If it is not registered - he cannot prove he owns it! So if it is not registered, GOOD LUCK with getting a registration
Canada does not use a "title" system for vehicles. Registration
is documentation of ownership. Selling a vehicle here (from one Canadian to another - at least in BC)) goes like this:
You buy it. I remove my license
plates off it, and I fill in a form conveying ownership to you. That form, which is actually a part of my "previous" registration
is what you take to the motor vehicle place to register it in your name and get YOUR plates issued for it. License
plates belong to the OWNER, not to the car/truck/trailer
So - if it ain't registered, how is he going to convey (potentially non-existent) ownership to you?
All may not be lost, however.
HE can get a serial number search done, to track down the owner previous to him, and THAT person can convey "title" (ownership) to you.
However, since ownership cannot be proven, a bill of sale is really nice piece of paper for use as a .........?
Now- what documentation will your state require for you to register it when you get it there? What will US customs require you have to bring it into the US of A?