strange idle racing

[p_s]

'85 GS550ES
This problem used to happen maybe once a day, now it is more regular, sometimes a few times an hour.

The problem is that I pull the clutch and the bike idles at 3k. I also feel less compression braking. If I turn the idle stop out a little bit it drops. Then I can turn it back in and it idles fine. When the problem happens I can still feel slack in the cable. Turning the bars one way or another doesn't help. Killing the motor and snapping the throttle a few times doesn't help either.

I also tried spraying wd-40 everywhere (when it was idling around 1200) and found nothing. I feel it is not an air leak, because when the symptoms occur, about an 1/8th of a turn out on the idle adjuster makes it go away, and then the idle adjuster works as normally.

I couldn't feel any problem in the linkage. The slack adjuster nuts seem to be right. What else could it be? Stuck CV piston? This doesn't make any sense to me.

New airbox boots, new intake o-rings, recent valves, very recent sync. I'm on a long bike trip, about 500 miles a day, and this didn't happen until day 5 (once), day 6 (twice), day 7 (10 times or more). What gives?

[psyguy]

stuck carb butterflies (not returning freely all the way back)?

[p_s]

So sometimes if I whack the throttle open and closed it will fix itself. But if I pull the clutch and do that no go. I'm thinking one of the cv pistons is getting hung up. Anything I should look for when I rip into them? Bad diaphragm?

[chef1366]

Possible stuck slide.
You might not detect an air leak that way all the time.