We will consider the operation of the carburetor using the example of the 139FMB motorcycle gasoline engine carburetor. All carburetors work according to this principle, but this option is the simplest and most understandable for a beginner.
A carburetor is a device that mixes fuel (gasoline) with air. This is necessary in order to ensure optimal energy output. The mixture must be in the correct proportion. Deviation in the components, both in one and the other direction, leads either to a lean mixture, a decrease in efficiency and a poor start (the engine may not start at all), or vice versa, to detonation of the fuel inside the engine.
The principle of operation is extremely simple. A running motor creates a vacuum similar to a conventional vacuum cleaner. Because of this, air is sucked into the inside of the engine. The air passes through the carburetor where it is enriched with fuel. Then this mixture enters the combustion chamber and the engine runs. The amount of fuel is regulated by the throttle or the throttle handle (pedal).
The carburetor device is very simple. Fuel comes out of the gas tank. Fuel enters the so-called. float chamber. The float eliminates the access of excess fuel (works similarly to a conventional toilet). From this chamber, fuel is drawn by a stream of air that passes through an air filter and is captured from the street. The hole through which the fuel enters is plugged with a needle throttle valve.
In addition, an idle channel is provided on the carburetor. This is the hole through which the minimum amount of fuel always flows, causing the engine to idle.
