This is one of the most famous custom motorcycles in the world – it’s Allen Millyard’s Viper V10-powered bike that’s both street-legal and proven to be capable of over 200 mph.
Millyard is a British mechanical engineer, a popular YouTuber, and a host of TV shows like The Motorbike Show and Junk & Disorderly. He’s also the builder of some of the wildest custom motorcycles in history, including V12, V10, V8, and straight-6 powered specials that he often fabricates the engines for himself.
Above Video: This is an episode from Allen Millyard’s YouTube channel all about the Millyard Viper V10 motorcycle. Its shows him giving it a service, taking it for an annual inspection, and then taking it for a ride.
History Speedrun: The Millyard Viper V10 Motorcycle
The Millyard Viper V10 is a one-off, road-legal motorcycle built around the 8.0 liter V10 engine from a Dodge Viper. It was finished in 2009 by celebrated British engineer Allen Millyard in the one-car garage at his home in Berkshire, England. Amazingly, the engine is good for 500 bhp and 525 lb ft of torque.
When it was tested at the Bruntingthorpe Proving Ground later in 2009, it ran 207.101 mph in the hands of Motorcycle News chief test rider Bruce Dunn. In 2023, ridden two-up by Millyard and television presenter Henry Cole, the bike set what was then the Guinness World Record for the fastest speed achieved by a tandem motorcycle over a standing-start mile – 183.5 mph.
Millyard had been building unconventional motorcycles for over a decade before the Viper project began. From the same suburban garage he had built a series of multi-cylinder Kawasaki two-stroke specials, a 1,600cc V8 grafted from two Kawasaki Z1 fours, and a 2,300cc V12 built from KZ1300 engines – always finishing his builds to a standard close enough to factory condition to fool many into thinking they were unheard of production bikes or official prototypes.
Millyard’s Viper bike was prompted by a public demonstration at the 2004 Goodwood Festival of Speed, the Dodge Tomahawk was on display – the four-wheeled, V10-powered concept bike that DaimlerChrysler had unveiled at the 2003 Detroit Auto Show.
Stephen told his father he could build something better. They returned home, found a Dodge Viper GTS engine for sale on eBay, and won the auction. Stephen was about to be proven right.
The Tomahawk had been designed by Chrysler’s Mark Walters and engineered and fabricated for DaimlerChrysler by RM Motorsports of Wixom, Michigan. It was never road-legal, nor was it meant to be.
This is one of the most famous custom motorcycles in the world – it’s Allen Millyard’s Viper V10-powered bike that’s both street-legal and proven to be capable of over 200 mph.
A total of 10 were reportedly built, with as many as nine sold through the Neiman Marcus catalogue at $555,000 each as static “automotive sculptures,” with claimed top speeds ranging from 300 to 400 mph that were never substantiated. Millyard’s intent from the outset was quite different – he wanted to build a road-registered motorcycle, potentially even useable as everyday transport, and built from the bare engine outwards.
The 8.0 liter (488 cubic inch) pushrod V10 (a Gen II Viper unit from a mid-1990s GTS), complete with the snake’s-head magnesium rocker covers it left Detroit with, sat in the garage for around two years before serious work began in July of 2007.
By Christmas of that year Millyard had a rolling chassis. The bike was complete in April of 2009. He later estimated the actual build time at roughly a full year of part-time work between the other projects he was working on simultaneously.
The Millyard Viper V10 has no conventional motorcycle frame, the engine itself acts as the bike’s primary structural element, a stressed-member. A tubular steel subframe bolts to the front of the engine and carries the steering, an aluminum subframe bolts to the back, and a single-sided swingarm is attached directly to the gearbox.
The engine alone weighs 700+ lbs and accounts for the majority of the motorcycle’s 600+ kg (about 1,300+ lb) curb weight.
Stock motorcycle forks couldn’t even hope to handle the loads involved, so Millyard made his own. As you do. The 75 mm stanchions are 75mm JCB hydraulic ram components, the damper rods came from a Vauxhall Carlton, and the springs were supplied by Hagon.
Rear suspension uses two Yamaha R1 monoshocks, recalibrated for the bike’s prodigious weight. The exhaust headers were hand-made and ceramic-coated, with heat shielding made from a high-temperature ceramic tile material similar to that used on the underside of the Space Shuttle.
