Somebody asked a similar question on advrider a few weeks ago so I have copied and pasted most of my answer from the one I gave there, I don't have a complete picture but here is an outline.
It might be useful to have a sticky with a list of where foreigners can register, any takers?
It is possible for a foreigner to buy a bike in South Africa or Namibia and travel most of Southern and East Africa from there, I know somebody who went as far as Kenya on a SA registered bike with no carnet.
The same in most SE Asian countries although if you particularly want to go to Vietnam you have to buy the bike there as foreign vehicles are not allowed in but you can take that one out to the rest of the subcontinent.
India you cannot technically buy there but there are ways around it involving it being registered to a local or you can rent.
South America you can buy in some countries, I am not sure which ones and then take it to others, no carnet needed there.
Australia it can be done but I am not sure if all states allow it, bloody expensive at the moment as well.
The UK and I believe other European countries allow foreign ownership, finding insurance in the UK is not easy but possible, once in Europe you can travel to Central and Eastern Europe from there.
RTW on native bikes? - ADVrider
If gaffer tape doesn't fix it then you haven't used enough tape