Abstract: A two-stroke internal combustion engine having a crankcase provided with a crank chamber, a suction port which opens to the crank chamber, a scavenging passage opening into the crank chamber, and a crankshaft is provided with a flow control surface formed on an inner peripheral wall portion of the crank chamber which is capable of retarding the flow rate of unatomized raw fuel and which extends from the vicinity of the suction port to the vicinity of the scavenging passage. The flow control surface is comprised of a large number of intersecting unit ribs.

Abstract: The present invention is a stratified scavenging two-cycle engine which has a more compact structure. The stratified scavenging two-cycle engine includes a scavenging flow passage (3) for connection between a cylinder chamber (4a) and a crank chamber (1a); and an air flow passage (2) connected to the scavenging flow passage (3), the scavenging flow passage (3) is continuously formed by a communication portion (30) extending from the crank chamber (1a) toward the cylinder chamber (4a) side; and a scavenging direction adjustment portion (31) extends from the communication portion (30) toward a cylinder inner surface (4b) side and opens at a scavenging port (3a) in the cylinder inner surface (4b). The air flow passage (2) extends into an area surrounded by the communication portion (30), the scavenging direction adjustment portion (31), and the cylinder inner surface (4b).

Abstract: A device for increasing crankcase compression in an internal combustion engine. The device includes a holder having an annular peripheral wall joined to an end wall. The holder is mounted on a crankshaft of the engine, between a main bearing and a crank portion with a counterweight. The crankshaft extends through the end wall and is surrounded by the peripheral wall. Lightweight filling bodies are disposed in the holder.

Abstract: The invention relates to a method for supplying fuel to a combustion engine which has an air inlet provided with a gas valve and an output shaft and wherein a fuel line in which a fuel supply device is arranged debouches into the air inlet. The method comprises of providing a pump with an adjustable, substantially continuous flow rate for the fuel supply device, determining the position of the gas valve, determining the rotation speed of the shaft, ascertaining herewith the required fuel flow rate and adjusting the pump accordingly. The invention further relates to a combustion engine of which the fuel supply is controlled as according to the above specified method.

Abstract: Fuel to which a predetermined pressure is applied is supplied to an electronically controlled fuel injection system of a engine for models in order to improve the rotation stability during low speed operation and the response to rapid acceleration or deceleration.The pulsatory air pressure is generated in a crank chamber of a engine for models during operation. An air pressure intake guide 51 of a fuel pressure control valve 1 receives air pressure from the crank chamber. The air intake guide is provided with an excessive pressure leak valve the actuation pressure of which is adjustable. The air pressure intake guide communicates with interposition of a check valve 56 to a controlled air pressure supply passage 54 which communicates to a fuel tank. The check valve 56 supplies the positive pressure of the pulsatory air pressure from the controlled air pressure supply passage to the internal of the fuel tank.

Abstract: An internal combustion engine includes a cylinder, a crankcase, a crankshaft rotatable in the crankcase, a piston, and a connecting rod supporting the piston for reciprocating movement in the cylinder and mounted on the crankshaft. A barrier member extends around the connecting rod to sealingly separate the cylinder from the crankcase. The barrier member is laterally displaceable to provide for angular motion of the connecting rod as the piston reciprocates in the cylinder.

Abstract: Disclosed herein is an internal combustion engine comprising a crankcase assembly including a crankcase member including a crankcase cover mounting surface, and a cylinder assembly mounting surface including therein an opening, and a cylinder block fabricately separately from the crankcase assembly and including a crankcase member surface fixed to the cylinder assembly mounting surface, and a cylinder extending from the crankcase member mounting surface and communicating with the opening in the cylinder assembly mounting surface.

Abstract: An improved scavenging control system for a multi-cylinder, V-type, two-cycle crankcase compression internal combustion engine. In each embodiment, a scavenging manifold extends along one side of the crankcase chamber and communicates with the individual sealed sections therein through respective scavenging control passages. A plurality of butterfly-type throttle valves controls the communication between the crankcase chamber and the scavenging manifold and these valves are all affixed on a common valve shaft. In one embodiment, the scavenge control system is disposed in the valley between the cylinder banks and in the other illustrated embodiment, the scavenging system is disposed on one side of the crankcase and outside of the valley between the cylinder banks.

