Recently, a wan Wan guangyang 125 scooter was repaired, with a total mileage of more than 40,000 kilometers. This is a typical case of a car owner's neglect of maintenance, which leads to the gradual aggravation of minor problems. In fact, many car owners are like this in life. When a minor problem does not affect riding, they will not bother to maintain and repair the car until the problem becomes bigger and bigger, and the car is not good to ride or even can't ride.

The owner to the store after the report, the car from last year will occasionally fire, due to less riding, has not been how tube.

But now the breakdown seems to be getting worse and worse. Not only are the shots fired more frequently, but the smoke starts to come out. It feels like there is no energy to run, and the gas pedal is no more than 50KM away. It really affects the cycling, so let me have a look.

From the point of view of the failure phenomenon, I think the main reasons are loose valve closing, improper ignition time, improper carburetor adjustment, igniter or fV fire break and so on.

But anyway, the car is old and it must be thoroughly checked and maintained.

First, the engine is disassembled, and the cylinder block and valve mechanism are inspected. During disassembly, it was found that the gear was wrong in ignition timing, causing delay, valve was seriously ablated, and the piston ring end gap had reached more than 0.8mm. The valves could be ground in this case, but it would take too long, so a new pair of valves and valve oil seals were replaced.

Replace the piston ring after checking the normal inner diameter of the cylinder block. When cleaning the carburetor, it was found that the air compensation screw could not be in place according to the normal data and only stayed on the 3/2 turn. After blowing and washing the oil duct of each airway, the float height was adjusted according to the technical value.

The reason this car is getting worse is because it's a gradual failure, and over time, it's going to get worse.

After the engine is installed, the walking part and the electrical part are checked, refueled and adjusted. After all the maintenance and repair purposes are achieved, the oil and the rear-drive gear oil are changed according to the normal standards. Then start the motorcycle to warm up for 5min and deliver to the owner.

After the test, the speed can reach 90km/h. Starting performance, low, medium and high speed working conditions are good, acceleration performance is excellent, the owner is very satisfied.