Carb Issues

[starkeyje]

I have an 81 GS850GL with carb issues. I just replaced the stock exhaust with the V&H 4 into 1 exhaust, and bought some carbs off E-Bay that are jetted with the V&H jets. I put the "new" carbs on, and they flood out to the point where gas comes out of the vent tubes and the airbox side. If I disconnect the fuel supply line from the gas tank, the engine runs perfectly. As soon as I hook them back up to the tank, they flood out. I replaced the needles/seats and floats using the ones on my old carbs, and they still flood out. There must be simple solution. Any thoughts would be GREATLY appreciated. Thanks in advance!

[chef1366]

It's not jetted right. Were the new carbs off an 850 or 1100? Did you measure float height? Is the plug over the pilot jet? Are the jet neeedle diaphragms seated properly? Where is the jet needle set? If these things check out your pilot jet is way too big. You need to jet to your bike because they are all different. Just because it is jetted with V&H jets doesn't really mean anything. Try using the stock jets from your old carbs and see if it runs. You'll have to bump up the main a few to make up for the extra air from the 4-1 pipes.

http://www.vanceandhines.com/download/S110IN.pdf

[starkeyje]

They're supposedly of an 81 GS850. They're virtually identical to the ones I took off. Thanks for the ideas--i will check them all. I'm confused because the bike runs great as long as the carbs aren't connected to the gas tank.

[Macmatic]

I'm no expert on carbs but it doesn't sound to me like this is a jet problem. It sounds more like one or more float needles isn't sealing allowing gas to just pour in flooding all of the bowls and overflowing. Others will have more ideas I'm sure but I'd follow Chef's advice to check the float height first off. Also check to make sure the springs in the float needles arn't stuck

Does this happen when the bike is not running too? Could be partly a bad petcock.

/\/\ac

[hungryman]

Sounds like a float height issue, or stuck needle and seat, or even a bad float.

[starkeyje]

Thanks for your help. I'm thinking it's the needles & seats or the float height. It only happens when the bike is running. In fact, I changed the petcock last year, so that's not the problem. I assume that if you turn the carbs upside down, you should not be able to blow air past the needles/seats, correct?

[chef1366]

Blow

Yes, this will close the floats and you shouldn't be able to blow air through the fuel line.

[UncleMike]

Yes, this will close the floats and you shouldn't be able to blow air through the fuel line.

You shouldn't be able to blow air through the fuel line? Just want to be sure, here.

I thought if you blew throught the fuel line and you couldn't pass any air, that meant your needle jets were blocked.

[chef1366]

Gas is first introduced into your carbs through your float needles and seats. Pilot jet doesn't come into play until your carb bowls are full of gas.

[starkeyje]

Ok, I think I solved the flooding problem. But now there's a new one. the bike will idle perfectly fine. But as soon as I blip the throttle, it stumbles and spews black smoke out the pipe--obviously running too rich. I synched the carbs, and it got a little better, but not enough to make the bike rideable. No power at all on acceleration, and the plugs are blacker than black too. I'm starting to think that it has the wrong jets in it for my V&H exhaust (as previously suggested by chef). Are these the symptoms of jets that are too big, thus too much gas is getting through?

[chef1366]

Jets

Try your stock jets from your old carbs if available. I put a link from Vance and Hines on how to jet your carbs for these pipes. There seems to be jetting in your future, good luck.

[starkeyje]

Yeah, that's what I was thinking. I still have the "old" carbs, so I'm going to switch them out. Thanks for you help!