I agree winter biking in Scandinavia can be fun, but the temperatures here are usually nowhere near as cold as in the eastern part of Russia. Siberia is among the coldest places on Earth in midwinter, so its a whole different ballgame.

The preparations we do here in Scandinavia would probably be insufficient for that region, I think. You will have to find the proper solutions to deal with that kind of cold, or your journey won´t be enjoyable (unless you like torturing yourself!) and it could also be very dangerous.

So especially if you´re not used to winter riding, and come from a warm climate, I´d advice to think about it very carefully. It may be do-able, somehow, but it is a huge challenge, and not to be underestimated.

In my opinion an 800cc bike is also a bit heavy for riding on snow and ice. On the upside, you should be able to find proper tyres for it, and can add studs to them. The thread pattern should be almost like an enduro or motocross tyre, so that wet snow wont block it so easily. And then how you can manage tyre life (not forgetting the studs) when riding partly on open tarmac, is yet another challenge.

Dave, Pecha does have a point. I have thought quite a bit about your dream. Go for it! But do choose the proper gear to do it with...
Have a look at these clips from Ural factory:
Ural | Russian Motorcycles

Check the snow clip - that's a "summer" clip to us...
URal | Movies

This is the military issue:
YouTube - Ural Sidecar Motorcycle Military Demo

Hard used sidecar:
YouTube - Ural Sidecar Урал зимой

Mud and mountain:
YouTube - Dnepr & BMW mud in mountain ural sidecar off road

Of cause you can do it on a solo - but it is shear madness. I ride a solo, but I communte down-town in heavy traffic. When you find yourself facing 10" of snow... a solo kind of chooses to get -stuck-. Skiis will help a lot (see recommended clips in previous reply) - but... is not enough.

Remember -you will have to carry a lot of petrol... full winter equippment (tent, sleepingbag, change of clothes, snowspade/spade, etc). The shear weight of the basic stuff you need to survice at -40'C (-40'F) and down will make a solo not possible to handle in "deep" snow. The traction you need can only be delivered by tires like Trelleborg Army Special or Winter Friction (knobby but not as knobby as motorcross tires) with long studds... and long studds will not make it possible to ride on hard ground like asphalt... you need quick possible tire-changes... i.e. you need a sidecar preferably with a powered sidecar wheel (like Ural, Djepner, Chang Jiang, i.e. BMW WW II).
Then you need a proper generator/alternator - the crap mounted on bikes (at least older) will not do at all - you need a 55-120A standard car alternator. You can hook it up via the crank and pullies, or a lawnmower engine.
http://www.webstruktur.com/svea/board/artik/bilgen.html
http://www.webstruktur.com/svea/board/artik/mont_bilgen.html
An eberspaecher is also a good idea - there are some really small once available today.

And perhaps most important - do not go on a trip such as this on your own. It is far better to be a group; there is safety in numbers.

It is possible to do this trip on your bike, but I would strongly recommend that you do not. An air-coold is far better to use than a water-cooled since you may be hitting -50'C to -70'C night tempratures. I saw that Ural says that their bike is operational down to -40'C/'F - using Omega Lubrication you will be able to push this down a bit further, perhaps down to -50'C.

You could do a "safe" test by driving the Ice-Road in Canada(?) - if you can ride that road (which is well kept) at their temps of about -43'C; then you have a good grasp if you could embark on a trip crossing Russia -

__________________
Drive Safely,
Albert