How do you get a title for a 1975 motorcycle when it doesn't have one?

It depends on what state you are in. You should add this info to your question.

Go to your local DMV and ask them what process they have in place to get you title.

They will inspect the bike to confirm the VIN.

They will input the VIN into the computer system to find out who the last registered owner was,

Then you will need to buy this information, and send a certified letter to the person to get them to send the title to you or a notirized Bill of Sale, which you will then send to DMV

They will then put the bike in your name.

All past titles are recorded, so it is definitely not 'lost' as everyone thinks it is- it will just take time to find out who it is registered to etc.

I had this experience with a truck. You cant get it back. Unless it turns up.

As long as you have a legitimate 'bill of sale' you can go to your DMV and explain the situation. Possession is after all 9/10ths of the law. There is a small fee (at least in my state) to do a 'lost title search' but other than that you should be fine. It isn't so much the 'age' of the vehicle as the street value. They aren't going to believe you when you drive up with a 2009 Harley Davidson that the guy you bought it from can't find the title... lol. A bike from 1975? You're going to be okay.

We just repo-d a car from New York. Even though it had a lien, the state of New York sends the title to the customer. We have spent days trying to get a duplicate title. I would say depending on the state where the MC was titled, good luck or not...

Just ship the bike over to my place.
I'll handle the rest.

Do it.
NOW.