Excuse me, why does the motorcycle stall when its idle speed decreases?

Even if the idle speed does not drop, you will turn off the engine no matter how hard you try to refuel. This is because when you refuel hard, because the air is much lighter than gasoline, a lot of air will rush in and little gasoline will enter. The mixture suddenly becomes very thin, and the engine will stall, which has nothing to do with idle speed.

Idle screw controls the opening of throttle station. Lowering will not only reduce the oil intake, but also reduce the air intake, but idling will not affect the fuel consumption (except when it is too high). And if it is too low, it will make the engine unstable. It is necessary to burn oil to keep running. If it is too low, it will rely on the inertia of the crank itself, which will increase the vibration and noise of the engine for a long time. When the idle speed is low, the oil supply of the oil pump will also decrease, which is not conducive to engine lubrication. In addition, the lower the idle speed, the more fuel-efficient it is. When the engine is at the economical speed, it can run as long as it needs a thinner mixture, while it must use a thicker mixture when idling. The measured fuel consumption of a car at idle speed will even be greater than that at economical speed (for example, a small-displacement car with a speed of 35KM/H), and artificially reducing the idle speed to save fuel will only be counterproductive.

The throttle valve also works as an oil needle on it. It controls both oil intake and air intake. The throttle valve mainly controls air intake, and the oil needle mainly controls oil intake.