62,
Nothing on the VIN sticker about site of assembly.
I found an old thread response I gave to someone in Saskatoon a while back who was also importing an xs650.
Here it is, most of the info is in there.
As it so happens, I bought mine there a couple of years ago and imported it into Manitoba. No big hassles so long as you have all your ducks in a row. I didn't ride mine back, I trailered it but the process is similar.
Firstly, make sure you have a clear title to the bike, or else you can only bring it back as "salvage", usually meaning it can never be registered to ride on the road.
Next, check for any safety recalls on the year and model. Those HAVE to be fixed (with proof thereof) before it goes across the border. I know, it sounds silly on a 30 year old bike, but thems the rules. I was lucky, mine was a 1977 with no recalls. Had it been a 78, there was a recall on leaky petcocks. You can just Google the recall list, or check the Yamaha website.
Because the bike is older than 15 years, you don't have to worry about all the paper work regarding pollution equipment checks.
Your HAVE to notify the American side of the border crossing you intend to bring the bike back across at least 72 hours before hand. They will want a copy of the title. You used to have to fax it to them, but you can now email them a jpeg of the title. I also included a shot of the serial number sticker on the steering head just to make sure. They don't need a bill of sale, they are only interested in the title. If all this is in place, you will spent only about 15 minutes at the American side. Basically they just compare the serial number on the title to the serial number on your bike and you are good to go. I don't even think there is any fee for this and I don't recall if there is a special form.
Once at the Canadian border, there will be more paper work. They will want to see the bill of sale and title. There is a lengthy yellow form regarding manufacturer, model, year, recalls, mileage, whether it is allowed to be imported, etc. You will need a copy of this form (at least here in Manitoba) before you can fully register the bike.
You will have to pay either the PST or GST, can't remember which. No duty on older bikes. If you only payed one of the taxes, you pay the other one when the bike is fully registered.
In Manitoba, the vehicle has to pass a safety test (brakes, lights, horn, etc) before it can be fully registered. To my surprise, they allowed the MPH speedometer for that year. I assumed that I would have needed a Kilometer speedo. Check things ahead of time such a brake lining thickness, headlight aim, drum and disk thickness, high and low beams, brake lights, signal lights, and sometimes fenders are even required. You can save a second trip (and fee) if you make sure all is well before getting the safety certificate. BTW, you can do all of this with a temporary registration.
Hope that answers most of your questions, if not, fire away. If I think of anything else, I will post.
It took me less than an hour to get through both the American and Canadian customs offices, just make sure you have all your paper work.