Abstract: A method for throttle progression control to minimize tip-in noise of an internal combustion engine by allowing the engine to receive only the required air for the commanded engine acceleration. The method comprises the steps of a) providing an electronically controlled throttle body and valve, b) providing an electronic control module, c) determining the engine air flow required to satisfy a desired engine acceleration, d) providing an input to the electronic control module corresponding to the engine air flow required, e) programming the electronic control module to limit the inflow of air during engine acceleration to match the engine air flow required for achieving said desired engine acceleration, and f) actuating the throttle body and valve to provide the limited air flow through the throttle body during the desired engine acceleration.

Abstract: A plurality of intake air amount control devices for controlling an amount of air drawn into a combustion chamber in association with a depression stroke of an accelerator pedal are provided. Each of the intake air amount control devices responds to a change in depression stroke of the accelerator pedal after the lapse of a predetermined delay period.

Abstract: A plurality of intake air amount control devices for controlling an amount of air drawn into a combustion chamber in association with a depression stroke of an accelerator pedal are provided. Each of the intake air amount control devices responds to a change in depression stroke of the accelerator pedal after the lapse of a predetermined delay period.

Abstract: A throttle control device includes a throttle body (1). In the throttle body, an intake passage (1a), a first space (24a), and a second space (44) are formed. In the intake passage, a throttle valve (2) is rotatably arranged. The throttle valve is rotated by a motor (4). The motor is accommodated in the first space. The second space communicates with the first space. In addition, the second space is adjacent to the intake passage through the intermediation of a wall portion (20a). This makes it possible for the heat generated in the motor to be effectively dissipated from the first space into the intake passage via the second space and the wall portion.

Abstract: A system for controlling a transmission throttle valve allows the transmission response to be quickly adjusted. The system includes an adapter assembly which is mounted on the rotatable throttle member of a fuel management device. A cam assembly is selectively positionable on the adapter assembly so as to adjust the rate of throttle valve cable pull. The cam assembly has guide pins which move within guide slots on the adapter assembly. The cam assembly also has an adjustment slot which receives an adjustment screw connected to the adapter assembly. The cam assembly is positioned on the adapter assembly so that the adjustment screw occupies a desired location along the adjustment slot, and then the adjustment screw is tightened to lock the cam assembly in place.

Abstract: To enable the detection of an accelerating condition from the phase of a crankshaft and an induction air pressure so as to obtain an acceleration feeling that corresponds to the accelerating condition so detected.

Abstract: A throttle-valve assembly (10) having a housing (12), which has a continuous throttle opening (16) through which a gaseous medium (62) can flow in a main flow direction (60), in which a throttle valve (20) fastened pivotably on a throttle-valve shaft (18) is arranged in the throttle opening (16), and the throttle-valve shaft (18) can be pivoted by an actuator (26) arranged in the housing (12), in which, starting from the axis of rotation (19) of the throttle-valve shaft (18) downstream along the main flow direction (60) of the gaseous medium (62), the throttle opening (16) has an approximately straight cylinder section (64) with a height H1 and a radius RZ and in which a spherical-cap section (68) adjoins the approximately straight cylinder section (64).

Abstract: A throttle system for a general-purpose engine, having an actuator (motor) connected to a throttle valve to open or close it so as to regulate amount of intake air. An output transmission mechanism constituted as a link mechanism or a gear mechanism is provided between the actuator and the throttle valve to transmit an output of the actuator to the throttle value such that an output of the mechanism relative to the output of the actuator when the throttle valve is fully closed, is smaller than that when the throttle value is not fully closed. With this, the system can finely open and close the throttle valve when its opening is small and can open and close it at high speed when its opening is large, while preventing throttle valve seizing.

