81 440 a ltd carb confusion

Checked this afternoon and it has slack so it cant be it.....

Slack does not rule out the cable. If the cable is corroded, dirty, gummed up or frayed, it may hang up sometimes and not let the carbs return immediately to idle. With the engine off, open the throttle all the way, then let go of it. If the throttles close with a "clack," then the cable or cables are probably serviceable, though they should be lubricated anyway. If there is no audible clack, the cable or cables may be hanging up.

tried it with the throttle cable detached from the carb end and ran the throttle manually. no difference.

When you cleaned the carbs, did you carefully run a small wire through ALL of the low speed jets and passages, then spray carb cleaner through each of them and then compressed air to insure that each of them is clear? If not, you may still have some blockage.
If you are certain that they are all clear, then I would place my bet on a very lean mixture, probably from leaky intake manifolds (boots). I know you checked them, but spraying stuff on them only reveals pretty large leaks. If they are hard or have surface cracks or if the carbs are not fully seated and the clamps not snug, there can be enough leakage to cause problems. A sticky timing advancer can cause problems as well.

I will run thru the carbs again to make sure. As far as the advancer, what should I use to un-stick it? I understand that wd-40 is a bad idea.

I use grease on the cam, oil on the shafts and springs.
Steve

Re-cleaned the carbs, ensured a great connection between carb boots and head with Three Bond 1211, lubed the timing advance and checked for stickiness. Checked and replaced copper crush gaskets on exhaust to sure of no leak there. Idles fine but when the throttle is run it hangs at 3500-4000 for about 10 - 15 seconds then drops to idle, so a little better as it would not come back down before. Might it have anything to do with the valve throws?

Well, if all the usual suspect are in good shape, maybe it's something less usual.
Something could be causing one or both of the pistons in the carbs to hang up, or something is causing the throttle shaft to hang up, or maybe the seals on the throttle shafts are shot and leaking.
Maybe aliens...........

Well lets not get silly. It can't be aliens, I wear a tinfoil hat when I work on the bike. They cant read my thoughts :woohoo:

:laugh:

Went out and tired it this morning, drove it for 3 blocks and it when i throttle up to 3500 - 4000 will hang at 3500 - 4000 until i come to a stop and use 1st gear against it. Then when the throttle is turned again to 3500 - 4000 it does it again. Is there some area in the carbs that controls that range or begins at that range that i should be looking at? :S

The transition from one circuit to another is much more influenced by throttle opening than rpm, though they do interact.
Basically, at small opening, say idle to 1/4 throttle or so, the low speed circuit (jets and passages) are doing the bulk of the fuel metering.
From roughly 1/4 - 3/4 throttle, the jet needle is doing the work.
From roughly 3/4 to wide open, the needle jet (main jet) has primary responsibility.

At a small throttle opening, even at 4000rpm, the low speed jets are likely still at work. As they are tiny, they are more dramatically influenced by an air leak than are the bigger jets.

Do your low sped mixture screws have o-rings? if so, they may be dried, cracked or missing.