But as you can see from my first message in this topic all was ok with:
With spark plug 9.
When the outboard temperature dropped to 5-10ºC / 41-50ºF I just changed main jet to 128 and spark plug to 8.
Never had problems in whatever hard modes I used the scooter no seizes or problems with temperature and spark plug always have nice right color.
Please let me add to my suggestion that go back to your Prehistory, which was pretty textbook.
Warning, I have no personal experience with this:
The T5 filter on your carb raises the height of the intake. The bore of the carb(24g) that it was designed for is different. It will be VERY difficult to jet for smooth acceleration at first throttle.
That go-faster filter/cover is made for 20 or so+ hp bikes, not daily ridden/touring bikes with your level of tune. Its effect is not linear through the rev range, making jetting it all more complicated, as you can see
Don't try to jet around a fixed 2.5 turns out on the mixture screw. The impact of properly adjusting that screw is big. And don't focus on the pilot circuit until you find your correct mj.
By the way, I've never seen a crush washer as crushed as yours!
It's no longer doing its job as a seal there.
"If I were you" I'd base jetting more on a combination of feel, sound, and CHT response vs plug peeks that show a combination of your ride.