How Carburetor Works
A carburetor is essentially a tube with an adjustable plate in the middle called a throttle plate that controls the flow of air through the tube. There is a constriction in the tube called a venturi where a vacuum is created. This constriction has a measuring hole through which fuel can be sucked in using a vacuum.
The motorcycle carburetor looks very complicated, but as long as you master some principles, you can adjust the motorcycle to the best condition. All carburetors work on the basic principle of atmospheric pressure. Atmospheric pressure is a powerful force that exerts pressure on everything. It varies slightly, but typically fifteen pounds of pressure per square inch (PSI). This means that atmospheric pressure is fifteen pounds per square inch of pressure on everything. By changing the atmospheric pressure within the engine and carburetor, it is possible to change the pressure and allow fuel and air to flow through the carburetor.
Atmospheric pressure spreads from high pressure to low pressure. When the piston of a two-stroke engine is at top dead center (or the piston of a four-stroke engine is at bottom dead center), a low pressure develops under the piston in the crankcase (above the piston on a four-stroke engine). At the same time, this low pressure will also cause low pressure in the carburetor. Because the pressure outside the engine and carburetor is higher, air will rush into the carburetor and into the engine until the pressures equalize. The air flowing through the carburetor will carry the fuel, which will then mix with the air.
Inside the carburetor is a section of pipe. The throat is the constriction inside the carburetor that forces air to accelerate through it. A river that suddenly narrows can be used to illustrate what happens inside a carburetor. The water in the river will speed up as it approaches a narrowing bank, and even faster if the bank narrows continuously. If the same thing happens inside the carburetor, the accelerated flow of air will cause the air pressure inside the carburetor to decrease.
The gasoline enters the carburetor from the fuel tank through the gasoline filter. The gasoline filter can filter out the impurities mixed in the gasoline and the oxide scale in the fuel tank. If the filter quality is defective, some impurities may still enter the carburetor through the filter. In addition, gasoline contains ingredients that can form colloid. After long-term deposition, colloid will condense and adhere to the parts of the carburetor (such as measuring holes), oil passages and the surface of the float chamber.
The air enters the carburetor through the air filter. Considering that the air intake resistance cannot be too large and other factors, the filter device cannot be too dense, so some tiny impurities in the air will still enter the carburetor through the air filter. If the filter quality is defective, it will cause more serious effects.
Many parts that make up the carburetor oil passage and air passage, such as the main volume hole, idle volume hole, main air volume hole, idle air volume hole, main foam tube, etc., all have holes with small inner diameters (inner diameter between 0.3 and 1.5 mm). The gasoline impurities, colloids and impurities in the air that enter the carburetor will often change or block these hole diameters, resulting in the carburetor air channel and oil channel being blocked, changing the oil supply characteristics of the carburetor, and even causing carburetor performance failure.
