1. The fuel of the four-stroke gasoline engine is clean gasoline (No. 90 or above), and the lubricating oil is SAE30 four-stroke oil. The new machine idle running 2 hours, the heat engine can be used normally after replacing the oil. Normal use of the cumulative work of about 30 hours to replace the oil. Check the oil level before and after each use. 2. When the four-stroke air-cooled gasoline engine is working continuously, the crankcase temperature cannot exceed 90 degrees, and it can continue to work after stopping for 15 to 20 minutes when it is overheating. Fuel filling must be carried out in the cold state. The cooler should be used normally after 3 minutes of low speed operation, and do not use the maximum throttle for a long time when the grass is not cut. 3. Do not overspeed the gasoline engine. Stop at a low speed except in emergency situations. 4. The oil should be correct, authentic and clean, and the gasoline should be clean and fresh. 5. Non-professionals should not adjust the carburetor. When it is necessary to adjust, generally tighten the oil needle clockwise gently, and then twist it counterclockwise for 1.5 to 1.75 weeks. 6. The air filter element should be checked frequently, cleaned with soapy water or replaced regularly. Seven. After 100 to 300 hours of operation of the gasoline engine, apply wood chips or bamboo chips to remove carbon deposits once. Remove the cylinder head and remove the carbon deposits attached to the cylinder, cylinder head, piston, valve, etc. Carbon deposits shall not enter the cylinder hole and valve seat. 8. Keep the gasoline engine especially the cylinder block heat sink clean. 9. When refueling, inspection, repair and maintenance, unplug the spark plug cap, do not smoke, and stay away from the open flame. 10. Do not operate indoors. When the machine is working, other than the operator, unrelated personnel are more than 15 meters away from the machine. 11. Check the tightness of bolts in working parts and other parts of the machine before and after each use. 12. If there is a clutch, the gasoline engine shall not be started before the clutch is exposed, that is, the machine is not installed. 13. Other lubrication parts of the machine should be regularly filled with lubricating oil or grease according to the instructions as needed.