Odd...fuel leak from vent tube while parked?

Over the weekend I visited my girlfriend and parked my bike in her garage for a day (on the center stand), and I forgot to close the fuel petcock.

When I went to leave there was a wet spot under the bike about 7-8" in diameter. Stuck my finger in it and smelled and it was gas, and when I looked it appeared that it had dripped out of one of the vent tubes hanging under the bike.

I left the bike parked all day and all night yesterday, on the kickstand, but closed the fuel petcock, and there was no wet spot this time.

What caused the leak?

What caused the leak? You shut the petcock off and it didn't leak. That must have something to do with it... The petcock must be there for some reason... hmmmm perhaps to shut the gas off when the bike isn't operating? AHA! The cause of the leak was not shutting off the gas when parking the bike... seriously, the float valves are NOT fuel shut offs and most any carburetors can leak gas if the fuel isn't shut off.

This is the reason that Kaw went to the vacuum petcock... took the cockpit error out of shutting the petcock off if the vacuum petcock is working right.

del

I don't know how different your bike is, but on the KZ650 the vent tubes are routed up under the tank and down into the air filter. The tubes from the bottom of the carbs are for overflow and drain behind the engine to the ground. Your carbs should not overflow even with the petcock on, although it's good to shut it off to be safe. I would suspect 1 or more of your float valve assemblies (basically a little stubby needle and orifice) are dirty or possibly worn and not shutting off the fuel flow when the carb bowls are full. The carb floats push these shut when the carb bowl is full. Another possibility is the carb floats may need adjusting or may be sticking. If you pull the carb bowls off (you can do this on the KZ650 without removing the carbs) you should be able to get to everything you need to find and fix the problem. Ed