Great explanation - now makes full sense.
Your assumption at the end is insightful - could it be the idle jet affecting the start/choke you mention vs main?
Clearly you are getting a lot more pull in the upper 1/3 of the rev range than you had.
Funny - mine as well - first kick - choke spring little too tight/strong so it wont stay out on its own - but bike doesn't need it - pretty much goes straight to idel at 55 degree outdoor temps (hey - I am in Cali - that's our version of cold).
Also experiencing what sounds like similar tuning needs - nice pull (even with my side car weighing it down) off the line - remarkably torky - but just no guts above the 2/3 RPM level.
Suspect my main is too rich based on your posts and Jack's tuning input. Due to run the plug test - but working on making the bike more sound over all before focusing there.