The invention concerns a method for controlling the fuel supply to an internal combustion engine at start-up, the engine having a fuel supply system. The invention also concerns a carburetor having a fuel supply system including a main fuel path connecting a diaphragm controlled regulating chamber to a main outlet in the region of the venturi section, the main fuel path including an actively controlled fuel valve, and an idling fuel path branching off from the main fuel path downstream of the valve and ending in at least one idling outlet in the region of a throttle valve, the fuel supply system further including a start fuel line starting upstream or downstream of the fuel valve and ending in at least one start fuel outlet to the intake channel.

In at least one implementation, a method of operating a combustion engine, includes determining a temperature equal or related to a temperature of an engine at an engine start and comparing the determined temperature to a temperature threshold, determining if an engine operating condition exceeds an engine threshold within a threshold time after the engine was started, and if the determined temperature is below the threshold temperature and the engine operating condition remains above the engine threshold and the threshold time has not passed, providing an enriched fuel and air mixture to the engine.

In at least one implementation, a method of operating a combustion engine, includes determining a temperature equal or related to a temperature of an engine at an engine start and comparing the determined temperature to a temperature threshold, determining if an engine operating condition exceeds an engine threshold within a threshold time after the engine was started, and if the determined temperature is below the threshold temperature and the engine operating condition remains above the engine threshold and the threshold time has not passed, providing an enriched fuel and air mixture to the engine.

An automatic choke device of a carburetor includes a wax attached to an engine main body, a rod configured to perform a linear motion in conjunction with expansion of the wax, a choke lever configured to rotate in conjunction with the linear motion of the rod, and a choke shaft arranged so as to be able to abut against the choke lever and connected to a choke valve of the carburetor. The choke lever includes a flat portion that engages with an engaging portion of the choke shaft, and a circular arc portion that is formed in a circular arc shape so as to be continuous from the flat portion and is brought into sliding contact with the engaging portion of the choke shaft.

An automatic choke device of a carburetor includes a wax attached to an engine main body, a rod configured to perform a linear motion in conjunction with expansion of the wax, a choke lever configured to rotate in conjunction with the linear motion of the rod, and a choke shaft arranged so as to be able to abut against the choke lever and connected to a choke valve of the carburetor. The choke lever includes a flat portion that engages with an engaging portion of the choke shaft, and a circular arc portion that is formed in a circular arc shape so as to be continuous from the flat portion and is brought into sliding contact with the engaging portion of the choke shaft.

In at least some implementations, a charge forming system for a combustion engine includes a first fuel supply device having a first passage from which fuel is discharged for delivery to the engine and a second fuel supply device having a second passage from which fuel is discharged for delivery to the engine. The first passage communicates with the second passage so that the fuel in the first passage is combined with the fuel in the second passage.

In at least some implementations, a charge forming system for a combustion engine includes a first fuel supply device having a first passage from which fuel is discharged for delivery to the engine and a second fuel supply device having a second passage from which fuel is discharged for delivery to the engine. The first passage communicates with the second passage so that the fuel in the first passage is combined with the fuel in the second passage.

An automatic choke device of a carburetor includes a wax attached to an engine main body, a rod configured to perform a linear motion in conjunction with expansion of the wax, a choke lever configured to rotate in conjunction with the linear motion of the rod, and a choke shaft arranged so as to be able to abut against the choke lever and connected to a choke valve of the carburetor. The choke lever includes a flat portion that engages with an engaging portion of the choke shaft, and a circular arc portion that is formed in a circular arc shape so as to be continuous from the flat portion and is brought into sliding contact with the engaging portion of the choke shaft.

An automatic choke device of a carburetor includes a wax attached to an engine main body, a rod configured to perform a linear motion in conjunction with expansion of the wax, a choke lever configured to rotate in conjunction with the linear motion of the rod, and a choke shaft arranged so as to be able to abut against the choke lever and connected to a choke valve of the carburetor. The choke lever includes a flat portion that engages with an engaging portion of the choke shaft, and a circular arc portion that is formed in a circular arc shape so as to be continuous from the flat portion and is brought into sliding contact with the engaging portion of the choke shaft.

A general purpose engine includes: a cooling fan fixed to an engine rotary shaft; a muffler to silence exhaust gases; a muffler covering to cover the muffler; and an auto choke device to control an opening of a choke valve in an air intake passage by the utilization of heat evolved from the muffler. The auto choke device includes: a drive source, which is fitted to the muffler covering in a non-contact fashion to the muffler and exposed to an outer surface of the muffler covering; and a link member to connect between the drive source and the choke valve. The drive source includes a bracket, which is fitted to the muffler covering, and a bimetal fitted inside the bracket. The bracket includes a heat shield extending towards an inner side of the muffler covering, and the heat shield blocks out a cooling wind then flowing towards the bimetal.