Motorcycle Options:  Thai people require an ID card plus a copy of their house registration paper to register a vehicle in their own name. Foreigners need the "same" - confirmation of ID and local address. This means a copy of your passport and a letter from your local immigration office or consul confirming your Thailand address. To get this, you should have a 3-month non-immigrant visa, suggesting that you live in Thailand. However this rule is not enforced all the time and people on tourist visas do get bikes registered, provided they have some confirmation of Thai address. Note too, that the originals must be presented at the vehicle licensing office, not photocopies.
 It is possible to take a vehicle out of the country, if it does not belong to you, but is in the name of another person. To do this you must have permission from the vehicle owner to export it. There is a standard form you can use for this. Click here to see what it looks like. Under this system then you can buy a motorcycle in another person's name still ride it out "overseas." To do this, you must have signed copies of the real owner's valid / current (not expired) Thai ID card and Thai house registration.
This normally works, however it is open to the duty Customs officer's personal discretion; and if you have a communication problem or a personality clash (I have good experience of this) it might not go down so well. For foreign riders with Thai registered bikes this is a not uncommon problem on the border. One of the Customs concern is that the motorcycle may be stolen, or may not be returned. So, be patient, tolerant and understanding of the system.
Don't believe the shop, where you buy the bike, that you only need a receipt & / or a photocopy of the bike registration. You won't get out of the country, and it is no fun riding all the way to the border, to discover that you've wasted your time and money & probably stuffed up your holiday.
Thai Bike Prices: to get an idea buy some Thai bike magazines. The best 2 bike mags are Motocross and Performance Bike. The most reputable bike shops in Bangkok to consider are Red Baron, Siam Speedway and Dirt Shop. As a rough guide, expect to pay at least 80,000 baht for a 250cc - 400cc bike. Cheaper than this and you will soon be sinking money into the bike, to get it up to scratch and reliable enough to tour long distances in the heat. 400cc plus recent models - less than 4 years old - should start from 110,000 baht. 
LICENCE / REGISTERING A BIG BIKE IN THAILAND: Big bike rego in Thailand is a very touchy subject. You see a lot of bikes up-country without a number plate, but without a plate your bike is technically illegal; & if you’re in Bkk / Pattaya / Phuket, the police will give you a hard time. Elsewhere up-country it does not seem to be such a problem, but you normally can’t leave the country on an unregistered motorcycle.
If the bike is not already legally registered, expect to pay 50 -70,000 baht for a licence plate & have to wait a 4-6 weeks for the ownership book to come through. If you’re buying a bike, try to get one already with a plate, or buy from a reputable shop that is selling bikes with plates already. If you deal with a shop that is not selling bikes with plates, they are probably not right inside the system dealing with bike rego. And after you have plonked down your money for the promised bike rego, they may well encounter problems beyond their control & either ask for more money or delays in supplying the rego.
Most of the books are recycled books with the bike having engine & frame numbers re-stamped to match up with an old book / bike that was previously registered. If you buy a bike that is not registered record the engine & frame number to keep an exact record of your bike model for ordering parts later on when it does not have the same engine & frame number.   There are dealers who claim their books are new and not recycled, how they manage this I don’t know. The rego crunch always comes when you either need to renew your bike rego or transfer the place of registration &/or ownership. Most of the time it works, but there are cases where the renewal / transfer is not approved. Sometimes this is because the bike might registered as 20 or 30 years old but it is only a few years old, the number of cylinders or capacity are wrong. These are all little traps you need to watch out for when buying a registered bike. If you never sell the bike or change the place of registration you might never have a problem, but if you’re buying, then check it all closely if you are going to change the place of registration from one province to another. Your local officials might like to be official & pay attention to what you’ve supposedly got.
Read some GT Rider Board Bike Rego experiences and comments:
Big Bike Registration Confusion
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