[SCadaddle]

I had this issue on a Honda ATV carb a few years ago that drove me nuts. Finally took it to a guy that rebuilds them for a living and he diagnosed a "rough spot" in the float valve seat. But it's how he did it that (I paid him for) that I retained.....

1) hook up a fuel line to the carb from a container of fuel---think IV bag here.
2) With the top off of the carb so that you can see the float and such, turn the carb **upside down**. This will make the float fall by gravity and **hopefully** the float valve needle will close like it is supposed to do. When you see it leaking, take a small tool such as a wooden dowel with a small piece of scotchbright and polish the float valve seat and try again.