The engine (air-cooled type) is overheating, which means that the temperature of the engine crankcase exceeds 90 ° C, the power is seriously decreased, and the driving acceleration is weak. Engine overheating, vehicle load or driving road conditions can not be improved in time, but also produce "cylinder" piston burn, crankshaft big head bearing bite and other malignant failures.

The main reason is that

1) Long time high-speed driving, low speed and heavy load driving, poor engine lubrication;

2) The quality of parts is poor and the maintenance is not standardized. Because of high speed, heavy load, long time driving caused by engine overheating, just reduce the load, control the speed or stop the engine temperature down.

The difference between engine overheating due to the failure of the lubrication system and heavy load driving at high speed is that the former is controllable overheating, and the latter is uncontrollable overheating.

a) Causes and inspection of overheating of four-stroke engine

50~100mL motorcycle: When the engine heat dissipation is good, it should check the lubrication condition and whether the engine heat sink is sticky with oil and sand. When the engine is running at idle, loosen the nut in the lower right corner of the cylinder head (with copper washer) and the organic oil will flow out. If inorganic oil flows out or the amount of oil is small, there is a problem with the engine lubrication system. Should check whether the oil pump, lubricating oil circuit is smooth (right crankshaft oil circuit, crankshaft center oil hole through the connecting rod big head bearing, through the oil hole to the clutch gear, connecting rod big head bearing, and "splash lubrication" mode, lubrication cylinder, piston assembly).

125~250mL motorcycle: Remove the valve cover and plug a piece of white paper in the valve cover mouth. If the engine is running at idle speed, if the lubrication system works normally, the oil is pressurized to lubricate the cylinder head valve system under the action of the oil pump, and there will be oil droplets on the paper blocked in the valve cover. Otherwise, check the engine lubrication system (oil pump, crankcase oil passage, crankshaft oil passage, oil filter).

b) Cause and inspection of two-stroke engine overheating

Remove the oil rubber tube of the oil pump from the carburetor, inject a few drops of oil into the lubricating oil pipe port on the carburetor, and start the engine in the cold state. If the cause of the engine overheating is caused by poor lubrication, the idle speed of the engine will immediately increase (the cylinder, piston components, crankshaft connecting rod bearings are lubricated, the sealing performance of the cylinder is increased, the operating resistance is reduced, the engine speed is increased), and the exhaust pipe is emitting smoke. Otherwise, the engine overheating is caused by ignition circuit or oil circuit failure.

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