Royal Enfield 650 cc twin cylinder engine – a closer look

Royal Enfield unveiled its first modern twin-cylinder engine at its new Technology Centre in Leicestershire, England. This new 650 cc, air cooled parallel twin will power the newest generation of Royal Enfield motorcycles. The core idea behind the modern 650 cc twin engine was to develop a global platform that would carry the Royal Enfield legacy and character into modern context. It will offer broad spread of torque which will make the motorcycle easy to ride without frequently shifting gears.

The new platform is a 4 stroke, single overhead cam, air-cooled, 648 cc parallel twin cylinder engine developed by Royal Enfield’s UK Technology Centre and Chennai teams. Precisely engineered to be able to accelerate and deliver higher power and torque at lower RPMs, this new engine has an output capability of 47 BHP @ 7100 RPM and 52 Nm @ 4000 RPM.

The folks at RE claim that this is a highly refined engine, with true highway capability, the 650 twin engine has been developed to excel across a wide range of real-world conditions. Classically styled, the engine has been designed to achieve a high level of modern refinement. The twin pipes and the cooling fins on the classic air-cooled engine render a visually beautiful impact.

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. Making this possible are a number of elements, starting in the very depths of the engine where there is a single-piece forged crankshaft (a first for Royal Enfield) which ensures strength and the ability to handle the twin’s torque. This crankshaft uses a 270-degree firing order, which gives a high degree of character to the engine’s power delivery. Also, thanks to the use of a balancer shaft, unwelcome vibrations have been eliminated.

The motor retains Royal Enfield’s ‘air-cooled’ engine legacy, which lends to a simple, cleaner, more elegant look with fewer components and less weight. It ensures that the engine remains as uncomplicated and uncluttered as possible. Using ambient air-flow combined with engine oil to keep engine temperature at an optimal level means that a radiator, fan, hoses, and other components are unnecessary. This keeps the motor beautifully clean and essentially pure, like the experience it provides. Although we are very keen to see how this will pan out in the long run with varied riding conditions.

Just as relevant as the engine’s individuality, is its sound. The characteristic ‘thump’ of Royal Enfield’s singles is cherished by legions of enthusiasts, and great lengths were taken to ensure that the new 650 twin gives an equally compelling soundtrack. Hours were spent tweaking every contributing variable to engine sound, resulting in twin silencers that rumble with just the right tone.

The entire platform, including the engine and chassis have undergone rigorous testing during the development programme. It has been subjected to lab and bench tests, in addition to being tested on proving grounds, race tracks and public roads.

Royal Enfield 650cc Engine Specifications

• Type: 4 stroke, 270 degree crank, single overhead cam, air-oil cooled, 648cc parallel twin
• Power: 47 bhp @ 7100 rpm
• Torque: 52 Nm @ 4000 rpm
• Bore x Stroke: 78 mm x 67.8 mm
• Compression Ratio: 9.5:1
• Gearbox: 6 speed
• Fuel Management:Fuel injection
• Ignition: Digital spark ignition – TCI

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