Abstract: A pump comprising a pumping chamber (3) for pumping a liquid; at least part of the pumping chamber (3) being formed by a pumping means (6) having a pumping area (A2); an actuation chamber (2) in communication with a source of pressurised fluid, at least part of the, actuation chamber (2) being formed by an actuation means (5) having an actuation area (A1); a connection means (7) connecting the actuation means and the pumping means, so that, at least during those times that liquid is required to be pumped by the pump, variations of the pressure in the actuation chamber effect movement of the actuation means which in-turn effects movement of the pumping means to enable supply of liquid to the pumping chamber and delivery of liquid therefrom; wherein the pressure within the pumping chamber is greater than the pressure within the actuation chamber.

Abstract: A multi-cylinder reciprocating piston internal combustion engine, preferably operating on the two-stroke cycle, having a cylinder block 8 incorporating a bank of cylinders 10 each communicating with a crankcase 15. Each cylinder having inlet ports 20,21,22,29,30 located on each of the two opposite sides of the bank of cylinders 10, and a conduit 17 communicating at least one port on one side of the bank with at least one port on the opposite side of the bank. That conduit 17 extends through a crankshaft bearing support portion 14a of the cylinder block 8 located within said crankcase 15 below the level of the cylinders 10. There is preferably one bearing support portion 14a within the crankcase 15 and below the junction between each two adjacent cylinders 10, with a respective conduit 17 extending through said bearing support portion 14a.

Abstract: A polymer composite reed for a reed valve is provided, wherein the reed has improved mechanical properties as a result of its construction and is highly resistant to chemical and thermal attack. The improved mechanical properties of the reed are primarily due to the reed being reinforced with two plies of fabric having a harness satin weave, which provides the reed with a flexural modulus that is substantially greater in one direction of the reed. The chemical and thermal properties are primarily due to the semicrystalline thermoplastic material from which the reed is formed. In addition, the thermoplastic material enhances the fracture toughness of the reed to improve the durability of the reed. As a result, the reed is highly suitable for applications requiring long life under high speed, cyclic loading, such as that found in two-stroke and four-stroke internal combustion engines for the automobile industry.

Abstract: A multi cylinder two stroke cycle internal combustion engine of known construction having an individual crankcase compartment for each cylinder 11 formed in a crankcase 12, the crankcase 12 including a wall 25,25 separating two adjacent crankcase compartments. A crankshaft 13 extends through the wall 25,26 with a journal 29 thereof supported in a bearing assembly 30 has an outer bearing ring 32 non-rotatably mounted in the wall 25,26. The outer bearing ring 32 has an axial extent greater than the thickness of the wall 25,26 to provide an internal annular surface co-axial with a shoulder 36 on the crankshaft that presents an opposing external annular surface to the internal annular surface of the bearing ring 32. A fluid seal is provided between the internal and external annular surfaces to prevent the passage of gas between the crankcase cavities.

Abstract: A multicylinder two-stroke cycle internal combustion engine (10) comprises an individual crankcase cavity (18) for each cylinder to receive the incoming air charge for that cylinder and a cylinder block (11) with at least two cylinders having cooperating crankcase cavities (18) provided with valve controlled intake ports (19) in a common wall (31) of the cylinder block (11). An air induction manifold (25) is detachably mounted to the common wall (31) to form a single air induction cavity (27), at least part of which is formed within the cylinder block (11), and has a single main inlet port for regulation of air inflow to the induction cavity (27). Individual passages (33) communicating each crankcase cavity inlet port (19) with the air induction cavity (27) are formed in the manifold (25). Acceptable performance with limited increase in the overall physical dimensions of the engine (10) can thus be obtained.

Abstract: Two embodiments of motor vehicles powered by two cycle crankcase compression internal combustion engines having air fuel injectors. The air fuel injectors are mounted in the cylinder head but are disposed in such a position so that the fuel injector portion of the fuel air injector extends toward the high side of the hood to permit accessibility without sacrificing the use of a low hood line.

Abstract: An internal combustion engine has a crankcase and a cylinder with an outlet with a first flange. A muffler having an inlet with a second flange is connected to the outlet with the inlet. The muffler is formed as a unitary part. The first flange has a first flange surface and the second flange has a second flange surface, whereby the first flange surface and the second flange surface contact one another so as to form a flange connection. At least two slip-on clamps are connected to a circumference of the flange connection. The clamp has substantially the shape of a bracket with two legs extending in the same direction. The legs have inner surfaces facing one another. The flange connection has receiving surfaces for the legs wherein the inner surfaces of the legs cooperate with the receiving surfaces so as to force the first and the second flange surfaces against one another.

