QuestionI have a 78 Honda xl 100. It has been sitting for a long time. I rebuilt the carburetor and it runs now but the gas is leaking out the drain hose. The floats are not stuck. Any suggestions?
AnswerRob, the carb overflow problem can be sourced to several things.
Pinhole in the float, causing it to absorb fuel and partially sink.
Incorrect float level setting. 12.5mm is the float level setting for that model. Even the plastic floats can become fuel logged, if that is what your carburetor has. Check it carefully. If float doesn't have an adjustable tang where it pushes the float valve closed, then disregard that step.
I have seen the brass tubes in the float bowl crack down the sides, causing a constant fuel leak.
Worn/etched float needle tip. When bikes sit for years with old gasoline in the bowls, all kinds of chemical reactions take place that can cause minute damage to metal parts of all kinds.
Be sure that the bowl venting system is clear. This allows a pressure balance between the outside atmosphere and the fuel in the bowl.
If you can hold the float up, with the bowl off and the fuel stops, you know that the float valve is not the problem. If it continues to leak with the fuel turned on then the needle needs replacing.
I don't know if your "rebuild" was installation of a kit or just a good cleaning. If you have new parts inside, then the bowl vent tube is the probable cause.
Bill Silver
