Decrypting Parallel Twin & V-twin Engines

With the demise of two-strokes due to increasingly strict emissions norms, almost all motorcycle engines these days are four-stroke units. however, they still come in multiple flavours, including the ever-popular single-cylinder mill that’s still going strong even after a century, and the more advanced twins, triples, fours and even six-cylinder engines, all of which are currently in production. here, we take a look at two of the more popular motorcycle engine formats – parallel twins and V-twins, examine their key differences, and take a look at the advantages and disadvantages they offer to the rider.

- Sameer Kumar

The majority of motorcycles produced today, especially in India and other Asian markets (except Japan), are powered by air-cooled single-cylinder four-stroke engines of 100-250 cc capacity. However, in markets like Europe, North America and Japan, where motorcycling is also a leisure activity, and where motorcycles are not used only for commuting, larger displacement engines are common, and two of the more popular formats for such engines are twin-cylinder units in either the V-twin or, to a lesser extent, the parallel twin layout.

Starting in the 1930's, motorcycle manufacturers like Triumph started using parallel twin engines to power their motorcycles and other British manufacturers like Norton, AJS, BSA and Ariel also produced parallel twin-powered machines.

From the 1960's onwards, Japanese manufacturers like Honda, Yamaha, Kawasaki and Suzuki followed suit, with the parallel twin format becoming quite popular in the period from the 1960's to the 1980's. With parallel-twins, the cylinders are placed side by side above the crankshaft, with a firing order of 360°, 180° or 270°.

V-twin engines, where the two cylinders are arranged in a ‘V’ formation, have also been used on motorcycles for the last 100 years. Currently, manufacturers like Harley-Davidson, Indian and Victory use the transversely-mounted (cylinders in line with the chassis) V-twin engine format for their cruisers and touring bikes, while Ducati uses V-twins for its high-performance super bikes and dual-purpose machines. In fact, Ducati V-twins are some of the most advanced,high-tech V-twin motorcycle engines ever produced and are now not too far behind higher-revving inline-four and V4 engines in terms of specific output.