At this point, and as many times as I've had the carb off, I can't imagine anything is plugged/dirty there. Tempting to by a new 32mm Mikuni and try that; if I knew where to obtain one that would directly swap.
The power of my leg has diminished at 72 years old ha ha; but kicking the bike over seems to take as much effort as it always did.
I did the compression test two ways; both with several vigorous kicks. Did one at closed throttle which gave me 75psi and then one at wide open throttle which produced 80 psi. I have done compression tests before but, only on old school auto engines, the last being on my 292 Y-block in my 64 F-100, so I have some experience. The gauge I used this time was a loaner from Auto Zone using the 14mm adapter, (don't rememeber the brand).
One of my old timer buddies is coming over this week and we will do some more experimenting with things including removing the exhaust and checking for blockage and maybe we can peek inside to see if the ring is stuck?? This guy is a few years older than me and about 3 times the mechanic who still does all his own work on everything from Harleys, Porsches, cars from the 40's to present day; so hopefully we'll find this issue.
Thanks again for all the good comments and suggestions.

You need 3 things for an engine to run. Spark, fuel, and air. It can be really frustrating to tackle all of them at once, so I like to start with one and work down the list.

Spark: replace the plug, even if it appears good. I've had plugs that fire outside of the engine, but not under compression. I've also gotten new plugs that were junk out of the box. Assuming you have a nice healthy blue spark, check ignition timing. If it all checks out, move on to fuel.

Fuel: The easiest way to diagnose a fuel issue is a small bit of starting fluid in the carb with the throttle open then try to start. Some people dislike starting fluid, but it shouldn't causes damage if you don't use a lot. You could also pour a small amount of premix in the plug hole then kick it over a couple times with the bike OFF before installing the plug and seeing if it will pop. If you get nothing move on to air.

Air: Remove the air filter and kick it over. Remove the exhaust and kick it over. If it pops with the exhaust off, immediately shut it off so you don't damage the engine. With the exhaust still off, use a flashlight to look in the exhaust port with the piston at the bottom of the stroke. Ideally you shouldn't see any scoring on the intake side of the cylinder. Rotate the piston to the top of the stroke and check the exhaust side of the piston for scoring. If everything checks out, do a leak down test to check for air leaks.

This should cover most of your bases.

80psi does sound a bit low to me. Although as others have stated, your results could change due to a number of factors. Does your head have a decompression valve in the second spark plug hole by any chance? If it does, it's possible that it's carboned up and not closing entirely. If you have a decomp and suspect it being an issue, remove it and install an old spark plug in the hole to block it off.

Might be worth checking that the tiny jet in the float bowl isn't blocked.

As someone might have suggested already, have you tried starting with "Easy Start"?

Did i mention flywheel locating key. I guess i have. Determie's timing so it goes bang at the right time. Not just flooded up & need full throttle to start. I'll link my brutal way of clearing its throat one running. I'm coming up 77 so feel your pain haha. I'll find my video's but they're bloody boring & go on at a distance for a while so i'm just referring to the start up & throat clearing on the first one after a long hibernation--me & the bike lol. Mine's a 360 & about the age of yours & based on a "72 trail bike. On second thoughts i'll link the page with my video's so i don't clog up your post. Hope it works. Don't take too much notice of me i'm just woffling. Too much time on my hands & just thinking what you'll need to do when you get yours fired up. Best of luck [& good management].
Ok first video at an earlier time clearing throat.
yamaha-enduros.com/index.php/forums/1972...mpteenth-time#155016
Then how it goes after a clean out & experimenting at a later date.
yamaha-enduros.com/index.php/forums/the-...smooth-out-the-power
 

Thanks to all for your time responding to all my questions about this issue; and I have good news: the bike is starting and running like it should.
I think I had 2 issues that played against each other. After cleaning the carb the first time I must have backed out the throttle adjustment too much and it was probably completely closed, with my friends help, once we got it started I was able to keep it running while he did the adjustment so it would idle properly. I did q couple of laps around the back yard and then it died, I thought what the??; anyway I loosened the gas cap and it started and ran normally. I think the problem there was created by myself when I homebuilt a new gas cap gasket out of neoprene that was way too thick which wouldn't let the tank vent properly.
So the end of this long saga is; it boiled down to 2 fairly simple problems that really had me fooled and heading in all the wrong directions.
Meeting my buddy for a ride this week.
Thanks again for reading and replying to all!

That's good news. Sorry to sound [whats the word] dubious, but not convinced on the gas cap theory & more than happy to be proved wrong. Could prove that point by letting fuel free flow into something for a minute or two & see if it stops. But sure hope she runs well on the ride & pulls a few wheelies.

The old "too thick" gasket got tossed so I can't do a test on my theory; but I did 2 rides this week with no problems, bike ran great. The second ride was about 40 miles offroad with about 4 1/2 miles fairly technical (steep and rocky), intimidating but fun.  The only failure was my front knobby is looking pretty sad, (50 year old original); it got me back luckily. So now I'm on the hunt for a replacement for the original 2.75-21 Dunlop Sports 4 ply, I have a never used Chen Shin for the rear that has been stored in a dark corner for many years, just never needed to install it. After seeing the condition of the front tire after my ride I need some new rubber!

If you haven’t changed your brake shoes do it while you are changing tires it’s dangerous using 50 yr old shoes they can and have delaminated before ask me how I know 

I will check brakes also, thanks.