Before we can truly appreciate Harley’s ageless wonder and its half-century of winning and losing, we must hit the way-back button all the way to 1968 and the annual meeting of the American Motorcyclist Association’s competition committee.

They had a problem. For 30-plus years, the AMA’s national championship had been contested by bikes powered by side-valve 750s or OHV 500s. The rivals were roughly equal in performance, were the sporting models of their day, and were what Harley-Davidson, Indian, and the English importers had to sell. The world’s economy was in ruins and the sport was nearly dead; and anyway, this equivalency formula had provided years of close and fair racing.

But that was then. Now—in 1968, that is—the 750 side valves and OHV 500s no longer duked it out at the top of the heap.

Therefore, the committee voted for production bikes, made in fleets of 200 or more, limited in modifications suitable for racing.

The English were ready, with a variety of sporting 650 twins.

The Americans, that is Harley- Davidson were not. Their challenge to the Brits’ 650s was the 883cc Sportster, and anyway, the Motor Company was in financial trouble.

By lucky chance, that 1934 formula had an exception: an open class for TT, which was supposed to attract the big twin back then. In 1968, H-D had a stripped Sportster, the XLR.

The racing department did what it could. It developed a destroked, to 747cc, version of the XLR, fitted with larger valves, magneto ignition, and a single Tillotson carburetor.

It’s worth noting here that Harley did not make all its racing parts; it made the engines and designed the frames, but ordered frames and the fiberglass tank and seat (and fairings for the roadrace XRTT) from reliable suppliers, and used top-quality suspension, as in Ceriani forks and Girling shocks, then it assembled and tested the finished machines, to be sold to the public through the H-D dealer network. “Race what you sell and sell what you race” would be the slogan today.

One of the purest motorcycle forms ever produced, the Harley-Davidson XR-750 is also the winningest racing motorcycle, thanks to its long competition life.

Oh, and the Harley racers had to look like Harleys.

The new rules—750 four-strokes for miles, half-miles, TTs, and road races; 250cc singles for short track— went into effect in 1969.

Harley-Davidson wasn’t there, not having built all the 200 examples in time.

So, in the lobby of the Houston Astrodome at the opening of the 1970 Grand National season, a production XR-750 was parked.

The engine’s left side case half was stamped “lCl” for competition engine, then the serial number followed by “HO” for 1970, the eighth decade of the 20th century, all in Railroad font, which is tough to copy.

The XR introduced there was as clean, functional, and attractive as any motorcycle ever made, and no one has improved on that profile. That said, next must come the fact that the original XR-750 was a mitigated disaster.

First, disaster. Although H-D had been fitting its big twins with aluminum heads since 1948, the XR used iron heads and barrels, as in the XL series. The reworked version made too much heat, not enough power, and broke down, as witnessed at the 1970 Daytona 200 when all the team bikes dropped out.

Something like 100 iron XRs went out the door, followed by factory bulletins telling the new owners how to improve the handling and reduce heat by reducing power. Sorry, but that’s the truth. They won a few races before the next chapter began.