Abstract: A dual fuel, natural gas/diesel two-stroke engine includes a cylinder and a piston in the cylinder, and inlet ports around the cylinder which are uncovered by downward movement of the piston. A blower forces air through the inlet ports when the latter is uncovered, and the engine includes an exhaust port and valve for exhausting combustion gases once each cycle. Diesel injection takes place near top dead center to ignite the gaseous mixture. An injector is provided for injecting natural gas into the cylinder once each cycle, including a delivery conduit which opens into the cylinder at a location above the inlet ports for air, such that the piston when descending completely uncovers the conduit before beginning to uncover the air inlet ports.