The engine alone weighs 700+ lbs and accounts for the majority of the motorcycle’s 600+ kgs (about 1,300+ lbs) curb weight.
Due to the V10 engine’s power, it was decided early on that gear changes wouldn’t be needed. Instead, the bike runs the Viper’s drivetrain as a single fixed ratio, with the V10’s torque making conventional gear switching unnecessary.
Different rear sprockets are fitted to set the calculated top speed for the conditions, theoretically ranging from 160 mph to over 270 mph. Interestingly, the original cast-iron Viper flywheel was replaced with an aluminum one after the bike’s first start nearly threw Millyard off, owing to the reactive torque.
The Millyard Viper V10 passed the UK’s Single Vehicle Approval inspection at the first attempt and was first registered for the road on August the 1st, 2009, as RX09 LVH. That made it a 2009 motorcycle in the eyes of the DVLA rather than a “Q”-plated kit machine. After winning the “Most OTT” (Over The Top) award at the 2014 Salon Privé Concours d’Élégance, the bike was re-registered with the plate “V10 OTT,” which it carries today.
Millyard invited Bruce Dunn to test the bike at Bruntingthorpe in August of 2009. With a higher-geared rear sprocket fitted and reportedly without using full throttle, Dunn recorded a single-pass top speed of 207.101 mph, measured by satellite telemetry.
Millyard had earlier run 192.53 mph himself before handing the bike over for the faster passes. MCN described the result as a record for the fastest unfaired motorcycle ever tested. According to later MCN reporting, only three people have ever ridden the Viper V10 – Millyard, Dunn, and former MCN road tester Trevor Franklin.
In May of 2023, Millyard and Henry Cole (his colleague on ITV’s The Motorbike Show) set what was then the Guinness World Record for the fastest speed achieved by a tandem motorcycle over a standing-start mile, riding the Viper V10 two-up over the runway at Elvington Airfield in North Yorkshire at an officially timed 183.5 mph.
Millyard invited Bruce Dunn to test the bike at Bruntingthorpe in August of 2009. With a higher-geared rear sprocket fitted and reportedly without using full throttle, Dunn recorded a single-pass top speed of 207.101 mph, measured by satellite telemetry.
The previous record, held since 2011 by Americans Erin Hunter and Andy Sills at 181.42 mph, was beaten by roughly two mph. The mark stood until March the 23rd, 2025, when Jack Frost and Paul Milbourn recorded 234.7 mph at the same venue on a turbocharged Hayabusa.
Despite its weight, astonishing fuel consumption, and the lack of any concessions to comfort, the Viper has been ridden plenty. Millyard has covered more than 9,000 miles on it, including trips to Guernsey, the Isle of Wight, and a lap of the Isle of Man TT circuit.
In June of 2026, Millyard announced that the Viper V10 would be sold at the H&H Classics motorcycle auction at the National Motorcycle Museum in Solihull on July the 22nd.
It’s the first Millyard creation to be offered at auction directly by its maker. “I don’t think I’ve got anything to prove with it anymore,” he told MCN. “It takes up a lot of space in the house, and there’s a responsibility in keeping it maintained.”
In June of 2026, Millyard announced that the Viper V10 would be sold at the H&H Classics motorcycle auction at the National Motorcycle Museum in Solihull on July the 22nd.
The bike will be sold with two interchangeable seats and its V5C document. Whatever it makes, the proceeds will fund whatever Millyard chooses to build next in the world’s most famous little Berkshire garage.
The listing for the H&H Classics is here with a price guide of £100,000 to £150,000 ($132,000 to $198,500 USD).
Images courtesy of H&H Classics
Articles that Ben Branch has written have been covered on CNN, Popular Mechanics, Smithsonian Magazine, Road & Track Magazine, the official Pinterest blog, the official eBay Motors blog, BuzzFeed, Autoweek Magazine, Wired Magazine, Autoblog, Gear Patrol, Jalopnik, The Verge, and many more.
Silodrome was founded by Ben back in 2010, in the years since the site has grown to become a world leader in the alternative and vintage motoring sector, with well over a million monthly readers from around the world and many hundreds of thousands of followers on social media.
