Motorcycle Insurance for Touring
If you're a UK resident, with a UK registered motorbike, I wouldn't expect to obtain long-term motorcycle insurance from a UK company for anywhere further a field than Europe. My current UK motorbike insurance also gives me up to 30 days in Europe as part of my yearly insurance for UK roads. Chris Scott suggests that you can probably get insurance for as far east as Turkey and South to Morocco and Tunisia. He also states that if a UK company does offer you motorbike insurance for further than this it may be that they don't fully understand your needs or they just want your premium and you probably won't be covered anyway!
From what I've read, it seems that you buy motorcycle insurance as you go and don't be alarmed if you can't buy any at all. You can often buy motor insurance at the border crossing. Many parts of the world do not have as developed insurance industries as the in the UK. Whilst a little unnerving, I also find this concept rather refreshing.
I've also read of other riders, stopped at check points, providing official looking documents (with lots of stamps and signatures) as proof of insurance regardless of whether it's an insurance document. Would you know what a UK insurance certificate looked like if you were a Bolivian police officer?
However, 2Insure4Less are a good starting point for searching for motor insurance.
The downside of an undeveloped insurance industry is that should you cause an accident out there it could take a lot of time and money to resolve. You may be imprisoned and your motorbike impounded. I don't have any answers for this other than ride in good weather, daylight and make sure you are healthy, well rested and alert. Another piece of advice I was given was to carry a small amount of local currency in an easy to reach pocket. If you're involved in an accident and the locals are kicking up a fuss, offer them the money, tell them you are with the [Your National] consulate and ride off (if you can). I don't know how I feel about this approach but thought I'd pass it on. I guess you can make a judgment based on your circumstances.
I've only looked into motor insurance for USA, Mexico, Central and South America. For Temporary motor insurance for USA you can use an insurer called Dairyland through a broker called Motorcycle Services (also called Motorcycle Express). You have to send the application to the states at least 45 days before you want the policy to start. They send you the policy certificate by email. Very helpful people. For Mexico, Central and South America you buy insurance as you go (generally at borders). I'll update my blog with progress and any difficulties in this area.


