Nine Degrees Above Zero

With today's gas that "expects" it will be used in a fuel injection system, starting with a carburetor is funny in deep cold.

Yours is working perfectly but if it gets 10 below or more, you gotta give it 3 or more shots then wait up to 30 seconds for the butane to vaporize.

Low VOC (lighter distillate proportions) gasoline doesn't WANT to evaporate.
But that's necessary in a carb application.
Good little slantys want to run forever.
My 72 started on hot summer days with a slight detonation knock on the first crank, from yesterday's last cylinder charge.