Source: Bike Bound
[[{“value”:”Terror & Euphoria: Al Hackel’s 1700cc Single-Cylinder Chopper…
The Wright R-975 Whirlwind was a family of 9-cylinder 975 cubic-inch radial aircraft engines designed by Wright Aeronautical and produced from 1929 until the 1950s. Each cylinder had a bore of 5 inches (12.7 cm), the piston stroke was 5.5 inches (14 cm), and the 16,000cc engine had a gear-driven supercharger.
Continental (Wright) R-975-46A, Radial 9 Engine
The R-975 was rated for 300 to 550 horsepower depending on the model, and while it was designed as an aircraft engine, it would power everything from fighter planes and airliners to helicopters and tanks. Some of the best-known applications include the Ford Trimotor, Beechcraft Staggerwing, M18 Hellcat, and M4 Sherman tank — talk about a workhorse!
The ultimate refinement of this Wright-designed, Continental-built engine was the R975-46, a 550-hp helicopter engine that powered the UH-25 Army Mule — aka the HUP Retriever — a single-engine tandem-rotor SAR helo reminiscent in basic layout of the better-known CH-47 Chinook.
So what does a beefy 9-cylinder radial have to do with motorcycles? Nothing much for nearly a century until our new friend Al Hackel got his hands on a single Wright R-975-46 cylinder. Al runs a small shop out of his backyard doing agricultural repair, prototyping of all kinds, and general fabrication. Originally, he was interested in building a Harley Knucklehead…until he realized what even a basket case would cost. So he started thinking outside the box…
“I found the [Wright] cylinder head on ebay and thought it was pretty neat looking so I decided to build a motor around it.”
Al had to make a custom case, conrod, and 5-piece crankshaft for the engine, while Justin Leineweber (@leinewebercambuilds) ground the custom cam. The result is a near-as-not 1700cc single-cylinder engine, which Al mated to a bone-stock 1947 Harley transmission…can you say THUMPER?
Of course, the engine commands attention as the centerpiece of the bike, but there’s so much more. The forks are a longer version of a Vincent “girdraulic” unit, and Al says he did much of the shaping of them with an angle grinder!
The rear hub is running a 9-inch drum brake from a Toyota Maxtrix, and Jesse Briggs of Canada’s Maritimer Glassworks blew the trick glass headlight, taillight, velocity stacks, and shift knob.
Al calls this retrofuturist chopper “Thunder at 10 Hz” — a reference to a frequency of 10 thumps per second, or 600 rpm. So what’s it like to ride a 1700cc single-cylinder chopper?
“Equal parts abject terror and unbelievable euphoria. It will shake your fittings loose, but tracks smooth down the road.”
Hehe, we’d certainly sacrifice a filling to test-ride such a brute! This Hackle-Wright chopper was featured at both the 2024 Handbuilt Show and One Moto Show, and we’re thrilled to showcase it today on BikeBound. Most of the shots are courtesy of Lance Merry (@themerryprairie), while credit goes to our man Fouad “Moh” Mohiadeen (@astronaut_bear) for The One Moto shots.
Photo: Handbuilt Show / Revival Cycles
Below is our full uncut interview with Al for more details. Enjoy!
Builder Interview: Al Hackel
Photo: @astronaut_bear
• Please tell us a bit about yourself, your history with motorcycles, and your workshop.
I run a small shop in my backyard doing agricultural repair, prototyping (anything not just ag stuff), and general fabrication. Although recently I have been able to take on more motorcycle projects.
• What’s the make, model, and year of the donor bike?
The only recognizable parts of this motorcycle are the bone-stock 1947 Harley transmission and the cylinder head that came from a Wright R-975 radial engine.
• Why was this bike built?
I originally wanted to build a knucklehead. Once I saw what even a basket case sells for, I gave up on that idea. I found the cylinder head on ebay and thought it was pretty neat looking so I decided to build a motor around it.
• What was the design concept and what influenced the build?
I tried to keep a retrofuturism theme in mind when making parts for the bike.
• What custom work was done to the bike?
The bike starts with one cylinder from a Wright R-975 radial engine. I made a custom case, cam, connecting rod, and 5-piece crankshaft. The cam was ground by Justin Leineweber.
The rear hub was made to accommodate a 9” drum brake taken from a Toyota Matrix.
The forks are a longer version of a Vincent girdraulic fork. I did the majority of shaping of the forks with an angle grinder. The glass headlight, taillight, velocity stacks, and shift knob were blown by Jesse Briggs (@maritimerglassworks).
• Does the bike have a nickname?
Thunder at 10hz.
• Any idea of horsepower, weight, and/or performance numbers?
Your guess is as good as mine. It’s pretty light compared to a knucklehead, but no actual numbers.
• Can you tell us what it’s like to ride this bike
Equal parts abject terror and unbelievable euphoria. It will shake your fittings loose, but tracks smooth down the road.
• Was there anything done during this build that you are particularly proud of?
No man… I’m just relieved it works.
• Is there anyone you’d like to thank?
Jim Dunham for painting the tank, Steve Knecht for painting the frame, Jesse Briggs for the glass, and Karl for the helping hand.
More Details
Follow the Builder
Instagram: @alhackel
Video: Freddie Abe (@fidget.fred)
Photographer: Lance Merry (@themerryprairie)”}]]
