VIN # for 110cc pocket bikes

That's the engine number. Every frame has a number. On a motorcycle them numbers together and a bill of sale, should get it registerd. All 9 of my bikes came with an ownership paper, from China.
If your putting an engine in a different frame. You get your numbers and bill of sale, and go to the DMV, and tell them the owner before lost it. They will give you a form. Can you contact the person you bought it from and they can sign it??
My twin boys jammed my printer w/ paper, but if you could get a real or color copy of someone elses ownership papers, cut white paper pieces to block out the vin number spaces or what ever. Take your copy, fill it in with your numbers and take everything to the DMV.
Since you changed engines you have re-register the bike and get new ownership papers.
I got this 750 Honda 1971, best engine ever 67 hp. These guys put the engine into a new frame, they gave it to me real cheap, its was beautiful like new. I took all the papers it had to the DMV, and had to turn the bike over to Hwy Patrol for inspection, and I did. The guys I got it from thru a friend, said it will register, so I waited. The HP called me 1 week later to come pick up the bike. So, I went, they told me the original bike was never paid off, but since I bought the engine from them and I put it in another frame it was Legal, and I was sweating Bullets. That's what the people I bought it from told me to say. It worked out great.
The moral of the story, the more you say at the DMV, the more you cut your own throat. Better to play it stupid, and let them tell you what to do.