Historic Motorcycle Brands
In 1901, 20-year-old William S Harley drew up plans for a seven-cubic-inch engine for use in a regular pedal-bicycle frame. Over the next two years, he and his friend Arthur Davidson worked on their motor-bicycle until it was finished in 1903, with the help of Arthur’s brother.
William A Davidson, Walter Davidson Sr, Arthur Davidson and William S Harley – North Shore Bulletin 1920
When they tested their power-cycle, Harley and the Davidson brothers found it unable to climb the hills around Milwaukee without pedal assistance, so they began work on an improved machine, with an inlet-over-exhaust-valve engine of 24.74 cubic inches (405cc), with some help from outboard-motor pioneer Ole Evinrude.
1903 Harley-Davidson Mono-cylinder – CJP
The bigger engine and loop-frame design took it out of the motorised bicycle category.
This prototype machine was functional by September 8, 1904, when it competed in a Milwaukee motorcycle race held at State Fair Park. Edward Hildebrand rode it and placed fourth in the race.
Walter Harley – Harley-Davidson archive
In January 1905, the company placed small advertisements in the Automobile and Cycle Trade Journal, offering bare Harley-Davidson engines to the do-it-yourself trade. By April, they were producing complete motorcycles on a very limited basis.
In 1906, Harley and the Davidson brothers built their first factory and produced about 50 motorcycles that year.
In 1907, Harley graduated from the University of Wisconsin–Madison with a degree in mechanical engineering and William Davidson quit his job as tool foreman for the Milwaukee Road railroad, and joined the company full-time. Production increased to 150 motorcycles that year, including some to police departments.
1916 Harley-Davidson 1000cc HT – Lars-Goran Lindgren
Production jumped from 450 motorcycles in 1908 to 1149 machines in 1909.
Back in February 1907, Harley-Davidson had displayed a prototype at the Chicago Automobile Show, powered by a 45-degree, V-Twin engine. However, very few were built between 1907 and 1910. These first V-Twins displaced 53.68 cubic inches (880cc) and produced about 7bhp. That was double the power of the H-D single and top speed was said to be 60mph.
In 1911, the company introduced an improved V-Twin model, with a displacement of 49.48 cubic inches (811cc) and mechanically operated intake valves, as opposed to the ‘automatic’ intake valves used on earlier V-Twins that were sucked open by engine vacuum. This smaller engine gave better performance.
In 1912, Harley-Davidson introduced their patented ‘Ful-Floteing Seat’ (sic), which was suspended by a coil spring inside the seat tube. The spring tension could be adjusted to suit the rider’s weight, and more than three inches (76mm) of travel was available. Harley-Davidson used seats of this type until 1958.
By 1913, Harley-Davidson was already pulling ahead of Indian, with the majority of bikes produced by Harley-Davidson being V-Twin models.
1912 Harley-Davidson X8E Big Twin
From 1914, Harley-Davidson dominated motorcycle racing and production that year swelled to 16,284 machines.
William Harley and Arthur Davidson – 1914
In 1917, the United States entered World War I and the US military purchased more than 20,000 motorcycles from Harley-Davidson.
By 1920, Harley-Davidson was the largest motorcycle manufacturer in the world, with 28,189 machines produced that year and dealers in 67 countries.
Single-cylinder motorcycle engines had been discontinued in 1918, but were reintroduced in 1925 as 1926 models. These singles were available either as flat-head engines or as overhead-valve engines until 1930, after which they were only available as flat-heads.
1923 Harley-Davidson 1000cc HT – Lars-Goran Lindgren
Harley-Davidson put several improvements in place during the 1920s, such as a new 74 cubic-inch (1213cc) V-Twin introduced in 1921 and the ‘teardrop’ petrol tank in 1925. A front brake was added to J/JD models in 1928.
In mid-1929, Harley-Davidson introduced a 45 cubic-inch (737cc) flathead V-Twin D model to compete with the Indian 101 Scout and the Excelsior Super X.
The Great Depression had an immediate effect and Harley-Davidson’s sales fell from 21,000 in 1929 to 3703 in 1933. Despite this, Harley-Davidson unveiled a new lineup for 1934, which included a flat-head engine and Art Deco styling.
1928 Harley-Davidson 28B – Yesterdays Antique Motorcycles
To survive the remainder of the Depression, the company manufactured industrial power plants, based on their motorcycle engines. H-D also designed and built a three-wheeled delivery vehicle called the Servi-Car, which remained in production until 1973.
An 80 cubic-inch (1300cc) flat-head engine was added to the lineup in 1935, by which time the single-cylinder motorcycles had been discontinued.
In 1936, the 61E and 61EL models with ‘Knucklehead’ OHV engines were introduced, but early problems dictated a revised valve train.
By 1937, all Harley-Davidson flathead engines were equipped with dry-sump oil recirculation systems similar to the one introduced in the ‘Knucklehead’ OHV engine.
