I have a 1981!-250 reedvalve Maico. I want to bore it up with a 77 mm piston. Borexstroke will be 77x70=326cc. What would I have to change when it comes to porting. I mean, bigger, higher lower, wider, angle etc. I want a nice smooth engine wich will be used in sand tracks only. Or if I take a stroke of 83, it will be a 400. Can I take the ports of a piston port engine? I already sent an e-mail to Eric Gorr after reading his site. But I thought I would ask it here too Thanks!!!!!!!!!