Motorcycles

Wild twin-Wankel 690cc motorcycle makes 220 hp at 129.5 kg

Wild twin-Wankel 690cc motorcy...
220 horsepower, 129.5 kg – a very potent pair of figures for the Crighton CR700W
220 horsepower, 129.5 kg – a very potent pair of figures for the Crighton CR700W
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220 horsepower, 129.5 kg – a very potent pair of figures for the Crighton CR700W
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220 horsepower, 129.5 kg – a very potent pair of figures for the Crighton CR700W
Bitubo or Ohlins suspension options
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Bitubo or Ohlins suspension options
Dymag carbon wheels
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Dymag carbon wheels
Adjustable swingarm pivots and exposed cooling lines
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Adjustable swingarm pivots and exposed cooling lines
Underseat exhaust and offset monoshock
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Underseat exhaust and offset monoshock
The exhaust is designed to create a cold air vacuum that enhances engine cooling
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The exhaust is designed to create a cold air vacuum that enhances engine cooling
60 pounds lighter than the minimum weight of a MotoGP bike
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60 pounds lighter than the minimum weight of a MotoGP bike
British Supersport GP2 champion Mason Law takes the CR700W out for a strop
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British Supersport GP2 champion Mason Law takes the CR700W out for a strop
Dual-rotary 690cc engine makes insane horsepower and torque
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Dual-rotary 690cc engine makes insane horsepower and torque
A higher horsepower-to-displacement ratio than the most power-dense twin-turbo monster in the automotive world
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A higher horsepower-to-displacement ratio than the most power-dense twin-turbo monster in the automotive world
With a switchable cassette gearbox and slipper clutch, the engine weighs in at 43 kg
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With a switchable cassette gearbox and slipper clutch, the engine weighs in at 43 kg
View gallery - 11 images

The extraordinary Crighton CR700W extracts an incredible 220 horsepower from a 690cc twin-rotor Wankel engine, and weighs just 129.5 kg (285.5 lb) dry for a MotoGP-level power-to-weight ratio. Its maker believes it could be the final word in combustion bikes.

Brian Crighton pioneered the use of twin-rotor Wankel motors in race bikes in the late 1980s. Working as a maintenance tech at Norton, he took the 85-hp, 588 cc motor from a crashed Norton Commander police bike, and hotted it up into a 140-hp fire-breather with almost no initial support from the factory. When coupled with a Spondon frame, this twin-rotor beast ran rampant through several British championships, including the 750cc Supercup, British F1 and British Superbike championships, until it was banned from competition.

Now, he's distilled everything he learned campaigning those Nortons into an engine and bike of his own making, and it looks like an absolute monster. Turns out there is a replacement for displacement after all, and it's a motor that doesn't require pistons to constantly change direction.

Dual-rotary 690cc engine makes insane horsepower and torque
Dual-rotary 690cc engine makes insane horsepower and torque

The track-only CR700W features one of the most power-dense combustion engines ever created. Displacing just 690cc, this "Rotron" unit generates 220 hp at 10,500 rpm. That's 319 hp per liter, naturally aspirated – more than the chart-topping Koenigsegg Jesko gets out of its 5-liter, 1,578-hp V8 even with two huge turbos bolted on.

It's a cast-aluminum donk, with just three moving parts and it uses silicon nitride ceramic apex seals and low-friction, durable molybdenum and nicasil plating on all engine wear surfaces. Crighton says it exhibits "close to zero wear characteristics" and weighs in at just 43 kg (95 lb) including a bespoke Nova cassette gearbox and slipper clutch.

It's not some peaky, unmanageable beast either; its 105 lb-ft (142 Nm) of torque at 9,500 rpm is nearly as much as you get out of a 1,300cc Gen 2 Suzuki Hayabusa on a dyno. How's this for confidence: "the CR700W's rotary engine delivers the most tractable and useable power of any motorcycle engine in the world today," says Crighton, "bar none." We'd gladly volunteer to be the judge of that!

Underseat exhaust and offset monoshock
Underseat exhaust and offset monoshock

Crighton has stuck with what he knows chassis-wise, using a Spondon-derived aluminum alloy frame. Interestingly, the engine oil reservoir is in the frame spars, and the double-sided swingarm uses a single shock offset to the right side of the bike so a cavernous-looking exhaust can run right up behind the engine and under the seat.

This exhaust is interesting in itself; the energy of its airflow is used to develop a vacuum that sucks cool air into and through the engine, where it's directed right through the finned apex of the rotor tips, giving the engine a free cooling boost that saps zero power from the engine. The remainder of the cooling is handled by an innovative liquid cooling system that runs channels right down into the core of the main rotor bearing journals.

