Gas leak after a couple months off

[Grimmpatrick]

Hey Everyone!

I live in AZ but needed to spend 7 weeks in SD, so the old girl sat for a while. Filled the tank and added some Sta-Bil. I took her out and immediately I noticed a trail of gas as I was backing out of the driveway. I was hoping after a little bit it might fix itself, but after tooling around the neighborhood for a few minutes, I looked back and was still leaking, so I just went home. I didn't look too closely, but it's coming from the upper part of the bike, dripping down onto the engine.

I realize that I'm in the desert, so I figure that a seal might have dried out. My mechanic said that I might want to add Startron to see if that helps. He thought something might be either dried out or stuck open.

Any thoughts from anyone would be much appreciated.

[WintrSol]

So, it didn't leak when it wasn't running? Something is likely wrong with the petcock, which is vacuum operated. Have to pull the tank to look for it.

[98valk]

Hey Everyone!

I live in AZ but needed to spend 7 weeks in SD, so the old girl sat for a while. Filled the tank and added some Sta-Bil. I took her out and immediately I noticed a trail of gas as I was backing out of the driveway. I was hoping after a little bit it might fix itself, but after tooling around the neighborhood for a few minutes, I looked back and was still leaking, so I just went home. I didn't look too closely, but it's coming from the upper part of the bike, dripping down onto the engine.

I realize that I'm in the desert, so I figure that a seal might have dried out. My mechanic said that I might want to add Startron to see if that helps. He thought something might be either dried out or stuck open.

Any thoughts from anyone would be much appreciated.

the OEM o-rings don't dry out unless fuel additives that are not compatible with Buna-N aka nitrile are use.
and/or the end nuts of the carb thru bolts have gotten loose allowing the carbs to start separating from themselves. there is reference in the service manual to check all nuts and bolts every so many thousands of manuals. every vehicle service manual I've seen always mentions bolt tightness service. yes I'm strange I read manuals.

gasoline itself provides a slight swell to the o-rings vehicle engineers calculate this. The carbs will dry out from just sitting for wks, so it will leak at first. shut petcock and next day zero leaks.
I've had this happen to me and/or thru bolts loose.  next day zero leaks for yrs and 1ks of miles.
only additives I use sta-bil and TC-W3 in every tank. TC-W3 cleans the entire intake tract, including the piston ring packs. Most important it lubricates the needles in the needlwells. needlewels in these carbs are not replaceable. to read about TC-W3  https://www.ls1.com/forums/showthread.php?t=91206

[Grimmpatrick]

Thanks for the tips. I'm no mechanic, but here are my thoughts so far:

I replaced the petcock about four years ago. Not because I needed to. More to see if I could and, thanks to this forum, I developed a fear of hydrolock.

I always shut my petcock, so it was closed the whole time.

I don't know which bolts to tighten or check. Also, I'm not sure how they could have loosened when it was literally just sitting there for 7 weeks.

Might be time to take her in.

[WintrSol]

I always shut my petcock, so it was closed the whole time.

So, you rode it with the petcock closed, or it was closed while it sat those weeks? In any case, I'm assuming you opened it, started the engine, then noticed the leak.

I suggested the petcock area because you said fuel was dripping down onto the engine; maybe it was leaking much closer to it, e.g.: from the fuel rail(s) on the carbs? From various posts here, this can begin after a time of sitting, and your air *is* dry.

If you're not comfortable with tools, as you imply, you will have to find a vintage mechanic, then. Good luck with that.

[John Schmidt]

Once the bike was running for a while and fuel passing through the rails, you might discover the leak has stopped. That is an indication the fuel rails o-rings are leaking once dried out from storage and will swell again once fuel is passing through. Tightening the nuts on either end of the rails as 98 Valk suggests often will give a temporary fix, sometimes it turns out to be a semi-permanent fix...until the next storage period usually. If it stops leaking after your ride, at least you'll know what the issue is and can put off needed repairs to a later date and more convenient time.

[Grimmpatrick]

Update: I think John was right. I fired her up again today and didn't leak a drop. Thanks, everyone who responded. I really appreciate your time and experience.