1931 Harley-Davidson 1200cc SV – Lars-Goran Lindgren
The revised 74 cubic-inch (1210cc) V and VL models were renamed U and UL, the 80 cubic-inch (1300cc) VH and VLH were renamed UH and ULH, and the 45 cubic-inch (740cc) R was renamed W.
In 1941, 74 cubic-inch ‘Knucklehead’ models were introduced as the F and the FL. The 80 cubic-inch (1300cc) flat-head UH and ULH models were discontinued after 1941, but the 74 cubic-inch U and UL flat-head models were produced until 1948.
Harley-Davidson Canadian WLC – Mork
Harley-Davidson produced large numbers of motorcycles for the US Army in World War II and on the eve of the War was already supplying the Army with a military-specific version of its 45 cubic-inch (740cc) WL model, called the WLA.
More than 90,000 military motorcycles – mostly WLAs and Canadian WLCs – were produced and many went to allies. Shipments to the Soviet Union under the Lend-Lease program numbered at least 30,000.
Production of the WLA stopped at the end of World War II, but was resumed from 1950 to 1952, for the Korean War.
Harley-Davidson XA 600 flat-twin – Jeff Dean
The U.S. Army also asked Harley-Davidson to produce a new motorcycle with many of the features of BMW’s side-valve, shaft-driven R71. Harley-Davidson largely copied the BMW engine and drive train and produced the shaft-driven, 750cc 1942 Harley-Davidson XA. However, by then the Jeep was doing many previous motorcycle tasks, so only 1000 were made.
As part of War reparations, Harley-Davidson acquired the design of a small German motorcycle, the DKW RT 125, which they adapted, manufactured and sold from 1948 until 1966.
Introduced in 1957, the Sportster family was conceived as racing motorcycles that proved popular on dirt and flat-track race courses throughout the 1960s and 1970s. Smaller and lighter than the other Harley models, later Sportsters made use of 883cc or 1200cc Evolution engines.
Winton Racetrack – Harley-vs-Indian – Stevenson Photography
Another European acquisition was the Italian Aermacchi-built, two-stroke powered M-65, M-65S and Rapido range. Harley-Davidson purchased full control of Aermacchi’s motorcycle production in 1974 and continued making two-stroke motorcycles in Italy until 1978, when H-D sold the facility to Cagiva.
In 1969, American Machine and Foundry (AMF) bought out Harley-Davidson and streamlined production, slashing the workforce in the process. This tactic resulted in a labour strike and cost-cutting produced lower-quality bikes.
H-D-owned Aermacchi Turismo Veloce – Piero
On top of that came the Japanese bike invasion and Harleys were expensive, as well as inferior in performance, handling and quality to Japanese motorcycles. Sales and quality declined, and the company almost went bankrupt.
In 1981, AMF sold the company to a group of 13 investors led by Vaughn Beals and Willie G Davidson (son of the founder).
Harley-Davidson claimed that Japanese manufacturers were importing motorcycles into the USA in such volume as to harm or threaten to harm domestic producers and, in 1983, President Reagan imposed a 45-percent tariff on imported bikes with engine capacities greater than 700cc.
Protected by this massive tariff, the new management exploited the ‘retro’ appeal of Harleys, building motorcycles that deliberately adopted the look and feel of earlier machines.
Softail Heritage Classic – EVB
Under tariff protection, many components, including brakes, forks, shocks, carburettors, electrics and wheels were outsourced from foreign manufacturers. As a result, quality increased, technical improvements were made and buyers slowly returned.
Harley-Davidson bought a cantilever-swing-arm rear suspension design from Missouri engineer Bill Davis and fitted it into its post-1984 Softail series that began in 1984, with the FXST.
In response to possible motorcycle market demise, caused by the ageing of baby-boomers, Harley-Davidson bought luxury motorhome manufacturer Holiday Rambler in 1986, but sold it again in 1996.
Sportster 883 Custom – B Plinson
Harley-Davidson’s association with sports bike manufacturer Buell Motorcycle Company began in 1987, when it supplied Buell with fifty surplus XR1000 engines. Buell continued to buy engines from Harley-Davidson until 1993, when Harley-Davidson bought 49 percent of the Buell Motorcycle Company.
Harley-Davidson increased its share in Buell to 98 percent in 1998, and to complete ownership in 2003, before closing it down in 2009. H-D also acquired MV Agusta in 2008 and sold it a year later. Weird goings on!)
The ‘Sturgis’ model, with dual belt-drive, was introduced initially in 1980 and was made for three years. This bike was brought back as a commemorative model in 1991.
By 1990, with the introduction of the ‘Fat Boy’, Harley-Davidson once again became the sales leader in the over-750cc US market.
In 1993, the FXR models were replaced by the Dyna (FXD), which became the sole rubber-mount FX Big-Twin frame in 1994.
The FXR was revived briefly from 1999 to 2000 for special limited editions (FXR2, FXR3 & FXR4).
