Inside Look At the Electrogenic and Maeving Collaboration

Actor and motorcycle enthusiast Jason Momoa has had three of his prized vintage Harley-Davidsons converted to electric and hybrid power by Electrogenic, a British EV technology company based in Oxford.

The three H-Ds span the early 1920s: a 1921 Model FD, a 1924 Model JD, and a 1927 Model JD. The two JDs are now plug-in hybrids, with their original 20-horsepower 74 ci V-twins still intact and running alongside a new electric drivetrain. The 1921 FD had a seized engine beyond repair, so it was converted to electric-only power.

Electrogenic fitted all three bikes with an 11kW (15 horsepower) hub motor from UK electric motorcycle manufacturer Maeving. The hub motor produces about 190 lb-ft of torque, substantially more than the 50 lb-ft the original engines delivered. On the hybrid JDs, riders can select EV-only, gasoline-only, or combined power with a simple switch. The electric motor also acts as a starter for the gasoline engine, eliminating the kickstarter.

Each bike carries its batteries in a pair of custom panniers. They are slightly deeper than original items, and finished in leather or fabric to suit the owner and look period-correct. Each pannier holds a 2.7kWh removable battery pack that can be charged on the bike or pulled out and plugged in separately.

A full charge takes about 2.5 hours on a standard household outlet. EV-only range is rated at more than 50 miles, with more available from the gasoline engine on the hybrid bikes. The right-side pannier still has room for a packed lunch.

Safety got a serious upgrade as well. The original bikes had no front brake and relied solely on a band-style rear brake and engine compression to slow down. Even when new, it was a risky and demanding design. Electrogenic replaced the band brake with a modern rear disc brake, a significant improvement for motorcycles that are now about 100 years old.

This is Electrogenic’s first work on motorcycles. The company built its reputation on performing bespoke EV conversions of classic cars, and the Momoa Harley-Davidson project required the development of new solutions. Electrogenic CEO Steve Drummond said the Maeving hub motor was the only unit on the market powerful enough for the job.

“When Jason outlined his concept of a petrol Harley with an electric motor in the rear wheel, we researched the technical options, and the only company in the world that manufactures a motor powerful enough is Maeving,” Drummond said. “Getting it to all work, and work seamlessly, required a great deal of R&D and extensive calibration. The acceleration when you select second gear while cruising on combined petrol and electric power is addictive.”

Momoa was enthusiastic about the result. “This is the best thing we’ve ever made,” he said. “It’s so smooth. I’ve ridden on e-bikes before. I’ve ridden on e-motorcycles. But the idea of riding on an old electrified bike, it was just unlike anything I’ve experienced. If I want to hear the sound, I can, and if not, I can just flip it over to electric. I can have a full conversation with my friend going through the mountains, cruising on this old 1920s bike, and totally feeling it’s a 1920s bike.”

Electrogenic’s approach to all its conversions is to leave the original machine structurally untouched. Nothing is cut, drilled, or welded, and every conversion is fully reversible. The same hardware that went on Momoa’s Harley-Davidsons is now available as a £14,500 plug and play kit for vintage Harley-Davidsons.

The company develops its own hardware and software in-house, including EG-OS, its proprietary vehicle control software that enables precise tuning of power delivery and character for each build.

Momoa and Electrogenic have been working together since 2024. The first collaboration was the conversion of his 1929 Rolls-Royce Phantom II to electric power for the first season of On The Roam, a documentary series in which Momoa travels and explores while showcasing his passion for classic vehicles and the outdoors.

Drummond described that project as still the most ambitious EV conversion carried out anywhere in the world. The Harley builds were a different kind of challenge: making technologies born 100 years apart work together transparently.

The bikes are featured in Off The Grid, episode 4 of the second season of On The Roam, now streaming on HBO Max via Amazon Prime, and Discovery+.

Jason Momoa’s Electric and Hybrid Vintage Harley-Davidsons Photo Gallery