To improve responsiveness of fuel supply control, a rotary carburetor 100 has a nozzle 8 including a fuel discharge port 8a and a needle 10 disposed coaxially with the nozzle 8 and disposed with a portion inserted into the nozzle 8. The needle 10 can be displaced relative to the nozzle 8 to change an effective area of the fuel discharge port 8a. The rotary carburetor 100 has an electric motor 14 for displacing the needle 10 along an axis, and a drive mechanism component 12 interposed between the electric motor 14 and the needle 10 and converting a rotational movement of the electric motor into a linear movement.

To improve responsiveness of fuel supply control, a rotary carburetor 100 has a nozzle 8 including a fuel discharge port 8a and a needle 10 disposed coaxially with the nozzle 8 and disposed with a portion inserted into the nozzle 8. The needle 10 can be displaced relative to the nozzle 8 to change an effective area of the fuel discharge port 8a. The rotary carburetor 100 has an electric motor 14 for displacing the needle 10 along an axis, and a drive mechanism component 12 interposed between the electric motor 14 and the needle 10 and converting a rotational movement of the electric motor into a linear movement.

A flow control restrictor includes: a needle valve; and a limit cap which is made of metal and attached to the needle valve. In the needle valve, a first shaft portion which is made of metal and screwed into a regulation hole and a second shaft portion which is made of metal and housed inside the regulation hole are formed. On the second shaft portion, a first projection-and-recess portion is formed, and a pressed portion made of resin is provided on the first shaft portion side relative to the first projection-and-recess portion. The limit cap is fitted onto the second shaft portion. On the limit cap, a projecting portion which is inserted into a restriction groove of the regulation hole and a second projection-and-recess portion which is engaged with the first projection-and-recess portion are formed. The pressed portion is pressed against an inner peripheral surface of the limit cap.

A flow control restrictor includes: a needle valve; and a limit cap which is made of metal and attached to the needle valve. In the needle valve, a first shaft portion which is made of metal and screwed into a regulation hole and a second shaft portion which is made of metal and housed inside the regulation hole are formed. On the second shaft portion, a first projection-and-recess portion is formed, and a pressed portion made of resin is provided on the first shaft portion side relative to the first projection-and-recess portion. The limit cap is fitted onto the second shaft portion. On the limit cap, a projecting portion which is inserted into a restriction groove of the regulation hole and a second projection-and-recess portion which is engaged with the first projection-and-recess portion are formed. The pressed portion is pressed against an inner peripheral surface of the limit cap.

A needle valve body (220) has a needle hollow part (230) and a slit (232) extending in an axial direction and opened forward in a tip region. The carburetor body (B) has a body hole (202) receiving the needle valve body (220) in a longitudinally displaceable manner along an axis and a step-part circumferential edge (240a) formed in the body hole (202) and forming an orifice (250) with the slit (232) of the needle valve body (220). By operating the needle valve body (220) to adjust the size of the orifice (250), an amount of fuel supplied to a fuel discharge part (Fout) can be adjusted.

A needle valve body (220) has a needle hollow part (230) and a slit (232) extending in an axial direction and opened forward in a tip region. The carburetor body (B) has a body hole (202) receiving the needle valve body (220) in a longitudinally displaceable manner along an axis and a step-part circumferential edge (240a) formed in the body hole (202) and forming an orifice (250) with the slit (232) of the needle valve body (220). By operating the needle valve body (220) to adjust the size of the orifice (250), an amount of fuel supplied to a fuel discharge part (Fout) can be adjusted.

A rotary throttle valve for a carburetor may include a body and a throttle lever integrally formed with the body in one piece. The body may be generally cylindrical and adapted to be received in a cylindrical valve bore of a carburetor for rotation within and relative to the valve bore, and the body includes a valve passage through which air flows. The throttle lever is integrally formed with the body and adapted to be coupled to a driver that rotates the throttle valve. Among other things, by being integrally formed from the same piece of material as the valve body, the throttle lever can be accurately aligned with the valve body, and hence, the valve bore in which the body is received in use.

A rotary throttle valve for a carburetor may include a body and a throttle lever integrally formed with the body in one piece. The body may be generally cylindrical and adapted to be received in a cylindrical valve bore of a carburetor for rotation within and relative to the valve bore, and the body includes a valve passage through which air flows. The throttle lever is integrally formed with the body and adapted to be coupled to a driver that rotates the throttle valve. Among other things, by being integrally formed from the same piece of material as the valve body, the throttle lever can be accurately aligned with the valve body, and hence, the valve bore in which the body is received in use.

A dual fuel carburetor includes a carburetor body, a main jet pipe and a float chamber housing to form a float chamber, the needle valve device includes a pushing needle and a needle valve base, the pushing needle is movably inserted in the float chamber housing, and a window is formed at a bottom of the float chamber housing, the needle valve device further includes a sealed corrugated sleeve positioned around the pushing needle, which has a first end hermetically connected with the pushing needle and a second end hermetically connected with the float chamber housing, a driving spring is positioned around the pushing needle, and the pushing needle has a driving end extended out from the float chamber housing and opposite to that end cooperated with the valve base hole. The needle valve device is in a reasonable design to obtain mechanical controls or other automated drive controls.

A dual fuel carburetor includes a carburetor body, a main jet pipe and a float chamber housing to form a float chamber, the needle valve device includes a pushing needle and a needle valve base, the pushing needle is movably inserted in the float chamber housing, and a window is formed at a bottom of the float chamber housing, the needle valve device further includes a sealed corrugated sleeve positioned around the pushing needle, which has a first end hermetically connected with the pushing needle and a second end hermetically connected with the float chamber housing, a driving spring is positioned around the pushing needle, and the pushing needle has a driving end extended out from the float chamber housing and opposite to that end cooperated with the valve base hole. The needle valve device is in a reasonable design to obtain mechanical controls or other automated drive controls.