I noticed 4000 rpm in 5th it was bogging. 4th gear unaffected. 6th I don't know...

That's low in the rpm band. Like 1/4 throttle. Not a whole lotta pickup down there, in that high a gear.

Do your floats float?

Scratch, the floats seem to work fine through 4 gears and at idle. No leaky when the bike is off, level is even with the gasket.

ok, runs fund in lower gears up the rpms? had this issue once before and it didnt go away till i changed every damn Oring and ran Fine wires and compressed air through every damn port. the one that gave me the most trouble was the O-ring right under the Slide guide (plastic part the slide sits in) that O-Ring was about turned to gooo. changed it, re synced them as i tore them both down to nothing. and ran fine, the other thing is that damn choke. i believe it tends to "flutter" for lack of a better term and screw up the mixture in topend. you shouldnt need to keep adjusting the idle stop screw, once warmed up, set it and leave it. you will drive yourself mad as you keep turning it up and down.

Thanks Blue, I was looking hard at the slide glides when I had it apart the last time. The plastic didn't seem to come up outta there so I left it. Is it just a press fit or is it held in place by something? I ran the fine wire through and used air compressor pressure through all small ports. I also made sure the carb cleaner exited elsewhere when sprayed into the ports all ok.  The orings under those glides are an unknown so I reckon thats my next step. At least so I know.

On a GS carb set ... if any of the vital O rings are bad ... it will leak gas. The only O ring that will affect performance is that one under the top. Its got O rings under the plastic insert the emulsion tubes go into etc, but they all dont do anything. Float and T fitting O rings keep them from leaking, and the one on the Air screw does that and possibly from sucking air ... though I dont think air in any significant quantity can get in that way at all.
Cool.
Srinath.

Alright guys. This is starting to wear me down here. I work on lift trucks everyday. Fuel injection systems on modern stuff and 25 years ago cut my teeth on old carbs but this is kicking my arse. I think my next step is to reclean the carbs.. again and add another washer under the needle to get a richer mix at high demand. Since it starts ok, even without the choke and runs fine up through 4th gear I have to surmise that either its starving for air or fuel when in that needle jet fully up and main jet supplying fuel. With the air filter laying in the garage it still bogs.
Its gotta be in the needle. I know my diaphrgms are ok, small orings are in place. Nothing acts like its vacuum leak, no revving. Can someone tell me otherwise?
I appreciate all the comebacks and will look closely at any tips provided as I tear these things down again.

Send it to me ... trouble shooting is free ... Yea you'd pay for 2 way shipping ... but I have seen many people get stumped by these carbs ... Yea they are simple, they dont have too many delicate parts or very tricky anyhting ... Frankly I have seen people that tear apart engines and fully rebuild them ... get stumped by these ...
FWIW - Your problem sounds like rich not lean ... so choke staying open or some weird screw up in the fule supply ...
Cool.
Srinath.

remove all the top stuff and the slide and needle assembly (mind that tiny ass oring when you first pop the top off)

Pull the float bowl, Float/Idle circut plumbing, and unscrew the Main jet acouple turns only, Now with screw driver handle or something plastic that wont deform Brass, SMACK the main jet like your trying to hammer it back in,  it will shift the emultion tube out the top (its what is holding the slide guide into the carb) back the jet out a few more threads squirting some WD or PB Blaster helps this along. keep working it till you can get the emultion tube all the way out, then the slide guide, You will now see that Hiden but oh so critical PAIN IN THE ASS Oring.  Make sure all your orings Fit Nice and snug when you reassemble it.

Hey bluknyt ... that emulsion tube O ring ... what exactly does it prevent or allow to happen ... I didn't think it did anything ... its entirely encased in metal and plastic ... no passages to or out and OK it being there will maybe prevent a tiny bit of fuel bleed out at high intake velocities ... I didn't make much of its usefulness ... its usually crushed and crumpled by the time you get it out ...
Cool.
Srinath.

