The 60s were a time when those from “across the pond” had a tremendous impact on many parts of American culture. While it might not be thought of often by the general public, one way that America changed operations during this period dealt with the types of bikes that were being raced at the AMA Grand National Championship.
The Brits influenced the AMA to include bikes with engines up to 750 CC where both side and overhead valves could be included in the races. Because of that, the greats at Harley felt that they needed a new, redesigned motorcycle to be able to compete with the English in the world of competitive racing.
When they went to the drawing board with plans to design this new bike, those at Harley could never have imagined that they would be creating the plans for what would become THE winningest bike in racing history.
Manufactured for five decades, the XR-750 continues to win races. Even though the original series of racers stopped being produced in 1985, they continue to win races and dominate the sport despite their age, a testament to the brilliance that was put into the design for this motorcycle that will no doubt continue to keep up with the newer bikes on the circuit.
In the late 60s, Harley realized that they were being outperformed in the racing world by the likes of the classic British Triumph, so Harley knew it was time to either get their head (and bikes) in the game or get out.
While the successful reentry into the motorcycle racing world was not something that would occur overnight, everyone at Harley would agree that the work put into designing the XR-750 was well worth the extra time it would take to configure the bike and it was more than worth it.
The idea was to modify the already-well performing XLR, but that would end up being a bigger job than the folks at the design helm at Harley realized. Dick O'Brien, head of Harley Davidson’s racing division, decided to modify the cylinders and cast-iron heads, but there would be much more modification ahead to create the XR-750.
For starters, the XLR came with a 900 cc engine, and somehow the team would have to find a way to make a peak-performance engine that was trimmed down to 750 ccs. After adjusting the bore and stroke, the engineers believed the issues were solved, and they were ready to rock, roll, and race, but that was not the case.
During its earliest incarnation, the XR-750 had a few bugs that needed to be worked out before it would become the winnest racing bike ever. One of the most significant issues the bike had was the cast-iron heads. While they seemed like a perfect solution at the time, they would soon be deemed problematic.
Because they were crafted from cast iron, it would heat up rapidly, causing the bike to overheat unless they were being raced in cooler weather. Taking it a step further, if the metal were to cool too quickly, it could cause the heads to crack.
The early versions of the XR-750 did well in cool climates and short races, but they did not fare well in lengthy races in hotter weather.
In 1972, two years after its release, Harley made some significant changes to the XR-750. One of the first things to go was the cast iron heads, and they were replaced by a much lighter, more heat-friendly aluminum alloy. A tweak here and there with the bores and stoke included some of the changes needed for this bike to be reckoned with.
The engine was also mounted as far from the carburetor as possible to continue to aid with the engine cooling process, which seemed to be the main thing that kept the XR-750 from being a genuine threat at the races.
Another issue that faced this bike was its weight. The engineers had to find a way for the XR-750 to go on a diet and fast. A few of the modifications made in this area included:
A small fiberglass gas tank that held only 2.5 gallons of gas.
Aluminum-spoked wheel rims.
The seat for the bike was low-riding and made of light fiberglass.
The bikeś base itself was changed to make it lighter in general.
These changes seemed to be just what the doctor (or mechanic?) ordered. From ´72 through 2008, this Harley XR-750 won 29 out of 37 AMA Grand Nationals and earned the distinction of winning more of those races than any other motorcycle in the sport's history.
From its introduction to the racing world through 1976, the Harley XR-750 was the motorcycle of choice for legendary stuntman Evel Knievel. He did opt for the new version of the bike that came out in ´72 because it was much lighter than the original version, making it easier to make his death-defying jumps and stunts.
Knievelś support of this motorcycle helped to assist with its legendary status, as the American public loved him and his events and antics. Grown-ups and little kids alike wanted to be like him, and what better way than to own the same type of bike he was known for riding?
Looking at just what the bike was all about will help the layman get a better grasp of just how truly amazing the machine was. Some of its more impressive stats include:
Its ability to reach an impressive 82 hp and reach max speeds over 115 mph.
Evel Knievel achieved a crazy jump of almost 130 feet, clearing 19 cars.
Knievel made an even more impressive jump of over 130 feet, clearing 14 buses.
In 2015, modern stuntman Doug Danger used Knievelś personal ´72 XR-750, clearing even more space and cars than Knievel did himself.
Even after half a century since it hit the track, the Harley XR-750 continues to be one of the most legendary bikes ever created. It still holds the record for being the most winning bike in motorcycle history, and for a good reason.
The XR-750 found the right formula for what it took to win races and the hearts of not just America but the world over. It will, no doubt, be a difficult feat for anyone, even with all of today´s modern technology, to create a bike that is as legendary as the Harley XR-750.