GS won't idle - spectacular gas regurg from carb! Help!!

[shinyside]

I never did resolve this problem, but I thought I'd steal a picture from the carb section to better explain.  My bike has a difficult time starting, and won't idle, but runs spectacularly from 4K-redline.  When I let it drop under 3K, it sputters and starts spitting gas from only the left carb (with the airfilter off).


Gas spits out of the two holes on the bottom of the intake circumference of the left carb, as seen in picture.

Are these some sort of relief mechanism indicating that a jet/port is plugged?  Also, on the other side of the left carb (attached to the engine), it has a brown caramelized color around the circumference... the right carb is completely clean and doesn't spit

I haven't actually looked all that closely to see if both of the two holes on the left carb spit, as it is likely to blind me with gasoline!

Thanks,

SS

[scratch]

Those are air jets that meter in air to the pilot jet and somewhere else (I'll have to look when I get home), the fact that they're spitting tells me that they're not plugged, at least, that's a good thing.
    The carmelizing is old gas.
I suspect too high of a float setting.

[Hi-T]

When I rejetted i got rid of the vaccum lines and stock petcock... I mistakenly plugged the 'T' above the gas intake on the carb (thinking that it was a vaccum line when it is a vent).  I was filling my air box at idle with gas shooting back through those same little holes.

So after a couple "what the Hell"s and a couple trips here I figured it out... anyways- if that line is plugged or clogged or pinched you will probably get the same effect.

[octane]

Sounds like vacuum leak or high float.

[scratch]

The other air jet goes to the needle jet (the tube the jet needle resides, or the tube that the main jet screws into).

[shinyside]

Those are some great ideas.  I checked my float height yesterday and the spring loaded nipple hit the tang when the float was parallel with the casing of the carb.  Do you suggest that I should switch the floats on either side and see if the spitting switches sides?  

Would such a condition cause difficult starting as well as an inability to idle?   It will start easier when the engine is already warmed up - I still need to crack open the throttle 1/8.  Couldn't start it from the cold (70 degrees not really cold) today  

BTW, the T-fitting isn't plugged  I don't think there is a vacuum leak, as the intake manifolds are new.  


Thanks again,
SS

[MacDuff]

Have you checked the valve clearance lately?  

MacDuff

[Kerry]

I checked my float height yesterday and the spring loaded nipple hit the tang when the float was parallel with the casing of the carb.

I'm not sure exactly what you mean about the float being "parallel with the casing of the carb".  But in case it will help, here is the measurement that the Haynes manual says to take when the "spring loaded nipple hit(s) the tang":



The distance between the lines should be 14.6 mm +/- 1.0 mm.

EDIT: Changed link from sisna.com to bbburma.net.

[shinyside]

Thanks for the pic Kerry.  I meant that the two lines depicted in the picture are parallel in my float adjustment.  I will try to go back and measure again.

Do you think a bad valve adjustment might cause this condition?  A mechanic had adjusted them a thousand miles ago, but he was pretty damn incompetent, because he took my $400 and still left me with the bike in this condition.

Thanks,
SS

[scratch]

Maybe. Does it make a loud metal to metal tapping sound? Does it sound like it is actually firing through the carburetor? If combustion chamber pressure was leaking past the intake valve the pressure would hit the butterfly valve, maybe leak past the butterfly valve, but also pressurize the floatbowl through the pilot holes, thus causing gas to pulse out the airjets, needle jet? Pull the sparkplug on that side and see what color it is and if it's wet with gas. Then pull that sparkplug wire while the bike is running and see if gas is still being spit out those jets. Put your hand over the mouth of the carburetor while the bike is running to see if you can feel pulses of air coming from inside.