Recently receive repair a dayang DY90 motorcycle, very old car, but very classic! According to the owner's description, his car has been very good use, but in the past six months, the engine accelerate bad fault, and easy to flameout.
The owner went to several repair shops for maintenance, because did not find out the fault suspect, also failed to eliminate the fault, today to my shop to try luck.
After receiving the car, turn on the ignition switch and start the engine for inspection. When the starting rod is pressed, the resistance is very large, indicating that the engine cylinder is well compressed. When the starting rod is pressed, the engine starts smoothly and catches fire, and idle operation is stable.
Momentum motivation fully after warming up, slowly increase the carburetor throttle opening, and improve the engine working speed, good engine began to accelerate, turn the throttle to turn it over and over again, to continue the engine acceleration test, engine appeared slowly add the feeling of not oiling, finally to stall due to add not oiling, inspection confirmed engines have accelerated bad failure.
Immediately start the engine, the engine only think about the phenomenon, but always can not start the fire. After a short pause, the engine can start up again and accelerate well.
According to the analysis of the inspection results, it is likely that the carburetor is faulty and the oil supply is not smooth, which causes the engine to accelerate badly and flameout easily.
Restart the engine, slowly close the carburetor choke and conduct engine acceleration test. The engine acceleration condition is not significantly improved.
Then loosen the carburetor blowdown screw to confirm whether the gasoline can flow into the carburetor, and the gasoline flows out of the blowdown hose, indicating that the gasoline can flow into the carburetor, which also eliminates the engine acceleration failure caused by the lack of carburetor oil supply.
Next, the igniter and high pressure package were replaced successively for comparative inspection, and the engine was still poorly accelerated.
Using the method of hanging spark plug can not only check whether the spark plug has soft fault, but also can check the high voltage ignition spark. Pull out the high voltage wire from the spark plug, hold the high voltage wire to the spark plug and keep a distance of 6 mm, start the engine and engine acceleration inspection, the engine is still poor acceleration.
No wonder so many repair shops did not solve the problem before, because everyone was following my idea in the investigation, I also along this traditional route test for a long time, but did not find the problem.
Motorcycle acceleration is bad, nothing more than oil and electricity two parts of the problem, the oil circuit can be ruled out, that is electricity, but from the ignition, the main components have been replaced, no improvement, it should be other circuit parts have an impact.
Suddenly remembered the previous maintenance of a similar fault, there is a leakage point in the circuit to keep up with the electricity, resulting in the ignition ability to decline.
Think of to do, first to affect the ignition of the peripheral circuit to disconnect again, to minimize the impact, so I only retain the ignition of the most basic lines, auxiliary lines will be disconnected test.
When I disconnected the flameout line for test, I found that the condition of the car seemed to be significantly improved. According to the connection of the line, I suspected that there was something wrong with the ignition switch, so I replaced it decisively and found that the fault had disappeared.
After measuring the replaced ignition switch, it was found that the fault of the car is really strange, ordinary people really can't find it.
According to the working principle of the ignition system of the vehicle, when the insulation strength between the switching static contact of the ignition switch and the grounding static contact is reduced, especially when it is lower than 1 megohm, when the engine is working, the ac power output from the charging winding is charged to the electronic igniter energy storage capacitor, Some alternating current will leak from the switch static contact of the ignition switch to the ground static contact through the circuit board with reduced insulation strength, so that the energy storage capacitor of the electronic igniter is undercharged, and the ignition system can not work normally.
In particular, when the insulation strength of the circuit board has just begun to decrease, it is very unstable due to the influence of ambient temperature, which makes the engine work up and down.
Replace the new ignition switch, restore the ignition line, and start the engine for inspection. After the engine caught fire, the acceleration was good, the engine working speed decreased slowly, and the fault phenomenon of easy flameout disappeared.
The motorcycle road test inspection, the motorcycle all the way normal, no engine acceleration failure and self-flameout phenomenon.