What should I do if the valve clearance is too large?

Solution to excessive valve clearance: 1. Preheat the engine to make the temperature of cooling water reach 80 to 90 degrees; 2. Open the clutch housing timing mark inspection hole and cylinder head cover; 3. Confirm that the cylinder head bolts have been tightened to the specified torque; 4. Turn the crankshaft so that the "0" line of the flywheel is consistent with the line of the clutch housing, and confirm that the cambered surface of the rocker arm of the intake and exhaust valve of the first cylinder is in contact with the base circle of the camshaft cam, that is, the piston of the first cylinder is located at the compression top dead center. (The crankshaft should rotate 360 degrees when the rocker arm contacts the cam) At this time, the valve is in the closed position. 5. Loosen the lock nut 2 of the adjusting screw 1 and turn the adjusting screw with a screwdriver to make the clearance between the lower end face of the screw and the upper end face of the valve stem 3 reach the specified clearance value. In order not to move the screwdriver, after tightening the lock nut to the specified torque, insert the gauge into the gap A for reconsideration, and adjust the gap between the intake valve and exhaust valve of the first cylinder; 6. Then turn the crankshaft clockwise. Seen from the front end of the engine, the valve clearance of the next ignition cylinder can be adjusted according to the ignition sequence of 1-3-4-2 every time the four-cylinder engine rotates 180 degrees. For a three-cylinder engine, it can be adjusted every 240 degrees according to the ignition sequence of 1-2-3 (the crank angle can be converted according to the number of teeth of the flying rim).