Gas leak

[Timothy Lentz]

I need to know if I am in danger if I ride home tonight.

I stopped the bike after a 30 minute ride to work. Approx. 4 hours later a co-worker noticed a gas flow under the bike. I rushed over and shut off the stock valve. That stopped the leaking.

I waited about 2 hours and started it up. (Whew, no hydrolock). After shuting down, the flow had stopped.

Can anyone tell me what is happening?

[fstsix]

No one here can recommend riding with gas leaking under the the bike, however, if it has stopped start it and run it for 10 minutes or so and turn it off and check, Do you have a fire extinguisher close by just in case? it could be the petcock or carb float, no telling untill you check each, if it does not leak after you turn it off well? your call.

[Chrisj CMA]

It would be hard to guess whats happening without knowing where the gas was leaking from.  If the fuel valve did stop the flow, I guess its safe to say the vacuum side is T/U so dont forget to turn it off until you can replace it....but normally gas isint going to flow to the ground just because the valve is left on, so theres something else going on too.  So, if the gas was flowing directly from the valve, then Id say you are grounded until you replace that thing.  If the gas was coming out of the carbs overflow, then Id say you were darn lucky you didnt hydrolock, and youd have to try to figure out if it was a needle valve thing.......doubtfull if was from the tank vent hose but that has happened when the tank is VERY full and then it warms in the sun.  maybe the fuel line from the petcock to the carbs is loose AND the vacuum side of the valve is T/U that sounds most likely to me......if thats the case then tighten that line and see if anything leaks in the ON position and STILL replace with a quality valve

[R J]

IF, I really pack my tank full, it will leak gas when stopped for a short period of time.
 

Never really figured out what avenue of hoses it was coming out of, however I suspected the vent hose.     Gas expands and has to go somewhere..

Been doing it since 1987, no problem........   Also, no hydro lock.

Word of advice, IF you SUSPECT HYDRO LOCK, keep your firkin finger off that starter button.

Pull the plugs, all 6 of them, stand back behind the seat and then hit the starter button on open cylinders.    If it was hydro locked, the gas or liquid will fly out the plug holes..........

This is a lot cheaper than pulling that motor and putting in gears.

[Timothy Lentz]

Thanks for your response. I suspect the reply stating the full tank and vent to be the case, as that is what I did this morning.

I went ahead and got home with no incident and the leaking has stopped.

Thanks again for your responses.

[Robert]

You are one lucky guy, if the gas was leaking and closing the valve shut it off then the valve is no good for one. There should be no gas leaking with the bike off, no vacuum, no fuel. Next I would say that one of the floats is stuck and since you waited 2 hour after you turned off the gas it may have drained out of the cylinders into the crankcase or out the exhaust. I would check the oil and see if the level is ok and see if it smells like gas. The other idea is that you have a leak in one of the hoses or connections to the carbs. I really dont think that this would be the problem because it wouldn't leak then not leak. It would be more consistent. But in either case the valve is bad. Unless you filled it up to the tippy top and then didn't ride then I really dont think that this is your problem, not to mention you said you shut the fuel off and the leak stopped. If you look at the bottom of the bike at the hoses that are next to each other at the rear of the engine you may be able to see traces of where the fuel was leaking from. Find the hose and you can see where that hose went and find the problem.

[Pete]

++++++111111 Robert. Tim check it out, the Valkyrie is telling you there is a problem, so please fix it before something happens that you will not like.   

[roboto65]

I had a leak when I first picked mine up and it was coming from under the tank now mind you I JUST bought it and had not read all the great stuff here but it leaked the whole way home found out that it was the quick disconnect the orings were bad.

[Friagabi]

If the tank was just filled and you squeeze in the last drop I vote for the overflow/vent line to the tank.

If the factory tank valve is on the bike. And manually shuting it off stopped the fuel flow onto the ground I would still vote for the tank overflow/vent line if it was just filled.

If it is comming from the tank overflow/vent unlock the filler cap and it will be very full or the act of opening the tank will stop the flow to the ground. Once drainage is started it can keep on draining for some time.

If the tank has a air pocket,,,, keep your body parts off the starter button. Dismember anyone else who reaches for it. Pull the plugs READ THIS AS PULL THE PLUGS. Remember if you crank over the bike with the key on then there will be spark at the plug wires. Think about this, spray gas all over the engine and surounding right and left side and strike a spark at six plug wires. Hum... fire?

Learn how to jump the starter relay with the key off. MAKE SURE IT IS OUT OF GEAR! Spin it over if it is dry go ahead and spin it for awhile just to make sure. If it spits gas don't let it spray back as far as the right side cover.

