Motorcycle Repair: gas coming out of overflow, honda750, float valve

Question
my 1982 /honda750 nighthawk is dumping gas out of the last carb outflown only. what is happenning to my machine, it also seemed to run faster when it dumping gas out of overflow in that last carb. thanks,please help.

Answer
Randy, apparently there is dirt or varnish in the float valve on that carburetor. If the bike has been sitting for a long time, the gasoline will turn to a green goo and begin to block passages, jets and float valves.

Try to tap on that carb body with the plastic end of a screwdriver or something that won't damage the carburetor to see if it will reset the float valve needle. If that doesn't work the bowl will have to come off for inspection and perhaps float valve replacement.

Sometimes you can dodge the overhaul bullet by using some of Yamaha's carb cleaner product mixed with gasoline.

The carb flooding in that cylinder will artifically raise the fuel level, enrichening the mixture. If the petcock has a vacuum operated diaphragm, it may be torn or have a pinhole which makes a vacuum leak, leaning out the mixture.

Bill Silver