BSA Piston B33/M33 1954-60 std. Made in Italy STD=85 mm middle gudgeon pin to Crown 48 mm Gudgeon Pin 19mm Piston Clearance 0.12mm or 45thou for short rod Compression Ratio: 7.25:1 65-1613 ConrodCmp Hight 43mm+5mm domewith Piston Rings, Circlips and Gudgeon Pin