Abstract: An outboard motor having an improved cooling system wherein liquid coolant is circulated through an exhaust manifold cooling jacket then through a cylinder head cooling jacket and then through an upper portion of the cylinder block cooling jacket. A thermostatic valve controls the flow from the upper cylinder block cooling jacket through a lower cylinder block cooling jacket so as to avoid quenching of the intake charge by coolant which has not reached operating temperature.

Abstract: This invention relates to an event timing apparatus for an internal combustion engine, and more particularly to an improved control arrangement for a fuel injection and ignition arrangement. In accordance with this invention, a timing detecting arrangement is disclosed having a timing correcting circuit for correcting deviations between the actual timing measurements made and the true, desired timing signal required for accurate operation of the fuel injection system. Thus, a fuel injection system and ignition system is provided that is able to provide accurate crank angle timing measurements with reference to which crank chamber pressure and other measurements may be made, in spite of possible manufacturing and/or assembling variations in the timing measuring means. The way in which the manufacturing or assembling of variations are measured is also disclosed.

Abstract: In a fuel injected internal combustion engine, the fuel injection is based on computation rather than direct measurement of air intake. To correct for air intake volume changes caused by external factors, a pressure sensor detects the pressure inside the exhaust manifold and, based on this detected value, a correction is made either to the computed value for air intake, directly to the computation of the amount of fuel to be injected, or both. The corrected air intake volume and the corrected fuel injection amount are then used as the basis for ECU control of the time power is applied to the fuel injector.

Abstract: A number of embodiments of mounting arrangements for the pressure sensor of a control for the fuel injection system of a two cycle crankcase compression internal combustion engine. The pressure sensor is mounted in such a way as to avoid the likelihood of the pressure signal being deteriorated due to fuel and lubricant accumulation and deterioration thereon. In some embodiments, this is done by an insulated mouting and in others this is done by positioning the pressure sensor in a scavenge passage to the engine. In the scavenge passage mounting arrangements, insulation is also employed.

Abstract: A plurality of cylinders have a predetermined firing order. The crank case of the engine is divided by partitions so that each piston has its own crankchamber. Air is induced into the crank chambers via reed valves and subject to compression as the respective piston descends. Transfer ports are provided which open when the pistons have descended by a predetermined amount from TDC and which inject scavenging air from the crankchamber of the previous cylinder on the firing order, into the combustion chamber of the instant cylinder.

Abstract: Several embodiments of charge forming systems for crankcase internal combustion engines each of which embodies a first charge forming device having a main fuel discharge that delivers a fuel/air mixture to the crankcase and a second charge forming device having an idle fuel discharge for delivering a fuel/air mixture to the transfer passage. The second charge forming device is provided with means for providing cold running enrichment. In addition, a priming fuel pump is adapted to supply priming fuel of a higher quality to the first charge forming device upstream of its venturi section. The two charge forming devices are each supplied with air from a common air inlet device that includes at least a air silencer. The communication of the second charge forming device with the air supply device is such so as to preclude the likelihood of fuel leakage if the engine is oriented in other than its normal condition.

Abstract: A crankshaft support structure comprises a crankshaft, a crankcase for supporting the crankshaft, a lubricant-sealed bearing interposed between the crankshaft and the crankcase. This structure enables the amount of a lubricant in combustion gas to be reduced and the structure of an engine to be simplified by avoiding the provision of a oil passage for suppling the bearing with a lubricant.

Abstract: A port for equalizing the pressure between crankcase compartments of a two-cycle internal combustion crankcase compression engine. In one form of the invention, the port is formed in a common web between the crankcase compartments. In another form of the invention, a pair of ports are located in a common reed block, each of the ports being in communication with one of the crankcase compartments.

Abstract: Disclosed herein is a marine propulsion device comprising a lower unit including a rotatably mounted propeller and an internal combustion engine operable in a predetermined mode and adapted to be drivingly connected to said propeller, the engine including an engine block, a sump having an outlet and having an unobstructed inlet communicating with said engine block to provide a free gravity flow path from the engine block into the sump, a controllable valve communicating with the outlet, a fluid conduit communicating with the controllable valve and with a preselected location within the engine block, and a control mechanism responsive to operation of the engine in the predetermined mode for opening the controllable valve when the engine is operating in the predetermined mode.

