ion of oil, the fault has not been ruled out, the cause of the engine overheating failure is unknown.

The car has been riding more than 40,000 kilometers, the vehicle maintenance is improper, the engine around the dust impurities, maintenance workers clean the vehicle outside, start the motorcycle, wait for a moment, slowly increase the throttle, the engine sound from the beginning of the low, to the medium speed when the sound gradually becomes louder, the body began to heat, stop the inspection.

There are many reasons for engine overheating failure, in line with the principle of easy after difficult, remove the spark plug, the electrode color is mostly brown red, the side electrode is slightly white.

Check the oil level of the carburetor float chamber, loosen the oil release screw of the float chamber, so that the oil release rubber hose mouth moves up and down between the carburetor float chamber and the body. When the float chamber and the carburetor body are combined to face down 2mm, the gasoline in the carburetor just emerges from the rubber tube, indicating that the oil level of the carburetor float chamber is normal.

At the same time, it is also verified that the spark plug electrode color is mostly brownish-red, indicating that the combustion of the combustible mixture is basically normal, and the cause of overheating failure is not here.

Disassemble all the plastic parts on the sides of the vehicle, wash them on the intake pipe and the combination with the cylinder head, start the engine, and no air leakage is found. Open the cylinder head cover, without the fuel door, start the engine, and carefully observe the oil splash at the cylinder head, valve rocker arm and camshaft at idle, and initially judge that the amount of oil is low.

Stop the machine, check the crankcase oil oil scale, the oil level is basically normal. According to the oil spatter at the valve rocker arm and camshaft, the feeling is not normal.

According to the mechanical principle analysis, the root cause of the small oil flow when the motorcycle travels more than 50,000 kilometers is likely to be related to the abnormal wear of the oil pump.

Disassemble the crankcase and take out the oil pump for inspection. In addition to the serious wear of the rotor inside and outside the oil pump, it was accidentally found that the contact between the crankcase and the bottom surface of the oil pump is uneven (as shown in the figure below), and the installation plane of the oil pump itself is also uneven (as shown in the figure below), which should be caused by the processing defects of the original mechanical parts.

Because there is oil leakage here, resulting in a decrease in oil flow, can not meet the normal lubrication and cooling requirements of the engine.

Consult the user's opinion, replace the new crankcase and oil pump assembly, add high-quality selection of motorcycle special oil. Start the engine to warm the car slightly, more than 10 kilometers on the road test, the motorcycle accelerated basically normal, confirm that the original car overheating fault was completely eliminated.

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