50th Anniversary Of Jet Fire Orange

1970 Harley-Davidson XR-750

I’m talking about the Harley-Davidson XR-750, which last month marked the 50th Anniversary since it’s debut.

From 1953 to 1969,  Harley-Davidson manufactured the KR750, the backbone of American dirt track racing.

The motorcycle engine was an air cooled, side valve 4-stroke 45° V-twin (flathead), 45.125 cu in (739.47 cc) displacement built for racing.  Unique for Harley’s at that time, the KR model shifted on the right, like a British bike, which worked great for dirt track.  It wasn’t until 1975, when DOT specified that all motorcycles sold in the U.S. had to have a standardized, left-side gear shift.

Harley-Davidson Flat Track Racing

Prior to 1969, the American Motorcyclist Association (AMA) rules for the Grand National Championship were structured to favor “sidevalvers” (side-valve engines) rather than overhead-valve (OHV) engines.  The intent was to deliberately favor American made bikes such as those from Harley-Davidson with their side-valve engines, and disadvantage the competition which was mainly from British manufactures i.e., Triumph, BSA, and Norton. The AMA rules allowed side-valve engines of up to 750cc capacity but OHV engines were limited to 500cc. The 50% engine size advantage stacked the odd in the favor of the side-valve bikes.

As you might imagine, the British manufactures complained…about everything—the rules, the manufactures, the officials, the drivers, the races, and the racing itself.

Harley-Davidson XR-750

As a result, in 1969, in prep for the 1970 race season, the AMA approved that all professional Amateur & Expert dirt track and speedway engines could be 750cc, regardless of configuration or valve style. This rule change eliminated the 250cc penalty for OHV engines that had existed since 1933.  Many British manufacturers begin designing and developing OHV 750cc engines for competition. To be approved by the AMA (for Class C competition), a motorcycle must be a standard catalogued production model and at least 200 units of the same model with identical engines and transmissions and must be available for inspection and/or purchase within the United States.

XR-750 Engine – Ported and Polished Heads

Unhappy with the decision, but with a desire to continue the racing legacy, Harley-Davidson set out to create a new overhead-valve racing motorcycle.  The Milwaukee motor company leveraged their OHV V-twin racing engine based on the Sportster XLR.  However, it’s engine had a displacement of 900cc (55 cu. in.) and would need to have its capacity reduced to 750cc. Harley-Davidson engineers accomplished this by decreasing the engine’s stroke from 3.81″ to 2.983″ and increased the bore from 3.0″ to 3.2″ bringing the engine in just under the 750cc maximum.

The AMA approved the Harley-Davidson “XR”, a 750cc V-twin overhead valve engine, for Class C competition on Feburary 27, 1970. It had been tentatively approved in late-1969 as the “750 Sportster”, but the motor company lacked having 200 units available for inspection at the time. The motorcycle is dubbed the “iron XR“, or “Iron Head,” due to its steel cylinders and heads.

Even Knievel

For the 1972 race season, there were a number of changes.  A vote was taken on November 18, 1971, and the AMA Competition Congress voted to allow qualified women to compete in all forms of AMA Racing.

The Water-Cooling was approved, as long as it is an integral part of a production motorcycle.  Titanium frames were outlawed from all AMA competition. The AMA approved the Harley-Davidson XR-750, an updated version of the XR, for Class C competition on April 12, 1972. The updated engine used aluminum cylinders and heads to address the overheating issues that plagued the XR model. However, due to delays in getting all 200 units completed, it wasn’t approved in time for the Daytona 200, but debuts at the Colorado Springs national on April 30, 1972.

Speaking of aluminum heads, they were made, then shipped to Jerry Branch of Branch Flowmetrics in Long Beach, California to be ported and assembled. The new cylinder head design included larger valves. The cylinder heads were then shipped back to Harley-Davidson’s factory in Milwaukee for fitting to the new engines. This V-twin engine was not quite of the same dimensions as the Iron Head. The bore was increased to 3.1” and the stroke reduced to 3”. Carburetors were 36mm Mikuni, one for each cylinder. The exhaust systems were mounted high on the left side of the motorcycle well away from the carburetors.  Power was 82hp at 7,700rpm giving the bike a top speed of around 115mph.

Harley-Davidson Flat Track Racing Team

Branch wrote engineering books on his engine air flow work and eventually sold Branch Flowmetrics to Mikuni in the late 1990s.  Branch was the only independent company to ever supply Harley-Davidson ported and polished heads!

In 1972, Harley-Davidson was the first-ever “Grand National Manufacturer’s Championship“, which compiles the highest finish of each brand at every Grand National Championship event.  Between 1972 and 2008, the XR-750 won 28 of 37 AMA Grand National Championships. The XR-750 racked up more wins than any other motorcycle in AMA racing history and earned the description of being the “most successful race bike of all time.”  In addition, the XR-750 became a cultural icon with legendary stuntman Evel Knievel at the handlebars. Evel Knievel began jumping an XR-750 at the height of his career from 1970 to 1976.

Harley-Davidson created one of the greatest bikes in the history of American motorcycling.

For 2020, the Harley-Davidson Factory Flat Track team will use the updated Harley-Davidson® XG750R flat tracker, powered by the liquid-cooled, fuel-injected and race-tuned 750cc Harley-Davidson® Revolution X™ V-Twin designed for the Street 750 motorcycle.

Full details on the Flat Track team can be found HERE.  Flat Track racing news is HERE.

Photos courtesy of Harley-Davidson

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Postcard From Hells Canyon – Part 2

Oregon Trail Interpretive Center - Baker City, OR

On Friday we were up early to grab coffee and breakfast before making our way out to the ‘Devils Tail’ and Hells Canyon Dam.

