Abstract: A cooling system for an internal combustion engine is provided with coolant paths through the cylinder block and cylinder head which are connected in serial fluid communication with each other. In parallel with the cooling path through the cylinder head, a first drain is connected in serial fluid communication with a pressure responsive valve and the path through the cylinder block. A temperature responsive valve 64 is connected in serial fluid communication with the cylinder head path and in parallel fluid communication with the first drain. A pump is provided to induce fluid flow through the first and second coolant conduits and the first and second drains, depending on the space of the pressure responsive valve and the temperature responsive valve.

Abstract: In a two-cycle internal combustion engine (10), the piston (20) has an outer peripheral oval shape (58) with a minor axis (62) offset from the centerline (54) of the wrist pin (26) towards a line (56) through the intake and exhaust ports (16 and 18). The outer peripheral shape of the piston also has increasing ovality, from at least the wrist pin (26) upwardly to at least the piston rings (22, 24).

Abstract: A preassembled throttle cable and pulley assembly includes a pair of pulleys contained within pulley housings. A pair of throttle cables are strung around the pulleys in a predetermined manner and the cable ends are contained within the pulley housings. The pulleys are keyed so as to insure their attachment to a tiller and throttle linkage in a proper configuration.

Abstract: In a two cycle internal combustion engine (2), a turbulence generator (70) is provided by a freely rotating fan (72) in the fuel-air stream to the reed valves (16) which supply the fuel-air mixture into the crankcase chamber (8). The freely rotating fan (72) is driven by the fuel-air mixture flow and rotates to generate turbulence to provide more uniform distribution of the fuel-air mixture.

Abstract: Horsepower and fuel economy improvements, and a reduction in horsepower variation, are realized in a two cycle loop scavenged internal combustion engine by enhancing combustion chamber (10) intake directional flow (28) by directing flow along the outermost portions (54) of the transfer passages (12), and blocking flow along shorter paths (56) adjacent the cylinder (6) which otherwise short-circuit the outermost flow and adversely affect directional flow into the combustion chamber from the intake ports (16), to substantially eliminate intake flow directed toward the exhaust port (26) from the intake port otherwise caused by the short-circuiting. The intake port flow in the combustion chamber is afforded in a direction determined by the non-short-circuited path in the transfer passage, and the direction-altering flow in the combustion chamber from the intake port otherwise due to the short-circuit path is substantially eliminated.