I had a benelli 50cc moped in holland around 1969. i replaced the piston with a berini piston, that had same diameter, but was +/-0.5 cm higher. so compression rose, so i used different handmixed octane petrol/oil mixture. I also polished the petrolstream below- and into the cilinder. I made 135 kmph om standard carburator. only thing, all screws vibrated loose and i, lost them. the tank, but also the clipon stearings also became loose while riding. so riding became verry dangerious. the police took it from me on a full out try on the