Abstract: An electric positional actuator that includes a default device for positioning the actuated device in a default position. The actuator includes an electric motor that controls the rotational position of a shaft through a gear system. When the shaft rotates, it moves a link-bar that actuates the actuated device. A rotational sensor coupled to a printed circuit board detects the position of the shaft, and provide a feedback signal of the shaft's position. The default device includes a spring wrapped around the shaft. When the link bar is rotated away from its default position, one leg of the spring remains in contact with a housing spring boss while the other leg of the spring is in contact with the link bar opposing the movement and trying to return the link-bar to the default position.

Abstract: A vacuum management system for an engine with variable valve lift includes a vacuum control valve at the entrance to the intake manifold to increase vacuum within the manifold as needed and preferably only when it can be done without impairing fuel economy or engine performance. Vacuum may then be used for any of various vacuum-assisted devices and functions, for example, boosting a vehicle braking system. The numerical relationships among important operating parameters are determined in a laboratory, and a programmable engine control module (ECM} is provided with algorithms and tables of such values by which the ECM is able to vary valve lift and vacuum control valve position to provide optimum flow across the intake valves and optimum manifold vacuum under all engine operating conditions.

Abstract: A throttle system for a general-purpose engine, having an actuator (motor) connected to a throttle valve to open or close it so as to regulate amount of intake air. An output transmission mechanism constituted as a link mechanism or a gear mechanism is provided between the actuator and the throttle valve to transmit an output of the actuator to the throttle value such that an output of the mechanism relative to the output of the actuator when the throttle valve is fully closed, is smaller than that when the throttle value is not fully closed. With this, the system can finely open and close the throttle valve when its opening is small and can open and close it at high speed when its opening is large, while preventing throttle valve seizing.

Abstract: In a negative pressure actuator which is provided with a negative pressure tank storing an intake negative pressure of an engine, and operated by a negative pressure stored in said negative pressure tank as a power source, an operating possible time of the negative pressure actuator is calculated based on an intake negative pressure, the operation of the negative pressure actuator is permitted when it is within the operating possible time, while the operation of the negative pressure actuator is prohibited when it is over the operating possible time.

Abstract: An integrated intake manifold assembly including a first poppet valve assembly disposed at the air inlet to the manifold to regulate air flow into the manifold; a second poppet valve assembly disposed on the manifold to regulate exhaust gas flow into the air intake system; and a bi-directional camshaft with cams for operating simultaneously the manifold vacuum regulating (MVR) valve and the exhaust gas recirculation (EGR) valve. The valve bodies are integrally formed in the wall of the intake manifold. The camshaft is driven by a DC motor and gear train. The cams are arranged on the shaft to provide optimum synchronized opening and closing of the related valves. When used on a diesel engine, the manifold assembly may further include a swirl valve plate disposed between the manifold and the engine head and having a plurality of ganged swirl valves actuated by levers connected to the camshaft for coordinated motion with the MVR and EGR valves.

Abstract: In control apparatus and method for an internal combustion engine having variably operated engine valves, a target vacuum pressure is calculated on the basis of an engine driving condition and an opening angle of an electronically controlled throttle valve is disposed in an intake air passage to achieve the target vacuum pressure. A target air quantity to be sucked within an engine cylinder on the basis of the engine driving condition is calculated and a valve closure timing of an intake valve of, e.g., an electromagnetic operation type is controlled to achieve the target air quantity. At this time, in accordance with the target vacuum pressure TBOOST(or in accordance with an actual vacuum pressure BOOST detected by means of a vacuum pressure sensor), the target air quantity to calculate the valve closure timing of the intake valve calculated on the basis of target air quantity is corrected or the intake valve closure timing IVC per se is corrected by a correction value of &Dgr;IVC.

Abstract: The present invention relates to a piston-type internal combustion engine comprising gas-exchange valves which can be driven in a completely variable manner by a motor control (2) and which communicate with an air supply channel (4) provided with a device (6) for generating a negative pressure using the energy components of the air flowing through said air supply channel (4). This device is provided with means that can be driven for adaptation to the modifications in the flow energy which are inherent to the operation, and communicates with at least one negative-pressure user (8, 9, 10) through at least one negative-pressure duct (7).

