1968 Li125 S
Back in about 1987 I bought a small frame bike and started work on it immediately. I got it up and running after spending about $150 on it, went to the DMV to register it, and found it was stolen. The owner was very happy as it was stolen in a non-running condition, but I was out $150! From that point on whenever I start a new project the first thing I'll do is register the bike. In California it is pretty easy to do on older bikes because if they haven't been registered for a while the DMV doesn't know they exist. For this bike I had to fill out a couple of forms (links to DMV pdf files):
The certificate of non-operation is not totally necessary but it helps if you want to register the vehicle in your name and then work on it for a few months/years. The bike must be inspected by "a peace officer" or taken to a CHP center to verify the VIN# and engine# on the statement of the facts form. I called my local police station and they actually came out and verified the frame and engine numbers in my apartment! Once this was complete I went to the DMV and they handed me a new license plate with current registration (a new white type one, not a black plate). I think the whole process cost about $80.