If it's fuel, then it's almost certainly coming from the carbs, in
which case it's almost always a problem with the float level being too
high, or the float valve being stuck or dirty. Also could be a cracked
fuel line. Basically, you'll have to pull it apart and try to find out
exactly where the fuel is coming from. You didn't say what kind of
bike it is...but if it's a CB175 then there are three hoses that exit
at the bottom, one is the battery, and two are from the carbs.
Sometimes the carb overflow lines end farther up inside where you
can't seem them. So fuel could be coming out of one of them and it
would appear to be just coming from somewhere inside.

It's going to take some investigation to find the source.
JohnnyB