Abstract: A two-cycle internal combustion engine having a crankcase with a crankshaft rotatably mounted therein, a cylinder extending from the crankcase and having a piston slidably positioned therein with a connecting rod extending between the piston and the crankshaft, a combustion chamber defined at the end of the cylinder remote from the crankcase, an inlet channel communicating with the crankcase at one end and with an air-fuel mixture providing means at the other end, timing means to control opening and closing of the inlet channel to the crankcase, such timing means preferably being the piston skirt, a boost port extending from the inlet channel at a position between the air-fuel mixture providing means and the crankcase timing means at one end and opening to the cylinder volume at the other end, and a reed valve disposed in the boost port and oriented to control flow such that the air-fuel mixture may flow through the boost port into the cylinder but preclude reverse flow from the cylinder to the input channel.