Many things have been ruled out
Not slipping clutch
Not RPM related at all
Not speed related
Gas is fresh
Air filter clean and new
Only other bit of information is when 40* or colder, she gets fussy to start. Choke is sensitive and giving throttle when really cold she likes to die. That almost seems like running lean and too much air kills her. She has to warm up for a minute before you start playing with the throttle.
However, now that it is warm (50* and above) she starts pretty good without choke and takes right off.
Up to 1/2 throttle she runs great and has tons of power. There really does seem to be that fine line at 1/2 throttle where power suddenly goes away. I've gone a distance with the throttle in the bad zone then slowly rolled back and you can feel that spot where power suddenly comes back.
The bike is a 1992. Sat for maybe 6 years after a PO dropped here and quit riding. Supposedly the shop cleaned the carbs, and if they did probably not a thorough job. She has been ridden every couple weeks since I got her about 9 months ago.
Probably best to pull the carbs and let the experts fix them up. Also I have no idea if the PO did anything to them when he put on a Muzzy exhaust.
....and I see the WIKI says all gas tanks are interchangeable? I wanted a near perfect one in black with red, so I'll start looking.
and here is what she looks like today. Still have to fix the front fairing and maybe add a red stripe to the tank or replace the tank. all tail plastics have been replaced. Motad exhaust. Engine bars and rear carrier (Renntec) Many other parts were replaced with NOS or at least newer parts.