If you’re an avid motorcycle enthusiast, you’ve probably heard the term “Knucklehead” thrown around. But what exactly is a Knucklehead, and what makes it so special?
Let’s dive into the history of the Knucklehead motorcycle engine, the motorcycles that used this engine, and some interesting facts about this iconic piece of motorcycle history.
A Brief History of the Knucklehead Engine
The Knucklehead engine, officially known as the Harley-Davidson EL, was introduced by Harley-Davidson in 1936. This overhead valve, V-twin engine got its nickname from the distinct shape of its rocker covers, which resemble two clenched fists with protruding knuckles.
The Knucklehead was a significant technological advancement for Harley-Davidson, as it was their first production motorcycle to feature overhead valves.
Motorcycles That Used the Knucklehead Engine
The Knucklehead engine was primarily used in the Harley-Davidson EL and FL series of motorcycles.
The EL model, also known as the “61,” was introduced in 1936 and featured a 61-cubic inch (1,000 cc) engine. In 1941, the FL model, also known as the “74,” was introduced with a larger 74-cubic inch (1,200 cc) engine.
These bikes were popular among riders for their power and reliability, and they quickly gained a reputation for being the ultimate cruising machines.
Throughout its production run, the Knucklehead engine underwent several improvements, such as aluminum cylinder heads for better heat dissipation, increased oil capacity, and better oil circulation. Production of the Knucklehead engine ended in 1947 when Harley-Davidson introduced the Panhead engine.
Interesting Facts About the Knucklehead Engine
- The Knucklehead engine was initially designed by Harley-Davidson engineers Joe Petrali and Bill Ottaway. They were inspired by the overhead valve engines used in aircraft.
- The Knucklehead engine played a crucial role in Harley-Davidson’s success during World War II. The military version of the motorcycle, the XA, used the Knucklehead engine to power thousands of bikes for the U.S. military.
- The Knucklehead engine is considered one of the most iconic and collectible motorcycle engines. Original Knucklehead-powered motorcycles are highly sought after by collectors and restored or original bikes can fetch a premium price at auctions.
- The Knucklehead engine’s unique design has inspired several custom motorcycle builders, such as Indian Larry, who often used Knucklehead engines in their custom builds.
- In 2016, Harley-Davidson celebrated the 80th anniversary of the Knucklehead engine by unveiling a special-edition Softail Slim S model, featuring styling cues that pay homage to the original Knucklehead-powered motorcycles.
The Legacy of the Knucklehead Engine
The Knucklehead engine holds a special place in the hearts of motorcycle enthusiasts, not just for its distinctive appearance but also for its historical significance. It marked a turning point for Harley-Davidson and set the stage for the company’s future innovations.
Today, the Knucklehead engine serves as a reminder of Harley-Davidson’s rich history and commitment to engineering excellence.