market dynamics
You have to keep the choke off at all times to run. What is that?
Release date:2020.08.26

A few days ago, a Honda CG125 straddle motorcycle of a car friend had a strange phenomenon. When starting, it could not start if the choke was closed, and it was not easy to start if the choke was closed. After the successful start, the car has been driving normally with the choke closed, but as long as the choke is opened, the car will not run, the acceleration is very meat. Car friends said to run a few places can not find out the reason, so today to my here to try your luck.

In the previous post, we analyzed why the air door should be closed when a cold car starts. Because the cold car gasoline atomization is not good, the mixture meets the cold cylinder wall will condense into oil droplets, further make the mixture thin, close the choke, the carburetor supply cylinder of combustible mixture will become thick, starting easier.

The motorcycle had difficulty starting the cold car after closing the choke, indicating that the mixture was too thin, and too thin, and closing the choke was not enough to raise the concentration to easy ignition. There must be something wrong with the carburetor.


From the principle analysis, the causes of excess mixture gas mainly include improper adjustment of the mixing ratio adjusting screw, too low position of the oil needle in the main quantity hole, obstruction of the oil channel or oil hole, etc.

In addition, if the carburetor and cylinder head air leakage at the junction, will also make the mixture too thin, serious leakage, even if the choke, the car will not be able to run normally.

First, the carburetor was decomposed, thoroughly cleaned, and the oil holes of each oil channel were blown through. Then, the oil needle position of the main quantity hole was checked, the mixing ratio was adjusted, and the carburetor was installed. However, the fault was still not significantly improved.

Since it is not in the carburetor itself, it is in the relevant part. Check the carburetor and the oil circuit again. When you check the carburetor and the cylinder interface, you find traces of gasoline infiltration, indicating that there is a leak here, and the gasket is not ok. Replace the new gasket, tighten the nut and try again. The fault does not appear again. It is proved that the fault has been eliminated.

Note: the open and closed choke mentioned in this article shall be based on the actual position of the choke, and the choke shall be open in normal driving condition. The pictures cited in this article are from the network.