It was rather obvious while eating my scrambled eggs and looking out across the vendor parking lot that there were some hard-living characters who had run wild the night earlier.  They weren’t totally burned out, but obviously moving a little slower.  It got me to thinking about how Harley like virtually every other motorcycle manufacture, is facing a huge, looming crisis; the ageing of its core clientele.  Like every other market they touch Boomers dominate the motorcycle industry, especially for those expensive touring cruisers that generate so much profit for the corporate coffers.

Depending on whose data you reference; AMA states the average age of its members is 48, the American Motorcycle Industry Council’s most recent survey (2008) has the average pegged at 43 years old (up 5 years from 1998) and a JD Power and H-D survey has the average at 49 years old.  It would seem that motorcycling is no longer a young man’s sport.   Based on my observation this morning I would concur and while I didn’t see anyone trading their favorite ride in on an RV, I did see a lot of interest in the Boss Hog trikes and customers lining up for demo rides.  Most were intrigued with how to navigate the parking lot in reverse gear.

Hells Canyon Dam

I’m not sure about you, but I’m the kind of person who gets satisfaction when my mechanical stuff is humming.  It puts a smile upon my face and makes me feel glad all over.  I felt that way on the ride out to the Hells Canyon Dam.  The departure temperature hung in the mid-60’s – cool for eastern Oregon — and looking around the horizon it was clear there was going to be a mix of rain showers and blue sky.  Yeah, we were going to be dancing between the rain drops all day long on this ride.

We traveled out on Baker-Copperfield Hwy (Hwy 86) toward Richland, through Halfway with a brief pit stop at the Scotty’s Outdoor Store just prior to Oxbow as we headed back to the bottom of the canyon.  Hells Canyon is on the border of Idaho and Oregon, and the ride is deep in the valley alongside the Snake River.  Yeah that one — the one where Evel Knievel attempted his X-1 Skycycle jump over the canyon, unsuccessfully, back in 1974.   Many people will disagree when you remind them that the Hell’s Canyon is North American’s deepest river gorge at almost 8,000 feet, 2,000 feet deeper than the Grand Canyon, but it’s true.

Posse On Devil's Tail

And as a bonus it has one of the most famous rides in the area — the Devil’s Tail — a 22 mile route from Oxbow, Oregon to Hell’s Canyon Dam. There are hundreds of S-curves and twisty’s with picturesque views.  The Devil’s Tail is not for the novice, and requires attention to riding. Last year we talked to a motorcyclist who misjudge the road and dump his bike.  Fortunately they had only minor injuries.

Baker City "Rain Out"

Back in the day this road was used to deliver workers and supplies to the site of the dam construction when it was being built in 1966. Today Idaho Power employees use it to access the dam and outdoor hobbyist use it for recreational access.  At the end of the road the dam and water were nearly level with the road.  As you drive across the dam we were greeted with a loud “whooshing” sound and at the visitor’s center which is a short, but steep ride below the dam we took pictures of the large volume of water flowing through to make hydro electrical power.  It’s a spectacular sight and the close proximity means you literally feel natures power.

Interstate 84 North - Departing HCMR

We reversed directions and headed back to the Sunridge Best Western where we met up with some other riders who arrived late-afternoon.

On Saturday the weather was a mixed bag.  The morning started out partly cloudy with the occasional sun burst, but the Whitman National Forest was socked in with storm/rain clouds which is where the posse planned to ride for a ghost town tour.  We downed some breakfast and remained optimistic the day would bring something better.  It turned out that optimism was sorely misplaced!

Hwy 14 - West of Umatilla

Thinking it would clear later in the day we elected to hang out in the vendor booths in downtown Baker City and wait it out… but, rain is a life metaphor – into every ride a little rain must fall, right?   Well it did.  I know the Folkestad’s like to state that the HCMR has never been “rained out” and I’m not sure what criteria they use, but it started raining around 1pm with showers at first and then turned to a steady hard rain from 2pm through most of the night.  We graced the downtown area refreshment centers and talked shop with the High Desert H-D folks from Meridian, ID.  Downtown was jammed and by the time we returned to the motel restaurant/bar it was packed with wet riders who called the day a total bust.  Good for Baker City businesses, but it seemed the weather conditions were conspiring against us.

Near Maryhill Winery - Goldendale, WA

On Sunday morning you could smell the cool breath of mother nature as we wiped off the previous night rain soaked seats.  Unlike Western Oregon, the majority of the landscape in Eastern Oregon is wide open which allows riders to see the lay of the land and it provides plenty of time to take it all in.  For me I enjoy Eastern Oregon because it’s different.  The people are different (in a positive/good way), the weather is different, it looks different and the roads are different.  It seems that people have a habit of never appreciating a place until you’re about to leave it.   I had some regrets that I didn’t get time to explore the ghost towns, but we were about to point the bikes north hoping for a dry day!

We rode out of Baker City on I-84 and encountered cooler temperatures as we traversed the Wallowa Mountains.  The sun shined brightly and by the time we stopped to re-fuel in Pendleton is was actually warm.  We cut over to Umatilla and rode Hwy 14 on the Washington side of the Columbia River.  The pull toward home and returning to “normal” life was getting stronger as the pace quickened back to Portland.  We dodged some rain drops near “The Couve” and got home in time to learn that yes, the self-proclaimed “King” — Lebron James — was still not a NBA champion and that my friends means the only place celebrating more than Dallas that night was Cleveland!

In spite of the ‘rain out’ on Saturday the Hells Canyon Motorcycle Rally was a great experience.  If you have not attended it should be something on your bucket list!

Postcard From Hells Canyon – Part 1 HERE.

Photos taken by editor. Previous HCMR posts: 2010 HERE, 2009 HERE

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