Abstract: A direct injected two stroke cycle internal combustion engine having a cylinder, a cylinder head at one end of the cylinder, a piston mounted for reciprocation in the cylinder, and an inlet port and an exhaust port in the wall of the cylinder at substantially diametrically opposite locations in the cylinder. A cavity in the cylinder head extending in a generally diametral direction from adjacent the cylinder wall at a location opposite the exhaust port. The cavity having substantially straight side edges in the direction of extension, and the longitudinal length of the cavity in said direction being about 0.55 to 0.77 of the diameter of the cylinder.

Abstract: Several embodiments of fuel injection systems for internal combustion engines wherein certain components of the engine are lubricated directly by lubricant supplied by a lubricant pump and the lubricant pump also supplies lubricant to a fuel injection pump. In some embodiments, the fuel delivered to the injection pump is mixed with the fuel pumped by the injection pump for delivery to the engine through an injection nozzle.

Abstract: A two-cycle engine for small watercraft for driving a propeller shaft includes a water discharge passageway located in the crankcase of the engine for communicating the crank chamber with outside to discharge water from the crank chamber. A closing member having a manually operated portion for opening and closing the closing member is fitted in the water discharge passageway. When it is desired to discharge water from the crank chamber, the manually operated portion is manipulated to open the closing member, so that the water can be discharged therefrom to outside via the water discharge passageway without requiring to remove the engine from the engine room.

Abstract: A system for discharging water from a crank chamber of a two-cycle engine of a compression-type crank chamber including a water discharge passageway for connecting a bottom portion of the crank chamber with an outside area, a first valve and a second valve mounted in the water discharge passageway, and an operating member for manually opening and closing the second valve. The second valve is located downstream of the first valve and the first valve is adapted to be brought to an open position by a positive pressure in the crank chamber.

Abstract: A system for discharging water from a crank chamber of a two-cycle engine of a compression-type crank chamber including a water discharge passageway for communicating a bottom portion of each crank chamber with an outside area, a valve for opening and closing the water discharge passageway, a water discharge pump mounted in the water discharge passageway and a manually operated device for operating the valve and actuating the water discharge pump to discharge water from the crank chamber. The manually operated device includes a lever, a wire connecting the lever to the valve and a switch adapted to be turned on to actuate the water discharge pump as the lever is manipulated.

Abstract: The two-cycle internal combustion engine includes an engine block having a cylindrical wall defining a cylinder having a head end, a piston mounted for reciprocative movement in the cylinder, and a passage in the engine block, such as an exhaust passage, a transfer passage, or a crankcase fuel intake passage, terminating at the cylinder wall in a port, such as an exhaust port, a transfer port or a piston-controlled, crankcase fuel intake port, having upper and lower edges. A valve mounted in the passage for movement relative to the port is operable to selectively vary the effective distance of one of the port edges from the cylinder head end and thereby provide the capability of varying the timing of the port opening and/or closing as required to obtain optimum engine performance at different operating conditions.

Abstract: The invention is directed to a control system for a two-stroke engine for limiting a control quantity thereof such as the rotational speed. For this purpose, a pressure line including a valve is connected to the crankcase and leads to a pneumatic controlling member which is responsive to a mechanical or electrical signal (vibrations or electric pulse from the ignition system). By means of suitable transmission means, the movement of the controlling member is transmitted to the carburetor throttle, for example.

Abstract: An internal combustion heat engine and cycle therefor comprising a two stroke cylinder and piston unit having a combustion chamber at the top of the cylinder, having a compression chamber at the bottom of the cylinder, and having a transfer chamber charged with compressed combustion support air transferred into the combustion chamber during initial movement of the piston in a first power stroke, followed by spark ignition and combustion to effect said power stroke with simultaneous compression in said compression chamber and with admission of compressed combustion support air into said transfer chamber during terminal movement of said power stroke, the compressed combustion support air being stored in the transfer chamber during a second exhaust stroke with simultaneous induction of air into the compression chamber.

Abstract: An internal combustion heat engine and cycle therefor comprising a two stroke cylinder and piston unit having a combustion chamber at the top of the cylinder, having a compression chamber at the bottom of the cylinder, and having a transfer chamber charged with compressed combustion support air transferred into the combustion chamber during initial movement of the piston in a first power stroke, followed by spark ignition and combustion to effect said power stroke with simultaneous compression in said compression chamber and with admission of compressed combustion support air into said transfer chamber during terminal movement of said power stroke, the compressed combustion support air being stored in the transfer chamber during a second exhaust stroke with simultaneous induction of air into the compression chamber.

