One Of The Coolest Motorcycles Ever Built Has A 500 HP Dodge Viper V10 Engine, Goes 207 MPH, And You Can Finally Buy It

Car engines and motorcycles usually don’t mix. Your car’s engine is probably too heavy and too bulky for a bike, and it was designed for completely different power needs. But every once in a while, bikes and car engines get along just long enough to create some of history’s craziest motorcycles. One of them is the Allen Millyard Viper V10. This is not so much a motorcycle as it is an eight-liter 500 horsepower Viper V10 engine with wheels strapped to it. The best part? You can buy it next month.

Back in 2003, Dodge stunned car and bike fans alike with a tantalizing concept. The Tomahawk paired an 8.3-liter V10 from the iconic Dodge Viper with four skinny wheels and a muscular body formed out of blocks of aluminum. It was a functional concept, too, with two patented hub-center steering swingarms providing steering up front, and two swingarms with dual chain final drives in the rear. The 500 HP engine in the center of it all had a fan from a Porsche 911 and dry sump lubrication. RM Motorsports of Michigan put real time and engineering into building a “motorcycle” meant to show that Dodge still meant business.

The bike was successful in that job, but it also created a bit of a fan club of people who wanted to swing a leg over a Viper 10 motorcycle.

The sad thing is that, despite claims of a theoretical top speed of 300 mph and lean angles as steep as 45 degrees, none of it was ever tested. The Tomahawk was never ridden above 100 mph. Nine examples were sold through Neiman Marcus for $550,000 as rolling sculptures that weren’t fully functional.

If you wanted a street-legal motorcycle with a comically huge engine, you were left with settling for the V8 power of a Boss Hoss or trying to build your own V10 contraption. Engineer and certified motorcycle nut Allen Millyard went the latter route with his Millyard Viper V10. Now, it’s going to roll across the auction block.

Motorcycle Magician

Englishman Allen Millyard has one of those brilliant motorcycle minds that repeatedly takes already famous motorcycles and turns them into something you would have never thought possible.

According to Classic Bike Guide Magazine, Millyard started his hijinks at only 10 or 11 years old after his dad told him that he couldn’t have a real motorcycle. Instead, the young Millyard got a tiny Mobylette moped. When the bike’s 49cc mill blew, Millyard’s response was to replace the engine with a hotter 175cc unit from a lawnmower before his dad figured it out. Then, only a few years later, Millyard took the engine that his dad discarded out of an Austin Mini and figured out how to cram it into the frame of a BSA Bantam. Or, more accurately, he figured out how to wrap a Bantam around an Austin Mini engine, because he cut the BSA in half and welded it back together around the engine.

Millyard went on to become a nuclear research engineer, but he never stopped building ridiculous motorcycles. He’s perhaps best known for the Flying Millyard, a boardtracker firing on two cylinders scavenged from a Pratt and Whitney 1340 aircraft radial engine. Then there’s the Millyard Kawasaki Z2300 V12, which features two Kawasaki KZ1300 inline sixes married into one beautiful V12.

He’s built a twin-cylinder Honda SS50 and a Kawasaki two-stroke with five cylinders. Millyard has built over 30 custom motorcycles over the decades, and he’ll modify just about anything, big or small, four-stroke or two-stroke.

Part of what makes a Millyard build so captivating, aside from the impressive engineering, is the fact that Millyard makes his custom bikes look like they were built from the factory that way. The Millyard Kawasaki Z2300 V12 looks like it came from Kawasaki, right down to the badging.

But for many, Millyard’s magnum opus is building the street-legal Viper motorcycle that Dodge didn’t.

The Millyard Viper V10

As Motor Cycle News reported, Millyard and his son, Stephen, saw the Dodge Tomahawk concept at the 2004 Goodwood Festival of Speed and were thoroughly unimpressed. Stephen believed that his dad could do better than what Dodge was able to do with its own engine. Millyard did just that.

