HELP! Stumbles off idle and low rpm light throttle, leaking choke circuit

[valvesprung]

A little background:
1993 GS500E, K&N drop in, dual high mount free flowing mufflers from stock headers. Currently geared 14-39 for off road use







Build thread here for those interested:
http://advrider.com/forums/showthread.php?p=23681181#post23681181


Stumbles off idle, stumbles on maintenance throttle, very happy on mid-full throttle above 2500-3000 rpm

-carbs fully cleaned and spotless
-O-rings, needle jet, and seat replaced
-Rejetted to 40 pilot, 127.50 mains, shimmed 2 washers on needle
-had to replace choke tubes on both carbs (cracked), drilled out, added threaded fittings and tug on hose.

-balanced carbs and improved power up top and smoothed out acceleration, but still stumbles, and low rpm quick throttle application causes sputter
-have found fuel in choke lines at all times, worse in right then left
-will Only take one turn on mixture screw or gets worse
-with right choke tube pinched off I was able to get it to 2-2.5 turns on the mixture screw, but still stumbles

I'm going to pull the tank and block the left choke tube, but it feels like there may be something else happening.

Beyond that, is there a way to repair the choke circuit from leaking internally?

hELp!


Oh...and thanks in advance

[The Buddha]

-balanced carbs and improved power up top and smoothed out acceleration, but still stumbles, and low rpm quick throttle application causes sputter

This is a dead giveaway - slow throttle = runs fine, quick = fall on its face and sometimes even recovers well enough to gasp ... wheel spin ... yes slide coming up too fast. You can train yourself to open slowly or close 1 hole in the slide and see if it improves. If it does see if you need to close part of the other hole.

BTW I want to suggest if you put a heavier spring it could slow it down the same way.
If you put in a little ball as a weight in the top it will slow it as well.

Dunno if any of those is more appealing to you.

Cool.
Buddha.

[valvesprung]

Thanks, I should have clarified. The off idle stumble and low rpm light throttle stumble still exist...in addition to the heavy throttle stumble (and I'm not really slamming the hammer down either way)

[valvesprung]

Eye candy added to first post

[BockinBboy]

Thanks for the pics... I now know what your problem is... you don't have a chain - you'll get a lot further with one of those   

- Bboy

[adidasguy]

-have found fuel in choke lines at all times, worse in right then left
-will Only take one turn on mixture screw or gets worse
-with right choke tube pinched off I was able to get it to 2-2.5 turns on the mixture screw, but still stumbles

I'm going to pull the tank and block the left choke tube, but it feels like there may be something else happening.

Beyond that, is there a way to repair the choke circuit from leaking internally?

You have a choke thingie/plunger on each carb. Probably there is dirt in there that keeps them from closing off.
Take off the choke connecting bar.
Remove the plastic caps holding in the choke plungers and clean things out in there.
Since you drilled, probably there are metal bits in there keeping the plungers from completely closing off the choke fuel flow.

[valvesprung]

The choke circuits have been fully disassembled and cleaned twice. No visible issues there. With the second choke circuit blocked its happier and even pops a little but in decel since it's not overly rich any more. It still wants to stumble slightly (dropping one cylinder) under load under 2800 rpm with light throttle. I can rev and feather through it much more manageable now, but it's till obnoxious to have to do that...

We're going to hook up an A/F reader next to check the mixture screw settings. I'm hoping that's the last of it. It'll be a couple of days though

[adidasguy]

With the choke off, those lines are completely blocked. Pinching off the tubes will have no effect if the choke is off.
Take another look at the choke and choke lever. Maybe your choke cable is too tight. Disconnect the choke cable. Choke will be off. Force the choke thingies in if they are sticky. Maybe the tip of one of your choke plungers is damaged so it can't shut off fuel.
So, no fuel will go through the choke tubes when the choke is off. If some is, you have a problem there.

[valvesprung]

Yes...I know...that's the point I was making 

I have a small amount of fuel going through even when we can see the plungers are completely closed. The plunger tips show no damage or pitting, and the circuit is free of debris.  It's not bad at first, but the longer it idles, the more fuel builds up, and the worse it gets.

[adidasguy]

Weak or missing springs on the plungers?

[valvesprung]

Springs are there, possibly weak, but even with pressure on the plungers it makes no difference. I may order new plungers and springs since they're not too spendy

[adidasguy]

You drilled: did you damage the inner surface? Did you screw in your thingies too far?
Look in the holes. What's in there? You may need a camera on a snake to see in there unless you separate the carbs.. Spy camera thingie.

[valvesprung]

As far as we can see, there is no issue of contact or debris in the choke circuit. Though I've not ruled out irrepariable damage from the retro fit. I figure the carbs were toast anyway, we just gave it a shot. At this point I've made improvements in the tuning by simply clamping the choke circuit off, but it still hesitates under 2800 RPM under load.

I'd love to hear any other suggestions on why, but I'll be dialing in the mixture screws with the A/F reader either way. I'm really hoping that fixes it. At this point I think I'll likely end up snagging a used set of 2nd Gen carbs to install down the road.

[valvesprung]

Spent some time messing with the mixture (albeit without an A/F reader), it makes a difference, but not much. Definitely have another issue, so any help is appreciated. I'm thinking I may try the stock pilots again as I had swapped in 40's