Dirty throttle will lower idle speed.

Unclean throttle will lead to low fuel air-fuel ratio and unstable idle speed!

The main cause of throttle scaling is oil and gas, followed by particles and moisture in the air. In other words, using qualified air filter and removing the crankcase ventilation pipe will slow down the throttle scaling.

The crankshaft is built in the crankcase, and the lower part is connected with the oil bottom. The working temperature of this part is about 100 ~ 180. Engine oil will be heated and volatilized during use. The longer the use time, the higher the temperature and the stronger the volatilization. In addition, the compressed gas of the cylinder will squeeze into the crankcase through the gap of the piston ring, so there must be a channel for the gas to escape, otherwise the oil bottom will form positive pressure.

The reason why the crankcase ventilation pipe is connected to the throttle valve is the requirement of environmental protection on the one hand, and the gas is pumped out of the crankcase by using the negative pressure of intake air on the other hand. When the oily steam reaches the intake pipe and cools, the oil in it will condense on the intake and throttle valve, and then the carbon deposit in the steam will also be deposited on these parts. Because the gap with the throttle valve open has the largest air flow, small space and low gas temperature, this part is the easiest to condense.