The “Northman” Honda GB350S from Jonathan Hull & Son…
The Honda GB350S, a 348cc air-cooled single-cylinder retro, has been getting great reviews since it hit the UK and European markets in late 2024. It was MCN’s 2025 Award winner for the A2 class:
“Honda’s new GB350S is a delight to ride at any speed. It’ll be a cinch to get on with for new riders but still entertaining enough for the experienced. It might not be super-powerful, but the characterful single cylinder is smooth, has enough oomph to zip you down a B-road with a smile on your face and can always keep up with traffic, even on motorways.” –MCN
Unfortunately, we’re not slated to receive the GB350S here in the States — more the pity because the GB is proving itself a great platform for customization. The 2025 Garage Dreams contest, which focused exclusively on the GB350S, showed a veritable kaleidoscope of transformations from dealers in Spain, Portugal, and Sardinia.
Now Jonathan Hull (@jhullmoto) of the UK’s Jonathan Hull & Son has made the GB350S the focus of his Northman series. Known for his minimalist designs, Jonathan has created Northman to showcase his skills without compromise or client influence, incorporating the highest levels of craftmanship, design, materials, and finishing.
“These exclusive motorcycles are offered as limited, numbered, and certificated runs by application only. To retain exclusivity, he is publicly committed to only producing five of each model in the Northman collection.”
Whereas many of the Garage Dreams builds fully transformed the bike from its retro roots, Jonathan has focused on a more classic design that complements the bike’s spirit and intended use. Of course, transforming a modern fuel-injected, ECU-controlled donor into a minimalist machine that looks like it stepped out of another era is easier said than done.
For instance, one of the biggest challenges was the air box delete, which is thought to be a world first for this model. Jonathan and team had to figure out how to fool the ECU into thinking the air box was still there — “a triumph and a closely guarded secret,” says Jonathan.
Other highlights include a conversion from mags to tubeless spoked wheels, fully-adjustable YSS shocks, upgraded front suspension, stainless custom exhaust (“sounds like a Spitfire”), solid brass hand-rolled cat cover, Tom Hurley custom saddle of Chesterfield leather (like the classic British sofas), bespoke carbon fiber frame insert (designed with digital-scanning and modeling help from Ravenworks UK), full lighting upgrade, Antigravity Lithium battery, and more.
The small details here are a big part of the overall effect. Manually machined brass details can be found throughout, including the solid brass Northman tank badges, and the bike is finished in a “glass gloss” Jaguar British Racing Green — the perfect hue for a bike of this character.
Overall, the “Northman GB350S” reminds us of a modern version of what a pilot might have ridden out to his Spitfire on a misty dawn morning, his silk scarf wrapped around his neck. Moreover, this isn’t just an aesthetic upgrade. The Northman GB350S is 33 pounds lighter than the original.
“Jonathan spent time working for Minnovation Racing and took away with him the importance of power-to-weight ratio. This was already a fairly light bike for its class, but Jonathan has managed to lose a massive 15kg from the stock bike. Fully wet, the Northman GB350s weighs in at just 163kg [359 lbs].”
The Northman GB350S looked great at London’s recent Bike Shed Moto Show, and just five of them will be built. You can follow Jonathan on Instagram (@jhullmoto) or reach out to him directly here: [email protected].
Below is our uncut interview with Jonathan’s team about the build, along with a full build sheet and more photos from Roberto Garagarza (Bike Shed Show shots) and Adam Swales.
“Northman” Honda GB350S Custom: Builder Interview
• Please tell us a bit about yourself, your history with motorcycles, and your workshop.
Established in 2019, Jonathan had discovered a passion for the reimagining of motorcycles. Inspired by the Ton-up Boys and their Café Racer motorcycles of the mid 20th century. Jonathan began researching and learning the key philosophies and skills needed to be able to create his own unique style of motorcycles. Jonathan builds his motorcycles with one particular philosophy in mind: “If it doesn’t make the bike go fast, stop fast or road legal, it’s gone!”