Abstract: A method for updating an air flow ratio of a current engine load to a maximum engine load includes calculating an approximate air flow ratio based only on throttle position changes. The approximate air flow ratio is calculated by modifying a normal, conventionally calculated air flow ratio based on a difference between two throttle position loads. The throttle position loads are ratios between sampled throttle positions and a reference throttle position. By approximating the air flow ratio rather than conducting an exact calculation, the invention method can update the air flow ratio to reflect changes in throttle position without adding significant chronometric burden.

Abstract: An air duct for inclusion in the air intake tract of an internal combustion engine in which flow obstacles, especially wire-shaped flow obstacles, are arranged in the vicinity of the duct wall (21) in order to improve the acoustic characteristics of the duct. The flow obstacle may, for example, be wire strands (29). The flow obstacles are capable of decreasing the acoustic noise emitted by the air duct while maintaining a low flow resistance since the center part of the duct cross-section remains unaffected by the flow obstacles. The flow obstacles may advantageously be arranged in the discharge area of flap valves since so that the valves are prevented from whistling when they are only open a small way. In order to simplify the manufacturing and assembly costs, the flow obstacles may be disposed in the area of a flanged joint in the air intake duct.

Abstract: A method of controlling supply of combustion air in an internal combustion engine comprising at least one combustion chamber, a piston slidable in said combustion chamber and adapted to perform suction strokes, an inlet passage for feeding combustion air to said combustion chamber, an inlet valve for controlling flow of combustion air into said combustion chamber and adapted to be opened during opening periods, and a supplemental valve assembly disposed in said inlet passage and movable between opening and closing positions, in which method combustion air supply is selectively controlled by said supplemental valve assembly during said opening periods of said inlet valve such that combustion air supply to the combustion chamber during said suction strokes of the piston is interrupted prior to the end of the respective suction stroke or enabled only towards the end of the respective suction stroke or is enabled in two phases such that combustion air flows into the combustion chamber in a first phase during a fi

Abstract: A disc type throttle stop selectively regulates the power of an internal combustion engine by controlling the flow between an air metering device and the intake valves and presents substantially no restriction to the flow in the full open position of the throttle stop at wide open throttle conditions of the engine.

Abstract: A number of embodiments of engines that improve engine performance and lean running stability by employing internal EGR controlled by controlling the volume of the intake passage between the throttle valve and the intake port in relation to the maximum combustion chamber volume.

Abstract: A revolution speed control apparatus is provided. In particular, a variable valve drive apparatus for an internal combustion engine is provided, capable of continuously and variably setting a valve lift in conjunction with use of a three-dimensional cam. The apparatus provides a proper fail-safe system by setting an appropriate allowable engine revolution speed. An actual amount of adjustment in the position of a cam shaft, that is performed by a valve lift varying actuator, is detected by a shaft position sensor. Based on the actual amount of adjustment, the apparatus determines a cam profile of each intake cam contacting the corresponding cam follower. That is, the apparatus determines what portion of the oblique cam surface of each intake cam is providing a present valve lift. A valve lift is thus specified in addition to other parameters needed to determine an allowable revolution speed. These parameters include the valve spring load and the valve mass, for example.

Abstract: An air control valve for an engine includes a throttle body defining an air intake passage and a throttle valve rotatably mounted in the passage. The range of valve rotation includes an idle control portion extending from a minimum air flow position to an intermediate air flow position and a power control portion extending from the intermediate air flow position to a maximum air flow position. The intake passage is defined by an internal wall of the throttle body having a pair of arcuate surfaces spaced from the valve periphery, at a maximum first radius from the valve axis, with gradually increasing clearance on opposite sides of the valve axis in the idle control range from the minimum to the intermediate air flow position of the valve. The arcuate surfaces are defined by second and third radii greater than the maximum first radius and centered on second and third axes spaced laterally of the passage a predetermined offset distance beyond the valve axis relative to their respective surfaces.