The Harley-Davidson V-Twin
The classic Harley-Davidson engines are V-twin engines, with a 45-degree angle between the cylinders. The crankshaft has a single pin and both pistons are connected to this pin through their ‘fork and blade’ connecting rods.
This 45-degree angle is covered under several United States patents and is an engineering tradeoff that allows a large, high-torque engine in a relatively small space. It causes the cylinders to fire at uneven intervals and produces the choppy ‘potato-potato’ sound that is so strongly linked to the Harley-Davidson brand.
Electra Glide Polizei Harley Hamburg – Gulp
To simplify the engine and reduce costs, the original V-twin ignition was designed to operate with a single set of points and no distributor. This is known as a dual-fire, or ‘wasted-spark’ ignition system, causing both spark plugs to fire, regardless of which cylinder was on its compression stroke.
Harley-Davidson has used various ignition systems throughout its history, from the early points and condenser system that was used on Big Twin and Sportsters up to 1978; magneto ignition on some 1958 to 1969 Sportsters; early electronic with centrifugal mechanical advance weights, on all models from mid-1978 until 1979 and late electronic ignition control.
The 45-degree design of the engine creates a plug firing sequencing where the front cylinder fires and the rear cylinder fires 315 degrees later, followed by a 405-degree gap until the front cylinder fires again, giving the engine its unique growling sound…with some ‘popping’.
H-D XL1200C Anniversary Edition – UCIMBZ
The post-1984 Evolution engine that’s popularly known as Evo is credited with saving Harley-Davidson from bankruptcy. It was made in 82 cubic-inch (1340cc) displacement for Harley-Davidson Big V-twins bikes, replacing the Shovelhead engine and the Sportster version was released in 1986, with 67 cubic-inch (1100 cc) displacement until 1988, then 53.9 cubic-inch (883cc) and 73 cubic-inch (1200cc) [displacements.
The heads and cylinders of Evolution engines are made from aluminium to reduce weight and improve air cooling efficiency, but the heads and cylinders are the only parts of the two Evolution engine series that are similar: the Big Twin and Sportster incarnations of the Evolution are significantly different.
The 1340cc Evolution has a single, four-lobe, gear-driven camshaft located just above the crankshaft axis. While this simplifies camshaft replacement, it complicates the Big Twin valve train, with lifters and pushrods that deflect from the camshaft at wildly different angles.
The Evolution Big Twin motor was, until the introduction of the Twin Cam engine, the last of the line of single cam, overhead-valve engines that traced their lineage back to the seminal Knucklehead design, penned by founder Bill Harley.
In contrast, the unit construction of the Harley-Davidson Sportster, which was essentially unchanged since its inception as the side-valve 750cc ‘K’ Model in 1952, was retained with the Evolution engine upgrade in 1986, resulting in a unique valve train configuration.
At left, a color-coded approximate diagram of the Sportster Evolution valve train superimposed over an image of a Sportster Evolution. Crank output is purple; cams are red; pushrod/lifters are yellow; rockers are blue; valves are dark green, with seats shown in light green – EricD
Unlike any other pushrod engine, the Sportster Evolution uses one cam per engine overhead valve, resulting in four individual, single-lobe, gear-driven camshafts.
The cam lobes are located one behind another and the pushrods are arrayed in pairs, parallel to the cylinder axis. This allows each lifter and pushrod to deflect from the cam lobes perpendicular to the lobe plane.
This configuration allows fitment of high-lift cams, making the Sportster Evolution a natural choice for the once Harley-Davidson-owned line of Buell Motorcycle Company sports bikes.
A simplified derivative of the engine was used on the Buell Blast entry-level motorcycle from 2000 to 2009. The Blast engine had the rear cylinder removed, along with other concessions to reduce overall cost and maintenance.
In 1991, Harley-Davidson began R&D to ensure its bikes could comply with EU standards for 1998, while still retaining the ‘Harley’ sound. H-D even tried to trademark the Harley Sound, but was unsuccessful.
Starting in 1995, the company introduced Electronic Fuel Injection (EFI) as an option for the 30th anniversary edition Electra Glide and EFI became standard on all Harley-Davidson motorcycles, including Sportsters, in 2007.
The Revolution engine is based on the VR-1000 Superbike race program, developed by Harley-Davidson’s Powertrain Engineering, with Porsche helping, to make the engine suitable for street use.
Harley-Davidson Revolution engine in a V-Rod – Bengt Nyman
It is a liquid cooled, dual-overhead-camshaft, internally-counterbalanced, 60-degree, V-twin engine with a displacement of 69 cubic inches (1130cc), producing 115bhp (86kW) at 8250 rpm at the crank, with a redline of 9000rpm.
It was introduced for the new VRSC (V-Rod) line in 2001 for the 2002 model year, starting with the single VRSCA (V-Twin Racing Street Custom) model.
The Revolution marks Harley’s first collaboration with Porsche since the V4 Nova project, which, like the V-Rod, was a radical departure from Harley’s traditional lineup until it was cancelled by AMF in 1981, in favour of the Evolution engine.