gas leaking from carbs

hi all,when my '86 vfr 750 sits for a few weeks between uses it leaks gas from the carbs terribly when I have the choke on and start it.
What causes this?
I have gone on rides with the fuel shut off valve in the off position before by mistake and it never ran out of gas.
I am the 20th owner of this bike (yes you read that correctly) is it possible the shut off valve has been removed or bypassed?

 

first I would get the manual for it.. second, it sounds like you have a bad petcock... third, 20th ?!!!!! hopefully it hasn't been worked over to badly.. you can check you petcock by pulling the tank and letting fuel run out of the hose, and give tyour petcock a turn.. where is the fuel leaking from? like is it the carb bowls the carb feed tubes......

 

Yes,I am guessing the petcock. Who knew a petcock could actually fail?
that would fill the fuel bowls overtime would it not then when choke is applied causing leakage? I best take the tank off and investigate further. Where can a guy find a replacement knob for said petcock?
Thanx

 

J yard or ebay.... I bet your gonna have to buy a whole tank ..... you might however be able to obtain the rubber gasket inside the petcock....you might check your oil for fuel...if your petcock has been leaking it would fill your bowls up with fuel then fill the carbs and then down into the intake valves and .....you get the picture.... if that has happened then you not only have a leaky petcock but a bad float needle

 

it is the float heights and the fact that the jet seats aren't sealing. time for a carb rebuild.


....

 

You can pick up a universal inline fuel shutoff valve for about ten bucks(google it) and mount it inline as long as you can reach it and it can be plumbed in a way that wont affect the gravity feed from the tank. Just another option as parts may not be available. Bikebandit lists the petcock assembly for 43 bucks on their site but it may no longer be available. Good luck with the bike.

 

Carbs

Nice advice..

But this is what has to happen.. The carbs are due for a rebuild, Parts are at Motorcyclecarbs Carburetors, Carburetor Parts and Carburetor Restoration.

Goggle them and look up the bike. Lookup my posting about Pin-Sol, to clean the carbs. They may have the petcock parts to. Good luck.Mike pm me if you need help on how to do this I have Skype to ..