Abstract: A number of embodiments of gaseous fueled internal combustion engines in which the charge former has no throttle valve in it. A separate throttle body is provided downstream of the charge former in which the flow controlling throttle valve is positioned so as to protect the charge former from deposits being formed on its metering arrangements. In some embodiments the throttle body is disposed at an angle to the air passage through the charge former to provide further protection. By separating the charge former from the throttle body, the engine height can be kept low because the charge former can be positioned at any desired location. Both in-line and V-type arrangements are provided and with the V-type arrangement the charge former is disposed externally of the valley between the cylinder banks so as to further maintain a low hood line.

Abstract: A method and an arrangement for controlling an internal combustion engine is suggested wherein, in at least a first operating range, a lean air/fuel mixture are pregiven and, for a power command from the driver (for example, in transient operating states or in the vicinity of the full load range) a switchover to a stoichiometric mixture takes place; during the transition, the torque change (caused by the change of the air/fuel ratio) is essentially compensated by correspondingly influencing the air supply to the engine.

Abstract: In order to obviate the drawbacks of fluid-dynamic character which affect the traditional carburators equipped with control valves of throttle or of guillotine type, the carburation device provides for the feed duct to be a tubular portion made of an elastic material constrained at its ends and that at least one pair of relatively movable blades act on the elastic feed duct on its outer surface, squeezing it in a perpendicular direction relatively to its axis. The surface area of the cross-section of the inner bore of the duct varies taking (relatively to the fuel stream flowing through it) a gradually convergent-divergent shape, i.e., without sharp changes in the inner bore cross-section surface area, and the fuel stream therefore has a fluid-dynamically optimal motion which is independent from the actual revolution speed of the engine.

Abstract: A throttle device having a throttle-flap connection piece which is produced from plastic. For an efficient production of the throttle-flap connection piece form plastic in the plastic injection-molding technique, it is necessary to avoid undesirable shrinkage in the pivoting region of the throttle flap and to seal off the bearing arrangements against penetrating plastic during the injection operation. The throttle device includes an annular insertion part which is arranged in the pivoting region of the throttle flap and which, connected to the bearing arrangements is embedded into the throttle-flap connection piece made form plastic, in order to protect the bearing arrangement against penetrating plastic. The injected-round insertion part is suitable for throttle devices which are made from plastic and which are provided for mixture-compressing spark-ignition or air-compressing auto-ignition internal-combustion engines.

Abstract: A string trimmer with a control system for electric start, throttling, compression release, and engine kill control. An interlock is provided for preventing a start switch from being actuated unless the throttle trigger is fully actuated to a throttle fully open position. An idle setting system and engine kill button is provided at a control section at the throttle trigger. A single control cable is used for throttling, actuation of a compression release system at the engine, and stopping the operation of the engine.

Abstract: Dynamic adjustment of the impact of automotive vehicle accelerator pedal position on engine inlet air valve position in which a gain is varied in accord with vehicle speed and a limit varied in accord with vehicle speed, the gain being applied in a transfer function between sensed accelerator pedal position and desired inlet air valve position, and the limit being applied to the desired inlet air valve position, with the transfer function varying in accord with an operator selection from a set of transfer functions.

Abstract: A fail-safe throttle positioning device is disclosed for an engine induction system. A throttle body is provided having a fluid passage. A movable throttle valve is disposed within the fluid passage for at least idle speed control. An actuator mechanism is connected to the throttle valve for operably moving the throttle valve between a minimum fluid flow position and a maximum fluid flow position. A fail-safe mechanism urges the throttle valve toward an intermediate position between the minimum and maximum fluid flow positions to prevent inoperability of the engine during failure of the actuator mechanism.

