To close this out on a positive note, it's fixed no more backfire/afterfire
Thanks to everybody with advice.
It seems to have been the header bolts that were slightly loose....
Installed a Screamin Eagle , tightened everything down and sealed the header to pipe with exhaust goo.
Did the carb adjustments per Lancer's post, did the white spacer mod for the 8th time and voila, sounds awesome runs great and no more bangs.
Main jet: Dyna 144 Pilot #55 1.5 Turns on the pilot screw and 1 #4 washer on the needle.
Thank you Thank you Thank you