A superb and rare photo of the 1951 Harley-Davidson EL Hydra Glide - Harley-Davidson FL Hydra Glide, photographed for the publicity campaign of the model year 1951.

The Harley-Davidson EL Hydra Glide and Harley-Davidson FL Hydra Glide model series have a very interesting history that start with the introduction of the FL model designation name in 1941. Mostly applied to Harley's large-framed bikes, including the current Touring series and Softail series, the FL was introduced to the Harley-Davidson model line in 1941. It used a 74 cu in (1,210 cc) version of the "Knucklehead" OHV engine that powered the EL in 61 cu in (1,000 cc) form. The FL shared its frame with the EL and with the U and UL, which used a 74 cubic inch flathead engine. The FL replaced the UH and ULH, which used the same frame with 80 cu in (1,300 cc) flathead engines. The FL continued relatively unchanged until 1948, when it and the EL were given redesigned "Panhead" engines of the same capacities as before. These engines had several improvements over the earlier "Knuckleheads", including aluminum cylinder heads to reduce weight and improve cooling and self-adjusting hydraulic lifters. The U and UL flathead twins were discontinued in 1948, leaving the OHV EL and FL models as Harley-Davidson's large-frame motorcycles. The Harley-Davidson Hydra Glide was introduced in 1949. A year after receiving the "Panhead" engine, the FL was given a new front suspension. And in honor of their first production motorcycle with hydraulically-damped telescopic forks, the FL was officially called the Harley-Davidson Hydra-Glide. This name would change twice in the history of the basic large-framed FL bikes, each time signaling an improvement in the bike's technology. In addition, the Glide ending would be used on other models, based on both and FL and FX formats. In 1952, the Hydra-Glide's transmission format was reversed from hand-shift/foot-clutch to foot-shift/hand-clutch, although the original format continued to be offered as an option until 1978. 1952 was also the last year of the 61 cu in (1,000 cc) EL, making the FL the last remaining large-frame model. A more highly-tuned engine with high-compression heads, higher-lift cams, and polished ports, was offered with the FLH version of 1955. The FLH designation has continued up to the present. The FL model was given a new frame in 1958. This frame included a rear swingarm suspended by a pair of coil-over-shock suspension units. In honor of this fully-suspended chassis, the FL's model name was changed from Harley-Davidson Hydra-Glide to Harley-Davidson Duo-Glide. Unlike OHV configuration, aluminum heads, and telescopic-fork front suspension, however, this improvement in technology was applied to the small-frame bikes first, the K-series having received rear suspension in 1952.

The Harley-Davidson Panhead motorcycle engine was nicknamed like that because of the distinct shape of the valve-rocker covers. The engine is a two-cylinder, two-valve-per-cylinder, pushrod V-twin. The engine replaced the Knucklehead engine in 1948 and was manufactured until 1965 when it was replaced by the shovelhead. As the design of Harley-Davidson engines has evolved through the years, the distinctive shape of the valve covers has allowed Harley enthusiasts to classify an engine simply by looking at the shape of the covers, and the Panhead has covers resembling an upside-down pan. The "Captain America" chopper used by Peter Fonda in the movie Easy Rider (1969) had a Panhead engine, as well as the bike ridden by Dennis Hopper's character. Currently, a number of third-party engine manufacturers produce custom Panhead-style engines in a variety of bores, many much larger than the original-design displacements. Each manufacturer includes significant subtle upgrades to the original design to drastically improve the performance and reliability while still providing the original styling and overall engine structure.

This is a very nice and very rare non period photo that reflects a wonderful era of Harley ‘s motorcycle history in a wonderful way. This is your rare chance to own this photo, therefore it is printed in a nice large format of ca. 8" x 12" (ca. 20 x 30 cm). It makes it perfectly suitable for framing!

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