The carburetor is essentially a tube with an adjustable plate called a throttle plate in the middle that controls the flow of air through the tube.The tube has a shrinking part called the venturi tube, where a vacuum is formed.This shrinkage part has a measuring hole through which the fuel can be sucked in by vacuum.

Motorcycle carburetors look very complicated, but with a few principles, you can tune your motorcycle to optimum condition.All carburetors operate on the basic principle of atmospheric pressure.Atmospheric pressure is a powerful force that exerts pressure on everything.It varies slightly, but it's usually about 15 PSI per square inch.That means atmospheric pressure on everything is 15 pounds per square inch.By changing the atmospheric pressure in the engine and carburetor, you can change the pressure and allow fuel and air to flow through the carburetor.

Atmospheric pressure diffuses from high to low.When the piston of a two-stroke engine is at BDC (or the piston of a four-stroke engine is at BDC), a low pressure forms under the piston in the crankcase (above the piston of a four-stroke engine).This low pressure also causes low pressure in the carburetor.Because the pressure outside the engine and carburetor is high, air will rush into the carburetor and into the engine until the pressure equalizes.Air flowing through the carburetor will drive the fuel, which will then mix with the air.

Inside the carburetor is a tube.The throat is the constricted part of the carburetor that forces air to accelerate through.Can be illustrated by the sudden narrowing of the river

What happens inside the carburetor.The river speeds up as it approaches a narrowing bank, and even faster if the bank continues to narrow.If the same thing happens in a carburetor, the accelerated flow of air will cause the pressure inside the carburetor to drop.

Gasoline enters the carburetor from the tank through a gasoline filter, which filters out impurities in the gasoline and the oxide scale in the tank.If the filter quality is defective, there is still some impurities through the filter into the carburetor.In addition, gasoline contains colloidal components, after a long time of deposition will condense colloidal, attached to the carburetor parts (such as holes), oil passage and float chamber surface.

Air is through the air filter into the carburetor, based on the intake resistance can not be too large and other factors, the filter device can not be too dense, so part of the small impurities in the air will still enter the carburetor through the air filter.If the quality of the filter is defective, it will cause more serious effects.

In the airways of the carburetor oil duct, more spare parts, such as the main measure holes, idle hole, primary air quantity, amount of idle air hole and main foam pipe and so on all have inside a small hole (diameter between 0.3 ~ 1.5 mm), into the carburetor petrol impurity, colloid and impurities in the air, often will change the aperture or congestion,The result is that the carburetor airways and oil channels are not smooth, so that the carburetor oil supply characteristics change, and even cause the carburetor performance failure.

The operation of the car engine often changes in a large range, such as the car before starting and waiting for the green light at the intersection, the engine idle operation, at this time the load is zero, the throttle opening is the smallest, the speed is the lowest;The car is full load uphill, throttle fully open, but the speed is not high;Driving on flat road, throttle need not be fully open, engine output load medium, speed and speed medium;At high speed, the engine works at full load and the speed reaches its maximum.The requirements for gas mixture vary from time to time under complex operating conditions.If the mixture must be very thick at idle speed and is needed, the concentration needs to gradually dilute under small load;And medium load, in order to save oil, and need carburetor to supply the most economical gas mixture;At full load, the carburetor needs to provide a thick mixture for maximum output power of the engine.In addition, when the car cold start, there should be a thicker mixture of gas;When you accelerate, you need carburetors to supply extra fuel when the throttle suddenly increases, and so on.In such a complex situation, a simple carburetor is not suitable.

In order to meet different operating conditions, modern carburetors are usually equipped with a series of mixed gas concentration compensation devices.Such as the main supply pump, idle system, economizer, accelerator system and starter system, etc., to ensure that the gasoline engine under various operating conditions, carburetor can output the appropriate concentration of mixture.