TOPIC:

1981 GPz550 stock engine. Refreshed top end. Confirmed cleaned carbs. Pods because I don't want to do the airbox dance again. I saw through the pilot jets with my own eyes.

Battery is confirmed good.

Confirmed ignition by pulling 1 and 4 plugs, laying plug on cylinder head and seeing spark.

Confirmed fuel in bowls by cracking each screw on bottom of bowl. Fuel flows out.

Spins but will not do the first start. Choke on, choke off. No difference.

Tried a short spray of starting fluid on pods. #3 cylinder popped back a bit twice, but other than that, dead.
Spins over well.

Suggestions welcome.

TIA

Have you checked  you have full battery voltage to the coils? A spark from a plug laying on the head may not spark under compression when fitted if voltage to coil is low. 

Hate to admit this here, but when I tried starting my "refreshed" Z1 I got sort of a backfire thru the airbox and no start, but had spark with plug laying on head.  Turns out I had the coil trigger wires from the generic dyna ignition reversed. Switched them and it started right up.  (In my defense, the colors of the trigger wires on the conversion are white for 1-4 and black for 2-3; and I got them mixed up : wires from original points were black for 1-4 and green for 2-3).  It was still a noob error.         Maybe that happened to yours?  If so it's an easy fix !

I talked to my mechanic who suggested the same. Going for an inspection now.

Do you happen to know what the battery voltage is supposed to be to the coils?

I confirmed that the coils are connected properly. I also swapped to another set of functioning on a second bike carbs. Still spins like crazy and no start even on a shot of ether.

The coils should be getting as close to full battery voltage as possible,  I added the "wired george relay" to mine.  See Wookie's post from april 2022 titled "ignition by-pass relay - W"

No joy

No power to coils, or power to coils but no fire?

Cam or ignition time may be 180 degrees out.  Don't ask me how I know...

Ignition can be checked by switching coil leads.  Cam timing is best checked with the plug out, watching visually to make sure 1-4 is at the top of the stroke before you verify the cam timing marks are correct.

Another vote for checking the cam timing. Is there suction at the carb? Have you tried a shot of ether to rule out a fuel problem? 

After a start attemt Check if the plugs are wet. If they are dry and this sounds silly but did you remember to set the mixturescrews out. Check compression and as already mentioned check timing.