What is the reason why the valve is not closed properly?

The reasons for the lax valve closing are: 1, and the valve clearance is too small; 2. Excessive carbon deposition in the valve contact area; 3. Valve seat ring deformation or valve top deformation; 4, valve spring failure or rocker arm deformation. Throttle is a controllable valve to control air to enter the engine, and its function is to control air to enter the engine. After the air enters the intake pipe, it is mixed with gasoline to form a combustible mixture, thus the combustion is successful. The steps to clean the throttle are: 1, open the hood and find the throttle of the engine; 2. Remove the air filter and intake pipe with a flat screwdriver, and unplug the electric socket on the throttle; 3. After removing the screw, remove the throttle, and then block the air inlet of the engine with a dry rag to prevent dirt from entering the engine; 4. Spray the cleaning agent on the throttle for cleaning.