Failure phenomenon: after engine shutdown, carburetor overflows the tubing and drops oil outward. Check the oil discharge screw under the float chamber, which is in good fastening condition. Loosen the oil discharge screw to release the fuel in the float, and then tighten the oil discharge screw.
Cause analysis: road test examination, the engine starting for the first time is not easy to start, after starting a rich mixture of symptoms, but the traffic is good, () immediately after the engine flameout when you restart the engine, starting easily, after starting a rich mixture of phenomenon disappeared, stop to rest, when the carburetor tubing drops of oil spill, starting the engine test, the engine is not easy to start, and there are signs of a rich mixture, after starting continuous gas after a few times, a rich mixture of phenomenon is gone, according to the height of the phenomenon of the vehicle as carburetor float with the main oil needle height is not suitable, the float chamber with oil needle triangle the seat closed is lax.
When the engine is shut off, fuel accumulates in the float chamber, and when the oil level reaches a certain height, it leaks from the overflow pipe. At this time, when you start the engine, because the float indoor oil level is too high, too rich mixture, the engine is not easy to start, after starting the phenomenon of a rich mixture, as the engine working, the oil level of float indoor declines, mixture too thick will automatically disappear when the phenomenon, due to traffic, basic constant float indoor oil level height, all, triangle and oil needle seat closed lax traffic impact is not obvious.
Elimination method: eliminate the scale accumulation on the conical surface of the triangle oil needle in the float chamber, clean the carburetor, install and reassemble the disassembled parts, the phenomenon of spilled oil on the oil pipe disappears, the engine starts well, and the fault is eliminated.