From barefoot of the XLForum:
Harley never made any XR frames. They were ALL made by “some outside company.” Nichols Engineering did a bunch, maybe some other places as well. Terry (Knight) may have made the late “factory” frames, I don't know. The very first 'XR' frame was built by Jim Belland, by modifying a Sportster frame. At that time in Class C, aftermarket frames were not allowed. The history of the bike is much more important than trying to say “this is a factory XR.” If it was run by anyone with any chance at all, it's not stock. My dirt frame was a Lawwill discard, it had an inch added to the down tubes and an inch to the top tube. They were all modified … the sharp guys would walk around the pits eyeing each others' stuff, playing head games “Oh, I see you dropped the swingarm pivot a quarter inch. How's that working out”? So unless it was never raced, it's probably not stock. Terry and Mert sold frames. Terry made them, Mert sold them. It was Lawwill-Knight frames, or maybe Knight-Lawwill. Then they went into bicycles with Davey Ijams. Mert was always messing with his stuff - his XR's weighed 260 lbs and he regularly kicked HD ass. As I mentioned, the very first 'XR' frame was built by Jim Belland: Mert and Mark Brelsford ran them. At this time there were lots of people making frames for Triumphs, BSA's, Yamahas, even Kwackers. Trackmaster and Champion are the most famous, but there were others. But for HD, as far as my worthless brain can remember, it was pretty much just from HD. To be honest, nobody liked Harley very much. At least on the west coast, nobody was interested in working with the assholes from Milwaukee. If it hadn't been for Dudley, history would be different. People did stuff for Mert and Mark and Jim in spite of it being Harley-Davidson, not because of. Then around 1974-5-6 Mert (and Terry) started making frames complete rather than just cutting up the stuff from Harley. His first world-beater was an asymetrical design that won 24 3/4 laps of the San Jose mile before the chain jumped the tracks. (I paid $5 for that frame at the dump then sold it for $250 , woo-hoo ! If it's still floating around somewhere, that's a bit of forgotten history.) They struggled with that for half the season then gave up and went back to symmetry. I think it was the next year that Mert and Kenny sealed their own fate by winning the #1 plate as Lawwill-Roberts Racing - with Mert's old XR. They were sponsored by Yamaha. Real racers just can't help themselves. But the Virago was hopeless. The engine turned backwards. You couldn't make it handle. If Dick, Mert and Kenny working together can't makes something handle, it's probably a lost cause. That XR would have been a Lawwill frame. Around this time, if you wanted to go fast, you didn't run factory anything (except cases, I guess.) No HD frame, no HD cams, no HD ignition, no HD rocker arms or pushrods, no Jerry Branch heads. No HD clutch, either. HD was good for the raw materials but other than that, forget it. Even Harley bought Mert's go-fast kits (then they copied them and Willy Werner took the credit but oh well.) Those were really CR Axtell go-fast kits but Mert made it happen so he gets the credit … I wouldn't look down my nose at aftermarket parts. Those were the bikes that won. So. Is it a stock frame? Maybe. But if it is, it wasn't a winner (unless Springer rode it).

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