Totally focused on elite track riders, the CR700W comes with Dymag carbon wheels and the buyer's choice of Ohlins or Bitubo adjustable suspension. The steering head angle and swingarm pivot point are easily adjustable, allowing fine-tuning of the handling.

Adjustable swingarm pivots and exposed cooling lines
Adjustable swingarm pivots and exposed cooling lines

Crighton says he hopes this thing can give riders a MotoGP-like experience on track, but it looks to us like something entirely different. MotoGP bikes labor under a minimum weight of 157 kg (346 lb) and make up to around 290 hp, so the top dogs are putting out something like 1.84 hp per kilogram. The CR700W is not far off that mark, at 1.68 hp/kg, but at 27.5 kg (60 lb) lighter, this bike will be an exceptional dance partner in the corners and during changes of direction.

Mason Law, 2020 British Supersport GP2 Cup Champion, has had a chance to sling a leg over, here's what he reckons: "Riding the Crighton is a phenomenal experience. The raw speed of the motorcycle is mind-blowing. It feels like being propelled down the runway of an aircraft carrier in a F-35 fighter jet. This raw speed, coupled with its low weight, means it has the power-to-weight ratio of a modern Moto-GP motorcycle but with buckets more torque."

British Supersport GP2 champion Mason Law takes the CR700W out for a strop
British Supersport GP2 champion Mason Law takes the CR700W out for a strop

High praise indeed. Sadly only 25 will be hand-built by Crighton, and at a price starting from £85,000 (US$116,000). Rare and highly expensive to crash, then, so you'll be lucky to see one in action, or hear the awesome howl from those two rotors working hard.

But the CR700W is another terrific example of the British obsession with lightweight performance vehicles that has brought us incredible machines like the Spirit GP-R and the Gordon Murray T.50 in recent years. Long may they prosper.

The video below shows the bike in action.

Crighton Main Promo

Source: Crighton Motorcycles

View gallery - 11 images
20 comments
20 comments
ScienceFan
Pity to see so much ingenuity go to solutions of the past while the need to get rid of fossil fuels is so urgent. But good to see the maker thinks it is the final word in combustion bikes. Hope no one buys one.
riczero-b
For better or worse IC engines will be with us long term, so elegant light comparatively frugal solutions like this are to be encouraged. In de - tuned from it would make a great aero engine.
usugo
with buckets more torque
it seems an odd statement when you claim it has the torque of a road legal bike, that is much lower than a motogp, besides the fact wankel engines are notoriously lacking in the torque compartment
Grunchy
Everybody who keeps incessantly criticizing internal combustion, there are sustainable fuels, you know. Formula 1 is moving toward that end for 2025. In fact it’s the electrical grid that uses the planet’s most polluting fuels such as coal. But there are fuels derived from the chlorophyll-derived carbon cycle that are factually 100% solar powered. For certain applications, internal combustion might never be replaced! You might just have to live with it.
sally
Has a beautiful sound. Yes it’s the ultimate of the past as SF says but with only 25 being made, it has no effect on the climate while showing the pinnacle of what is achievable in terms of innovation and engineering which I suspect will be of enormous use to designers and innovators in the future in other more green activities especially in the use of colony materials and mechanisms. I find that cutting edge effort far more acceptable than producing many hundreds of thousands of vehicles offering little in terms of innovation but doing horrendous harm to the environment as epitomised by the disgraceful cover up of diesel emissions. And if nothing else when in a museum this incredible bike/engine will I’m sure inspire new generations to take what is possible to greater heights.
Peter Forte
You have to be a certain age to remember the NSU RO80 with its Wankel engine and the then insoluble problem of rapidly deteriorating seals.
It's wonderful to see the awesome potential of the rotary engine finally realized.
This was accomplished through developments in material science, manufacturing and design ingenuity, and the crusading zeal of a true believer!!
I have to believe that a lot of these developments will find themselves applied in everyday life and even find use in a carbon-reducing world.
Jay Gatto
An ICE swansong, maybe. I must say it's a good looking design, not a CAD-tastic mess.
Gone with the Wind
The Wankel engine has been around a long time but has always been plagued with reliability issues. Wonder how it’ll cope with 10 - 20% ethanol based fuels
Manuel Aguirre
Hope This could be useful to Mazda, are you guys there? Why don’t you guys hire engeneer Brian Crighton
Grelly
I didn't see anything about fuel consumption. Did I miss it? 'cos apart from problems with seals, the Wankel's biggest issue is it isn't historically fuel efficient.
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