Abstract: A control valve control apparatus includes a pivotally mounted accelerator lever linked to an accelerator operation and having a first engagement member, a drive lever linked to an actuator and having a second engagement member, a pivotally mounted control valve shaft lever assembled integral with a control valve and having a third engagement member, and a link lever for linking together the beforementioned levers. When the actuator 41 is not operated, the link lever 51 turns the control valve shaft 3 by means of the third engagement member 7 and the first engagement member 27 linked to accelerator operation. When the accelerator operation is fixed with the actuator operated, the link lever turns the control valve shaft 3 by means of the third engagement member 7 and the second engagement member 47 linked to the actuator 41. This arrangement provides a control valve control apparatus having few components and low cost.

Abstract: A two-stroke internal combustion engine comprising an engine block, a plurality of crankcases and including a mounting surface having therein a plurality of inlet openings each communicating with a respective one of the crankcases, a throttle housing defining a throttle passage and including a plenum mounting surface, a throttle valve in the throttle passage, and a plenum member which is separable from both the engine block and the throttle housing and which defines a plurality of intake passages each having an outlet end communicating with a respective one of the inlet openings and each having an inlet end communicating with the throttle passage such that the intake of the engine can be tuned solely by modifying the configuration of the plenum member.

Abstract: An engine output control apparatus is used on a vehicle having an engine driven by a drive-by-wire system and includes a device for setting a first target engine control amount in accordance with an amount of operation of a manually operated engine control member; a device for detecting wheel slippage and for setting a second target engine control amount at which wheel slippage is reduced when wheel slippage exceeds a predetermined value; a device for setting a third target engine control amount at which constant-speed running of the vehicle is maintained when a manually operated constant-speed control member is actuated; and a selecting device for selecting one of the first, second, and third target engine control amounts. The selection made by the selecting device is based upon a determination of whether wheel slippage has exceeded a predetermined value and whether the manually operated constant-speed control member has been actuated.

Abstract: A method of supplying a combustible gas into a combustion chamber of an internal combustion engine of the cylinder type during two phases. The supply of combustible gas is restricted at least towards the end of the first phase and restricting the supply of the combustible gas is terminated at least during the beginning of the second phase which ends when the piston begins to compress a charge in the combustion chamber. In this method the extent of restricting the supply of combustible gas and the times of starting and terminating to restrict the supply of combustible gas and the time of terminating the supply of combustible gas are coordinated such that the resultant piston work corresponds to the work necessary for filling the combustion chamber with a desired amount of combustible gas plus the energy necessary to increase the temperature of the charge for a predetermined amount.

Abstract: The present invention provides an intake control valve which is able to reduce intake air leakage, control the amount of intake air with high accuracy, and to allow easy installation to an intake manifold. The intake control valve of an intake control device according to the present invention has a valve body, a case, and an actuator. The valve body is rotatably installed in the case, opening and closing an openingclosing passage formed in the case. The case is fitted with the actuator, which functions to rotate the valve body. In the meantime, the intake manifold is provided for a mounting bore formed for insertion of the case. On the outer side of the case are installed sealing members, which contact the wall surface of the mounting bore to prevent air leakage. The intake control valve is installed in the mounting bore formed in the intake manifold after assembling the valve body, the case and the actuator into one unit.

Abstract: An intake control device for an internal combustion engine having a body member 1 and a throttle valve 5 disposed within an air passage 4 . The external circular edge of the throttle valve 5 is divided, with a throttle shaft 6 into a first edge portion 5a which moves toward the upstream side of the air passage 4 and a second edge portion 5b which moves toward the downstream side of the air passage 4. On an inner wall 7 of the air passage 4 of the body member 1 are formed an upstream-side spherical wall surface 8 in a position facing the first edge portion 5a and a downstream-side spherical wall surface 9 in a position facing the second edge portion 5b.