If it is dry, start looking for a leaking fuel line. Pull the #6 vacume line to the petcock and check it for liquid fuel. Learn where the float bowl overfill/vent line is and check for fuel in this line. All of the carbs are tied together if I remember correctly. If all of the above are clear of liquid fuel then it is time to do some carb work.

The tank vent/overfill line is on the bottom of the tank. On my bike it runs down past the clutch bleeder. It now is longer than the rest of the lines under the bike. Why? so I can lean over and look under the bike and know if I have overfilled the tank or have more serious problems. Also if I remember correctly it also has a "T" in it with the branch open to air.

Not all leaking carbs have to result in a hydrolock. The carbs on the high side of the bike tend to leak into the air intake rather than the cylinder. Any small air leaks could let the fuel drain and not build up enough to hydrolock the engine. But from this point on you are at a risk that will end up in a hydrolock. Liquid fuel running out the bowl vent line is the same thing, so long as it can drain the overflow the bike does not have to hydrolock. But as soon as the leak exceeds the lines ability then hope you don't touch that button until you clear the engine of liquid fuel.

Over filling the tank is so common and harmless as far as hydrolock goes I replaced the vent line with a longer one so I could always be sure any leaks are my fault for over filling and not a hydrolock. Simple to solve open the tank filler and watch the vent line if the drainage stops then roll the bike out of the puddle and fire her up and be on your way before the green police catches up with you.

I think this covers the possible sources. If the engine spits gas it is time to rebuild the carbs and petcock.

[asfltdncr]

I had a gas leak coming from the fuel petcock itself.My petcock did not have a way to service or repair the leak.I had to have the petcock replaced and frankly, haven't checked to see if this one is serviceable(on my list).

[Gryphon Rider]

Thanks for your response. I suspect the reply stating the full tank and vent to be the case, as that is what I did this morning.
I went ahead and got home with no incident and the leaking has stopped.
Thanks again for your responses.

Holding the bike upright while filling the tank in order to get the last drop in is fine (I'm assuming this is what you did) IF you're going to hit the highway right away.  If not, leave it on its sidestand and fill it only to the bottom of the filler neck.  I've never had it overflow filling it this way.

[Gryphon Rider]

The coefficient of thermal expansion of gasoline is 9.50x10^-4/°C.  If the fuel in the underground tank is at 10°C (50°F) and you put 20L (5.28 US gallons) in your tank, then your tank sits in the sun and heats up to 30°C (86°F), it will expand by 0.38L (0.40 US quarts).  So, if you fill the tank while it's upright, right to the top, you will get almost half a quart of gasoline coming out of your vent tube.

[RLD]

Word of advice, IF you SUSPECT HYDRO LOCK, keep your firkin finger off that starter button.

I agree. If I suspect anything, I put it in high gear and then see if the engine will turn over when pushed; if it does, you're good to go; if not, pull the plugs as stated.

[fudgie]

Word of advice, IF you SUSPECT HYDRO LOCK, keep your firkin finger off that starter button.

I agree. If I suspect anything, I put it in high gear and then see if the engine will turn over when pushed; if it does, you're good to go; if not, pull the plugs as stated.

Why a high gear?

[Chrisj CMA]

Word of advice, IF you SUSPECT HYDRO LOCK, keep your firkin finger off that starter button.

I agree. If I suspect anything, I put it in high gear and then see if the engine will turn over when pushed; if it does, you're good to go; if not, pull the plugs as stated.

Why a high gear?

The higher the gear the less leverage on the gear teeth in case it is locked....less chance of motoring through and breaking something

[Rocketman]

I agree. If I suspect anything, I put it in high gear and then see if the engine will turn over when pushed; if it does, you're good to go; if not, pull the plugs as stated.

Why a high gear?

The higher the gear the less leverage on the gear teeth in case it is locked....less chance of motoring through and breaking something

Actually, if you're rolling it, and not hitting the starter button, high gear increases the leverage.
I say high gear because it's easy to roll through several compression strokes in a high gear, if there's only air in there.  If it's liquid gasoline, then it's tough.  Easy determination of lock/no lock.
Now, if your cylinders aren't filled with air, but are filled with nitrogen, then...  Wait.  Wrong thread.  That's the tire thread.  Never mind.  (:

Back to serious:
While I second/third/tenth/whatever the sentiment of not touching the starter if you suspect a hydrolock, I think that you simply overflowed the tank.  The shutting off of the fuel probably had no effect on it, and it was already stopping.  However, to give a quick test, while cruising down the road, shut the fuel off.  If it doesn't die within a few miles, you have a petcock failure.  This test won't detect every failure, but it will detect the most common failure.

Mark