(1) The working clearance of the valve is too small or no clearance.

(2) The carburetor is defective.

Use a wrench to turn the rotor of the magnetomotor, align the compression top dead center mark, check the working gap between the inlet and exhaust valves, and check that the working gap between the inlet and exhaust valves is too large. Adjust the working gap between the inlet and exhaust valves to the standard value. Start the engine to check, the engine still has no high speed, and the fault has not been eliminated. It indicates that the high-speed fault of the engine has nothing to do with the abnormal working clearance of the valve.

After disassembling the carburetor and inspecting it, it was found that the main measuring hole has been loosened. After the main measuring hole is loose, it will cause abnormal fuel supply. Tighten the main measuring hole firmly, replace the carburetor, start the engine for inspection, and the engine has a high speed. The fault is still not eliminated.

After disassembling the carburetor again and carrying out repeated inspections, the fault point was finally found. It turned out that there was a small hole between the main measuring hole of the carburetor and the idle speed measuring hole. Normally, the idle speed measuring hole was blocked with a rubber plug, and the engine was working. At this time, gasoline first enters the main measuring hole, and then is divided into two channels, one way supplies oil to the idle speed nozzle through the small hole, and the other way supplies oil to the main nozzle.

Now the rubber plug has nowhere to go, so that when the engine is working, gasoline not only supplies oil from the main metering hole to the main nozzle, but also enters the gasoline from the small hole to supply oil to the main nozzle, making the fuel supply too large, resulting in too rich combustible mixture , Can not be fully burned, the engine speed is bad.

Find the rubber plug, plug the small hole, put it back into the carburetor, start the engine for inspection, increase the throttle for engine acceleration test, the tspemotor engine speed is good, and then conduct a road test, increase the throttle slightly, the motorcycle runs The speed reaches 80km / h. After inspection and confirmation, the failure of motorcycles to run at high speed has been eliminated.

Find more information,please contact Taizhou Spare Parts Expert Import & Export Co., Ltd.