Abstract: Disclosed herein is an outboard motor comprising a cylinder, a crankcase extending from the cylinder and including an upper portion having a bearing and a lower portion having a drainage outlet, a transfer passage extending between the cylinder and the crankcase, a drains return inlet in one of the cylinder and the transfer passage, a fuel supply system including an inlet manifold communicable with the cylinder and having a drains outlet and a carburetor communicating with the inlet manifold and having a drainage outlet, an overboard drain, and a valve and conduit system selectively operable for communicating the overboard drain with each of the manifold drains outlet, the crankcase drains outlet, and the carburetor drainage outlet, for communicating the crankcase bearing and the drains return inlet with the manifold drains outlet and the crankcase drains outlet, and for closing the carburetor drainage outlet.

Abstract: A two cycle internal combustion engine (10) has at least two cylinders (12, 13) which fire alternately with pressure in one crankcase (17 or 18) at the time there is vacuum in the other. Supplemental fuel flow passages (36, 41) extend from each crankcase and are joined at a common passage (46) connected to the float bowl (30) of the carburetor (20). A normally closed control valve (48) is disposed in the common passage. When the engine is to be started, the control valve is opened so that fuel enters the supplemental and common passage. Initial rotation of the crankshaft (16) causes pressure in one crankcase to force fuel toward the other crankcase, which has vacuum. Further crankshaft rotation reverses the pressures so that fuel is then forced toward the opposite crankcase. Continued engine operation with the control valve open causes alternate fuel flow reversals together with pressurized alternate fuel injections into the respective crankcases, which are independent of the throttle setting.

Abstract: A stratified-charge cross-flow scavenged two-stroke cycle spark-ignition engine (1) includes a piston (2) having a raised crown (6) with a baffle (7) and chamfered sides (8, 9) and reciprocal in a cylinder (3) between a combustion chamber (4) and a crankcase (5). Transfer passage structure is disclosed wherein a pair of elongated scavenging air passages (17, 18) extend between the crankcase and combustion chamber on opposite sides of a shorter fuel-air transfer passage (11). A pair of scavenging air inlet ports (20, 21) in the combustion chamber are adjacent the fuel-air inlet port (12) therebetween and substantially distally opposite the exhaust port (16). The scavenging air inlet ports face the baffle at its edges along the chamfered sides of the piston crown.

Abstract: A stratified-charge two-stroke cycle scavenged spark-ignition engine 1 includes a piston (2) reciprocal in a cylinder (3) between a combustion chamber 4 and a crankcase (5). A carburetor (17) is mounted to the crankcase substantially coaxially with the piston to afford narrow engine design. An elongated scavenging air passage (14) extends between the crankcase and the combustion chamber and has a length substantially greater than that of a fuel-air transfer passage (7), and the height of piston (2), to reduce fuel mixture in the scavenging air passage and afford substantially only air at an air inlet port (16), which port is between fuel-air mixture inlet port (8) and exhaust port (13).

Abstract: A crankchamber precompression type two-cycle internal combustion engine including at least one cylinder assembly, each cylinder assembly including a stepped cylinder constituted by a minor diameter cylinder portion and a major diameter cylinder portion, a stepped piston received in the stepped cylinder and constituted by a minor diameter piston portion and a major diameter piston portion adapted to be fitted in the minor diameter cylinder portion and the major diameter cylinder portion respectively, a crankchamber connected to the major diameter cylinder portion, a working chamber defined between the minor diameter cylinder portion and the minor diameter piston portion, and a sub-intake chamber defined between the major diameter cylinder portion and the minor diameter piston portion.

Abstract: A two-cycle internal combustion engine having reed valves in the fuel/air supply system is provided with an element in the flow path of the fuel/air into the reed valves, which element is shaped and positioned to promote uniformity of flow of the fuel/air mixture in the flow passage.

Abstract: The invention relates to a method and an apparatus for reducing to a minimum the predominant full load noise of port-controlled, two-stroke internal combustion engines by constructing the lower suction port boundary and the lower piston boundary, so that there is a gradual port opening during the upward movement of the piston and a gradual port closing during its downward stroke.

Abstract: A two-stroke internal combustion engine of the type having separate fuel and oil pumps delivering their outputs for mixture prior to entering the carburetor, the oil pump having a variable output relative to the fuel pump output, and means responsive to the amplitude of the pressure wave in the engine crankcase to vary the output of the oil pump to optimize the fuel/oil ratio for the operating conditions.

