tired of changing my oil!

[younastytwin]

Hey folks,

I've got the standard flooding/gas in the airbox and oil problem here. I've confirmed (and even slightly lowered) my float heights and confirmed with the clear tube method.

My problem is intermittent and seems to come back right after I've got a full tank. This leads me to believe the vacuum function of the petcock isn't working properly from what I've read on here. Although technically, the needle should stop the flow of gas once the bowl fills to its proper height. And that seems to happen most of the time, but not always.

I've replaced the whole valve needle, seat and o-ring assembly with OEM parts and confirmed that everything's clean in there, and that there's no debris catching anything. Seems to be happening on both sides from what I see on the airbox but who knows.

As my title suggests, this has been an intermittent but ongoing problem and I've changed the oil way too many times as a result. I've tried everything (tapping the bowls with a screwdriver, etc.) and I'm kind of at my wit's end here. What would you guys do?

[Shepa]

I've installed an electric valve that opens the fuel flow upon turning of the ignition key.

I just don't trust the petcock after the hydrolock I've experienced.


Sent from my toilet seat using HTC FartPhone

[adidasguy]

Your petcock may be assembled wrong or is dirty inside.
Or you are leaving it in PRIME.

You can shut off the gas and remove the petcock. Gently blow through the output port and see where air goes in the 3 positions. Air only when in PRIME.

To clean the petcock, do not unscrew the back. Remove the metal clip on the front and the innerds come out.

[younastytwin]

Thanks for the replies, guys.

Shepa, I hope it doesn't come to that!

Adidasguy, I'll give that a try and report back.

[Big Rich]

If it comes down to it, you could also install a simple on/off valve on your fuel line too. It's cheap and easily reversible for when the problem is fixed.

[bigfatcat]

Something that's happened with my '95 - the gas tank has on a few  occasions actually pressurized causing flooding - typically a nearly full tank , sitting in the sun for hour or two or more, and/or after a long trip with a very hot motor on shutdown.

Shouldn't happen, the filler cap valve should let the pressure out, but sometimes things just don't work like they should...

[Paulcet]

If the petcock is leaking through the diaphragm, it will let fuel into the carb via the vacuum line.

[thebigtuna]

I had the same problem till I rebuilt my carbs but since you said that you did that, it shouldn't be the needle. One thing I was told to try was to make sure that the float isn't getting filled with gas or something so its constantly staying open. Good luck man

[younastytwin]

Ok Adidas and company, the petcock is off. If I blow the outlet port in PRIME, I get air out of Reserve port but not the ON port. If I blow on the outlet port in ON and RES I get nothing, unless I blow harder, which then sounds like a kazoo probably because I'm flexing diaphragm...

Shouldn't air be coming it out if both ON and RESERVE ports when I blow on PRIME?

[adidasguy]

PRIME is a direct connection between outlet and reserve.

ON and RES require a vacuum on the back to open it up. Someone can such GENTLY on the vacuum port or create a small vacuum with a syringe or turkey baster.

There is a spring holding it closed until there is vacuum (except in PRIME). Blowing hard force it open like air going through a reed type organ pipe and the sound was the diaphragm opening & closing like a reed.

Oh, there is no such thing as a reserve "tank". All gas is in the same place. Reserve is just a low outlet from the tank where ON is a taller outlet pipe that goes dry when a gallon is left in the tank. Because reserve takes gas out of the tank at  the very bottom and gets all gas out, it is used for PRIME  (in case there is less than a gallon in the tank.)

[younastytwin]

Ok, thanks. All that makes perfect since. So sounds like petcock is good then, right?

Where else to go on solving my intermittent flooding problem?

[younastytwin]

Actually one thing to note regarding the discussion of too much tank pressure above. Looks like my drain hose on the bottom of my tank is pretty linked and misrouted. Could that cause excessive pressure in the fuel system and flooding the carbs?

[adidasguy]

The drain is for water and gas around the gas cap.
Inside the tank, you should have a vent on your gas cap. If that gets clogged, on a hot day air will expand. With nowhere to go, it will force gas out.
What really keeps carbs in check are the float needles in your carb bowls. They and they alone control the flow of gas into the carbs. If they are stuck open, you will get flooding. If floats are set wrong, you will get flooding (or not enough gas).
The floats are delicate. Pressure from a tank with no vent will force gas through there. The same happens if the gas supply was a couple feet higher: too much pressure due to gravity.


...and your frame petcock appears to be just fine.

[younastytwin]

Yeah, they seem to be incredibly delicate alright. Hmm... Well I've already checked my float heights with the tube method (when they were working) and came up with the right height, so I have to assume I set the floats properly (although I'm getting close to just shipping them out somewhere for another set of eyes). Seems like they just keep getting unseated somehow.

I guess we should assume there's pressure building up in the tank? If so, any hints on what to examine on the gas cap? Just try to take it apart and clean basically?

Again, appreciate all the help trouble shooting, all.

[younastytwin]

This look pretty exhaustive.

http://gstwins.com/gsboard/index.php?topic=41061.msg461586

[robfriedenberger]

I missed the year of your bike, but just so you know that is not accurate for years 04+ idk about any sooner though

[younastytwin]

Oh yeah, it's a 1994 so hopefully this should work. Thanks!

[younastytwin]

UPDATE:

Took apart the gas cap and lo and behold, somebody had already been in there. The little bearing and spring for the lock cover lid were missing. One of the two drain holes was clogged with what looked like some kind of fibrous material - like a cotton swab. I now suspect it might've been a filter element that was supposed to be in there but I cleaned it all out anyway.

Warmed the bike up pretty good on a neighborhood cruise and it started to flood. Came home, shut the bike off, put my gear up. When I walked back over to the bike after it'd been off for a couple minutes, I heard the sound of air rushing out and it smelled of gas. I figure that's the sound of the tank slowly depressurizing?

I needed a matching ignition, seat lock and gas cap anyway (ignition was from new model and does't lock bars, and seat lock tumbler was destroyed - I'm slowly realizing this bike was probably stolen at one point in its life), so I picked up all three from a 1993 on ebay for $65, shipping included.

Appreciate any thoughts as to what that rushing air sounds was from the tank and I'll provide an update after I get the new cap on.