CP Piston M piston kits are available for 4-stroke powersports applications. These CP Piston M piston kits include the piston, pin, locks, and rings. CP Pistons use X-forgings to minimize friction and weight without compromising strength. Double pin oilers add twice the amount of oil from the cylinder wall to the wrist pin. Radiused domes are used to maximize quench, while eliminating possible hot spots that promote detonation. CP Piston M piston kits have a V-shaped groove machined into the second ring to collect excess blow by between the top and second ring. This groove is known as the accumulator groove.