GS "blew," oil everywhere

Paulcet · February 06, 2012, 08:07:25 PM

Then fuel would flow down the vacuum tube into the carb on the engine side.

Watevaman · February 06, 2012, 08:30:55 PM

So just so I know what I'm looking at, it's the hose marked vacuum hose that I would remove and see if gas flows through the frame mounted petcock?

And to test it, could I connect a funnel to the ON Fuel Hose and run gas through it with the vacuum hose disconnected?

Paulcet · February 06, 2012, 08:36:36 PM

Yep. I think that would do it.

adidasguy · February 06, 2012, 10:27:44 PM

To see if gas flows through the frame mounted pet chicken, simply put it in PRIME position. No need to disconnect the vacuum line. If you disconnect that, gas will not flow in the ON or RES positions and your left carb will have a vacuum leak.

PRIME overrides the vacuum and will let gas flow even with the engine off.

If you pull that vacuum hose and gas squirts out of the vacuum input to the pet chicken, then it needs replacing or rebuilding. Unlikely that the diaphragm would get a hole in it, but it has been known to happen.

If it was bad, gas would get sucked into the left carb and not sure what it would do, but would mess it up. It would not affect the right carb as the vacuum to the petcock only connects to the left carb.

The gas side of the things is separate from the oil. There is no connection between the gas and the oil. Excess gas in the left carb should not cause gas in the oil. It can cause gas to flow into the air box or flood the carb.

Paulcet · February 07, 2012, 10:32:26 AM

Quote from: adidasguy on February 06, 2012, 10:27:44 PM
The gas side of the things is separate from the oil. There is no connection between the gas and the oil. Excess gas in the left carb should not cause gas in the oil. It can cause gas to flow into the air box or flood the carb.

On our bikes, this is usually the case. Unless the bike is facing downhill, or fuel is running into the vacuum port. I believe the port is forward of the bowl and throttle plate -- so fuel would run forward into the intake port, not back to the air box.

adidasguy · February 07, 2012, 12:31:19 PM

I think the gas in the intake would get blown out the cylinder, not mix with the oil unless the rings were bad.
I did have gas drip out of the air intake of the carbs (and into the airbox) when Trey was acting up. Also, when I had the shop gas tank too high, gas poured from the air intake of the carbs to the air box (once I remembered to close the float bowl drains, 'cause with 'em open the gas went all over the engine and floor

).

Watevaman · February 07, 2012, 03:30:28 PM

Just tested the compression. Both left and right cylinders were ~150 psi. According to Baltimore's youtube vid that's within spec, so I'm guessing that rules out piston rings?

Edit: This is turning out to be a pain the butt of a bike. Left header bolts feel like they're welded in, gas in the oil, oil leak, bah. I mean, it's "fun" learning what might be going wrong, but I just want to ride it again. Isn't that what we all want with our first bikes?

Kijona · February 08, 2012, 11:17:50 AM

Quote from: Paulcet on February 07, 2012, 10:32:26 AM
Quote from: adidasguy on February 06, 2012, 10:27:44 PM
The gas side of the things is separate from the oil. There is no connection between the gas and the oil. Excess gas in the left carb should not cause gas in the oil. It can cause gas to flow into the air box or flood the carb.

On our bikes, this is usually the case. Unless the bike is facing downhill, or fuel is running into the vacuum port. I believe the port is forward of the bowl and throttle plate -- so fuel would run forward into the intake port, not back to the air box.

Well, yes and no. If the floats are out of whack or stuck, what can happen is fuel can flow up through the jets, into the venturi, and then into the intake and airbox. Once it gets into the intake all bets are off. If it's left like that who knows what could happen.

As far as oil in the airbox, that can be caused by the excess of liquid in the crank and some of it overflowing into the vent line on the top of the valve cover which goes directly to the airbox. Or, in his case, off to the side somewhere?

All of this, however, is dependent upon the frame petcock being FUBAR'ed, or it being left on PRI. Since it can't continue to flow (theoretically) after the bike is stopped, no fuel could make its way into the intake/airbox. There would also be no pressure on it which would remove the possibility of what's left in the bowls getting in there.

Seems like the most logical explanation is either A) fuel is flowing into the carb through the vacuum line from the petcock or B) the petcock is not functioning properly and allowing fuel to continue to flow after the bike is shut off.

Option A seems very, very likely. We had another member recently who had the same issue. As far as fuel hosing is concerned, you've got basically 4 lines: RES, MAIN, VAC, and CARB. Reserve and main come from the bottom of the tank and go into the frame petcock. The frame petcock has two additional lines from there: VAC and CARB. Carb line is the line that goes from the petcock to the actual carbs. The vacuum is the one that's all the way behind everything else on the petcock (if memory serves). It's of smaller diameter than any of the other lines so it'll be easy to find.

The VAC line should be free of any gas or other liquids. If there's even a hint of gasoline inside it, then there is your problem.

Watevaman · February 08, 2012, 12:43:35 PM

Well, this is weird. I just went outside and looked at the hoses (can't test them, as I'm on the way to class in a minute), but I saw is what should be the RES fuel line (on the right of the frame mounted petcock) going to the bottom T connection, and the OUTLET hose was going to the tank. The two large hoses on the left were the ones going to the tank mounted petcock. Now, I'm not really thinking straight right now, but how the heck was the bike running if the outlet hose wasn't even going to the right place? Everytime I rode it over the course of the month that I did, I had the frame petcock on the ON position, not RES.

Quote from: Kijona on February 08, 2012, 11:17:50 AMAs far as oil in the airbox, that can be caused by the excess of liquid in the crank and some of it overflowing into the vent line on the top of the valve cover which goes directly to the airbox. Or, in his case, off to the side somewhere?

You know, I didn't think of it like that. Might not have been a gasket that blew at all, as that hose did have a lot of a liquid feel when I took the tank off. And as I said before, there was a bit of gas dripping off the air filter (lunchbox, so no airbox) a few weeks before this happened.

Kijona · February 08, 2012, 02:01:52 PM

At this point I think the best thing to do would be to start by removing the tank and all the lines associated with the carb and vents and everything else. Reconnect everything correctly, then go from there. Sometimes the best way to fix something is to start over from the beginning.

You'll also want to change that oil before you ride it.

Watevaman · February 08, 2012, 05:22:42 PM

I've had the tank off, that's how I got the carbs out to look at the float needles. And that's how I noticed this fuel hose issue.

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GS "blew," oil everywhere