Minarelli 38.6mm Original Piston 502/1a This Derbi is equipped with

This Derbi is equipped with a flat reed engine

3 sets of 3 springs

This will not mount up to your M01 powered frame without modifying the rear mount

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

Minarelli 38.6mm Original Piston 502/1a This Derbi is equipped withNew 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