Stop ? just cause it gets cold ?
You've gotta be kiddin !
Worst I've ever seen is about -30 with wind chill (not factoring the speed of the 'ped into that) and howling winds blowing big fat fluffy flakes the whole time, and that after hacking about 1/2 of ice off the controls to get the 'ped started.
Hail Tomos, it started, even then, within 3 kicks - I kid you not.
I've heard some of the 'peds with a battery in them don't do too well in subzero, but anything with a kickstart should be ok.
First off, you have to have a snowmobile suit, there really isn't any comparison, and it helps a lot, I wear a us army field jacket liner underneath, then the motorcross armor and then the suit.
(The armor is real small, got a heck of a discount on it cause they couldn't find anyone else that it would fit on, and the snowmobile suit is 2 sizes large to find the layers under.)
A full face helmet works, if you don't mind a blinding sinus headache when ya come inside, heh, but my pref is open-face with a (phonetic) bach-a-lava, or whatever the hell they call that thing, or a ski mask..
(Take if off before you go into 7-11 tho, or don't wonder why everyone screams and runs, hehehe)..and a set of goggles.
Sure, you look like a bug that way, but then so do paintball fanatics, you can use one of those masks too, if ya want.
Gloves are a must, but there are many lines of very good ones, so that's not a problem, and either thermal socks, or those nice ones they sell out of hunting catalogs that have a battery operated warming system (they still sell those ? I dunno, but they are real nice), and heavy boots with deep tread are reccommended.
As for tire chains, as someone mentioned, what's worked for me is hitting a garden store and buying a whole crapload of flat-linked ornamental brass chain, you can wrap it around the tires without chewing them up because it's soft brass, and hook it up with S-hooks.
(This may throw off wheel balance a little, after a while, mind)
If your insane enough to not back off the throttle, those chains, once you cut a couple pieces to size, only last about 2 days worth of riding, but if you take it easier they'll go 3-4.
Still, have some spare chain, some more S-hooks, and a cutter in your saddlebags just in case.
Riding a 'ped in 3 feet of ice, snow and slush is great fun, especially since due to it's lower ground pressure, you are unlikely to get bogged.
It's the one time you can ride around laughing at car owners, all of whom seem to be rather, umm, stuck. (oh and ain't THAT a pity..hahaha)
Word of warning tho, if you are going anywhere near one of those salt-thrower equipped trucks, stop and take cover as he passes, in case he decides not to turn the thrower off when he passes you - I've had my clock cleaned right off the 'ped that way once.
Happy motorin !