Abstract: A method and system for operating an engine wherein ignition of the engine is activated according to a predetermined timing schedule that references engine speed, and the ignition is suppressed above a predetermined engine speed threshold to allow engine speed to fall below the predetermined engine speed threshold. Thereafter, ignition is reactivated according to timing that is retarded relative to the predetermined timing schedule for a predetermined number of engine revolutions substantially when the engine speed has fallen below the predetermined engine speed threshold, thereby mitigating undesirable spikes in combustion chamber maximum pressure.

Abstract: A control system for a low cost, light duty combustion engine, where the control system generally utilizes engine speed and/or temperature input signals and independent operating sequences to determine a desired ignition timing and air-to-fuel ratio for a combustible mixture. There are several independent operating sequences, each one of which is designed to optimally control the engine under certain conditions. These operating sequences include a Cranking sequence that commences after the engine is initially turned on, a Warm Up sequence which follows the Cranking sequence, a Normal Mode sequence for typical operating conditions, an Acceleration sequence for certain increases in engine speed, a Come Down sequence for when a sufficient engine speed is followed by a certain decrease in speed, and a Recovery Bump sequence for when the engine speed dips below a predetermined level.

Abstract: A control system for a low cost, light duty combustion engine, where the control system generally utilizes engine speed or engine speed and temperature input signals and independent operating sequences to determine a desired ignition timing and air-to-fuel ratio for a combustible mixture. There are several independent operating sequences, each one of which is designed to optimally control the engine under certain conditions.

Abstract: Method of and mechanism for regulating fuel feed from a rotary valve type carburetor to an associated engine. A carburetor bypass air passage variably communicates the throttle valve hole with a bypass air source at engine idle setting of the throttle valve. The bypass air passage outlet is closed by movement of the throttle valve out of idle setting toward high speed. At an initial carburetor-to-engine set-up and calibration, a bypass regulating valve is maintained open while the engine is running at idle speed. Then the fuel-regulating needle is adjusted to maximum fuel to air (F/A) mixture ratio permitted by applicable engine exhaust quality regulations, and then is permanently set and sealed. During subsequent end user operation of the engine, the bypass valve is closed only when preparing to crank the engine for starting to thereby provide an enriched fuel-to-air mixture for starting of the engine. When the engine is running under its own power the bypass valve is maintained open.

Abstract: A carburetor having a throttle valve co-rotatable with a small diameter throttle shaft having a free end protruding from an exterior side surface of the associated carburetor body. A throttle lever detent arm is co-rotatable on and with the throttle shaft free end adjacent each body surface. Interengageable detents on the detent arm and body surface are spaced radially away from the throttle shaft rotational axis by a distance, for example, of about three times the shaft diameter. The arm and body detents are releasably engageable with one another for thereby yieldably holding the detent arm and hence the throttle shaft and associated throttle valve in any one of a plurality of selected angular settings.

Abstract: Method of and mechanism for regulating fuel feed from a rotary valve type carburetor to an associated engine. A carburetor bypass air passage variably communicates the throttle valve hole with a bypass air source at engine idle setting of the throttle valve. The bypass air passage outlet is closed by movement of the throttle valve out of idle setting toward high speed. At an initial carburetor-to-engine set-up and calibration, a bypass regulating valve is maintained open while the engine is running at idle speed. Then the fuel-regulating needle is adjusted to maximum fuel to air (F/A) mixture ratio permitted by applicable engine exhaust quality regulations, and then is permanently set and sealed. During subsequent end user operation of the engine, the bypass valve is closed only when preparing to crank the engine for starting to thereby provide an enriched fuel-to-air mixture for starting of the engine. When the engine is running under its own power the bypass valve is maintained open.

Abstract: A fuel needle valve assembly of a carburetor has a retainer which yieldingly restrains the rotational fuel flow setting capability of the needle valve. The retainer engages a shank of the needle valve and a parallel shaft, both of which project from the carburetor body. The retainer exerts a force which laterally displaces the projecting shank with respect to the shaft. The retainer has sufficient strength to ensure the factory set rotational setting of the fuel needle valve does not alter when a limiter cap is press fitted to a distal head of the needle. Furthermore, wherein the shaft is also a shank of a second needle valve, the same retainer laterally displaces the projecting shanks of both needle valves.

