This is a fully warmed bike, she starts on the 2nd crank pretty reliably, pulls great. Just not sure what this pulsing idle could point to, I am not certain I have the air/fuel/idle adjusted correctly... 

Video: youtube.com/shorts/LM-qwlNhRcQ?feature=share

Thanks for the Vid.
To me it just sounds terribly lean.
Shortest answer i've ever given haha.

Might be the best answer ever! we'll see

Classic lean idle drone sound..... richen up your idle mixture a 1/4 to 1/2 turn, IF it can't be richened enough before getting close to closing the air screw then richen the pilot jet one size (or two sometimes). You want that nice bubble sound
This video shows about what you want.
The later street two strokes (Dt's and the RD's) were leaned out a bit much for me..lol.
Good luck-- Ray

Yep exactly as WRENCH66 says.
Not a 400 but same end result of a good mixture setting.
Yours being so lean at idle [& even higher up above a proper idle].
'i think' you'll need to go up in pilot jet size by quite a bit [or it's almost blocked--something to check first].
On listening to the original video again, it answers to throttle positively, so re-thinking that it's all pilot related.
Have you had the carb right apart, needle jet [emulsion tube] right out to inspect plus check airway to 'that tube' although a blocked airway would make it richer up towards & also when the needle taking over.
The pilot outlet hole to the venturi on the motor side is on an angle & the progression hole is straight up, but both fed by the pilot jet & could get blocked or restricted although unlikely.
Float level not so low the pilot can't find the fuel?.
If [in my opinion] the pilot jet is big enough & sounds about rich enough at 1.5 to 1.75 turns out then turning it right home should just about stall it from richness [if its idling slow enough in ther first place].

With the idle speed so high, my thought is air leak.

Trye that!!.  edit Meant 'True that'!!--I go for hard stuff first lol then find its running out of gas.