Hanging Idle or No Idle 1981 CB750C

[mkaser26]

Okay... Hoping this is the forum that can help. Have spent maaany hours now trying to figure this out.

Either hangs the idle with Idle Screw in or doesn't idle with Idle Screw out. (No happy medium) Air/Fuel screws do not seem to affect idle when tweak out or in from factory spec.

Initial info.
 -Does this in neutral and when clutch is in.
 -Timing is good.
 -New plugs
 -No air leaks (at least in the carb to boot connections)
 -Tail light disconnected (didnt know if this could cause electrical issue)
 -Floats all set to factory spec (non adjustable but had to bend one slightly)
 -needle valves not hanging up
 -IDLES FINE ON CHOKE (which i would think allows it to suck harder on the small pilot jet holes pulling a more sufficient amount of gas out?)

Issue-
-Took off carbs and cleaned with compresed air and carb cleaner twice. Blew out all holes.
-blew carb cleaner and compressed air in the pilot jet (this is the pressed in non-adjustable jet) - air would blow through each but definetly not easily. Still would like to press guitar string through this hole to make sure it is clear.
-Noticed all the jets were on wrong from PO- fixed to 102main, 68pre-main, factory set pilot jet (non adjustable)
-adjusted air fuel screws to stock spec and would try to tweak from there (no real noticable change in idle when adjusting)
 
Things to check/try next...
 -check compression
 -bypass Air Cutoff Valve or atleast check and replace (any suggestion?)
 -recheck timing
 
Has anyone had this issue and what was your fix?! Please help!!!  Seems like this could be the Air Cutoff Valve since the bike idles great and does hang the idle when the choke is on, allowing it to more sufficiently pull full from the Pilot Jet holes.  With the Air Cut off valve continuously letting air pass through when the choke is off I think there is not enough pressure to pull fuel from the pilot jet?  

Suggestions?

[TOOLS1]

This is really simple. You have a vacuum leak. Most likely  the carb boots, or the vacuum port for the gas petcock is open. Also, do you still have the stock airbox on the bike, or are you attempting to run pods?
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[mkaser26]

I sure wouldn't say it is really simple.  Checked the boots really good for leaks with starter fluid and visually.  I've already been bypassing that gas on/off "Spawn of Satan" thing and I plugged the vacuum port to carb 2 when I removed it.  

If there is no leak in the boots and said vacuum port is plugged is it possible bad Air Cut Off valves could be letting air through stalling the bike out?  Bike does run fine on choke.  I wish it was just a vacuum leak because taking these carbs all apart to get to the Air Cut Off valves is going to be rough.  I took the one apart that I could get to and the diaphragm was wore out and clearly passing air through it and the tiny O-ring for the hole that goes toward the cylinder was missing.

Pic showing missing O-ring and raggedy diaphragm.  

Looking to see if this would cause the symptoms I'm having before separating each carb to get to the Air Cut Off valves.

Thanks,

[mkaser26]

Oh and no pods. stock air filter. stock exhaust.

[TOOLS1]

If the diaphragms is torn, it might cause a vacuum leak. A lot of people plug the aircut valves with a little piece of rubber put in place of the O-ring. However you will need to have valves with good diaphragms. Also as dirty as those carbs look, your pilot circuits could be plugged. You must remove the jets to clean them.
TOOLS