Abstract: An engine control system is disclosed for reducing the hydrocarbon content in the exhaust gas of a crankcase scavenged, two-stroke engine in the operating range near idle, with light operator induced engine loading. As operator demand for engine output power is increased, the system increases the fuel per cylinder supplied to the engine while restricting the supplied mass of air per cylinder to a value less than that flowing at unloaded engine idle.

Abstract: A marine propulsion device comprising a propulsion unit which is adapted to be mounted on a boat and which includes a propeller shaft and an internal combustion engine drivingly connected to the propeller shaft, the engine including engine block structure having a combustion chamber and defining an air intake passage communicable with the combustion chamber, a throttle plate movably supported by the engine block structure and located in the air intake passage, structure for moving the throttle plate in response to movement of an operator control member, and structure supported by the engine block structure for providing a signal indicating the position of the control member independent of the position of the throttle plate.

Abstract: A gaseous fuel rotary piston engine has a rotor housing and a rotor. A side housing of the rotor housing is provided with an air intake port for supplying air to working chambers defined in the rotor housing and a gaseous fuel port which is connected to a gaseous fuel source through a fuel supply passage and through which gaseous fuel is supplied to the working chambers. The air intake port is formed to open near the top dead center on the intake stroke and close after the bottom dead center on the intake stroke. The gaseous fuel port is formed to open near the opening time of the air intake port and close substantially at the middle of the compression stroke.

Abstract: This is a device for reducing gas exchange or pumping losses of an internal combustion engine having a throttle (1) for controlling the pressure in the inlet manifold for the combustion air with or without fuel to the cylinders of the motor. In the inlet manifold (20) to every cylinder there is provided a separate (1) throttle whereby the low pressure side of the inlet manifold relative to the throttle is supplied air or fuel-air mixture of higher pressure than the pressure of the low pressure side by a valve which at the start of every inlet stroke is kept open and which closes before the inlet valve of the engine closes with the closing function of the valve is actuated by the position of said throttle.

Abstract: An Otto-cycle engine in which the expansion ratio is set in the range 11:1 to 16:1, comparable to the expansion ratios of Diesel engines and which has a rotary valve mounted in the suction passage. The valve is equipped with a valve actuating timing-adjusting device. The valve is closed prior to the bottom dead centre of each induction stroke to set the expansion ratio higher than the compression ratio set under full load conditions. The engine further includes a knock sensor for sensing or forecasting knocking. Valve closure is advanced by the adjusting device in response to the output signal from the sensor to adjust the compression ratio of the engine.

Abstract: A throttle body comprises a light metal first body having an operation space of a throttle valve and a synthetic resin second body which faces to the first body through a space. The first body and the second body are connected by a connecting member through a seal member.

Abstract: An apparatus for assisting a primary governor device (20) on an engine at certain load conditions or during transient loading is disclosed. The primary governor device has a control arm (12) which is moved by a primary governor spring (15) via a primary governor arm (14). The control arm (12) governs opening and closing of the throttle plate (10) on the carburetor (11). Four embodiments (47, 54, 30 and 78) of the governor assist mechanism are disclosed. The governor assist apparatus has an assist spring (48, 55, 32, 76) operatively connected to the control arm (12). A vacuum capsule (41) actuates the assist spring (48, 55, 32, 76) from the primary governor device (20) according to the vacuum in the intake manifold and load on the engine. The first embodiment or linear mechanism (47) has an assist spring (48), an intermediate link (49), and the diaphragm plunger (40) in linear alignment.

Abstract: An internal combustion engine includes at least one valve flap mounted for swinging movement in the intake duct upstream in the cylinder intake valve. The flap is magnetically attracted to a closed position when an electromagnetic is activated, in order to effect a delayed charging of the cylinder. When the electromagnet is fully or partially deactivated, a pressure differential acting across the flap swings the flap open.

