Gas coming out of exhaust weep hole

[Grandpot]

I was at Inzane yesterday and had a situation that made me go, "What the ..."

There was a stock Interstate that had just filled up with gas, then parked in the hot North Carolina sun during lunch.

After lunch we noticed gas on the ground that evidently expanded and went out the vent tube.  The engine would not start.

The starter turned the engine over effortlessly.

Raw gas was leaking out the weep holes in both exhaust pipes.

Suspected the engine was flooded.  Pulled plugs 3, 5, and 6.  They were bone dry.

Checked for spark.  It was good.

After several more tries, the bike started.  I was ready to perform a ceremony with a paper bag, a dead chicken, and some whiskey.

The only logical answer was that we had a vapor lock.  The big question is how did the gas get into both exhaust pipes to the point it was running out in a stream while still having the spark plugs dry?  With that much gas coming out, I would have expected the plugs to be soaked or have hydra-lock.  There's no direct path for the gas to get to the exhaust without going through the cylinders.

[sandy]

My guess is it’s actually water vapor that smells like gas because of a rich start condition.

[Grandpot]

My guess is it’s actually water vapor that smells like gas because of a rich start condition.

That's an interesting theory.  The fluid coming out of the pipes smelled like gas.  There also was so much of it, it's difficult to think it is water vapor. Now I wish I took a sample of it.

[Bighead]

It will smell exactly like gas.

[Moonshot_1]

I was at Inzane yesterday and had a situation that made me go, "What the ..."

There was a stock Interstate that had just filled up with gas, then parked in the hot North Carolina sun during lunch.

After lunch we noticed gas on the ground that evidently expanded and went out the vent tube.  The engine would not start.

The starter turned the engine over effortlessly.

Raw gas was leaking out the weep holes in both exhaust pipes.

Suspected the engine was flooded.  Pulled plugs 3, 5, and 6.  They were bone dry.

Checked for spark.  It was good.

After several more tries, the bike started.  I was ready to perform a ceremony with a paper bag, a dead chicken, and some whiskey.

The only logical answer was that we had a vapor lock.  The big question is how did the gas get into both exhaust pipes to the point it was running out in a stream while still having the spark plugs dry?  With that much gas coming out, I would have expected the plugs to be soaked or have hydra-lock.  There's no direct path for the gas to get to the exhaust without going through the cylinders.

I know of this ceremony. The chicken MUST be live.

[Gryphon Rider]

I am thinking that the cylinder that the fuel leaked into just happened to be between the exhaust and intake strokes (with intake and exhaust valves open) when the engine stopped therefore the gasoline went straight through into the exhaust pipe.

[CoreyP]

Do realize the gas at a station is coming out of the ground, at ground temperature which will be fairly cool. Top the tank off leaving the bike in the hot sun, it will heat up and expand.  Does not surprise me gas went out the over flow tube.

As far as the rest of that, I'm not sure what happened?

[Grandpot]

I am thinking that the cylinder that the fuel leaked into just happened to be between the exhaust and intake strokes (with intake and exhaust valves open) when the engine stopped therefore the gasoline went straight through into the exhaust pipe.

That makes sense. There are a few more variables, like did the owner have the petcock off?  Did the gas go down the petcock vacuum tube?

[Ricky-D]

Seeing that the OP said there was drippage from both exhausts

ought to quell all the responses regarding leaking gas from the carburetors or the petcock.

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