California does not qualify as cold. :)
My bikes have been fine staying uncovered in an unheated garage in the Toronto or Boston areas (down to -30C). Batteries will do fine but watch for tires and such.
How long has the bike sit idle? Could be dead completely.
It happened to a Tesla Roadster back in the days when someone did the same thing. Had to replace the pack.
Let me correct you here since I sourced those :D
They're industrial grade, but while they last a lot longer in cars, they don't see the kind of vibrations/abuse a dirtbike submits them to.
*pouts*
For good reasons; it can be extremely dangerous both in the act itself and in the end product you create.
Unless you have a sandpit at home, you would not be able to extinguish the fire it may create.
Shit is no joke.