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.

An improved carburetion system is provided. The carburetion system embodied in the present invention relocates the throttle plate anterior to venturi in an oversized throttle plate bore. By removing the throttle plate and shaft and its inherent interference imposed on the air/fuel mixture flow in the post-venturi chamber, the present invention delivers an increased cubic volume of uniform turbulent air/fuel mixture flow to the intake manifold. As a result, increasing the power at full throttle operation relative to the prior art.

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.

To optimize fuel supply of an engine with a carburetor during engine operation, a throttle opening degree detection sensor detecting a throttle opening degree and a control unit controlling a valve body variably controlling an opening degree of a fuel discharge part or a fuel supply passage based on a map are included. The map includes a plurality of sections divided based on the throttle opening degree and an opening degree of the valve body set for each section. The opening degree of the valve body set for each section is the opening degree of the valve body at which the engine rotation speed is highest in each section. The control unit controls an electric actuator driving the valve body to achieve the opening degree of the valve body set in a section to which the throttle opening degree detected by the throttle opening degree detection sensor belongs out of the plurality of sections.

A charge forming device includes a body with a main bore through which air flows and a fuel inlet through which fuel enters the main bore. A diaphragm defines part of a fuel chamber that leads to a fuel passage. The valve body is received in the fuel passage and has a first end, a second end, a sidewall, a valve passage having an inlet into which fuel from the fuel chamber enters and an outlet from which fuel exits for delivery to the main bore, and a cross passage extending through the sidewall between the first end and the second end and opening into the valve passage. A valve is carried by the body and has a valve head received in the cross passage and extending into the valve passage to at least partially inhibit fuel flow through the valve passage.

A carburetor has a housing wherein a control drum is rotatably mounted. A section of an intake channel is formed in the carburetor. A subsection of this section is formed in the control drum. The control drum controls the free flow cross section of the intake channel. A fuel opening is connected to a fuel chamber via an unbranched fuel channel which opens into the subsection of the intake channel. A simple configuration of the carburetor is achieved by the carburetor including an electrically actuated valve which controls the flow of fuel through the fuel channel. For a method for operating an internal combustion engine with a carburetor, a temperature (T) is determined before or during the starting of the engine and that the flow of fuel through the fuel channel during the starting of the engine is controlled in dependence upon the temperature (T).

In at least some implementations, a carburetor includes a main bore and a valve bore that has a bottom wall, and a throttle valve is received within the valve bore for rotation and axial movement between an idle position and a wide-open position. A first chamber is defined in the valve bore between the bottom wall and the throttle valve, and a second chamber is defined at least partially in the valve bore between the throttle valve and the throttle valve plate. A first passage communicates with the first chamber to permit fluid flow into or out of the first chamber, and a second passage communicates with the second chamber to permit fluid flow into or out of the second chamber. Various implementations may use any combination of inlet passages to the first and/or second chamber, and outlet passages from the first and/or second chamber.

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.

To optimize fuel supply of an engine with a carburetor during engine operation, a throttle opening degree detection sensor detecting a throttle opening degree and a control unit controlling a valve body variably controlling an opening degree of a fuel discharge part or a fuel supply passage based on a map are included. The map includes a plurality of sections divided based on the throttle opening degree and an opening degree of the valve body set for each section. The opening degree of the valve body set for each section is the opening degree of the valve body at which the engine rotation speed is highest in each section. The control unit controls an electric actuator driving the valve body to achieve the opening degree of the valve body set in a section to which the throttle opening degree detected by the throttle opening degree detection sensor belongs out of the plurality of sections.