Pakistan

Mentioned above but in this case I'd be heading north and up the Karakorum Highway (reputedly one of the best roads in the world -- not the surface, mind, the view) and into China over the Khunjerab Pass at 4700m!

There was a time when the troubles in the Swat Valley closed the road but the problem today (July 2010) is that a landslide in January blocked the Hunza river which has become a 25km lake. Whether that lake remains (and you can get ferried across) or whether the dam collapses and the whole area is devastated is anyone's guess.

China

Here's the fun bit. The Chinese don't like foreigners driving foreign vehicles on their roads so you need to enter into a three month paperwork loop to get Chinese registration for your bike and a Chinese licence for yourself. Plus all the paperwork required for you to travel through the various Chinese provinces.

On top of that, the Chinese don't want you roaming around unsupervised so you need an escort. All well and good but you are paying for him, his food, his fuel, his accommodation (and you'll be staying in tourist hotels) etc..

Hmm, several hundred dollars a day. So, best not hang around too long. However, I must travel through the Taklamakan Desert (Taklamakan means, you go in, you never come out). Top!

The 'stans

Here I'm a bit vague but I do know I want to double back down from Kyrgyzstan (the likely exit from China) down into Tajikistan and follow the Pamir Highway, then round the Afghan border up through Uzbekistan and into Khazakhstan and on my way.

Russia

Ukraine

I've not heard of any problems.