Abstract: A carburetor fuel flow control device having an elongate annular body received in a cavity with an inlet in its side-wall communicating with a fuel supply passage and an outlet downstream of the inlet and adjacent to an end of the body, and a needle valve with a metering portion adjacent one end rotatably and slidably received in the body with the metering portion at least partially lapping or blocking the inlet to change the effective flow area of the inlet in response to generally axial movement of the needle valve relative to the inlet.

Abstract: A carburetor fuel flow control device having an elongate annular body received in a cavity with an inlet in its side-wall communicating with a fuel supply passage and an outlet downstream of the inlet and adjacent to an end of the body, and a needle valve with a metering portion adjacent one end rotatably and slidably received in the body with the metering portion at least partially lapping or blocking the inlet to change the effective flow area of the inlet in response to generally axial movement of the needle valve relative to the inlet.

Abstract: A carburetor valve and limiter cap assembly for limiting adjustment of fuel flow in a carburetor may include a needle valve and a limiter cap. The needle valve may have a tip, a threaded portion, a head having a flange with an outer diameter greater than the rest of the head, and one or more serrations formed on the head. The limiter cap may have a sidewall, a tab extending outwardly from the sidewall, a first cavity having an inner diameter sized for an interference fit with the flange, and at least one driving feature to engage at least one serration so that rotation of the limiter cap causes rotation of the needle valve. The interference fit between the flange and the limiter cap inhibits removal of the limiter cap from the needle valve to prevent undesired adjustment of the needle valves by an end user.

Abstract: A carburetor valve and limiter cap assembly for limiting adjustment of fuel flow in a carburetor may include a needle valve and a limiter cap. The needle valve may have a tip, a threaded portion, a head having a flange with an outer diameter greater than the rest of the head, and one or more serrations formed on the head. The limiter cap may have a sidewall, a tab extending outwardly from the sidewall, a first cavity having an inner diameter sized for an interference fit with the flange, and at least one driving feature to engage at least one serration so that rotation of the limiter cap causes rotation of the needle valve. The interference fit between the flange and the limiter cap inhibits removal of the limiter cap from the needle valve to prevent undesired adjustment of the needle valves by an end user.

Abstract: A rotary throttle valve carburetor has a start assist device with an operating member that interacts with a throttle lever of the throttle valve to axially displace the throttle valve, preferably without rotating it. The operating member may be rotated and moved linearly for selective engagement with the throttle lever by any one of a plurality of starting features generally spaced circumferentially about the operating member. Preferably, each starting feature has a face that faces axially outward with respect to the rotary axis and when in contact with the throttle lever. Each face is spaced at a different distance from the operating member axis thus selection of each will cause the operating member to contact and move the throttle lever a different distance. The different distances correspond to varying fuel enrichments that may be associated with different temperatures of an engine to be started.

Abstract: A rotary throttle valve carburetor has a start assist device with an operating member that interacts with a throttle lever of the throttle valve to axially displace the throttle valve, preferably without rotating it. The operating member may be rotated and moved linearly for selective engagement with the throttle lever by any one of a plurality of starting features generally spaced circumferentially about the operating member. Preferably, each starting feature has a face that faces axially outward with respect to the rotary axis and when in contact with the throttle lever. Each face is spaced at a different distance from the operating member axis thus selection of each will cause the operating member to contact and move the throttle lever a different distance. The different distances correspond to varying fuel enrichments that may be associated with different temperatures of an engine to be started.

Abstract: A rotary throttle valve carburetor has a fuel-and-air mixing passage which extends through a carburetor body. A cylindrical throttle chamber extends down from a top surface of the body and communicates transversely with the fuel-and-air mixing passage. A rotary throttle seats rotatably and vertically or axially movable within the chamber and through the fuel-and-air mixing passage. The rotary throttle has a bore fully communicating and longitudinally aligned with the fuel-and-air mixing passage at wide-open throttle. The rotary throttle has a throttle shaft projecting upward through the top surface of the carburetor body and through a hole of a base portion of a plastic lid plate engaged between the top surface and a metallic bracket. An upward projecting annular shoulder of the lid plate is disposed concentrically to and spaced radially apart from the throttle shaft.

