Editor’s Note: We don’t typically feature choppers on Silodrome as it’s not really our wheelhouse, however we do make exceptions to this every now and then for special bikes.
For a brief time the JRL Cycles Lucky 7 was the only radial-engined production motorcycle in the world. The unusual machine is powered by an Australian designed and built 7-cylinder radial aircraft engine with a swept capacity of 2,800cc and a power output of 110 hp and 160 lb ft of torque.
A small number of custom bike builders have created their own radial-engined motorcycles over the years, and more than one has developed aircraft-engined motorcycles including the legendary Lucky Keizer who sliced two cylinders off the end of a Merlin V12 to create a V-twin motorcycle with a capacity of 5,000cc.
The fact that the word “lucky” is frequently associated with aircraft-engined motorcycles is likely not an accident – these engines are typically larger, heavier, and much more awkwardly shaped than your typical motorcycle engine, with oftentimes prodigious power output figures.
It’s probably a good idea to have luck on your side when riding them.
The JRL Cycles Lucky 7
The JRL Cycles Lucky 7 was originally developed with the goal of building 50+ production motorcycles however the cost to developed and build them resulted in an MSRP of over $100,000 USD – severely limiting the number of potential buyers.
Despite the costs we know that four examples of the JRL Cycles Lucky 7 were built – one prototype and three production bikes.
The machine you see here is the first of the production motorcycles, it uses a custom-designed frame with monoshock rear suspension and Roger Godammer forks up front. Braking is accomplished with single discs front and back, and power from the engine is sent back through a 6-speed gearbox to the 300mm rear tire.
The Rotec R2800 radial engine was developed by Matthew & Paul Chernikeeff in Australia in the 1990s as a modern radial aircraft engine that could be used to safely replace the original radial engines in many antique aircraft to keep them flying.
In the years since it was first released in 1997, Rotec R2800s have been bought by over 3,270 people worldwide and they’ve been fitted to a huge array of aircraft – from WW1 fighters to Kitfox kit-built STOL bush planes.
The engines have proven to be exceedingly reliable, the 7-cylinder radial layout results in ample torque output and a large frontal area for air-cooling.
The engine was designed with twin independent ignition systems and two spark plugs per cylinder as a failsafe, with a square bore x stroke of 3.15” (80 mm x 80 mm), two pushrod actuated overhead valves per cylinder, a 45 amp alternator, and fuel consumption of 22 litres (5.8 gallons) per hour at 75% power.
The Rotec R2800 tips the scales at 100 kgs or 220 lbs (dry weight) giving it a power-to-weight ratio of 0.49 hp/lb (0.80 kW/kg).
The JRL Cycles Lucky 7 Shown Here
As the first of only three production bikes the Lucky 7 shown here is likely to attracted the attention of collectors when it crosses the auction block with Mecum in late January.
This motorcycle previously won the “Best Bike” at the World of Wheels in 2020, it’s also won the John Myers Memorial Award 2020, it took 1st place at the World of Customs Tupelo, and it won the “Bikers’s Best Top 5 Award” and the “First in Class” at the World of Wheels in 2020.
If you’d like to read more about this unusual motorcycle or register to bid you can click here to visit the listing on Mecum.
Images courtesy of Mecum
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