I am at my wit's end with this carb. I have a problem that I have never had and I am completely stumped by this simple little carb.
When I bought it it would run fine up to about 30mph and then start stumbling and running rich. A quick look at the carb revealed that it was dirty and needed new gaskets so I cleaned it all up and installed a new Honda gasket set. It ran exactly the same. I double checked my work and found everything in order so I began to suspect the fuel level in the bowl. I attached a clear line to the drain on the bowl and found that the fuel level was all the way up to the bowl gasket. This carb has a plastic float with no adjustment and a needle with a rubber tip. Float level measured at a correct 8.5mm but the fuel level was clearly too high. No fuel came out the overflow. I decided to just order a new needle and float from Honda and polish the seat to ensure a good seal. New parts installed and the exact same problem. The fuel level was still right at the bowl gasket. The bike starts and idles fine but at open throttle positions and higher rpm it sucks unmetered fuel through the intake and runs rich as hell.
I then found that a Canadian version of this scooter had the same carb but used a plastic float but the with metal mounting tabs and an adjustable tang. I ordered the part, it fit perfectly, and I was able to adjust the float level. Still no luck. I have tried numerous settings but even if I set the float as high as I can it has no effect on the fuel level in the carb. After all this it runs exactly as it did when purchased.
I have installed a new plug, a new vacuum operated petcock, and have bypassed the automatic choke and I am confident that the problem is the fuel level. I have completely run out of ideas. Any input will be greatly appreciated.
