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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1940 Era Norton and BSA Motorcycles—79 Years Later

SS Thistlegorm Bow

I like fish.

When SCUBA diving, as you descend through the water, just at that point where the reef or wreck features become clear, fish of all kinds will often swim right up to you and nibble anything they can, in order to get a better idea of just what you are.

It’s common practice to tuck away longer hair and keep your fingers balled up to avoid having them nicked by pesky fish passing-by.  In some parts of the diving world, the nibbles seem to take this habit to another level.

SS Thistlegorm Stern

I’ve dived in some of the same pristine blue waters as the “Father” of SCUBA diving, Jacques-Yves Cousteau, and his legendary dive team, but I’ve never descended through water in the Egyptian Red Sea where these were first ‘discovered.’

I’m talking about the SS Thistlegorm.

It’s a 4,900 ton British armed freighter that was launched in April 1940 during World War II.  In 1952, Jacques Cousteau ‘re-discovered’ the SS Thistlegorm Wreck after following fishermen’s information and in 1956, the National Geographic with Cousteau made the first documentary on this war grave.  The local folklore is that Cousteau chopped down the mast so others would not as easily find the wreck.

Cousteau on SS Thistlegorm.  Article in the February, 1956 National Geographic Magazine.  Photo by Luis Marden

After the SS Thistlegorm three successful voyages to collect war related resources from the United States, Agentina, and the West Indies, she set sail on her fourth voyage from Glasgow in June 1941, destined for Alexandria, Egypt.

The vessel’s cargo included trucks, armored cars, Norton 16H and BSA motorcycles, guns, ammunition, radio equipment , aircraft parts, railway wagons, and two steam locomotives, which were carried on deck. The cargo was to resupply allied forces in Egypt, which would become part of the famed British Eighth Army in September 1941.

The Albyn line named all of their ships after the thistle, the national flower of Scotland. Gorm is Gaelic for blue.  Between 1901 and 1960 the Albyn Line owned 18 ‘thistle’ ships, from the first Thistledhu, the black thistle, to the last, Thistleroy, or red thistle, the second of her name.

Motorcycles in Hold #2

Notably, there were more than 100 motorcycles aboard the SS Thistlegorm. The Birmingham Small Arms (BSA) produced the famous motorcycles found on the wreck, which are located in Hold #1.  The Norton 16H’s are in the lower level of Hold #2 and many are loaded onto Fordson War Office Transport (WOT) trucks.

Norton was the primary motorcycle supplier to the British Military during WWII, almost 100,000 of the Norton 16H Model were built for service. Due to the relatively high ground clearance and solid reliability the Norton, it was favored for despatch work, it was also used for training, reconnaissance, convoy control and escort duties.

Motorcycles in Hold #2

The Norton 16H had an extraordinarily long lifespan, they were originally introduced in 1911, then built through to 1954. The 16H was fitted with a 490cc side-valve engine and had a bore/stroke of 79/100mm. The “H” in the name simply means “Home”, the Nortons that were built for service overseas with the Australian, New Zealand, Indian and the Canadian Armies were denoted with a “C” for “colonies”.

The SS Thistlegorm was part of a convoy of 16 ships heading to Alexandria resupplying the British 8th Army at Tobruk.  The convoy was halted at Sha’ab Ali (Safe Anchorage F) because a tanker had run into a German mine at the entrance to the Suez canal, and the convoy had to wait until the wreckage was cleared.  The Thistlegorm was sunk during a surprise attack by a pair of Heinkel He-111 bombers dispatched from Kampfgeschwader (flight squadron) KG26 in Crete.  The German bombers were originally ordered to search for, and sink, the RMS Queen Mary.

After failing to find the RMS Queen Mary, they were heading back to base in Crete due to being low on fuel when they came across the ship convoy by accident.

SS Thistlegorm Prop

Four sailors and five members of the Royal Navy gun crew died in the bombing (Wreck Location Map: 27° 49′ 03″ N, 33° 55′ 14″E) as ammunition stored in Hold #4 exploded and ripped open the hull.

Most of the cargo remained on board following a long period of disinterest.  Until Dr. Adel Taher, the founder of Sharm’s Hyperbaric Medical Centre, ‘rediscovered’ the wreck in the early 1990s with three friends and dived it in secret for a few years.