Captivated by the simplicity of the early Café Racer machines, Jonathan was keen to keep his bikes as clean and clutter free as possible. However, Jonathan also understands the importance of technological advancements in both the build processes and components. Underneath the classic styling of these machines are ultra modern bikes with full digital, LED, lithium-ion powered electronics.
Jonathan is highly active on Instagram and is passionate about the custom bike community. He documents much of what he does for others to reference if they wish to. Jonathan has followers from all corners of the world and tries, whenever possible, to help others with their own custom projects. Feel free to follow his account and reach out: @jhullmoto.
• What’s the make, model, and year of the donor bike?
2025 Honda GB350S.
• Why was this bike built?
Northman represents the very best of Jonathan’s work. Motorcycle design that is deeply personal to him with no compromise or outside influence. The very highest quality of craftmanship, design, materials, and finishing.
These exclusive motorcycles are offered as limited, numbered, and certificated runs by application only. To retain exclusivity, he is publicly committed to only producing five of each model in the Northman collection.
• What was the design concept and what influenced the build?
The challenge for Jonathan was to take a brand new motorcycle and build a machine that people would instantly recognize as one of his. Jonathan is known for ultra minimalism, bare frames and engines. This was a challenge on a modern ECU-controlled, fuel-injected donor vehicle.
• What custom work was done to the bike?
Tubeless Spoked wheel conversion
Anlas Capra tyres
Full lighting upgrade
Dropped clock on manually machined brass spacers
Wide handle Bars, grips & weights
Rear, fully adjustable, YSS suspension upgrade
Front suspension upgrade
Custom front mudguard
Custom, stainless, straight through exhaust tail piece plus a hand rolled, solid brass CAT cover
Bespoke carbon fiber frame insert
Machined butterfly inlet insert, pod filter and custom brass butterfly assembly covers.
Airbox delete
Pillion delete
Antigravity Lithium battery upgrade
Manually machined solid brass details throughout
Foot peg upgrade
Custom, chesterfield leather seat on a custom seat pan.
Luxury ‘glass gloss’ paint finish in Jaguar British Racing Green
Custom, solid brass, Northman tank badges.
• Does the bike have a nickname?
Northman GB350s.
• Any idea of horsepower, weight, and/or performance numbers?
Jonathan spent time working for Minnovation Racing and took away with him the importance of power-to-weight ratio. This was already a fairly light bike for its class, but Jonathan has managed to lose a massive 15kg from the stock bike. Fully wet, the Northman GB350s weighs in at just 163kg. That makes it the lightest in its class. It has a VHP Gain of +2HP purely in weight reduction.
• Can you tell us what it’s like to ride this bike?
Jonathan road-tested the stock bike in the North Yorkshire national park to assess what needed to be done. It is now lighter, more nimble, steadier in the corners, and has more climb. It’s more comfortable for longer journeys and sounds like a Spitfire.
• Was there anything done during this build that you are particularly proud of?
The successful airbox delete is, as far as we know, a world first for this model. It was a complicated design process that involved a great deal of trial and error. The engineering involved in fooling the ECU into thinking the air box was still in place was a triumph and a closely guarded secret.
The carbon fibre / nylon frame insert was designed to protect the electrical and hydraulic system while offering the unique “see through” design and keeping weight to an absolute minimum. This was a large part of the overall 15kg weight loss and a unique achievement for this build.
• Is there anyone you’d like to thank?
Ravenworks UK were a big part of this build from digitally scanning the frame and tank to assistance in modeling and finishing the frame insert. They are a valuable member of the Northman team. Tom Hurley for his beautiful upholstery as always and Small Scale CNC for their exceptional work realising the Northman tank badges.
Follow the Builder
Web: jonathanhull.co.uk/northman
Instagram: @jhullmoto
[email protected]
Photographer: Adam Swales
