Carb leak (or fluid on carbs)

[Guest]

I've got fluid accumulating on the carbs. I tried cleaning it up and periodically stopping to see where it originates, but that's been unsuccessful; I don't see anything dripping when the bike is parked and I've got to ride maybe 100 miles or more before I notice much. I can't tell where its coming from. Petcock is new and doesn't appear to be leaking and I don't see it coming from the choke rod, but I could be missing it. Maybe it's coming from the float bowl gasket and dripping/splashing? Or is it something else? Carbs have been rebuilt a few hundred miles ago, but still have original diaphragms.

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[Steve]

A couple of those pictures look like it's the float bowl gasket, some of the others look like maybe the throttle shaft seal.

Diaphragms would not make anything leak like that, they never see any gas.

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[Joe Garfield]

Thanks Steve. That seems like it can wait 'til winter...

[JTGS850GL]

Those are minor leaks. More like seepage. The debris in the middle may even be some oil residue collecting dirt. I'd wait till winter and do a complete rebuild of the carbs. Check your timing chain tensioner and make sure the oil isn't coming from there.

[geol]

I would consider investing in some new carb holders/orings. They look like the originals and since made of rubber, are not expected to last forever. As far as the very minor gas leak, gas accumulates in the # 1 & 2 carb bowls when the bike is on sidestand. I would invest in new bowl gaskets and it looks like a fuel rail may be seeping which means the assembly has to come apart if it bothers you. Note you don't get any drip on the #4 side because this stuff likely happens when the bike is on sidestand as I noted.

[2BRacing]

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In this photo it looks like there is a breather pipe missing from that plastic fitting just to the left of the yellow circle (unless it is the fuel supply T-piece?). Usually the breather pipes go up and over the airbox, extending some way down behind the airbox.

[Brendan W]

I think the bowl retaining screw should be more fully engaged with the carb body casting, even sticking up a bit.

[Joe Garfield]

I think the bowl retaining screw should be more fully engaged with the carb body casting, even sticking up a bit.

Which is the bowl retaining screw?

[geol]

The four screws that hold the bowls on are M5x16. Yours are M5x12 or 14 asd not quite as long as the originals but they are not the reason for the small leakage. They catch enough thread to be tightened securely.

[Joe Garfield]

In this photo it looks like there is a breather pipe missing from that plastic fitting just to the left of the yellow circle (unless it is the fuel supply T-piece?). Usually the breather pipes go up and over the airbox, extending some way down behind the airbox.

Good catch! Thank you. I've been confused about vent, vacuum, and breather hoses. Looking again at BikeCliff's site, I now realize I don't have vent hoses hooked up. That seems a likely culprit for the fuel on carb #2.

[Joe Garfield]

The four screws that hold the bowls on are M5x16. Yours are M5x12 or 14 asd not quite as long as the originals but they are not the reason for the small leakage. They catch enough thread to be tightened securely.

Thanks - I see it now. I'll check that #1 is tight enough. The carbs were fully rebuilt and got some new hardware. I believe the gaskets are all new but the bolts could have loosened up a little.

The bike has a really gassy smell and I think is 'using' a little extra fuel. My reason for posting this was just to make sure there weren't signs of the carbs not shutting off or something, but it sounds like were mostly just seeing seepage (or missed breather hoses). This bike still has a lot of other maintenance needs, and being my only bike I don't want to start pulling apart carbs unless its really necessary. I will take care of the breather hoses though...

[Nessism]

When the carbs were rebuilt/cleaned did you break them down and replace all the various O-rings, including the ones on the interconnection tubes between the carbs? Was the fuel level verified using the clear tube method?

[Joe Garfield]

When the carbs were rebuilt/cleaned did you break them down and replace all the various O-rings, including the ones on the interconnection tubes between the carbs? Was the fuel level verified using the clear tube method?

I'm not totally sure (I forget what was in the rebuild kit); and no, float height was measured but fuel level not checked - I will do that.

[Nessism]

I'm not totally sure (I forget what was in the rebuild kit); and no, float height was measured but fuel level not checked - I will do that.

Did you ungang all the carbs from the joining bars? Doing so is the only way to replace the fuel transfer tube O-rings. Those are the O-rings that are most routinely hard and brittle, thus failure to replace them can lead to leaks. Also, as the float needles age and the springs get weak it's critical to check them using the clear tube method to be sure the fuel level is correct. The float height check is just to get them close, sort of like the difference between bench sync and vacuum sync.

[Joe Garfield]

Yes, carbs were fully broken down to individual components, soaked/cleaned, and rebuilt. I feel like old, crusty o-rings would have been replaced but it was over a year ago and I can't remember. During the off-season I'll check things out more closely.

And thanks for reminding me about the float level. I was gearing up to do an idle mixture check, but it seems like I should check/adjust the floats first.