The Harley-Davidson XA: The Secret Shaft-Drive Harley Built for War

When most people think Harley-Davidson, they picture big V-Twins, roaring pipes, and classic American styling. But hidden in the archives is a strange and rare beast: the Harley-Davidson XA, a shaft-driven, flat-twin military motorcycle built for World War II—and unlike anything else the Motor Company ever produced.

At Caliente Harley-Davidson, we love digging into the weird corners of Harley history. And the XA? It's about as weird—and cool—as it gets.

🛠️ Why the XA Was Built

In the early 1940s, the U.S. Army wanted a rugged motorcycle similar to what the Germans were using—specifically the BMW R71. So they asked Harley-Davidson to create something new. The result was the XA, short for "Experimental Army."

It looked more like a BMW than a Harley, with:

• A horizontally opposed 45ci flat-twin engine

• Shaft drive instead of chain

• A foot shifter and hand clutch

• Low center of gravity for off-road balance

The goal? Build something that could handle brutal conditions, desert heat, and rough terrain—all with minimal maintenance.

⚙️ Ahead of Its Time

The XA ran cooler than the typical V-Twin thanks to the flat-twin design, which allowed air to hit both cylinders evenly. It also required less chain upkeep, thanks to the shaft final drive. It was fast, agile, and reliable.

In fact, some early testers said it was the smoothest and best-handling military motorcycle ever built in the U.S. So what happened?

❌ Why You’ve Probably Never Seen One

Despite its promise, the XA was short-lived. The U.S. Army decided to shift to the Jeep as its primary field vehicle, which could carry more troops and gear than any motorcycle could.

Only about 1,000 XA units were ever built. Most were scrapped after the war. The ones that survived? Rare, pricey collector items.

🏍️ A Piece of Forgotten Harley DNA

While the XA never went into mass production, it left a legacy. It proved Harley could experiment and innovate far outside its usual comfort zone—and nail it. Shaft drive, opposed twin engines, and foot-shift setups all became common in later motorcycles around the world.

The XA remains a symbol of Harley's engineering versatility and its role in helping win a global war—one forgotten flat-twin at a time.

Want more Harley oddities, prototypes, and one-offs?
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