I am wanting to build my own motorbike using old motorbike parts from imported bikes. What is the deal with getting it registered when it is made from second hand parts?

The deal is you are going to have a very hard time. Has been discussed on bike forum. It would be nice to ship a harley into LOS piece by piece to avoid the customs tax. However, Thai government specifically enacted laws to prevent you from doing that. If you are going to do something like that, it is better to start with the frame of a bike that is registered and has a green book already. Then just add engine and change it in the green book.

Moved to Bike forum.

As Sub said unless you have a existing frame registered to a green book. Impossible.

best is getting a registered bike and playing on it.

I know a guy building a custom 1950's Merc in BKK.

Asked him about getting a book for it - if memory serves he said 250K Baht.

And his family is well connected - VERY well connected.

So ... if you got the coin, and the connections, possible.

Get a frame with a green book and build around that. Usually should do.