Abstract: A variable venturi carburetor for a combustion engine has an uprighted cup-shaped piston head which forms an integral part of a venturi within a fuel-and-air mixing passage carried by a carburetor body, and a needle that projects rigidly downward from the head into a fuel feed passage. The position of the piston head controls air flow by adjusting the air flow cross-section of the variable venturi, and the needle simultaneously controls fuel flow into the fuel-and-air mixing passage at the venturi via obstruction of the fuel feed passage. The piston head and needle move in unison by a flexible diaphragm engaged to and disposed above the head. An atmospheric chamber is defined below the diaphragm and a vacuum chamber is defined generally above the diaphragm. A vacuum passage extends through the bottom of the head communicating between the fuel-and-air mixing passage at the venturi and the vacuum chamber.

Abstract: A variable venturi carburetor for a combustion engine has an uprighted cup-shaped piston head which forms an integral part of a venturi within a fuel-and-air mixing passage carried by a carburetor body, and a needle that projects rigidly downward from the head into a fuel feed passage. The position of the piston head controls air flow by adjusting the air flow cross-section of the variable venturi, and the needle simultaneously controls fuel flow into the fuel-and-air mixing passage at the venturi via obstruction of the fuel feed passage. The piston head and needle move in unison by a flexible diaphragm engaged to and disposed above the head. An atmospheric chamber is defined below the diaphragm and a vacuum chamber is defined generally above the diaphragm. A vacuum passage extends through the bottom of the head communicating between the fuel-and-air mixing passage at the venturi and the vacuum chamber.

Abstract: An improved fuel flow control device of a diaphragm-type carburetor having a lever which can be easily coupled to a flow control valve body. The lever has a resilient portion which flexes to permit a cooperating portion of the valve body to pass thereby and into an opening in the lever. After the valve body is received in the opening, the resilient portion returns at least in part to its unflexed position to retain the valve body and prevent its separation from the lever.

Abstract: A throttle valve lever for controlling the rate of fuel flow in a rotary throttle valve type carburetor is proposed, wherein the throttle valve lever has increased stiffness to help prevent structural deformation due to excessive force exerted and applied to the lever over time. The throttle valve lever basically includes an oblong structure comprising synthetic resin and an oblong reinforcement plate comprising metal. The resin structure has a hole defined therethrough, which is capable of fitting around the shaft of a throttle valve of a carburetor, and also has a lever portion at one end of the resin structure. The metal plate has a hole defined therethrough, which is capable of fitting around the shaft of a throttle valve of a carburetor, and also has a lever portion at one end of the metal plate.

Abstract: A fuel jet supporting structure for a carburetor includes a support column (5) provided with a fuel passage which introduces fuel to an air intake passage (9). The fuel passage includes a fuel passage bore (24), an air passage bore (19), a threaded bore (18) and an outlet passage (16) which has subsequently reduced diameters. A stepped portion between the threaded bore (18) and outlet passage (16) is tapered. The fuel jet body (25) has a middle portion forming an emulsion tube (26) and a downstream threaded portion (28) which engages the threaded bore (18). A downstream end (27) is tapered and abuts the tapered section in the bore to form a seal.

Abstract: A rotary throttle valve carburetor has a fuel-and-air mixing passage which extends through a carburetor body. A cylindrical throttle chamber extends down from a top surface of the body and communicates transversely with the fuel-and-air mixing passage. A rotary throttle seats rotatably and vertically or axially movable within the chamber and through the fuel-and-air mixing passage. The rotary throttle has a bore fully communicating and longitudinally aligned with the fuel-and-air mixing passage at wide-open throttle. The rotary throttle has a throttle shaft projecting upward through the top surface of the carburetor body and through a hole of a base portion of a plastic lid plate engaged between the top surface and a metallic bracket. An upward projecting annular shoulder of the lid plate is disposed concentrically to and spaced radially apart from the throttle shaft.