Re: 1951 Schwinn Panther - maybe?
Well, its not a skiptooth. From what silverbear said, looks like a Panther. Its in amazing condition for being a 1951. I would guess as someone else suggested that the worn spot on the frame is from the bottom bracket being loose. Those aren't too hard to adjust, but you may want to just take it apart and inspect/grease the entire assembly. The chain looks a little kinked, and after years of sitting around and rusting, I would suggest replacement. As far as motorizing, there is no law against it. Its yours to do with as you wish. If it were mine, I'd be going all out with a big 4 stroke, somewhere in the 79cc to 100cc vicinity, and an in-frame gas tank with fat tires and any vintage accessories I could find that went with that style of bike, such as headlights, luggage rack, etc. But that's just me. Either way its a beautiful bike.