Examine and Repair of Intake and Exhaust Valve

1) When the working surface of the valve(including intake and exhaust valve) is worn, grooved, widened, or ablated and spots or depressions appear, it should be polished. When the wear is serious and cannot be repaired by polishing, it should be replaced.

2) The wear of the valve stem (the most worn part is generally the part where the rod part is in contact with the upper and lower ends of the guide tube), and a micrometer can be used to compare the most worn part and the unworn part of the rod. When the wear amount exceeds 0.05mm, or touch it by hand The stepped feel, the valve should be replaced. Please also check the position of rocker arm after replacing the valve.

3) The runout error of the oblique ring on the cylindrical surface of the cylinder surface of the valve head should not be greater than 0.03mm;
The straightness error of the rod should be no more than 0.02mm. When it exceeds the specification, it can be corrected by cold pressing. The method is: wrap the valve stem with copper skin and clamp it on the vise, try to make the valve head close to the plane of the vise, and gently tap the valve head with your hand to correct the deflection. Bend is corrected by placing the valve on the wood and hitting the valve stem with a steel hammer or mallet. The straightness of the valve stem can be rolled on the flat plate, and the seam inspection can be measured with a thickness gauge.

4) The lower end face of the valve stem, if there is a dent in the wear, should be smoothed.

5) If the end face of the valve stem is not flat, the end face of the "V"-shaped groove of the grinding end face frame and the flat grinding wheel can be used for grinding, and the cumulative grinding amount should not exceed 1.50mm.

6) If the groove of the valve lever lock piece is worn, the valve should be replaced. 

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