Harley-Davidson’s first sidevalve engine was also its first horizontal flat-twin engine.
1919 H-D Model W Sport
Engine: 35.64ci (584cc) air-cooled sidevalve horizontally opposed twin w/cylinders in line w/frame, 2-3/4in x 3in (69.9mm x 76.2mm) bore and stroke, 3.75:1 compression ratio (est.), 6hp (factory claimed)
Top speed: 50mph
Carburetion: Single 3/4in (19mm) Schebler
Transmission: 3-speed handshift, chain final drive
Electrics: Magneto ignition
Frame/wheelbase: Single downtube keystone-style w/engine as stressed member/57in (1,448mm)
Suspension: Trailing link w/single spring front, rigid rear
Brakes: 7in (178mm) external contracting drum rear
Tires: 3in x 26in front and rear (3in x 20in modern equivalent)
Weight (wet): 250lb (114kg)
Seat height: 29.5in (749mm)
Fuel capacity: 3gal (13.6ltr)
Price then/now: $355/$25,000-$45,000
During most of its long existence, Harley-Davidson has built its reputation more on making powerful, reliable and sturdy V-twin-powered motorcycles than on innovation. Yet in 1919, Harley introduced an entirely new engine with essential features that wouldn't become part of the family lineup for almost another decade.
By the end of 1918 and with World War I over, the Harley-Davidson company looked forward to peace, prosperity, and selling motorcycles — especially to veterans who had been introduced to motorcycles while in the military. Company engineer William Harley thought these new riders would want an innovative, user-friendly motorcycle with updated features, and he headed for the drawing board to deliver.
The bike that H-D introduced to dealers in mid-1919 was definitely innovative. Advertised as the Harley Sport, the Model W was the first Harley with a sidevalve top end, which was state of the art at the time. Before 1919, all Harley-Davidson engines featured the intake-over-exhaust valve configuration used on most motorcycle engines since the 1890s. Running without valve seals, inlet-over-exhaust engines routinely blew oil mist all over the rider's pants. Competitor Indian was proving that sidevalve engines were not only quieter and cleaner, but also powerful, reliable and fast, and Indian's sidevalve motorcycles regularly won both speed contests and endurance races. It seemed reasonable for Harley to experiment with a setup that had been proven by other companies.
The engine William Harley conceived was unlike any previously built by Harley-Davidson. Unlike Indian's V-twins, Harley's new engine was a flat twin. Except unlike the now-familiar BMW with its cylinders sticking out to either side, the cylinders on Harley's new sidevalve were in line with the frame, one forward of the crankcase and one aft. Interestingly, this cylinder arrangement, chosen to minimize vibration, was used by Indian on the 1917-1919 Model O, which was taken out of production the same year Harley introduced its own flat twin. A single casting combined the intake from the carburetor and the exhaust to the muffler. Advertising literature of the time claimed that heating the intake charge helped atomize the fuel for combustion. Given the poor quality gasoline that was generally available, it probably did.
One camshaft operated both the intake and exhaust valves. The engine and gearbox for the 3-speed transmission were housed in the same set of castings, split vertically. A "bacon slicer" outside flywheel was covered by a pressed steel cover. Oil was circulated by a plunger pump, and rear drive was by an enclosed chain.
Motorcycles of the era needed constant maintenance thanks to a combination of dusty roads, lack of air cleaners, and oil that was chock full of carbon coating the interiors of gasoline-powered engines with a black goop that needed to be cleaned out on a regular basis. The Harley Sport had features that made maintenance easier. The valve guides on the Sport screwed into place, and the cylinders could be removed for cleaning and the valves could be ground without removing the engine from the frame. The frame used the engine as a stressed member.
A Sport selling point was its 29.5-inch seat height. Early motorcycles, most based on bicycle frames, were very tall, and often scared new riders trying to get a foot down on a gravel road. Sport sales brochures pointed out that the flat-twin engine lowered the center of gravity, helping with easy riding, making the low seat on the Sport ahead of its time. In the mid-1920s, frames began to be designed that would allow a short rider to firmly plant both feet on the ground, and low seat heights were trumpeted in advertisements.
Yet another innovation of the Sport was the front fork, which was different from other Harley models. Like contemporary Indians, it was a trailing link design, but instead of a large leaf spring the Sport had a central spring link connected to the downtubes through pull rods. The chain final drive was fully enclosed, helping the bike stay cleaner and helping with chain lubrication. The Schebler carburetor was protected by Harley's first-ever use of an air cleaner.
On paper it all sounded wonderful. In the real world, there were a few problems. First of all, the competition for the Harley Sport was not other motorcycles — it was the Ford Model T. Before World War I, four wheelers were too expensive and complicated for the average person to own. The first Model T's cost $825 when introduced in 1908, at a time when the average worker's salary was about $3,000 a year. By 1919, the price of a Model T had dropped to a little more than $500. People bought motorcycles to get from Point A to Point B. A motorcycle had to be either significantly cheaper or much more fun to compete.
The 1919 list price for the Sport was $335. Advertising for the Harley Sport emphasized its advanced features, its powerful engine, and the pleasure a rider would experience. Advertising copy assured the prospective buyer that all of the Sport's new components had been thoroughly tested. Harley-Davidson claimed the opposed twin was designed for cross-country riding, and to back this up sponsored Hap Scherer on a long-distance run on the Sport while also trumpeting the achievements of Jack Fletcher, who rode his Sport up loose rock and dirt to the top of 10,064-foot Mt. San Antonio north of Los Angeles.
