Float bowl leak

[MGordon]

The #1 carb is weeping fuel around the float bowl drain screw...when the bike has been sitting all night.

I drained the float bowl yesterday, put a tiny plastic straw up inside to see if the float arms were pivoting (yes..maybe they were stuck, or float needle?) and went for a ride. The bike has also been gasping/sputtering from that carb since the last sync--however, it has been weeks since, and only now the fuel weep is showing up.

What I don't understand is how it does this overnight if fuel is on a vacuum demand from the petcock?? After draining the bowl and re-tightening the plug, and riding the bike for an hour yesterday, no sign of fuel leak. I'll check again this morning, but I'm predicting fuel will be present. Yes, I have checked to see if it is not a cracked bowl or leaking bowl gasket. It has to be sitting for a few days for the gas to drip down onto the engine case.

[natemoen]

Is the crush washer still on the drain screw?

[MGordon]

Is the crush washer still on the drain screw?

Yes. Crush washer still present. Maybe switch the screw/washer with another bowl and see if the problem switches?

[CatatonicBug]

What I don't understand is how it does this overnight if fuel is on a vacuum demand from the petcock??

Remember that the bowl remains full of fuel at all times. The float turns off the flow once the bowl is full, keeping the top level just below the top of the bowl. I like the idea of swapping the plugs between the bowls. Or, better yet, replace the crush washer with a new one at the same time.

[MGordon]

Remember that the bowl remains full of fuel at all times. The float turns off the flow once the bowl is full, keeping the top level just below the top of the bowl. I like the idea of swapping the plugs between the bowls. Or, better yet, replace the crush washer with a new one at the same time.

Does that mean that if the float is stuck in the down position, or the needle jammed up, that fuel could overfill the bowl with the throttle not actuated or bike running? If so, would that still leak out at the drain plug, with the screw threading in securely?

[natemoen]

Yes, if the needle or float were not working that would cause to bowl to overflow. Usually that is seen coming out the back side of the carbs into the airfilter.

[SFerinTEXAS]

Or maybe its not leaking there at all. If its leaking anywhere above that carb it will run down and appear to be from the bottom of the carb. Dry everything off and see if you can find wet fuel up higher.

[CatatonicBug]

Does that mean that if the float is stuck in the down position, or the needle jammed up, that fuel could overfill the bowl with the throttle not actuated or bike running? If so, would that still leak out at the drain plug, with the screw threading in securely?

If the petcocks are sealing properly, they will prevent additional fuel from leaving the tank. However, if the float needle is not sealing, it will still allow the fuel that is in the fuel lines to flow into the float bowl. That usually ends up as a small puddle under the bike, as Nate said, coming out of the airbox.

If the drain plug is not sealing, as the fuel drains out of the plug, the float will drop, causing the same problem, except it will stop the flow again once the bowl fills up with what is in the fuel lines. Rinse, repeat, until all the fuel in the lines has drained out the leaky drain plug.

[MGordon]

wrong washer

It is still leaking this morning. Wrong washer, and a brass screw. Doesn't match the other 3 drain plugs. The washer is oversized and overhangs the drain plug tube mouth. Anyone know that size screw/washer?

[DGXSER]

Not certain, but you have three more you can take to the hardware store and be sure you have a match.

[DAVINCI]

It's an 8mm plug. You want the correct washers? I've got a boatload, I bought a pack of 100 last year. PM me your address. I'll throw in a couple of used plugs, too.

[MGordon]

The drain plug wasn't leaking until i opened up the drain a couple of weeks ago. I just re-tightened it snugly...maybe I didn't have the washer tightly sealed...

[MGordon]

Never mind...it's already seeping again.

[MGordon]

It's an 8mm plug. You want the correct washers? I've got a boatload, I bought a pack of 100 last year. PM me your address. I'll throw in a couple of used plugs, too.

Sent you a PM....