Spent time in Alaska. Cold is one thing, -30 and below is another. When in AK, below -35 strange things start happening to metal, plastic, and rubber turns to rock. Materials shrink at different rates, molecular structures shange, lubricants turn to cement, metals crystalize and become brittle. In those climates, stores sell lubes and such made for low temps.
If it was me, and it aint, if I was gonna ride in that kind of cold, I'd keep the bike inside until ride time, and if parking for ashort time, I'd leave it running or park it inside to keep the engine from cooling and heating that radically; I don't think China Girls metalurgy is what you find in a quality snowmobile built for that use. And lube everything with a very light oil or light grease formulated for Artic use. Bye the way block and tank heaters are not only to keep oil thin, they are also to keep the core metal in the engine at a temperature not likely to shatter pistons, rods, and bearing caps when starting at -50. Even batteries have to be kept heated at those levels to work, old DieHard TV commercials notwithstanding.
Riding bikes at -40? BRRRRRRRRRRR!!