A quarter century ago, KTM released their first-ever street bike, the original Duke — a 609cc, hard-thumping supermoto destined to become a cult classic. Fast forward to present day, and the contemporary incarnation is the formidable 690 Duke, the world’s most powerful single-cylinder production motorcycle, offering some 70 horsepower from its fuel-injected, 690cc engine.
Enter Paul Ling of Old Barnstormers Motorcycles, who comes from a long line of mechanics, engineers, and racers. His grandfather competed in hill climbs on the land that would become the legendary Brands Hatch, his father tore around Kent on a hopped-up 350 AJS in the 1950s, and Paul began racing a TZR250’s alongside his brother in 1991, spending 15 years in the saddle of those two-stroke furies:
“While they took chunks out of body and wallet – don’t regret a single moment.”
More recently, Paul decided to take a break from the big city of London to build a cafe racer, finding a workshop situated between the Kent villages of Hawkhurst and Flimwell. Working over a period of 18 months, he created the staggering machine you see here: The Hawkhurst Harrier. If the tail cone and exhaust remind you of the sleek nose and exhaust ports of a Merlin V12-powered Spitfire or Mustang fighter, it’s no coincidence:
“The Hawkhurst Harrier is inspired by 20’s and 30’s aviation, specifically the planes of the Schneider Trophy Races — with an extra dollop of later Supermarine thrown in.”
From 1913 to 1931, the Schneider Trophy was awarded to winners of a race held for seaplanes and flying boats, which competed over a triangular course of 280 to 350 kilometers. It was one of the world’s preeminent aviation spectacles, drawing crowds of more than 200,000 spectators, and the advancements in civil aviation design would translate directly to the fighter aircraft of World War II, including the liquid-cooled engines and streamlined shapes of the legendary Supermarine Spitfire and P-51 Mustang.
Paul chose a 2015 KTM 690 Duke as the platform for this aviation-inspired build. Single-cylinder engines are a cornerstone of motorbiking history, and the big KTM’s is the most powerful ever produced. Says Paul of 690 Duke:
“The heart of the bike, its engine, is absolutely hilarious.”
While he had plenty of experience spinning wrenches/spanners from his racing days, the build required a great leap forward in his skills:
“While I view the build as quite conservative, it was a big jump for me in terms of up-skilling, so I broke the build down to a range of smaller tasks that could be run in parallel and be progressed as my skill level increased.”
The result is one of the most stunning builds we’ve seen in quite some time — a bike that captures the lethal elegance of the Supermarine Spitfire and the 400-mph seaplanes that preceded it. Below, we get more details from the builder himself.
KTM 690 Duke Cafe Racer: In the Builder’s Words
About the builder…
My grandfather, father, uncle and brother are/were all bikers and either mechanics or engineers. My grandad used to compete at hill climbing on the land that was to become Brands Hatch. My dad used to tear up the streets of Orpington in Kent on a tuned 350 AJS in the late fifties.
Started riding at 21, having crashed my first car and couldn’t afford another one so bought a KH125. Moved on to a TZR125, FZ600, FZR400RR & GSXR400RR, road-going TZR250 (which used to inherit my part-worn club compound Avons) (running out of RRR’s here), 916 (with Ohlins front and rear and kick myself for selling), current 955i.
Started racing TZR250s in 1991, joining my brother Brian who started a year earlier. I raced them for 15 years with the KRC and then the BMCRC. While they took chunks out of body and wallet – don’t regret a single moment.
After taking a break from the City of London, it took me a while to find a suitable workshop, which is based between the Kent villages of Hawkhurst and Flimwell (leading me nicely to a working title for a second build: “The Flimwell Flyer”). The workshop is quite small at about three normal car garages, but probably more than I need. Next steps on the skill side will be casting, then CNC. I’ve learned a lot across a range of disciplines – but still a huge amount to go.
About the bike…
I took a sabbatical from working in London to build a cafe racer. “The Hawkhurst Harrier” is inspired by 20’s and 30’s aviation, specifically the planes of the Schneider Trophy Races — with an extra dollop of later Supermarine thrown in.
I chose the big thumping KTM Duke, as a single cylinder is one cornerstone of biking, while the performance provides a true rider’s bike experience. There are a few really nice Duke customs out there, but it has not been over-done. This is perhaps a shame, as the heart of the bike, its engine, is absolutely hilarious.
I raced a TZR250 for about 15 years, so while I could twirl the spanners, I’d never done any metal fabrication or welding before. The build took me 18 months, and I’m still fiddling with some of the cable routing. While I view the build as quite conservative, it was a big jump for me in terms of up-skilling, so I broke the build down to a range of smaller tasks that could be run in parallel and be progressed as my skill level increased.
My favourite bit of the build is the reverse curve into the lower dorsal fin that carries the brake light. This just made me chuckle when I made it, and still does.
I hope I’ve hit the “Era” feel of the bike, while the performance and agility has a new age “350LC” vibe about it.
Thank you to the following for photo opportunities and exhibiting:
- Aero Legends at Headcorn Aerodrome
- Shuttleworth Collection
- Goodwood Circuit
- Brooklands Museum
- The Bike Shed
Follow the Builder
Also, our friends at The Bike Shed have published a piece on The Hawkhurst Harrier, which includes additional photos from the Goodwood race circuit not published here. Here’s the link: thebikeshed.cc/paul-lings-ktm-duke-690/