In the end it was a good decision to buy old Honda Win motorbikes. Not because they are very durable (they aren't). They are cheap and spare parts are available everywhere in south east asia. Commons problems where chains which came off frequently and some sparks which had to be replaced.
My bike had some big troubles with its carburator caused by some dirty gas I bought somewhere on the street.
Simon lost his exhaust pipe, because of the lack of inert gas welding equipment in Lao, he bought a chinese rip off. It didn't really fit, so he lost it again. But this time we found someone with good equipment who crafted a fixture.