Abstract: In a two-stroke internal combustion piston engine, a piston is reciprocally movable within an axially elongated cylinder. The piston has a bottom dead center position and in the region of this position, the cylinder has an exhaust opening and a number of pairs of scavenging openings. An axially extending plane within the cylinder divides the exhaust opening in half and in each pair the scavenging openings are arranged symmetrically on opposite sides of the axially extending plane. Each pair of scavenging openings is located at a different distance from the exhaust opening. The projection of the side surfaces of the pairs of scavenging openings extending in the axial direction of the cylinder each form a different angle at the point of intersection of the projections and the point of intersection is directed away from the exhaust opening.

Abstract: A two stroke engine having an exhaust port formed in the cylinder wall. At the upper portion of the exhaust port, there is provided a rotary type exhaust timing control valve which is adapted to be actuated by a centrifugal governor device to control the exhaust timing in accordance with the engine speed. The centrifugal governor device has a governor shaft which extends coaxially with the engine crankshaft and directly connected at one end with the adjacent end of the crankshaft. At the other end, the crankshaft is provided with a magneto device so that the magneto does not have any magnetic influence on the centrifugal governor device.

Abstract: A two-cycle engine is disclosed which conventionally includes a piston that reciprocates between a closed combustion chamber and crankcase. The piston reciprocates through a connecting rod that is eccentrically connected to the crank discs of a crankshaft. The crankcase is partially circular in configuration, and the crankdiscs conform in shape to the crankcase. Each crank disc has an annular recess or pocket extending around its periphery for approximately 180.degree. and in opposition to the eccentric point of connection of the connecting rod. The pockets cyclically communicate with a fuel inlet port and carburetor, both of which are positioned below the crankshaft rotational axis on the downstroke side of the crankcase. Fuel transfer passages between the crankcase and combustion chamber are positioned to receive the fuel charge from each recess as it is thrown tangentially upward with rotation of the crank discs.

Abstract: An internal combustion engine comprises a combustion chamber and a piston movable relative to the combustion chamber between top dead center and bottom dead center positions. A fuel transfer passage introduces fuel-air mixture into the combustion chamber in response to piston movement. An auxiliary chamber is also provided which is communicable with the combustion chamber in response to piston movement shortly after the ignition of a fuel-air mixture, such that high pressure ignition gases enter the auxiliary chamber. The high pressure ignition gases thereafter flow back into the combustion chamber in response to piston movement before communication is established between the combustion chamber and the fuel transfer passage. The incoming flow of high pressure ignition gases serves to influence the normal scavenging streams.

Abstract: A front transfer port system to help ensure a regular cooling of the piston and cylinder temperature at the points where the heat conditions are more severe, and to improve the transfer process of the mixture that transfers from the crankcase to the cylinder with more scavenging efficiency to displace spent products to the atmosphere through the exhaust ports in an internal combustion two-stroke cycle engine. The front transfer port system is situated in the cylinder wall at the front and between the exhaust ports.

Abstract: In a two cycle internal combustion engine having a cylinder, a piston, and an exhaust port, the improvement comprising tapering the edge of the exhaust port farthest into the cylinder where it intersects the cylinder wall as an isosceles triangle.

Abstract: A cylinder for crankchamber precompression type two stroke engines includes three pairs of main scavenging ports which are symmetrical with respect to a longitudinal plane passing through the centers of the intake and exhaust ports and containing the longitudinal center line of the cylinder. A pair of auxiliary scavenging ports are provided at the opposite sides of the longitudinal plane in such a manner that in a horizontal cross-section the flows from the auxiliary ports do not intersect with the flows from the main ports. Further, the auxiliary scavenging ports are directed further upwardly than the main ports.

Abstract: An in-line, multi-cylinder, two-cycle loop charged engine 10 has transfer passages 21, 22, and 23 partially formed by cavities die-cast in the cylinder block 14. The transfer passages are completed by covers, 24 and 25 bolted to the block 14. An efficient loop charging system is thus provided in a completely die-cast cylinder block.

Abstract: A two cycle internal combustion engine with improved cylinder scavenging. The described engine embodiment is a baffled piston two cycle internal combustion engine whose power is substantially increased by directing fuel mixture in the normally spent gas filled region behind the piston baffle during each intake-exhaust portion of the engine cycles to scavenge spent gas from this region and increase the total volume of fuel mixture in the cylinder at the time of ignition. According to the preferred practice of the invention a portion of the fuel mixture displaced from the engine crankcase to the cylinder intake port or ports is diverted to auxiliary ports in the cylinder wall which direct the mixture against the rear side of the piston baffle to effect through scavenging of the region directly behind the baffle.

Abstract: In a two-stroke, water-cooled internal combustion engine the improvement is disclosed which permits to have a removable cylinder liner type of engine in spite of the intricate constructional arrangement of such engines having transfer ports and exhaust ports. The improvement consists in that the transfer and exhaust ports are formed through the liners and flanged fittings are provided between the liner transfer ports and the transfer ducts so as to ensure complete tightness. Differential-firmness gaskets are provided where appropriate and the engine is then assembled by stay bolts as usual. The construction suggested by the invention not only solves the tightness problem satisfactorily, but minimizes the stresses on the liners, especially the bending stresses.

Abstract: The exhaust port of a spark ignition two cycle engine has the general shape of an inverted T with a base portion and a narrower upwardly extending stem portion. The top of the base portion is approximately at the level of the top of the transfer port which admits fuel-air mixture to the engine cylinder. The top of the stem is from 20.degree. to 55.degree. of crankshaft rotation in advance of the opening of the transfer port. This configuration of the exhaust port produces a low broad blowdown pulse which in turn results in a low noise level of the exhaust.