Leaky transfer tubes or stuck float/bad needle valve ?? 1981 GS550

[Guest]

I thought I had/have a stuck float or bad needle valve. I replaced what I thought was the bad valve and all the floats seem ok. I poured some gas through them on the bench and discovered it appears to be leaking at the tubes between the carbs that fill the outer carbs (are these called transfer tubes?)
Is this where fuel would leak out if there was float/valve trouble? Or do I have a problem with those tubes?
And/or where does the fuel normally leak out of when float is stuck?


Thanks

 

[Cipher]

The fuel would flow from the emulsion tube if float stuck

If its coming from the tubes dismantle and replace o rings

 

[Guest]

Thanks for the reply. I'm still on the learning curve here... What /where are the 'emulsion' tubes?

 

[Cipher]

Thanks for the reply. I'm still on the learning curve here... What /where are the 'emulsion' tubes?

In the carb throat the cylindrical slide has a needle that penetrates the top of the emulsion tube.
Regardless no fuel should escape the tube to carb body joint unless the o rings are bad

 

[Guest]

I replaced the o-rings on the transfer tubes. All good. No leaks.

 

[Cipher]

I replaced the o-rings on the transfer tubes. All good. No leaks.

awesome a PITA to have to disassemble all that but nothing else for it.

 

[Guest]

PITA yes, but it turned out to be not quite as difficult as expected. The inlet 'T' was fine so I just had to remove the outside carbs (leaving 2 & 3 connected).
Though I got impatient waiting on my order of JIS drivers and stripped one of the screws. Ended up grinding it so I could get a pair of vice grips on it. Didn't try anymore of them until I got the JIS's...lesson learned.
Used 6mm x 2mm o-rings from a multi-pack from Amazon.
Just getting the carbs on & off of the bike is more of a PITA...but I get faster each time.:smilet-digitalpoint
Thanks for the help.

 

[sacruickshank]

BTW, even though you still consider yourself "on the learning curve", congrats on doing the fuel leak test while the carbs were still off the bike. Much easier than wrestling them back on only to discover the leaking fuel when smoke starts coming from your hot exhaust from a fuel leak ... like some of us have done.

While the carbs are off the bike, you should also bench sync them. It's much easier to understand the impact of tweaking the sync screws when you can visually see the results. You may still need a final sync once on the bike and running, but the bench sync will get you very close, assuming your valves are also set.

 

[Guest]

Thanks for the tip. I got the bike running but plan to remove the carbs again for a good cleaning/re-build. It takes a long time to warm up but will run eh, ok once it does. Have to keep the choke on for a few minutes and then it surges just a bit.
I came across this link: https://gsarchive.bwringer.com/mtsac/~cliff/storage/gs/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf posted in another thread here which is just awesome.
Next up, I will need to learn about adjusting valves. I've also got an '81 GS650L that has always run as smooth as a dang sewing machine in the 10 yrs that I've had it. It's got just over 26k miles and from what I've read, probably needs the valve job.