Piston skirt

The term "Piston skirt" refers to the area of the piston below the wrist pin. The purpose of the Piston skirt is to help stabilize its travel in the cylinder, as well as to control intake timing on engines without case induction. By modifying the piston skirt, one can alter the port timing on piston port engines. Some piston skirts also have cutouts to work with reed valves, or an additional transfer port.