Abstract: In an IC engine of the piston type comprising at least one engine inlet valve placed between an inlet duct and each combustion chamber and a swing type check valve, which is arranged in the inlet duct upstream from the inlet valve, is adapted to shut against the direction of inlet flow and in the shut position engages an electromagnet, said check valve having an opening threshold able to be adjusted with respect to its time lag in relation to the start of inlet by the engine inlet valve, the power supply circuit of the electromagnet includes an interrupter actuated in accordance with the operating parameters of the engine.

Abstract: An intake air control system for a multi-cylinder reciprocating internal combustion engine. The intake system is comprised of a plurality of intake air passages which are respectively communicable with a plurality of combustion chambers each defined in each engine cylinder. A communication passage is contained with each intake air passage to establish communication between upstream and downstream sides of a throttle valve disposed in each intake air passageway. A bypass valve is disposed in each communication passage to control the flow amount of air flowing through the communication passage, in accordance with an output torque in each cylinder. The opening degree of the throttle valve is controlled in accordance with a target opening degree set in accordance with a depression angle of an accelerator pedal.

Abstract: An internal combustion engine has a plurality of cylinders and intake passages leading to the cylinders respectively. A plurality of intake control valves block and unblock the intake passages respectively. Drive devices open and close the intake control valves mutually-independently. A detecting device serves to detect a predetermined condition of the engine under which a speed of the engine is required to vary. A control device performs a control of closing the intake control valves mutually-independently by use of the drive devices after the detecting device detects the predetermined condition of the engine.

Abstract: The variable ratio linkage is disclosed for use with a throttle valve having a rotary shaft and comprises a primary lever fixed at one end to the throttle shaft, a secondary lever pivotally attached between its first and second ends to the primary lever, a cable which connects the secondary lever first end to an accelerator pedal, and a throttle return spring for elastically biasing the throttle shaft to a closed position. In the closed position, the secondary lever first end engages a first limit and the secondary lever second end abuts a stop. When the accelerator pedal is depressed, the cable moves the secondary lever first end away from the first limit and causes the primary and secondary levers to rotate relative to one another and slowly rotate the throttle shaft until the secondary lever first end engages a second limit. When this occurs, further movement of the secondary lever first end away from the first limit causes the throttle shaft to rotate at a relatively faster rate.

Abstract: A throttle control system for an internal combustion engine includes a first lever which is pivotable around a longitudinal axis of a throttle shaft depending upon movement of an accelerator pedal, and a second lever which extends radially from the throttle shaft and is fixed thereto. The system further includes a transmitting mechanism which mechanically transmits pivotal motion of the first lever to the second lever so that the angular position of a throttle valve fixed to the throttle shaft varies in response to depression of the accelerator pedal. The transmitting mechanism optionally changes the ratio of the pivotal angle of the first lever from that of the second lever, so as to change the relationship between the depression rate of the accelerator pedal and the opening angle of the throttle valve.

Abstract: An engine including an engine block, and spark timing structure for advancing and retarding spark timing between a minimum spark advance and a maximum spark advance, the spark timing structure including a spark timing link comprising a stop and being movable between a minimum advance position and a maximum advance position spaced in one direction from the minimum advance position, the spark timing structure also including a spark timing lever including a surface and being movable between a first position wherein the surface is spaced from the stop when the link is in the minimum advance position, a second position wherein the surface engages the stop when the link is in the minimum advance position so as to provide common movement of the link and the spark timing lever in response to further movement of the lever in the one direction, and a third position wherein the link is in the maximum advance position when the surface engages the stop.

Abstract: A two-stroke internal combustion engine comprising an engine block, a plurality of crankcases and including a mounting surface having therein a plurality of inlet openings each communicating with a respective one of the crankcases, a throttle housing defining a throttle passage and including a plenum mounting surface, a throttle valve in the throttle passage, and a plenum member which is separable from both the engine block and the throttle housing and which defines a plurality of intake passages each having an outlet end communicating with a respective one of the inlet openings and each having an inlet end communicating with the throttle passage such that the intake of the engine can be tuned solely by modifying the configuration of the plenum member.