Abstract: A carburetor preferably of a diaphragm type for an internal combustion engine has a low speed circuit for starting and idling of a cold engine. An air bleed line of the low speed circuit communicates between an inlet of a fuel and air mixing passage of the carburetor and an emulsifying chamber of the low speed circuit. Fuel flows to the emulsifying chamber from a fuel metering chamber and is regulated by a low speed idling adjustment needle screw. The bleed air and the fuel mixes within the emulsifying chamber and flows into the mixing passage between the throttle valve and the outlet of the mixing passage. Promoting this flow is a high vacuum produced by cranking and idling of the engine and accentuated by the substantially closed throttle valve. The fuel-and-air mixture is rich during cold idling as a result of the closed air bleed line. When the engine warms up, the air bleed line is opened via the restrictor valve.

Abstract: A carburetor preferably of a diaphragm type for an internal combustion engine has a low speed circuit for starting and idling of a cold engine. An air bleed line of the low speed circuit communicates between an inlet of a fuel and air mixing passage of the carburetor and an emulsifying chamber of the low speed circuit. Fuel flows to the emulsifying chamber from a fuel metering chamber and is regulated by a low speed idling adjustment needle screw. The bleed air and the fuel mixes within the emulsifying chamber and flows into the mixing passage between the throttle valve and the outlet of the mixing passage. Promoting this flow is a high vacuum produced by cranking and idling of the engine and accentuated by the substantially closed throttle valve. The fuel-and-air mixture is rich during cold idling as a result of the closed air bleed line. When the engine warms up, the air bleed line is opened via the restrictor valve.

Abstract: A control system for a low cost, light duty combustion engine, where the control system generally utilizes an engine speed input signal and independent operating sequences to determine a desired ignition timing and air-to-fuel ratio for a combustible mixture. There are several independent operating sequences, each one of which is designed to optimally control the engine under certain conditions.

Abstract: A carburetor having throttle valve co-rotatable with a small diameter throttle shaft having a free end protruding from an exterior side surface of the associated carburetor body. A throttle lever detent arm is co-rotatable on and with the throttle shaft free end adjacent each body surface. Interengageable detents on the detent arm and body surface are spaced radially away from throttle shaft the rotational axis by a distance, for example, of about three times the shaft diameter. The arm and body detents are releasibly engageable with one another for thereby yieldable holding the detent arm and hence the throttle shaft and associated throttle valve in any one of a plurality of selected angular settings.

Abstract: A carburetor throttle and choke control mechanism incorporating a choke-throttle cold-start fast idle setting latch mechanism having, in a first embodiment, a blade of a fast idle lever specially contoured for creating upon interengagement with a tang on a throttle lever initial torque resistance to co-rotation of the fast idle lever toward latched condition and then effecting force reversal for creating aiding torque to accelerate the fast idle lever relative to choke lever and thereby open a gap in the push coupling that remains in the latched position of the choke and throttle valves. The choke lever has a relatively rigid pusher leg portion adapted for abutment in push relation with a fast idle lever tang. In a second embodiment an extension of the leg portion in the form of a generally U-shaped resilient spring hook portion is adapted to overlap the tang and releasably hook engage the same when the leg portion is brought into full push abutment with said tang.

Abstract: A carburetor throttle and choke control mechanism incorporating a choke-throttle cold-start fast idle setting latch mechanism having, in a first embodiment, a blade of a fast idle lever specially contoured for creating upon interengagement with a tang on a throttle lever initial torque resistance to co-rotation of the fast idle lever toward latched condition and then effecting force reversal for creating aiding torque to accelerate the fast idle lever relative to choke lever and thereby open a gap in the push coupling that remains in the latched position of the choke and throttle valves. The choke lever has a relatively rigid pusher leg portion adapted for abutment in push relation with a fast idle lever tang. In a second embodiment an extension of the leg portion in the form of a generally U-shaped resilient spring hook portion is adapted to overlap the tang and releasably hook engage the same when the leg portion is brought into full push abutment with said tang.