Then growth of sport diving took off in the Red Sea and Sharm El Sheikh became a popular scuba diving destination.  The depth of the wreck is around 100 feet and makes it ideal for diving without the need for specialized equipment and training, but dive operators didn’t practice social distancing and word spread as the location became the most popular scuba diving and tourist destination in Egypt and the Red Sea.  Now there are severe issues with preserving artifacts and the history of the ship wreck.

1940’s Norton-Model-16H-Military

It would be tempting, even with unexploded ordinance, to retrieve a Norton or two, but the ship wreck is a war grave and not to be disturbed.

Bonus: A 1942 training film prepared for the British Army during World War II on maintenance of the Norton 16H via YouTube HERE.

References: Wikipedia, Dive Magazine UK, Dive Zone, Red Sea Wreak Project, The Thistlegorm Project 

NOTE: Trademarks, copyrights and other names or brands may be claimed as the property of others.

Photos courtesy of Denis Zorzin, National Geographic, Luis Marden, Dive Magazine UK, Super Jolly

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Metisse Desert Racer

Stop.  You had me at McQueen!  You didn’t need to remind me of the Triumph 6T engine and desert racing heritage to make me think it’s cool.

I’m talking about the Metisse Desert Racer.   The original Desert Racer was built by actor Steve McQueen and his friend, stuntman Bud Ekins for off-road competition.  The  photo (above) is of a replica. 

As an avid motorcycle enthusiast and product developer McQueen pulled together the first American team in the Olympics of motorcycle racing (International 6 Days Trials) held in East Germany in 1964.  The team consisted of McQueen, Bud Ekins, Dave (Bud’s bother) Ekins and Cliff Coleman.  Dave and Cliff both returned with gold medals.  McQueen continued to race the Triumph Metisse during 1966 and 1967.  The motorbike was originally built in Carswell Oxfordshire.  The distinctive design proved to be very successful and in 1973 the company received the prestigious Queen’s Award to Industry.

Steve McQueen - Metisse Desert Racer

In 1980 the Rickman brothers ceased motorcycle manufacture. At about that time the original tooling and the remainder of the stock was sold off.  In 1982, Pat French purchased all of the company’s assets.  Production continued until the mid-90’s when the economic recession forced a decrease in production due to lack of demand.

Under license and the endorsement of the McQueen estate, the company will hand-build 300 authentic motorcycles.  The completed bikes use a fully reconditioned period Triumph TR6 engine and faithfully include the ideals employed by McQueen from years ago. They include items like the styled footrests, 35mm Ceriani forks, with seven inches of travel and the yokes are from BSA which is what McQueen preferred as the handlebar position was set behind the steering stem for better control.

It’s great to see the company bring back some of the magic and easy to visualize a clear sunny California morning – a perfect day to go racing in the desert on this bike!

Photos courtesy of Metisse web site and Flickr.

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Happy Days

I’m a week away and unfortunately missed the return of happier days and the “Bronze Fonz” dedication. 

This week Henry Winkler was in Milwaukee to dedicate a Fonzie statue (located on the west side of the river at the Rock Bottom Brewery) along with Anson Williams (Potsie) who toured the Harley-Davidson museum and even Cindy Williams from Laverne & Shirley stopped by the Miller brewery.  I guess to reminisce about Schotz Brewery, a fictitious analogy to “the beer that made Milwaukee famous”… the Joseph Schlitz brewing company.

The show Happy Days ran for 11 seasons on ABC starting in 1974 and was cancelled in 1984.  It was inspired by the real-life experiences of Thomas Miller who served as exec producer on the series and grew up in Milwaukee.  

A lot has changed in Milwaukee in the past 25 years  The positive aspects of TV for one and the good nature and optimism of life. The Milky Way Drive-In which was the original inspiration of Arnolds Drive-In has long since been demolished and clearly Joanie no longer loves Chachi (Erin Moran and Scott Baio) a testament to how life is now much tougher to live.

For those of you who are too young to remember or too old and can’t get enough of the show here is an online tribute site.

Oh yeah, for those of you curious about which type motorcycle “The Fonz” rode during the 11 seasons…in the early days he rode a custom Harley Knucklehead then drove a variety of other bikes like a Triumph (TR6 Trophy), Triumph 500 cc twin and a BSA.  In real life Henry Winkler was afraid of motorcycles.  In the only scene he was ever taped riding a Triumph he didn’t know how to stop the bike and crashed into two production assistants.

Poster courtesy of the web site.

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