Minarelli 38.6mm Original Piston 502/1a This is a really nice

This is a really nice upgrade for your NSR

Nice and firm foam

Original Polini piston for the Polini 39mm 50cc Motobecane kit

This Derbi is equipped with a flat reed engine

The Revolution GS has the later style engine with modern scooter style transmission

Minarelli 38.6mm Original Piston 502/1a This is a really niceNew old stock, original Minarelli 38. 6mm piston kit. Most of your V1 engines have a 38. 7mm or 38. 8mm piston. This one is a little smaller than the rest so that's unusual. Otherwise, the dimensions are the same. From the edge of the crown to the center of the wrist pin opening is 29mm. Total length from the edge of the crown to the skirt is 49. 5mm