mix screws

[KEITH KRAUSE]

Dark exhaust could very well be the floats too rich. In light of everything you've tried, I would try leaning them again if you still have room for adjustment. Like I said, I've heard some people actually go beyong the factory min/max to get what they want, but I can't say I recommend doing that. I'm not sure what you're using to measure with or your exact procedure or your float valve spring conditions. You can always put them back if you don't like the results. I know you're getting tired of messing with it though.
I'm assuming you haven't kept a record of adjustments though. At least you don't say. Then you'd know what you can still do. I assume you have the factory min/max info? Records of each adjustment and the results will allow you to put things back to a known value/performance if you go too far and don't like the results.

[Jethro]

Dark exhaust could very well be the floats too rich and that fits the mixture screw thing, and all 3 jetting circuits would be effected.

Barely, my tangs on the floats are bent at about a 20 degree angle already to get the factory settings. I am going to try and set them a little leaner.

I use a caliper to measure the 22.4mm float height best I can. But I wouldn't doubt that my float jet springs are bad. I need to replace them.

I'll let you know what happens with my float settings.

I'm also gonna try undrilled slides and stock piston springs (for the slide, right?)

It's a shame to change things, with it running this good, but I don't want it running rich.

[KEITH KRAUSE]

Yes, the diaphragm/piston assembly springs.
I'm not doing the work, but I think I'd try the float adjustments first. If you have the room for adjustment.
Float problems are the most common, that's why I suggest that first. Could be the slides or springs, but I'd go with the floats.
I know the temptation to do several things at once because you're tired of taking things apart.
It doesn't help much, but know that you're not alone. :roll:

[Jethro]

I know the temptation to do several things at once because you're tired of taking things apart.

Right. I have a habit of doing that. I'll just try the floats for now.

Is the fact that changing my float levels (by quite a bit) had no negative affect on my mixture a good indication that I need to lean them further? Just wondering.

Also, which circuit is more sensitive to float heights- pilot, needle or main? Or are they all equally affected by float heights?

[KEITH KRAUSE]

I know the temptation to do several things at once because you're tired of taking things apart.

Right. I have a habit of doing that. I'll just try the floats for now.

Is the fact that changing my float levels (by quite a bit) had no negative affect on my mixture a good indication that I need to lean them further? Just wondering.

Also, which circuit is more sensitive to float heights- pilot, needle or main? Or are they all equally affected by float heights?

Well, as for a good indication I don't really know how far you've moved the floats and at what measurement you started. You're saying they are at 22.4 mm now, correct? They couldn't have been too far off from the beginning if the bike ran as well as you say, but I suppose it's possible. If the bike still runs good, then we haven't caused a problem. You did say it's improved actually, but not much I think.
In my opinion, you should stay within the factory min/max range. I believe most others have that have re-jetted.
As for which circuit may be the most sensitive to float adjustments, I can't say for sure, but I believe it's the pilot circuit. The pilot circuit uses much smaller holes to keep the motor running correctly, so I think an incorrect fuel level would effect the pilot circuit easier.
Lastly, (I gotta get to work) you ARE measuring the float at the correct point? You have the odd shaped floats I believe? You measure at the top of the float, not the arm part of the float. If you measured at the arm part, you would actually be very rich. Talk to you later.

[Jethro]

I measure to the top of the bulb, as that was what it looks like in the manual. Is that what you mean by the arm? Have I been measuring my float height wrong? Should I measure from the flat part closest to the pivot itself? That would make my carbs way rich! Jezuz, don't tell me this, I've been messing with GS carbs for the past 10 years!

I swear, the manual shows the gauge at the bulb, not the flat part close to the pivot... I just checked it again...

[Anonymous]

I just got myself a set of K&Ns and in the instructions for adjusting the Idle Mixture and Pilot Jet they state:

Adjust for hightest idle speed. If less than 3/4 turn out is required, change to a richer (larger) pilot jet. If two (2) turns out or more are required, go leaner (smaller) in jet size.

this shed any light?

good luck brutha, I'm going through the same stuff.

M.

[KEITH KRAUSE]

Jethro, maybe you missread my last post. Maybe I worded it funny?
Yes, you measure to the top of the float. Some people make a mistake and measure at the very top, the ARM that holds the floats, and that would actually result in a rich setting. If you measured to the top of the float itself, the rounded "bulb" as you say, then you're good. But because of others making this mistake, I thought I'd mention it.
If there's ANY doubt, post a pic'. I would, but don't know how. But it sounds like you've been doing it right.

[KEITH KRAUSE]

Too early in the morning to think and I gotta go to work, but I'll continue this later.

[inquisitive]

Jethro,

[quote]
Yeah, I bent the tangs on the floats a lot, and measured off the gasket surface.

Do different carbs have different methods of measuring float height? I think my 79 GS850 manual says measure from the carb body. Not sure how big a difference that would make.

[Jethro]

Adjust for hightest idle speed. If less than 3/4 turn out is required, change to a richer (larger) pilot jet. If two (2) turns out or more are required, go leaner (smaller) in jet size.

This doesn't make sense to me. The mix screws effectively richen up th emixture when turned out, so if you have to set them 3/4 turn or less out, that would indicate too rich of a pilot. The more you turn out, the more you are compensating for a lean jet. Whatever- none of what my carbs are telling me makes sense.

So I'm glad to know that for the past 8 years I have been adjusting my floats correctly. That's good news. I am still gonna lean them a little bit.

Interesting test last night Keith, the bike was running well last night, but I decided to pull off the air filters as a test thinking maybe I oiled them too much, and that was why the jetting seemed too rich. The bike didn't want to idle at all without the filters on. Weird, I would think that taking them off would make a slightly leaner condititon, and that the bike would idle higher, but the idle went down about 400 rpms with nothing more than pulling the filters off. What does that tell me?

[KEITH KRAUSE]

The CV carbs just don't operate well without some kind of filter on them.
Some say they don't operate well with pod filters, period. Their design seems to require a certain amount of restriction.
If you visit different websites on jetting, carb tuning, etc, you'll find small bits of info here and there about the mixture screws. I know how they work, but sometimes you'll get some info about what different symptoms mean.
The mixture screw allows more MIXTURE, which is both air and fuel, and this amount increases until roughly 3-4 turns out, then the screw has no more effect. The screw regulates a second passage to the carb throat and is meant to fine tune, or assist, the pilot jet.

[Octain]

Great thread! Found it while searching through "future" problems I may have on my not yet assembled carbs.

Jethro, did you get that studder figured out? Timing, P jet?
An update on your issue would be awesome!