Throttle opening 12 is related to air cleaner element.

This is very important. The throttle opening mode of 12 degrees can only be opened when the air throughput of the air filter element meets the airflow speed of throttle 12 degrees. Throttle is a controllable valve that controls air to enter the engine. After the air enters the intake pipe, it will be mixed with gasoline to form a combustible mixture, and the combustion is successful.