It can be a royal PIA!!
Mich did not title/register off-road motorcycles until sometime in the early-mid '90s. I have about half a dozen old dirt bikes....MX'ers, enduro, trail bikes, that I had acquired from private parties over the years before the title/registering was requierd. The bike I trail ride most often is an old CR125, an '82. Am planning to go meet up some folks in another state for a ride this summer. Told me I wad have to get one of their states ORV permits. Ok, no big deal. Here you need one, but you can get them anywhere...just pay the store clerk the $16 and they give you the sticker to put on whatever you want. Then they tell me to be sure to bring my registration, too.

?? no got any!!
Called the 1-800# for the SoS here. Finally got it thru their head that I had purchased these yrs before they were required to be titled/registered from individuals. They said I would need a signed statement from the previous owners that they had sold me the bike. Like ok, lady......I've had some of these bikes for 30yrs and I don't have a clue as to where the seller may be living, if he is still alive and as a matter of fact, I don't even remember most of those sellers names!!!!! She also pointed out that if I did go thru with trying to title/register it now the state would likely want to collect sales tax on the sale and there would be a penalty for not having paid the sales tax at some point in the last 30yrs!!! Her advise was that the state really didn't care as long as I still owned the bike. What some other state would do if I was riding there with no registration or proof of ownership, that would be up to that state.