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Allen Millyard's V10 Viper motorbike hits 207mph

Published: 16 May 2018

Updated: 03 April 2019

No, your eyes aren't deceiving you - this 8000cc, 500bhp two-wheeler is possibly the maddest, baddest motorcycle ever built - and it's British!

The awesome, utterly unique machine is built around the massive V10 engine from the Dodge Viper supercar and was homebuilt by prolific 'wacky bike' builder Allen Millyard.

Millyard is world-renowned for creating mega-engined bikes, having so far built more than 30 multi-cylinder machines ranging from four and five-pot, two-stroke Kawasaki machines, to a V12 based on a Z1300.

But his Viper V10 is by far his most ambitious project to date. Not only was 90% of it handmade by Millyard himself in the single garage at his home in Thatcham, Berks, but the exquisitely engineered and finished machine is fully road legal.

It passed SVA (Single Vehicle Approval) at the first attempt and qualifies as a new motorcycle with the DVLA (so it has an '09 rather than 'Q' plate), named 'Millyard Viper 10'.

Allen Millyard in his single garage workshop

In fact, virtually the only thing Millyard didn't come up with was the idea for the bike in the first place.

The Viper's story began when Millyard and son Stephen were unimpressed by a Dodge Tomahawk demonstration at the 2004 Goodwood Festival of Speed. "When Stephen saw the Tomahawk he said, 'You could do better than that, Dad'," recalls Millyard.

"When we got home, he found a Viper engine on eBay. I bid and next thing Stephen's shouting, 'Dad, you've got the engine!'"

Work didn't start until July, 2007. But by Christmas Millyard had a rolling chassis. "When I first fired it up, it almost had me off, there was so much reaction from the cast iron flywheel," he said. "Now it has a lightweight alloy flywheel." It was finally completed - bar paint, chrome, etc - in April 2009.

"All told, it has taken about a full year to build," Allen told MCN. "Really, I did it to beat the Americans at what they do best. They've had two attempts at building a Viper-engined bike (the Tomahawk and a one-off Boss Hoss version) and this is better than both."

Allen Millyard rides his V10 Viper bike on the road

So what's it like? "Well, I've done just 250 miles so far and I'm still getting used to it. Even so, it's the biggest grin I've ever had on a motorcycle. When you open the throttle you just feel the power through the whole bike!"

Millyard couldn't find big enough forks to support the bike’s weight, so made his own. Stanchions are 75mm JCB hydraulic rams, damper rods are converted Vauxhall Carlton, springs are by Hagon. Two Yamaha R1 shocks bought off eBay and resprung by K-Tech provide rear suspension.

There’s no frame, as such. Instead, a tubular steel front subframe bolts onto the engine; a single-sided swingarm bolts onto the gearbox and an alloy rear subframe bolts to the back of the engine.

Allen Millyard's Viper bike engine

The exhaust headers are handmade and ceramic coated, while the heatshields use ex-NASA Space Shuttle tiles. The cans were inspired by a Suzuki TL1000S. "l wanted it to be a 'street cruiser', not a sportsbike, so I wanted the swept-back look," explains Allen.


MCN rides the V10 at Bruntingthorpe

The astonishing V10, 500bhp Millyard Viper has recorded over 200mph in its first speed test - and its creator has set his sights on achieving 250mph. It makes the Viper the fastest unfaired motorcycle ever tested.

MCN tried the single-speed, unfaired bike in its first 'shakedown' test at Bruntingthorpe test track - when it posted 163mph with ease. Now, with revised gearing and suspension, the astonishing machine has posted 207.101mph - and there's still more to come.

The speed came in the hands of MCN test rider Bruce Dunn and was measured by sophisticated satellite tracking telemetry. With 500bhp on tap, the main factor limiting the bike's speed was not any mechanical restriction, but the ability of the rider to hold on to the handlebars.

Allen Millyard V10 Viper bike

Millyard changed the bike's rear sprocket for the test (from 46 teeth to 35) which, theoretically, raised the machine's top speed at its 6000rpm rev limit from 160mph to 219mph.

Millyard himself piloted the bike's first exploratory speed runs and reported that, although more difficult to get off the line (with the new gearing the bike would do 40mph at idle), once above 80/90mph it was much improved. "You can use the throttle now," he told MCN.

"You can open it up at speed without it wheel spinning like it did before. Then, when it hits 100, the power comes in - but it's not mad power, it just goes."

On his first serious run, Millyard recorded 192.53mph. "That's mental!" he exclaimed afterwards. "It's the biggest flippin' thrill ever. It'll definitely do 200mph, it's totally stable.

"The biggest problem is; it felt like my head was going to come off. It got to 190mph and my visor was pushed on to my nose. I just couldn't hold on, I had to let go of the throttle."

A later run failed to improve on that speed, then MCN's test rider and speed testing expert had a run. On his second go, taking full advantage of Bruntingthorpe’s two-mile long runway, Dunn hit an astonishing maximum speed of 207.101mph.

"I felt like US astronaut John Glenn on top of the Atlas rocket," said Dunn afterwards, still visibly shaking. "The wind blast is so severe that it's like hanging from a bar in a gym. You're being stretched so much you can't throttle off. It’s a real problem. You have to just let go of the whole grip."

But an exultant Millyard is now aiming even higher. He's making plans to fit the bike with a small fairing and narrower bars, along with further gearing and fuelling revisions to make it capable of 250mph.

Quick facts

  • Engine: Currently geared for 190mph (although with different gearing is theoretically capable of 250mph)
  • Power: 500bhp@4800rpm
  • Torque: 525ftlb@2800rpm
  • Average fuel economy: 18mpg
  • Overall length: 9ft
  • Wheelbase: 80 inches
  • Dry weight: 630kg
  • Tyre sizes: 280 x 20 rear, 180 x 18 front

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