Great thread guys! I too have an MB5 up here in Seattle. It's kitted (70cc) with a Proma Pipe, 21mm PHBG carb (105 main) and is over geared at 16-43 (the P.O was ambitious lol, stock was 13-45) I have a new set of sprockets and chain for it that will be 14-43, a much more manageable gear ratio...