Need advice re 1983 Kawasaki KZ550 that idles high

Have a 1983 Kawasaki Spectre KZ550 that has only 1400 original miles. Carbs were rebuilt by wiredgeorge a few years ago down in TX. Bike has been in storage for last few years (winterized properly). Put in a new Yuasa battery, new petcock, fuel, and fired up the bike a few days ago. The idle is hovering around 4000 - 5000 rpms at startup. I can open the choke to just about halfway (were the detent is in the choke closure) and it will reduce to about 3000 rpms. If I open the choke any more, even when at operating temperature, the bike will cough and die. Starts right back up again, but after closing down choke a bit. Bike rides fine and has never perfect compression in all 4 cylinders (given the extremely low mileage for a 34 year old bike). I have not synced the carbs as I do not have a Motorcycle Vacuum Carburetor Synchronizer. Further, the idle set screw seems to have no effect on the idle. Last, throttle cable grip play is adjusted properly to 2-3mm. Any suggestions?

They all do that, the earlier slide carb 550's too.

Just avoid leaving on full choke when cold and move off as soon as started on half choke. Knock off the choke as soon as you can. The 550's are all grumpy when cold, after a mile it will wake up. Thrashing a cold engine is best avoided.

Can anyone give me advice on how to set the idle set screw - hot/cold, as it seems to have no effect once the bike is started and warmed up on the idle speed. Also, does turning it clockwise supposed to increase or decrease idle speed?

Backing out the screw reduces the idle.

Not sure of you model but KZ550 carbs have a high idle set screw. Loudvx has a page that details how you can put an adjustment knob on it instead of needing to wrench. Seasonally the idle RPM blasts high on full choke. It's an ambient temperature issue. Proper high idle in summer will die in the winter. Proper high idle set in colder temps will cause it to scream up to 6k rpm in summer. The knob is a great way to adjust high idle to ambient temp changes. Also like others have said, most 550s are cold blooded and will need to operate the first few minutes with choke on or they will spit sputter and die. Once warmed up this is not an issue. R

The Lou mod is for the older slide carbs IIRC,

Modifying the enrichment circuit 'aka choke' on CV carbs for seasonal variations might be more involved.

I've had a few kawi 550's - they all do it.