The world of custom motorcycles is full of imaginative creations, but few are as unique as the Hackel-Wright Chopper. Powered by a 1,700cc single-cylinder engine and based on components from a Wright R-975 Whirlwind radial engine, this chopper is an impressive blend of aviation and motorcycle engineering. Built by Al Hackel, a fabricator working out of his backyard, this bike is a testament to ingenuity and dedication to unconventional ideas.
Hackel initially intended to build a Harley Knucklehead, but after discovering the high cost of these engines, he pivoted to a more innovative project. His search for parts led him to an intriguing discovery. “I found the [Wright] cylinder head on eBay and thought it was pretty neat looking so I decided to build a motor around it,” Hackel explains. What resulted is a motorcycle powered by a single-cylinder version of an engine originally designed for aircraft and military tanks.
Origins of the Wright R-975 engine
The Wright R-975 Whirlwind engine has a storied history. Designed by Wright Aeronautical and produced between 1929 and the 1950s, this radial engine was primarily used in aircraft but also powered tanks and helicopters. The nine-cylinder, 975-cubic-inch engine was capable of producing between 300 and 550 horsepower, depending on the model. Its most powerful version, the R975-26-46, was rated at 550 horsepower and was used in helicopters like the UH-25 Army Mule.
This engine powered iconic vehicles such as the Ford Trimotor, the Beechcraft Staggerwing, and the M4 Sherman tank. The original design presented a unique set of challenges, especially when repurposing it for a motorcycle. Unlike a typical reciprocating engine, a radial engine requires a completely different crank drive and valve system, making Hackel’s project far from a simple engine swap.
Building the 1,700cc single-cylinder engine
Hackel had to essentially redesign and custom-build the entire lower half of the engine. This included fabricating a new crankshaft, custom conrod, and valve train, while his friend Justin Leineweber ground the custom camshaft to suit the unusual build. The result was a 1,700cc single-cylinder engine that Hackel paired with a 1947 Harley 4-speed transmission. This powerful combination is what makes the Hackel-Wright chopper so distinct.
The bike’s drive system uses three chains for various functions. A duplex chain drives the connection between the crankshaft and transmission, while a second chain handles the drive to the rear wheel. The third chain serves as a clutch linkage for the foot clutch, adding to the chopper’s manual control system. With a fully manual four-speed transmission and a kickstarter as the only means of ignition, this bike demands a strong leg and careful attention from its rider.
Unique design and components
Hackel didn’t stop at just the engine and transmission. He integrated unique design elements that reflect his commitment to building a truly custom machine. The bike features a Girder fork based on the Vincent Girdraulic model, a type of trapezoidal fork used in the 1940s. This addition provides some comfort for the rider, though Hackel’s description of the ride experience hints at its raw power: “Equal parts abject terror and unbelievable euphoria. It will shake your fittings loose, but tracks smooth down the road.”
Jesse Briggs of Maritimer Glassworks contributed custom-made glass components for the headlamp, taillight, velocity stacks, and shift knob, further enhancing the bike’s one-of-a-kind design. The rear wheel assembly uses a drum brake from a Toyota Matrix, a small sedan designed for the Canadian market. This brake, along with the custom rear spoke wheel, helps to manage the bike’s significant power. The fuel tank is also bespoke, with asymmetric cutouts to accommodate the hand-shifter and the cylinder head, surrounded by narrow bars and a sprung seat.
Riding experience and reception
Hackel’s chopper isn’t just a showpiece—it’s a fully functional motorcycle. Hackel describes riding the bike as an intense experience, saying, “It will shake your fittings loose, but tracks smooth down the road.” The name he gave the bike, “Thunder at 10 Hz,” captures the visceral nature of the ride, combining raw power with an unforgettable sound.
This unique machine has garnered significant attention, being featured at both the 2024 Handbuilt Show and One Moto Show, events that highlight exceptional craftsmanship and innovative design in the world of motorcycles.
Source: BikeBound
