Royal Enfield, the self-appointed “global leader in the mid-size motorcycle (250-750cc) segment,” has unveiled its first modern twin-cylinder engine at its new Technology Center in Leicestershire, England. The air-cooled 650cc parallel twin will power the newest generation of Royal Enfield motorcycles.
Fans of the original British marque have long lusted for a contemporary version of the Royal Enfield Interceptor of the early 1970s. While the India-based company has been producing traditional 350/500cc singles ever since it became an India-based company (RE, of course, was founded in the United Kingdom), the new twin has been “designed to offer the right balance between power, torque and usability to ensure a smooth and approachable riding experience. It will offer broad spread of torque which will make the motorcycle easy to ride without frequently shifting gears.”
Not, in other words, a sportbike. The single overhead cam, air-cooled, 648cc parallel twin was co-developed by Royal Enfield’s UK Technology Center and the factory team in India. The new engine is rated at 47 horsepower and 52 Nm torque.
According to Royal Enfield: “The engine maintains an under-stressed 9.5:1 compression ratio and the fuel injection system ensures that smooth, accessible power is available at all times. The focus of the development was on giving adequate torque, spread broadly throughout the rev range so that riders can tap into it instantly at anytime without the need for excessive shifting. As a result the engine feels fun, potent, and easy-to-use.”
The one-piece forged crankshaft is a first for Royal Enfield, designed for strength and the ability to handle the twin’s torque. The 270-degree firing order and use of a balancer shaft minimize the vibration factor. The designers spent considerable effort tuning the engine and designing an exhaust system to produce the proper tonal rumble of a vintage parallel twin.
4-stroke, 270 degree crank, single overhead cam, air-oil cooled 648cc parallel twin
Power: 47 bhp at 7100rpm
Torque: 52 Nm at 4000rpm
Bore x Stroke: 78mm x 67.8mm
Compression Ratio: 9.5:1
Fuel Management: Fuel injection
Ignition: Digital spark TCI