Abstract: A piston and cylinder for two-cycle engines wherein the fuel-air mixture is precompressed in the crankcase and flows to the combustion chamber through transfer passages formed in the cylinder wall and under the control of the piston movement. The piston skirt is formed with windows or openings adjacent the end faces of the piston pin, the latter being mounted in piston pin bosses carried by bearing brackets depending from the piston head and, when the piston is at its lower dead center, the windows or openings register with the inlet openings of the transfer passages so that the precompressed fuel-air mixture then flows through the interior of the piston, the openings in the piston skirt and the transfer passages and into the combustion chamber itself which contains a depression volume.