Thanks again Seshandri and Blue.
The weather is gonna be sh+tty here this weekend so I'm gonna take em apart one more time and go at those o'rings under the glides. I'd really like to fix this myself if I can. If after this they still bog I'll be sending them to you Seshandri.

yeah Its often goo, and the emultion tube is often locked in with corosion. the emultion tube has little ports on the side, kinda like a Bleed type jet and i think helps to smooth flow abit when needle shifts up and down.

now,when i first got my GS, i had running issues that had no end. cleaned, and recleaned, changed orings but still gave me hassles. once i changed that Oring it went away.  look at it this way, what does an Oring do? why machine a groove in metal and mold inner support in plastic if its not sealing?  i dont know if it keeps from sucking air while fuel sloshes, or if it keeps from sucking Fuel when it sloshes. biggest issue i remember, is when i would come to a stop, it would Die. fire rigt back up and idle like nothing happened. so im inclined to think its fuel slosh related from front to back, as leaning while sitting still did nothing.

Ok, tore the carbs completely down again.    Blueknyt, thank you very much on your help with the slide glide orings. They were junk.  Seshadri, I saw where the orings were mushed apart under the glides and there was a very distinct trail of gunk/residue from the main jet port to the edge of the carb intake hole under the glides indicating an open trail of fuel. Also this was the first time I've had the emulsion tube out and found the left carb that had the worst oring had a thick black build up of corrosion on the outside of the tube blocking up 2 of the 4 holes for fuel to exit. I had run carb cleaner through this passage many times and was surprised to fing that much in there. I say corrosion because nothing short of emery cloth would cut this black crusted mess. I really had to work to reopen the emul tube holes.   I replaced those orings and recleaned the carbs while apart. I went ahead and added a 2nd #4 washer under each needle. I reinstalled back on the bike. I also kreemed the tank while I had it off. Thanks to Seshadri's great info on treating the tank I was able to clean a lot of rust out of this tank ,"slosh it this side that side upside down, more rust do it again". As I reassembled the bike I installed 5/16 clear vinyl tubing ".20 a foot at Lowes" as fuel line and installed a new filter inline from the pitcock to the carbs.
The results....
Bike starts when using 1/4 choke. It runs a lot better. I can run through all the gears 5th and 6th included and there is no bogging/ starving going on. I installed the filter in a manner that I can glance down and watch it while riding and see what is going on. When you start the bike, the filter level doesn't move in idle, rev it up and the level starts to go down and eventually empties. Still runs ok though. When I hold 65 mph for longer than 5 minutes or so it gives a slight indication that its starting to lean miss. Clear filter empties as soon as I get out of the driveway. I suspect that this is strictly from the vacuum pitcock supply not keeping up with demand. IMO this is not a problem for me at this time.  I will spend the whole summer on the backroads of Ohio and don't want to mix it up :guns:  with highway cagers with my experience or lack there of. Posting another thread for some thanks to you guys and others.

ok next time your on the Highway or running 65mph, switch over to PRI on your petcock. see if this doesnt cure your issues, forsome reason when at Highway speeds, there isnt enough vacume at that port to properly open the petcock diaphram, and it will drain your bowls. my diaphram started leaking to the point the port was suckin fuel, so i blocked it off and just run on prim and switch to run or Res to stop fuel flow.  My res doesnt work anyway, prev owner Cut the stand pipe for tank valve so it will drain the tank from full to empty without switching.



Woot, Go blueknyt, whos the carb guru :mrgreen:

Fought with the little bastard twin fuel suckers for a weeks straight to figure out that issue.  also didnt know that i wsnt running stock needles at te time too.

Not familiar w/ gs carbs yet, but I'd say check for a tiny crack in the diaphragm.   Are they moving up freely?


my .02 cent

Jonah

carb diaphragms will kill its runnig above 5-6K ... even the tiniest rip ... Petcock Diaphragm will make it not run in anything other than prime ...
Cool.
Srinath.

Well I held the carb diaphragms up to strong light and really checked'm but saw no cracks or anything. They slide up nice & free together under a high rev as I watch them. Not worried about it at this point, its just a slight feel of starve at 65 or so and I'm just wanting to ride back roads for a while.
Rode tonight to W Milton & back 40 miles round trip and it ran great. I put a little gas treatment in the tank and will run it for a while and get some miles on it. It almost seems as though 1. The carbs might need 1 more washer, might try that. Or 2. The fuel system is restricted just enough from the tank petcock that it takes a while in high RPM under load to start depleting. But I still say, I can roll though that spot when I start to feel it and I get power. Gotta be needles folks.
Again I'll run it awhile before I do anything else.
Srinath have you ever had to use 3 washers per carb?