Four strokes can't take heavy porting you only can go so-far that's it. Once you start changing cams & porting they are a mother fucker to start. Your better off leaving it stock. Your performance will suffer if you go to far with the mods. Mickey Dunlop 4 stroke tech told me this years ago. When he did my honda 350x ATC back in 1987. mild cam, pipe, bigger carb, aries piston 11/1 thats it. No more than that. That bike was nothing to sneeze at. It hauled ass. But nothing like a banshee