Yamaha gasoline engine backfired and fired, and the carburetor was cleaned and the valve adjustment was invalid.

Carburetor backfire refers to the phenomenon that the flame flows back to the carburetor from the intake manifold. Generally speaking, the backfire of carburetor is mostly caused by too thin mixture and too early ignition time. In addition, you can also check whether the intake valve is not tightly closed or the valve clearance is too small, and whether the intake pipe leaks.

When the car is running, the engine can only work normally if the throttle handle is turned slowly and steadily, so that the throttle opening is gradually increased and the proportion of air and gasoline entering the carburetor mixing chamber is appropriate.

If the throttle handle is turned sharply to refuel, the throttle opening of the carburetor will increase rapidly, resulting in a large amount of air flowing through the carburetor at high speed. Because the fluidity of gasoline is worse than that of air, it is impossible to spray the corresponding amount from the nozzle to mix with air in time, thus making the mixture dilute.

After being ignited in the cylinder, the combustion speed of this lean mixture is slower than that of the normal mixture, so that the engine continues to burn at the end of the exhaust stroke. At this time, the fresh mixture just entering the cylinder is ignited immediately at the beginning of the intake stroke, and it is always ignited to the carburetor, causing the carburetor to backfire.

Carburetor tempering is an abnormal combustion phenomenon. After tempering, its biggest drawback is that the engine works abnormally and the power drops, and the advantages of carburetor are not reflected.

For example, when the carburetor backfires, the burning flame overflows the cylinder, which may lead to fires and accidents. There are many examples in this regard, especially some passenger cars caught fire due to engine tempering, causing heavy casualties. Therefore, we must pay enough attention to it and take effective preventive measures. In order to ensure the safe operation of the vehicle, the engine is required not to backfire and not to shoot. Therefore, measures should be taken in time to eliminate the causes of carburetor backfire.