Abstract: A fuel needle valve assembly of a carburetor has a retainer which yieldingly restrains the rotational fuel flow setting capability of the needle valve. The retainer engages a shank of the needle valve and a parallel shaft, both of which project from the carburetor body. The retainer exerts a force which laterally displaces the projecting shank with respect to the shaft. The retainer has sufficient strength to ensure the factory set rotational setting of the fuel needle valve does not alter when a limiter cap is press fitted to a distal head of the needle. Furthermore, wherein the shaft is also a shank of a second needle valve, the same retainer laterally displaces the projecting shanks of both needle valves.

Abstract: A carburetor fuel mixture adjustment assembly including a threaded cylindrical needle valve receptacle formed in a carburetor main body and intersecting a fuel passage. A needle valve body is threaded into the needle valve receptacle and includes a needle that extends into an axially-aligned needle seat orifice portion of the fuel passage. The needle is axially movable within the needle seat orifice by rotation of the needle valve body to control how much of the orifice is open to fuel flow. A valve spring disposed between a head of the needle valve body and the carburetor main body biases the head away from the carburetor main body. A needle stabilizer engages and cooperates with the valve spring in laterally biasing the needle into one position relative to the needle seat orifice. The lateral bias assures constant fuel flow through the orifice by resisting needle movement.

Abstract: A fuel needle valve assembly of a carburetor has a retainer which yieldingly restrains the rotational fuel flow setting capability of the needle valve. The retainer engages a shank of the needle valve and a parallel shaft, both of which project from the carburetor body. The retainer exerts a force which laterally displaces the projecting shank with respect to the shaft. The retainer has sufficient strength to ensure the factory set rotational setting of the fuel needle valve does not alter when a limiter cap is press fitted to a distal head of the needle. Furthermore, wherein the shaft is also a shank of a second needle valve, the same retainer laterally displaces the projecting shanks of both needle valves.

Abstract: For a four-stroke engine, a carburetor with a fuel pump diaphragm which defines a fuel pump chamber on one side and a pressure pulse chamber on its other side in communication with the engine to receive pressure pulses which actuate the fuel pump diaphragm to draw fuel into the carburetor and to discharge fuel under pressure to a downstream fuel metering assembly. An air passage communicates an air supply with the pressure pulse chamber to provide an air flow within the pressure pulse chamber which sweeps away, dries out or aerates and removes any liquid fuel within the pressure pulse chamber to avoid puddling of liquid fuel therein. In one form, a throttle valve carried by the carburetor body for movement between idle and wide open positions also actuates a valve which controls the flow of fluid through the air passage as a function of the position of the throttle valve.

Abstract: A method of reducing gaseous phase presence in the liquid fuel metering chamber of a diaphragm by providing a “High-Point Pick Up” hole positioned in the optimal metering chamber location (highest) to assure maximum purge evacuation of air and/or other gases prior to engine start-up and during running. This optimal location is dependent upon first determining, in advance of carburetor fuel feed circuitry and/or air purge system design, the orientation of the carburetor as mounted on the engine in its primary operator usage position, or so-called “standard operating position” (SOP). This SOP in turn is determined in the first instance by the engine manufacturer and/or the manufacturer of the portable engine-driven handheld appliance on which the engine is mounted.

Abstract: For a four-stroke engine, a carburetor with a fuel pump diaphragm which defines a fuel pump chamber on one side and a pressure pulse chamber on its other side in communication with the engine to receive pressure pulses which actuate the fuel pump diaphragm to draw fuel into the carburetor and to discharge fuel under pressure to a downstream fuel metering assembly. An air passage communicates an air supply with the pressure pulse chamber to provide an air flow within the pressure pulse chamber which sweeps away, dries out or aerates and removes any liquid fuel within the pressure pulse chamber to avoid puddling of liquid fuel therein. In one form, a throttle valve carried by the carburetor body for movement between idle and wide open positions also actuates a valve which controls the flow of fluid through the air passage as a function of the position of the throttle valve.

Abstract: A control mechanism for a carburetor having a throttle valve and a choke valve each having at least a cold-starting position and a full-speed position. The throttle valve is spring biased toward its third, low idle position, and the choke valve is mounted on a choke shaft and is spring biased toward its full-speed open position. When the choke valve is moved by a choke shaft lever from its open position toward its cold start closed position a fast idle lever associated with the choke valve shaft engages, via releasable latch parts, a throttle lever associated with the throttle valve. The interengaging latch parts of these fast idle and throttle levers hold both valves in their respective cold-starting positions in opposition to their respective biasing springs.