Piston Identification

PISTON IDENTIFICATION

Two sizes of piston are available as standard size replacement parts to ensure proper piston-to-cylinder clearance. When installing a standard size piston, make sure to match the piston with the cylinder as follows:








- Each piston has a stamped number 1 or 2. It indicates the outer diameter of the piston. The number 1 indicates a piston diameter of 73.98 to 73.99 mm (2.9126 to 2.9130 inches). The number 2 indicates a piston diameter of 73.97 to 73.98 mm (2.9122 to 2.9126 inches). There are also three stamped numbers 1 or 2 on the cylinder block. The first number indicates the inner diameter of the No. 1 cylinder bore, the second number of the No. 2 cylinder bore, and the third number of the No. 3 cylinder bore. The number 1 indicates a cylinder bore diameter of 74.01 to 74.02 mm (2.9138 to 2.9142 inches) and the number 2 indicates a cylinder bore diameter of 74.00 to 74.01 mm (2.9134 to 2.9138 inches).





- Use a number 2 stamped piston for installation in the cylinder identified with a number 2 and a number 1 piston for a cylinder with number 1 to maintain the standard piston-to-cylinder bore clearance of 0.02 to 0.04 mm (0.0008 to 0.0015 inch). A letter A, B. or C is also stamped on the piston head but ordinarily it is not necessary to discriminate each piston by this letter.