These are Berg/Cima GB 004 specials. For 69mm stroke. Case 91.5mm, Head 94.4mm, 39.6mm pin height. 6mm crown.RW 1.5/1.5/5
Our "special" Berg/Cima pistons have maximum silicone and magnesium content for use in air-cooled engines (not a cheaper piston for a water-cooled engine). Cylinders have maximum nickel and copper content. They are spun cast in a high-speed centrifugal mold to give an extremely dense cylinder that maximizes heat dissipation and concentricity through years of service. For best rigidity, our 88mm cylinder wall is thicker than a factory stock 85.5mm at the fin area. SW# 30