Thanks to everyone for the quick responses! Wow!
I found the problem. I am embarrassed but I will tell you.
I do have a regular battery charger with a 2 amp setting, but it takes too long to recycle...e.g. run the starter...battery runs down, put the charger on...wait many hours...repeat process. Too inefficient for troubleshooting.
The bike gas tank is setting on a table next to the bike with a piece of automotive fuel line connecting it to the bike.
I know there are mixed opinions on jump starting a bike from a car battery, but I decided to do it and it worked out fine. Starter did not sound any different than it usually does. I don't know if it could have damaged the bike battery...that would be the only thing...time will tell on that. It is an old battery anyway so I am not overly concerned.
After connecting cables from the car to the bike, the starter turned fine as it did off of the bike battery alone, but both cylinders still not firing at all. I adjusted the carb sych screw while running the starter motor to make at least a course adjustment. I replaced all 4 brand new plugs and then examined the ones I removed...damn they were all dry.
Without any further suspense, the problem turned out to be that the gas tank switch was on the regular tank, not the reserve. When I replaced the gas from last season, the tank was filled to just above the reserve setting. That's why it ran well at first, eventually quit and would not run again. Dumb a$$ mistake I know, but fortunately easily corrected. After switching to reserve the bike started immediately and ran smoothly in the usual fashion. I synched the carbs using the home made vacuum gauge as I have done in the past. Checked for coolant leaks and none were detected.
After some rest and a shower, I am going to put it all back together and hopefully (if weather holds out), go for a ride later today.
Thanks again for the quick responses.
'06 Shadow Spirit VT750DC, Candy Orange