Documentation is important in establishing the provenance and history of your bike.

Old receipts are important for several reasons. First, they establish a provenance for the motorcycle, showing that it existed at some past date when a prior owner bought a new tire for it. It was a running bike then and that helps to prove its a "real" bike and not a made-up one. A made-up bike would not have the value of a real bike.

Next, documentation helps to establish the story for your motorcycle. I have one bike in my collection that went to Africa to a British White Hunter or guide. It has the original log book which documents this colorful history. Documents add to the story and the story adds to the bike.

Never surrender an original title without keeping a photocopy. Much history is on an old certificate of title which the State will kindly shred for you when you register your motorcycle. And register it you should. No reputable auction company will accept bikes for sale anymore without a certificate of title. You never know when you will leave this Earth, so be kind to your wife and keep the paperwork up to snuff. "Open" titles are generally trouble for widows, and if you decide to sell it, your new buyer will be happier to have clean paperwork. The more expensive the bike, the more important it is to keep up the documentation. Club certificates of authenticity are good to have, as are copies of the works build information. They give you details to look for or to build toward if you are restoring. I personally don't think it harms the value if a bike is restored with some differences between its original specs and the restoration. You might add a Bonnikson speedo or luggage panniers which are correct for your year and model because you like their look. These can be undone. There's no particular magic about having exactly the original specifications unless its an extremely famous bike or expensive one.

If your motorcycle has history, getting a snapshot with the original owner next to it is a great idea. Tell the story of your bike. Many times, earlier owners will give you an old photo of the bike they may have kept or let you copy it for your file. I find that you can trade a "today" shot for their old photo.