1. Valve clearance is the clearance between the lower end face of valve adjusting screw and the upper end face of valve rod top. As long as the valve is closed and the engine is cold, this gap exists, and you can feel it by pushing the valve rocker arm up and down. If the valve is not in the closed position it is inevitable in open state, because the valve adjusting screw is pressure on the valve stem, so whatever is remained cold machine or heat engine is impossible of valve clearance, which means that no matter how much you had you can't shake the valve rocker arm -- -- -- -- -- - to know it is very important!

2. In order to ensure the normal operation of the engine, the manufacturer should give a standard valve clearance in the manual when the car leaves the factory. The clearance is too large or too small in the actual work, which will have a bad effect on the performance of the engine. So if you find a problem with the valve gap in your car, adjust it.

3. According to the first clause, the valve clearance can be adjusted as long as the machine is cold and the valve is in the closed state. Here's where the valve is closed:

     No matter the intake valve or exhaust valve, the intake valve is only in the open state during the intake stroke, and the exhaust valve is only in the open state during the exhaust stroke, while most of the other working sections are in the closed state. So it's not difficult to find the position of the valve in the closed state by simply turning the foot starter bar, rather than by aligning the magneto "T" mark with the mark on the viewing window. All you have to do is press the valve rocker arm up and down as you turn the crankshaft with your hand. If you feel the valve rocker swing slightly during this process, the valve must be closed (regardless of where the piston is now) and you can adjust the valve clearance.

4. Valve clearance adjustment is also very simple. The steps are as follows:

A. First screw the loosen air lock nut;

B. Use your finger to screw the valve adjusting screw until the bottom end of the screw is aligned with the top end of the valve rod (that is, to eliminate the gap);

C. Turn the screw "1/6 turn" (air intake); 1/4 circle (exhaust), after the twist lock nut screw lock live can (note: this is GT125 data), back to twist n of a pitch circle means that the screw back n points of distance, the distance is what we call out the gap size, GT screw pitch is about 0.5 mm, the other cars to be back to twist the circle don't know, but we can work out ourselves, method is to put the valve adjusting screw down, 10 with ruler to measure the length of the pitch, then divided by 10, namely each the length of the pitch, then you can know the valve adjusting screw every time n points of circle, bring up the clearance is how old. Then you can calculate a fraction of a turn according to your car's standard valve clearance. The advantages of using this method are: You don't have to worry about whether the car is new or old or how worn the parts are, you can adjust the gap to a very accurate degree.