The top speed on a Harley Sport was 50mph. That actually wasn't too bad for the era, a time when most roads were dirt. The Sport sold reasonably well after its introduction in the second half of 1919 and for the start of the 1920 season. Then Indian introduced the Scout, powered by a 596cc sidevalve V-twin.
Even though the Sport had a comparable displacement of 584cc, the Indian Scout was faster. Indian's chief engineer, Charles Franklin, may have happened upon the "squish" principle of flame propagation in cylinder heads independent of Harry Ricardo, who is usually credited with its discovery, and employed it on the new Indians. The Scout broke the Three Flags (Canada to Mexico) and transcontinental records set by larger bikes, and set a world record for covering the most miles over a closed course. The Scout was peppy — 11 horsepower compared to the Harley's 6 horsepower — and it was reliable: the Harley Sport's rear cylinder was out of the airstream and had a tendency to overheat. Not hurting things, the Scout also had that great V-twin sound. The Sport, by comparison, sounded tame.
Sport sales sputtered. In its first year, Harley built and sold fewer than 800 Sports. In 1920, that number jumped significantly, with over 5,000 Sports produced. But in 1921, less than half of that left dealers' showrooms, and in 1922, Harley sold fewer than 1,000 Sports. In 1923, 1,095 Sports left the factory. At that point, Harley gave up and retired the model.
Few changes were made during the model run. 1919 and early 1920 Sports were not available with electric lights. Riders wanting to ride at night used accessory acetylene lights, powered by a gas now mostly used as a welding fuel. From the mid-1920s on, Sports could be ordered with much safer electric lights. Changes for 1920 included a new battery case, a new toolbox cover and miscellaneous small parts. For 1921, a new tank logo was used and some additional, minor parts were changed. The engine was beefed up in 1922, but for 1923, with the model clearly on its way out, there were no changes.
Although the factory gave up on the Sport, it did not give up on sidevalve engines. In fact, the Model W paved the way for the future. Harley's intake-over-exhaust top ends were reaching the end of their possible development. Although overhead valve engines were being developed for racing in the 1920s, they were not yet practical on the street. Metallurgy and lubrication development had not yet reached the point where an overhead valve machine was reliable enough for everyday use.
Sidevalve engines appeared to be the way to go, and in 1924 Harley started developing a sidevalve single, largely for overseas markets, introducing its first motorcycles with this engine in 1926, featuring squish head technology licensed from Harry Ricardo. Sidevalve 45-inch V-twins appeared in dealers' showrooms in the summer of 1928, and 74-inch sidevalve V-twin twins appeared in 1929 — just before Wall Street collapsed. These sidevalve engines were accepted by riders and got Harley through the worst of the Depression.
Not wanting to give up on a proven — and frankly inexpensive — design too soon, Harley stuck with sidevalve engines for years. The company continued to build street sidevalve two wheelers until 1956, and KR racing sidevalves until 1969. Harley produced three-wheeler Servi-cars, powered by a 45-inch sidevalve engine, for parking enforcement use until 1975.
Few Model W Sports have survived. The Sport had something of a following in Europe (Harley-Davidson had a big export business there) and several have been found there, and in New Zealand and Australia. A few made it through the World War II scrap metal drives in the U.S. One, a 1919 machine, came to the capable hands of master motorcycle restorer Mike Parti.
In his earlier years, Mike was a hot rodder, motorcycle racer and all-round hell-raiser. In 1975, he broke both arms in a crash and decided to turn his interests and skills to restoring motorcycles. Mike was one of the earliest restoration experts, getting involved just before collecting antique American motorcycles went from the preoccupation of an eccentric few to a mainstream hobby. Like most restorers, Mike built bikes for customers, and if he took on a project on spec, he sold the bike as soon as it was finished in order to finance the restoration of the next machine. This Sport went to one enthusiast, who sold it to a second, who eventually decided to include it in the yearly antique motorcycle auctions in Las Vegas, Nevada. Which is where it came to the attention of Thom McIlhattan.
Thom is a man with many interests, and the former owner of Harley-Davidson of Vallejo in Northern California. Now more or less retired, Thom is assembling a collection of vintage motorcycles, which mandates frequent trips to the Las Vegas auctions.
"I got into collecting by a total mistake. I was still running the dealership at the time, and someone showed up with a 1950s K model in a pickup truck." Thom bought the K, and soon afterwards, he started looking to buy other historic bikes, with the intention of assembling a display of the evolution of the American motorcycle.
"I have a fascination with how things came to be. I wanted the Sport because I didn't have anything to fill that particular time period in motorcycle history. The Sport was such a change from what Harley-Davidson had been doing — so much was new, and the bike was lower and narrower than other Harley models. It's a shame about that rear cylinder, though. If the rear cylinder would overheat, you could kiss your exhaust valve goodbye." Thom continues: "There was only one other person vaguely interested in the motorcycle at the auction. The bike was in running order and needed no work at all. A collector's delight. I usually don't want to do much to a bike I buy for my collection, and this bike fired up when I bought it."
Thom points out that in 1919, people viewed motorcycles much differently than they do today. "The most important thing at the time was reliability. A motorcycle was a tool, something you used to get around. For example, the luggage carrier on the Sport was part of the bike as delivered and not an accessory. It had to work. I found a story about a contractor who used a Sport to survey Death Valley. He rode it 1,200 miles around some very unforgiving terrain with no problems," Thom says.
Although the Sport was Harley's first venture into sidevalve production and was not a success, Harley used the experience to improve its next sidevalve models, which were very successful. And the Sport still has its attractions — and increasingly its attractors — today. "I like looking at the Sport," Thom says. "I like its lowness and its narrowness, and I like that it is kind of Harley-Davidson's missing link." MC