I have a Honda Harmony riding mower that is leaking fuel from the overflow on the carb. The float operates smoothly and floats well and I have replaced the float valve and spring as well as cleaned and replaced seals, blown out the main valve, and cleaned the filter and fuel line. If I turn on the fuel and set the speed fuel leaks out almost immediately. I hear fuel flowing inside (almost a gurgle inside the carb) and then it comes out of the tube at a fairly rapid flow.

Thanks in advance for any ideas.

Replace carb , if you can't find anything wrong .
.did you check your float to make sure it wasn't filling with fuel
Luck