Intermittent Leaking Carb

[tcarr]

Hi,
I had a carburetor that was leaking fuel quite a bit, ended up discovering later that I had a bad petcock, and thought my float bowl gasket on that carb must have been bad too. I replaced the petcock with a brand new one, and recently put a new float bowl gasket on and the problem cleared up. Until today... it isn't leaking near the amount it was before, and the only thing that was different in my scenario was I had the petcock set to "reserve" today... which maybe that was part of my problem. Sometimes I just have that feeling that I'm ignorantly doing something dumb.

So here's my questions: Could my problem partly lie in the float needle on that carb? Probably wouldn't hurt to replace it.

And is there any thing I should put on those float bowl gaskets to make them seal better? When I put on some of my engine gaskets I used a wheel bearing grease to help them seal, but I don't know if I should put anything on these. The first gaskets I put on it were a fiber gasket, but the one I got to replace my leaking one seemed to be coated in some kind of wax - at least that's what it felt like.

And my last question - if the carbs have that lovely little overflow hose connected to the bottom, how does it leak out of the top of the float bowl? I assumed that's why those overflow hoses were on there... I guess you know what they say about assumptions...

Thanks for any input you have!

I should say that this is a '77 GS550 with the VM type carbs.

[allojohn]

Hi,
I had a carburetor that was leaking fuel quite a bit, ended up discovering later that I had a bad petcock, and thought my float bowl gasket on that carb must have been bad too. I replaced the petcock with a brand new one, and recently put a new float bowl gasket on and the problem cleared up. Until today... it isn't leaking near the amount it was before, and the only thing that was different in my scenario was I had the petcock set to "reserve" today... which maybe that was part of my problem. Sometimes I just have that feeling that I'm ignorantly doing something dumb.

So here's my questions: Could my problem partly lie in the float needle on that carb? Probably wouldn't hurt to replace it.

And is there any thing I should put on those float bowl gaskets to make them seal better? When I put on some of my engine gaskets I used a wheel bearing grease to help them seal, but I don't know if I should put anything on these. The first gaskets I put on it were a fiber gasket, but the one I got to replace my leaking one seemed to be coated in some kind of wax - at least that's what it felt like.

And my last question - if the carbs have that lovely little overflow hose connected to the bottom, how does it leak out of the top of the float bowl? I assumed that's why those overflow hoses were on there... I guess you know what they say about assumptions...

Thanks for any input you have!

I should say that this is a '77 GS550 with the VM type carbs.

Your problem has nothing to do with the gasket, it's not supposed to be a complete seal. Could be your float height allowing too much gas in the bowl and it could be the float needle and seat not stopping the flow of gas.
As for the overflow tube, it might be blocked. Have you cleaned the carbs at all?

[tcarr]

Yeah, they are all sparkly clean, gave them a thorough going over a couple months ago and they still looked great when I had them off 2 weeks ago (long story - I had to pull the engine for another little problem)

Thanks for the help, I have never really been satisfied with my floats, they seem to be a little deformed and sometimes feel like it wouldn't be difficult for them to get stuck. Would it be worth spending the money for new floats? That $35 bucks a piece kinda seems steep, not that I haven't poured way more money into this bike than it's probably worth already, it's becoming more off hobby/pet/friend than just a bike.

If it is in my best interest to get new floats is there an alternative to the oem ones?

[allojohn]

You can straighten them out, yes? If not I'd still go with OEM's. Have you tried ebay?

[tkent02]

Usually the round brass part gets bent slightly out of round when you pull on them with pliers to remove them, just enough that the needle sticks once in a while if it rotates just wrong. I don't know how you could straighten that out, maybe you could.

[tcarr]

I'll take a crack at straitening it out, If I remember correctly one of mine was pretty bent when I first did the carbs and I tried to straiten them all out. Maybe that's the one. Any reason that I would need to replace all the floats at the same time if I go OEM or would I be able to just replace that one? I guess while I'm going to the trouble of takeing them off it wouldn't hurt to replace them all...

[allojohn]

I'll take a crack at straitening it out, If I remember correctly one of mine was pretty bent when I first did the carbs and I tried to straiten them all out. Maybe that's the one. Any reason that I would need to replace all the floats at the same time if I go OEM or would I be able to just replace that one? I guess while I'm going to the trouble of takeing them off it wouldn't hurt to replace them all...

If the rest are OK, hell no! Apart from getting bent there's ought else that can go wrong with them. Save your money for the stuff that must be replaced.

[OldVet66]

What does sparkly clean mean, were they ever soaked in carburetor dip? If not the inside that you can't see might be quite a different story. If a float needle sticks opened, the fuel will rise to the top of the vent tube and then come out the bottom hose.It will spurt out, stop and spurt again in a rhythmic pattern. If you rap the side of the bowl with the plastic end of a screwdriver you can sometimes get it to behave for a while. I had one that would do it on occasions and then started working normally before I went in to fix it.

[robertbarr]

Remember, the seats don't pull out / in like the regular CV carbs. These screw in with a fiber washer. Look here: http://www.carbkitscapital.com/carb_...i&model=GS1000 You're looking for 13370-18111, according to Flatout.

There might be a better source. First, though, I'd be tempted to polish the inside bore of the valve with something like a Q-tip and progressively finer polishing compound.

The brass parts get pitted a bit by fuel (and I'm sure the ethanol doesn't help) -- hard to explain, but if you slide a fingernail across such a surface you get that creepy chalkboard feel; they're no longer smooth, shiny brass. I can't see how that fuel valve needle can slide smoothly and seal, within such a 'gritty' seat bore. I suspect this is the cause of a lot of intermittently 'sticking' inlet valves.

I lost track here of exactly what you think you might have bent / needs straightening.

[allojohn]

We're talking about a '77 550 aren't we?

[tcarr]

Yes allojohn, '77 550. And thanks for the input, somewhere I think I read that they could get hardened and have problems from sitting in fuel all the time... But I can't recall if that was specific to the GS bikes.

robertbarr, we were taking about the float itself, that may have been bent. But I'll double check that needle seat while I'm in there.

And OldVet66 they were dipped, soaked, and gone over as per the guides on this site. I'll go back through the bowl on that carb and spray some cleaner down the drain shaft, maybe even poke a needle in it - I can't recall off the top of my head right now if that is even possible...

Thanks guys!