Buying a Bike in Hong Kong and traveling S/E Asia

[Esquire]

Hey Guys,

I have been combing the forums for a while now trying to answer all the questions I have to a trip I am planning for August 2013.

The Trip i am planning is roughly Hanoi, Vietnam > head south West through to Laos > Head South Through Laos > Enter Thailand, head initially north to Chiang Mai > Head south West through Thailand to the Cambodian Border > Through Cambodia seeing the sights to Ho Chi Min City > ride north (a la Top Gear) back to Hanoi.

I have put 3-4 months aside for the trip, and by itself it is not to difficult, that said my sister lives in Hong Kong and I will see her first. Ideally I would love to buy a bike around there and take it south to Hanoi, and ideally I would love to be able to get a bigger bike than the 175cc owing partly to me being a big guy but that said I want a bike thats not going to be an issue to fix along the way.

The first major question is if it is even possible to buy and get a bike out of China or if it is way too much hassle.

Any either way what do you think is the best bike for that sort of trip?

Cheers,
Carl