Hi volit,
Obviously the main part, finding a bike on ebay, Autotrader, local paper, dealers etc are similar to most other countries.
Once you find the bike you want to buy, one thing that may be advisable is to get an HPI check. You can do this online for about 20 GBP, and it should tell you if the bike has been registered as an insurance write-off, or has finance owing on it. The check isn't an absolute guarantee that these problems aren't lurking though.
The registration certificate (V5C) is the title and effective proof of ownership. If memory serves, the previous owner puts your details on the form and sends it to the DVLA, and there is a "new keeper" section of the form he gives to you. I remember selling a car to a guy who insisted on watching me put the envelope in the postbox, might be worth doing that to ensure that it is sent. In fact, as the DVLA are notorious for losing documents and denying responsibility, it might be worth using recorded delivery. If all goes well you should receive a new V5C in the mail confirming that you are the new registered keeper.
I'm assuming that the regulations for foreign motorcyclists are the same as for car drivers, ie you have 1 year from when you enter the country to ride on your US licence, before you would have to take CBT and the bike test here.
