Leaking carb on 125cc pitbike

[Peterk]

Fuel was leaking out the overflow tube. I took the carb apart and cleaned the float chamber. The float appeared to be working Ok. I put everything back and now fuel is leaking out the filter (not out of the overflow tube). Any ideas? He is a link to a short video showing the problem.

[Tomcat]

Well, it's still leaking, the fact that it's coming from somewhere else doesn't mean it's not the same problem. First thing to do is check your float. Is it cracked, holed or full of fuel? If so it'll sit lower and not shut off the fuel coming into the carb. Also check it's set correctly and nobody has bent the tang that controls the float valve. The tang should normally be in the same plane as the rest of the bracket that it forms part of. Lastly it's possible the float valve tip or its seat are damaged. This can happen with wear. In a lot of cases these bikes are designed to be disposable and it might be easier to try and find a newer carb off ebay or a breaker or something.

[Peterk]

That you very much for your advise. Took it apart, checked everything you mentioned. It still leaked. Went to the shop where I bought it, he suggested adding a £2 filter to the fuel line and magic!! All fixed. Thank you again for your help.

[Tomcat]

The filter should stop any dirt getting to the float valve which could make it leak, but I don't see how it would stop the carb from flooding in its own right. But of the problem has stopped that's good, whatever the cause. Thanks for the feedback, it's nice when people do that

[Trogladyte]

Ours has done this at various times. The carbs are not brilliant quality. To be honest, I mostly just give the float chamber a whack with a rubber mallet, and it normally persuades the float valve to seat. It's almost always caused by the float valve being either worn or having a tiny bit of grit in it. For a longer term fix, I usually do what you have done, but also blast carb cleaner and then compressed air through the valve - and do the jets while I am at it.

[Peterk]

It Still Does it from time to time. But less than before I fitted the filter. I think some dust must be getting through the foam air filter. I usual just drain the Carb’s tank then blow up the drainage pipe.