Abstract: An engine comprising one pair of scavenge ports alternately covered and uncovered by a piston, a richer air-fuel mixture and a leaner air-fuel mixture being separately fed into the cylinder from the scavenge ports, the richer air-fuel mixture flowing into the cylinder towards the inner wall thereof, located opposite the exhaust port, and the leaner air-fuel mixture flowing into the cylinder so that it overlays the richer air-fuel mixture.

Abstract: Disclosed herein is an internal combustion engine comprising a crankcase, a cylinder extending from the crankcase and having an inlet port, a piston located in the cylinder, a transfer passage located between the crankcase and the cylinder inlet port, a fuel pump adapted to communicate with a source of fuel for normal operation, a carburetor having an air induction passage communicating with the crankcase and including a venturi, which carburetor also includes a float bowl communicating with the fuel pump and a high speed nozzle communicating between the float bowl and the venturi, a low speed fuel nozzle communicating with the transfer passage adjacent the inlet port, and a fuel line communicating between the float bowl and the low speed nozzle and including therein check valve means preventing flow from the transfer passage to the float bowl and permitting flow from the float bowl to the transfer passage, which fuel line also includes fuel flow metering means.

Abstract: Disclosed herein is an outboard motor comprising a cylinder, a crankcase extending from the cylinder and including an upper portion having a bearing and a lower portion having a drainage outlet, a transfer passage extending between the cylinder and the crankcase, a drains return inlet in one of the cylinder and the transfer passage, a fuel supply system including an inlet manifold communicable with the cylinder and having a drains outlet and a carburetor communicating with the inlet manifold and having a drainage outlet, an overboard drain, and a valve and conduit system selectively operable for communicating the overboard drain with each of the manifold drains outlet, the crankcase drains outlet, and the carburetor drainage outlet, for communicating the crankcase bearing and the drains return inlet with the manifold drains outlet and the crankcase drains outlet, and for closing the carburetor drainage outlet.

Abstract: Several embodiments of fuel injection controls for two-cycle crankcase compression internal combustion engines. In each embodiment, the fuel injection is controlled by measuring the amount of air inducted through measurement of the pressure generated in the crankcase. In each embodiment, abnormal pressure variations in the crankcase not due to the amount of air inducted are eliminated by measuring the pressures at predetermined crankshaft angles. In some embodiments, this is done through the use of a valving arrangement and in other embodiments, this is done electronically.

Abstract: The invention relates to a method and to a port-controlled two-stroke internal combustion engine in which the cross-sections of the intake and outlet are so constructed in the direction of the longitudinal axis of the cylinder that in the case of an upward or downward movement of the piston, the noise-generating intake and outlet pressure gradients and amplitudes are reduced by the gradual opening of the particular intake and outlet, the piston lower edge and intakes having special constructions.

Abstract: A method and apparatus for improving the performance and efficiency of a two-cycle internal combustion engine are described wherein the backflow combustion mixture gasses are captured at the reed valve and directed through a uni-directional passageway and injected back into the incoming air stream in the incoming air boot ahead of the carburetor so that the proper air-to-fuel mixture may be maintained by the carburetor. Recirculation of the backflow combustion mixture gasses as mentioned above increases the performance and the efficiency of a two-cycle internal combustion engine.

Abstract: An improved lubricating system for a two-cycle internal combustion engine having a vertically disposed crankshaft. In accordance with an embodiment of the invention, the crankshaft has a connecting rod journal that rotates in a crank chamber above which is positioned a lubricant chamber. A lubricant delivery passage extends through the crankshaft from the lubricant chamber and terminates in a connecting rod journal portion formed in the crank chamber.

Abstract: A two-stroke engine is provided comprising at least one cylinder (1) in which is slidingly mounted a piston (2) which defines in this cylinder a combustion chamber (C) and a precompression chamber (P), the lateral cylindrical wall of the cylinder being provided with at least two ports closable by the piston (2), namely at least one transfer port (3) through which opens a transfer channel (4) connecting the two chambers together and at least one exhaust port (5) communicating with an exhaust pipe (6). These two ports are arranged and disposed so that the opening of the transfer port (3) begins before that of the exhaust port (5) and special means are provided for making the pressure of the fresh gases admitted into the combustion chamber (C) through the transfer port (3), during opening of this transfer port, sufficiently high with respect to that of the burnt gases then present in the combustion chamber.

Abstract: A fuel injection control method and system for a crankcase compression two cycle engine wherein the amount of fuel discharge is controlled by the pressure in the crankcase.