Will someone point me to the correct site for information about the registering or lack off for a 50 cc scooter or moped.

Cheers

You can register a 50cc scooter, like any other engine size, at the Department of Land Transport. Most 50cc scooters you “currently” can find in Thailand are powered by a two-stroke engine, trying to register a two-stroke engine is extremely difficult. Also with the strict Thai emission rules trying to register a modern 50cc 4-stroke scooter is not easy. First the scooter needs to pass the Thai emission standard, testing exhaust emission costs more than 30,000 THB.

Also 50cc has no legal benefits, in Thailand everybody younger than 18 years can ride a scooter (with an engine size not exceeding 110cc) without a drivers license.

With the extra cost of 30,000 THB for the emission testing most people who are looking for a cheap scooter buy a 110cc from one of the leading manufacturers.

As registering a 50cc scooter is not different as any other motor vehicle you can find some additional information here Motorcycle Registration

OK the reason I asked is because I thought I read somewhere that scooters under 50 cc could not be registered an can only be ridden in sois and not on streets.