Harley Davidson History 1901 to Now

The initial, single-cylinder engine designed by William S. Harley in
1901 and installed in a pedal bicycle, displaced 7.07 cubic inches (or
116 cc). Two years later, with assistance from Harley’s boyhood friend
Arthur Davidson and Arthur’s brother Walter, they introduced another
vehicle; however, they found it did not produce enough power to
negotiate even the modest hills around their Milwaukee workshop.
Because of this, the men began work on a new machine, which had a
bigger motor (24.75 cubic inch, 405 cc displacement). When they placed
it into a “loop” frame, stronger and more adaptable to stress than the
bicycle frame, the young company had manufactured its first true
motorcycle

V-Twins

By 1905, Harley and the Davidsons produced perhaps a dozen saleable
machines; the following year they made 50.  All of these motorcycles
had single cylinder motors that displaced 26.84 cubic inches, or 439.8
cc. In 1907, after William Harley graduated with a degree in
engineering from the University of Wisconsin in Madison, the team
created their first V-twin engine. It displaced 53.68 inches (879.7 cc)
and put out 7 horsepower or 5.2 kW. Although only a few machines were
produced that year, by 1909 production was up to 1,149 units. 

In 1911, Harley and the Davidson brothers introduced a new V-twin
motorcycle, which featured mechanically-operated intake valves (the
prior V-twin had “automatic” intake valves which opened using engine
vacuum). It was smaller, displacing only 49.48 cubic inches (810.8 cc),
but the engine performed better. In 1914, the growing company
manufactured 16,284 vehicles. After the World War I, during which the
company shipped 15,000 motorcycles to the military, a new 74 cubic inch
(1200 cc) motor was introduced, as was the first “teardrop” gas tank
and front brakes.

Flatheads, Knuckleheads, Etc.

From 1929 to 1931, the company made the “D” model which featured a
45 cubic inch (750 cc) flathead V-twin motor. Nineteen thirty-five saw
the introduction of an 80 cubic inch flathead motor, and in 1936, the
company came out with the 61Eand 61EL “knucklehead” overhead valve
engine. By 1937, all Harley-Davidson flatheads featured the dry sump
recirculation system introduced in the knucklehead motor. Due to
retrofitting because of valvetrain problems, the original 74 c.i. V and
VL models were renamed U and UL, the former VH and VLH 80 c.i. models
were now known as U and UL models, and the 45 c.i. model was changed
from R to W. Nineteen forty-one saw the introduction of the F and FL 74
c.i. knucklehead motor. During World War II, Harley-Davidson supplied
the Army with motorcycles, distinguishable by an “A” in the serial
number, even producing a drive-shaft version.

In their various incarnations, the big and small V-twin engines are
distinguished by their differently-designed rocker boxes. Knucklehead
motors’ rocker boxes resemble knuckles, panheads resemble pans,
shovelheads look like shovels.

In the early 1980’s, Harley-Davidson came out with the Evolution
engine or “Evo.” Not entirely endearing to H.D. enthusiasts, the Evo
(aka Blockhead) runs more reliably, smoother and more efficiently
because of its aluminum construction, allowing for the less
mechanically-inclined to “buy” into the famed Harley mystique.
Following this was the Twin Cam 88 (and 88B) engine, which to some also
lessened the Harley mystique because it is rubber-mounted, and
therefore operates with less vibration. The recent Revolution engine is
again a departure from tradition because it is liquid-cooled with a
dual overhead cam.

In 1957, in response to competition from England’s Triumph,
Harley-Davidson introduced the Sportster, a light, fast motorcycle. The
Sportster initially featured an 883 cc engine with drum brakes, soon
upgraded to twin disc brakes. It is currently available with either the
833 or a 1200 cc motor.

Over the years, the company has also produced various “dirt-bike”
style motorcycles and other small, single-cylinder vehicles, including
the recently acquired (then recently sold) Buell line of lighter
vehicles. But the big “dresser” vehicles have been, and continue to be
the H.D. mainstay. This means large, V-twin road vehicles like the Duo
Glide, the first Harley-Davidson to feature a swingarm frame and
automotive-style shock absorbers; the Electra Glide, which at the time
boasted an upgraded electrical capacity and stock over-the-road
accessories; the Hydra Glide, which introduced the hydraulic front
fork; and the Dyna Glide, which has built-in motor balancing.

Styling changes, upgrades and add-ons have helped keep customers
interested. Designer William G. Davidson, grandson of H.D. co-founder
William A. Davidson, developed the Super Glide and its cousin the Low
Rider in the late 1970s, the first motorcycles riders could order which
came from the factory already customized. Willie G. and his design team
also introduced the limited-production Café Racer, an ultra-styled
Sportster; and have gone on to build the Sturgis, the first belt-driven
Harley from which all H.D. motorcycles built today have inherited their
belt-drives. The team recently introduced the new V-Rod, the
water-cooled, dual-overhead cam, hidden gas tank racer. With a history
that often can be traced directly back to the first motorcycles,
Harley-Davidson continues to intrigue and inspire its many enthusiastic
followers.