Motorcycle insurance in Southeast Asia

Short answer: travel insurance that you purchase beforehand from a reputable organization can cover you in case of accident on a two-wheeled vehicle (and possibly in case of loss).

Long answer: Tons of posts and travel forums are dedicated to this issue, and I spent hours reading them both before and during my five months in SE Asia. The best way to make sure you're covered is to read your insurance documentation and then speak directly with an agent. I used WorldNomads (here's their page on SE Asia/motorbikes) and knew beforehand that they wouldn't have my back because they require you to have a motorcycle license in order to be covered in case of an accident. (Interestingly, in some states in the United States your car license allows you to operate a two-wheeled vehicle under a certain number of CC's, but this varies by state and still has to be ratified by your insurance company.)

Even deeper into the fine print you'll find that acquiring all the necessary documents for coverage can become a paperwork obstacle course; for example, when items get stolen you need an official police report - good luck getting one of those in rural Laos (good luck finding the official police in rural Laos, for that matter). However, dealing with an internationally recognized company is still a much better bet than whatever "insurance" you'll find at a roadside scooter rental operation in Thailand, Vietnam, etc (unfortunately that doesn't necessarily mean they'll let you bypass their own overpriced/useless option). And I second Malvolio's rec for evacuation/expatriation coverage.

One last note: while your native license may be the key to getting insurance agency coverage, SE Asian countries have their own rules as to what you need to legally zip around their roads. I know in Vietnam you're technically required to have a Vietnamese license, although if you get caught and you're just there on a tourist visa you can probably get by with a bribe and a smile.

Loss of the bike?

I have never heard of such a thing in thing in Southeast Asia, nor would it be a good idea. Vietnam has a sketchily enforced limit on the displacement of motorcycles, around 150cc, so any bikes you would buy or rent are either little Hondas like the Dream and the Wave, or Chinese-made imitations. They can be had for $400 or less.

It's a good rule to never insure yourself against a loss you can afford to bear yourself, and if you cannot live with a $400 loss, you probably should not be traveling.

Insurance yourself against injury? Traveler's insurance will cover that, but check with your carrier if you will need a "high-risk activity" rider (a "rider" in insurance terms is coverage for particular risk that must be specially purchased -- nothing to do with your being a rider of a motorcycle). If you are going to ride, definitely definitely definitely get evacuation insurance: if you are in a serious accident, you don't want to be treated in country, and you don't even want to know what evacuation to Thailand will cost.

Insurance against liability? I have never heard of that but because of the sad economic state of the country, you can probably afford to pay for any amount of injury you can inflict, out of pocket.