The Millyard Viper V10 started with an eight-liter V10 from a 1995 Dodge Viper GTS that Millyard sourced from eBay in 2004. He kicked the build off in earnest in 2007, with the chassis coming together by Christmas of that year. Amazingly, Millyard took only a year of work time to build the bike, and it was completed in July 2009. Millyard hoped the Viper-cycle would hit 250 mph, but he’s thus far “only” taken it to a still impressive 207 mph, which is more than twice as fast as Dodge ever took the Tomahawk.

H&H Classics, the platform chosen for the sale, details some of the unique engineering work on display:

Credited with developing 500bhp / 525lbft, the monstrous powerplant has tubular subframes (steel front / alloy back) bolted to it, while the single-sided swing arm is attached to the gearbox. Typically well-executed, the Millyard Viper V10 features tailor-made forks, 75mm JCB hydraulic ram stanchions, converted Vauxhall Carlton damper rods, Hagon springs and two recalibrated Yamaha R1 shock absorbers at the rear. The original cast iron flywheel was supplanted by an alloy one, the handmade exhaust headers were ceramic coated and the ‘cans’ modelled on those of a Suzuki TL1000S in keeping with the bike’s ‘street cruiser’ aesthetic.

That’s right, this bike doesn’t even have a true frame. Instead, like many modern motorcycles, the engine is a structural element with the rest of the motorcycle bolted to it. Nor does it have multiple gear ratios to shift through; power reaches the rear wheel through a single-speed transmission with a clutch. Millyard had to make his own forks because the motorcycle weighs a whopping 1,389 pounds, of which a hefty 750 pounds is just the engine. He just couldn’t find any forks on the market that worked.

The brakes are equally impressive. Up front is a set of Pretech six-piston calipers with titanium pistons, titanium heat shields, and EBC ceramic pads for racecars. When it came to the exhaust system, Millyard used ceramic coatings and stainless steel heat shields to try to keep the ride from getting too blazing hot, but this didn’t work as well as he had hoped.

So, Millyard started researching a material that better resists heat and found that the material used to make simulated coals for gas fireplaces has similar properties to the material used to make the thermal protection tiles for NASA’s Space Shuttles. To test just how effective the material was, he cut one of the fake coals into a tile, put it onto one of his fingers, and then pointed a blowtorch at it. If it’s good enough to keep your finger from melting off, it’s good enough for exhaust heat shielding!

Also notable is that a Viper engine of this vintage makes 400 HP from the factory. Millyard cranked up the taps with ECU tuning to get 500 HP from the motorcycle version. Did he need to? Nope. Is it awesome? Yes! And all of it is road-legal with a valid MOT, too.

This motorcycle was last in the news in 2023 when Millyard and Henry Cole rode the Millyard Viper to V10 to 183.5 mph, scoring the Fastest Tandem Motorcycle World Record. Since completion, the motorcycle has covered over 9,200 miles of riding, proving itself not just fast, but reliable.

One of the bike’s build videos is embedded above; click here if you don’t see it.

Some Lucky Person Can Own A Piece Of History

But now, Millyard is moving on, sending the bike to a new home. On July 22, the H&H auction at the National Motorcycle Museum in Solihull will feature the Millyard Viper V10 for anyone to enjoy. The motorcycle is expected to sell for between £100,000 ($132,469) and £150,000 ($198,719), so bring a bank vault, or lots of friends who each want to own a piece of this thing. Given its one-off nature and fame, you should even be able to import it to America.

As for Millyard, he says that selling the bike will pave the way for future endeavors:

“I’ve decided to offer my 8000cc Millyard Viper V10 up for sale at the next H&H auction at the National Motorcycle Museum UK on the 22nd July 2026. This has been a very difficult decision for me to make, but it will make way for more exciting projects in the future”.

I love projects like what Millyard builds. Sure, his bikes don’t really serve a practical purpose, but who cares? His projects are the inspiring stuff of dreams. He built a better motorcycle than a massive corporation, then proved it worked. Hopefully, bikes like these inspire some people to follow their own dreams and become the engineers they want to be.

Top graphic image: H&H Classics