Our exclusive Forty & Deuce merch brings that spirit to life whether on apparel, prints, or accessories. Every piece channels the raw power and vintage style of the Knucklehead, perfect for those who appreciate authentic motorcycle heritage and want to wear a piece of it or showcase it proudly in their space.
The Harley-Davidson Knucklehead: The Engine That Changed Everything
When Harley-Davidson introduced the "Knucklehead" engine in 1936, it was a revolution. Officially named the Model EL, the Knucklehead was the company’s first overhead valve (OHV) V-twin engine, boasting 61 cubic inches (988 cc) of displacement and delivering around 40 horsepower. Its nickname came from the unique shape of its rocker boxes, which reminded riders of knuckles.
This air-cooled, 45-degree V-twin engine marked a massive leap from the flathead engines Harley had been using before, offering greater power, durability, and efficiency. The Knucklehead featured a dry-sump lubrication system that continuously circulated oil through the engine, an innovative design for its time. Paired with a 4-speed hand-shift transmission and chain final drive, it gave riders more control and reliability for the long haul.
The 1936–1947 period saw various improvements, including a bigger 74 cubic-inch (1200 cc) version introduced later in production, with a top speed around 95 mph. The classic styling of the Knucklehead bikes characterized by a steel double downtube frame, springer front forks, rigid rear, and distinctive "The Line" diagonal gas tank graphics made them some of the most beautiful and sought-after vintage Harleys today.
Despite the economic difficulties of the Great Depression and World War II's interruption in civilian production, the Knucklehead set the foundation for Harley’s heavyweight motorcycles for decades. In 1948, the Knucklehead engine was succeeded by the Panhead, but its impact endured.
Today, the Knucklehead remains a beloved classic among collectors and enthusiasts that represents American motorcycle heritage at its finest.
Key Specs:
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Engine: 45-degree V-twin, overhead valve, air-cooled
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Displacement: 61–74 cubic inches (988–1200 cc)
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Horsepower: Approximately 40 HP
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Transmission: 4-speed, hand shift
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Top speed: Around 95 mph
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Weight: Approximately 565 lbs
Ride the legend with Forty & Deuce and keep the Knucklehead’s roar alive off the road and into your daily life.