What is the white smoke on the motorcycle?

It may be because the engine burns oil. Those motorcycles are either old or the owners usually don't care about speeding. Changing the oil or dropping the throttle will cause the engine to wear and tear, and it will smoke if it is left untreated for a long time. In winter, if the temperature is below zero, you will also see "smoke", but the normal motorcycle exhaust pipe only emits hot air, and the problematic motorcycle will have a strong gasoline smell or other tail odor.

Extended data:

Carburetor is an important part of motorcycle fuel supply system, which is located between air filter and engine intake. Motorcycle engines generally adopt carburetor, plunger throttle valve and float chamber throttle valve with horizontal intake flow direction. The carburetor structure mainly consists of a float chamber and a mixing chamber. The float chamber is located below the carburetor, and the oil pipe is communicated with the oil tank through the throttle switch. The oil level in the float chamber is maintained at a certain height through the needle valve on the float, and the oil supply pressure is stable. The function of the mixing chamber is to evaporate and atomize gasoline and mix it with air, so that the engine can get the required mixture at various loads and speeds.

References:

Motorcycle-Baidu Encyclopedia