Flooding and gas leak from the carb? And a carb needle question on post 6

mustangGT90210 · July 28, 2012, 08:34:54 PM

Hey guys, I've had this '93 GS for about 2 months now. It's always had a faint smell of gas to it, but I always attributed that to what I think to be a bad gas cap(doesn't sit on there perfect). Anyways, a couple days ago, I woke up at 3am to the smell of gas in the house. Bike had a puddle under it. Figured "oops, left it on prime and it flooded." Fast forward to last night, bike reeked of gas when I got to it after work (my ride home) but I figured I'd try to start it. It cranked and I saw mist come out in front of the headlight, loose pipes at the moment made that happen. The bike was in the ON position on the petcock. This morning in the light I got a closer look, and found gas seeping and dripping very very very slowly from the carb, around the vent area according to the sticky I read here.

What could be causing this? It has just started happening, and it seems only when the tank is full. Tomorrow I'm going to be splicing a ball valve into my fuel line after the petcock for a true ON/OFF switch I can get to easily. But that only seems like a cover up to the real issue.

Any thoughts? Please and thank you!

RossLH · July 28, 2012, 09:26:18 PM

If the petcock is in the ON position and fuel is gravity feeding into the carbs, I'd start by checking the condition and function of the petcock. Make sure the O-ring and diaphragm are in good condition.

MNgs500 · July 28, 2012, 09:54:49 PM

ya my had the same time i changed the gaskets on the carbs(orings) it stopped. pretty easy to do also

mustangGT90210 · July 29, 2012, 08:27:52 AM

I'll give those a shot too, thank you for the input

Quote from: RossLH on July 28, 2012, 09:26:18 PM
If the petcock is in the ON position and fuel is gravity feeding into the carbs, I'd start by checking the condition and function of the petcock. Make sure the O-ring and diaphragm are in good condition.

The petcock under the tank or the one on the frame? To me it seems that with the stock frame mounted petcock, that fuel is always gravity feeding to the carbs. I've left the frame one on on, prime, and reserve and had the same thing happen on all 3 settings

bombsquad83 · July 29, 2012, 08:55:46 AM

This problem is caused by worn needle valves/incorrect float height. You will be chasing your tail until you replace your needle valves with OEM (NOT AFTERMARKET K&L), and check and adjust the float height with the clear U tube method.

The petcock might contribute to the problem by not completely shutting off fuel flow, but the needle valves ultimately should control fuel level in the carb bowls. You might need to replace the carb bowl gaskets as someone else had mentioned if they are mashed. You will want to check the condition of the other o-rings as well while you have the carbs open.

mustangGT90210 · July 30, 2012, 09:20:53 AM

Quote from: bombsquad83 on July 29, 2012, 08:55:46 AM
This problem is caused by worn needle valves/incorrect float height. You will be chasing your tail until you replace your needle valves with OEM (NOT AFTERMARKET K&L), and check and adjust the float height with the clear U tube method.

The petcock might contribute to the problem by not completely shutting off fuel flow, but the needle valves ultimately should control fuel level in the carb bowls. You might need to replace the carb bowl gaskets as someone else had mentioned if they are mashed. You will want to check the condition of the other o-rings as well while you have the carbs open.

So basically I need to rebuild my carb?

And I spliced a nice, simple On/Off valve from a lawnmower into the fuel line yesterday. Problem "fixed" for now. The bike is still rideable and doesn't reek of gas now.

mustangGT90210 · July 31, 2012, 11:33:12 AM

On/Off valve doesn't fully work... I don't think. Today I started tearing into the carb (very light tearing) just to check out the top half of it and see if anything looked amiss. The do appear to have been rebuilt from what I can see, everything in there is fresh looking. But then again I also only got the diaphram out before putting it back together.

My question is this: What order are the washers/seats supposed to go back on the needle? I don't know what I was thinking but they're all off. And I have an extra little metal washer that the sticky didn't show

Is that the proper way for the needle to go back in? Put the needle seat on the needle, then the spring seat sits on top of the ridge of the needle? And what might the extra little washer be for?

bombsquad83 · July 31, 2012, 11:38:26 AM

The washer was added by someone later on. This is a common method to lift the needle and give a little richer mixture in the mid-throttle range. The extra washer goes between the Needle Seat and the Position Clip as labeled on the picture.

mustangGT90210 · July 31, 2012, 11:41:58 AM

Thats good to hear

Now I think my final question regarding the needle is probably another newbie one. Does the seat have to sit on the needle exactly as in the picture? Because my needle will slide right through it...

Sorry for the multitude of questions, just trying to save some money and learn how to do everything myself. Thank you for your help!

bombsquad83 · July 31, 2012, 11:46:53 AM

The needle seat (along with however many washers you have), sit right underneath the position clip. It's just moved down in the picture.

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Flooding and gas leak from the carb? And a carb needle question on post 6