If it runs like its lean, but its not

if fuel is to low in bowl it you will run lean if fuel is to high you will run rich

 

there's thick and thin springs on the balance screws, the thicker one goes by the screw head.
the needle jet needle can get stuck up inside the slide, push them up and make sure they spring out.

look into this
might be the mixture because 900 rpm on 2 cylinders firing becomes about 3000 rpm when all 4 fire

 

Can you clarify "there's thick and thin springs on the balance screws"

 

look close at the diameter of the wire the springs are made of

 

look at the carbs in this post. warning you gotta wear shades notice the difference in the springs


OWWW, My Eyes!

 

do the plugs look like it's lean?

 

So, just for fun. I pulled my spark plugs after killing the engine at 6000rpm. Seemed a touch lean so i took my screws from 2.25 turns out to 2.5 turns out to make it more rich.
Then I tried again when the idle was hanging.
Bad news, it looks about the same. They are all a nice light brown. See photos.
Clockwise from top left 1,2,3,4.
Darker photos (at night) are engine at idle hang.

 

I've also been having this same issue with my 81 XJ550. Replaced all of the seals in the carburetor except the mixture screws which I could not seem to get out and the idle will jump up when I get it over 2000 and hang around 4000 until I cut it off. Spark plugs look lean when I look at them but messing with the mixture screws does nothing.

Correct me if I'm wrong but if it starts to act lean like this and you apply the choke shouldn't that correct the situation and bring the idle back down? I've tried this and it only made it much worse...

Next thing on my list to try is putting the smaller jets back in. After changing to pod filters and 4-1 exhaust I went to 120 main and 37 pilot.

 

This indicates that your pilot fuel circuit is dirty/plugged internally, or missing/damaged O-rings on the mixture screws, etc. You'll have to get those puppies out of there to inspect/replace/clean.....

No, applying choke creates an additional source of fuel, which typically will raise the RPM's (especially in a situation where the pilot circuits aren't fully working, and hence the engine is running very lean (which also causes a run-away idle). On the bright side, it means that the starter jet passages are not plugged up, which happens.

No, the next thing on your list should be to solve the underlying problems! Otherwise you'll end up creating more issues and chase your tail forever. A proper cleaning/rebuild, followed by an engine synch is what the doctor prescribes.

 

Please keep this in your thread. It's too easy to mix up which bike we're talking about when you add a question to someone else's thread. It also divorces your question from all of the context (and related work) that we've been using to help you solve your problem.