The new type â€œ995â€ engine, or more commonly known as the Rotax 1000 SDI, may use two different piston sizes. Each cylinder and pistons is identified with either an â€œAâ€ or a â€œBâ€ designation. This identifier is found on top of the piston crown, and off to the side of the exhaust port on each of the cylinders. A cylinder block may use two different sizes of pistons, and you MUST match piston â€œAâ€ with cylinder â€œAâ€ and piston â€œBâ€ with cylinder â€œBâ€.
When a cylinder needs to be replaced, the cylinder block comes as an assembly with two pistons if you order the cylinder block from Ski-Doo. Even if only one cylinder is damaged, you replace all of them together.