Top 10 Six

More is more, and more will always be better

While six-cylinder engines are commonplace in cars, they are a lot less so in motorcycles and, when they do appear, they are seen as being completely extravagant and over-the-top. Not only are they complex and expensive to produce, having 50% more components than a four-cylinder engine, they are also wide, heavy and the power advantage over four-cylinder engines is questionable. Having said that, they are ultra smooth, have a distinct character and an air of exclusivity. Honda built the ultimate straight six engines of 250cc and 350cc for Grand Prix motorcycles in the 1960s and there have also been plenty of road-going six-cylinder motorcycles, adding to the color of motorcycling.

Related: Top 10 Grand Prix Motorcycle Racers of All Time

OK, not a production model but important in the story of the six-cylinder motorcycle. The RC166 is from the time when the Japanese factories were spending millions of dollars trying to beat each other on the racetrack. While the likes of Yamaha and Suzuki were using two-stroke engines, Honda was opposed to this technology and persisted with four-strokes. But, in order to match the power of the two strokes, a four-stroke engine has to have more cylinders, so Honda developed the incredible six-cylinder 250cc RC166, later stretched to 297cc to compete in the 350cc class. In both classes, producing around 60 horsepower at 18,000rpm, giving a top speed of around 150mph, it was utterly dominant until the end of 1967, when Honda withdrew from racing.

If it was launched with a flat four-cylinder engine in 1974, the mighty Gold Wing gained a flat-six cylinder engine from 1988 and, from that point onwards, it became the ultimate touring motorcycle, with unparalleled comfort and weather protection. By 2001, this engine had grown to 1,832 cc and the 2012 model had ABS and cruise control, electrically assisted reverse gear, an optional airbag, a fairing with heating and an adjustable screen, panniers and top box, built-in satnav and a six-speaker audio system with Bluetooth connectivity. At 835 pounds weight for the Tour model, it’s not light, but the 1,833cc flat-six engine produces 125 horsepower and 130 foot pounds of torque, so performance is never an issue.

Produced in two separate tranches from 1997 to 2003 and 2014-2015, the Valkyrie was an attempt by Honda to meet Harley-Davidson head-on in the cruiser market. Early models had the 1,500cc engine, but the later models have the 1,833cc engine, both having six cylinders. The models lost a lot of weight over the Gold Wing and gained a style of their own by deleting the fairing, screen and built-in panniers and top trunk. Over 150 pounds was lost, which necessitated re-calibrated suspension that gave a much more sporting ride. Buyers still preferred the full-house Gold Wing model, so the Valkyrie was quietly dropped after only two years in the U.S.

Related: 2015 Honda Gold Wing Valkyrie

Given their love of engineering, it is surprising that the Italians haven’t embraced the six-cylinder engine more than this sole attempt by Benelli. Designed by Alejandro De Tomaso (of later sports car fame), there were two versions, the 750cc and the 900cc, the former being the first production six-cylinder production motorcycle in the world. The engine was based on that of the Honda CB550, with two cylinders grafted onto the end, and it produced 76 horsepower at 9,000rpm, with a top speed of 127mph, amazing smoothness - even compared to the still relatively new Japanese four-cylinder engines - and a blood-curdling exhaust note from the six individual headers and mufflers. The 900cc engine arrived in 1979 but less than 2,000 were built before production ended. A glorious machine.

Given the practical advantage of packaging a V6 over an inline six, it is again strange that it is the latter that is the most popular configuration for a motorcycle application. Horex was a German motorcycle manufacturer from 1923 to 2006 and later from 2010 to 2015. In its latter incarnation, a narrow-angle V6 engine of 1,218cc was designed, similar to that offered by Volkswagen, initially intended to incorporate a supercharger, a feature that was later dropped. 161 horsepower and 101 foot pounds of torque were claimed, with an overall weight of 549 pounds. Sadly, only a few examples were completed by the time the company declared bankruptcy in 2014 and nothing has been seen of the Horex VR6 since.

The 1970s were nothing more than a power race between the Japanese motorcycle manufacturers and Kawasaki was determined to be top dog. To that end, they designed a water-cooled six-cylinder engine which produced 120 horsepower (130 horsepower from 1984, with the help of fuel injection) and 85 foot pounds of torque. It was creamy smooth and not only did it look imposing, it really was imposing, with a 709 pound all-in weight. Despite this, the handling was reported to be acceptable, even though, in 2023, it would scare the pants off anyone who attempted to keep up with modern machinery. At this time the Japanese were still obsessed with power and not spending nearly enough time on chassis development. That would change but, thankfully, not before monsters such as this had appeared.

Yet again, BMW demonstrated its engineering prowess and showed that the inline six-cylinder engine still had relevance in the modern era. The heavily canted-forward, 1649cc engine is one of the most astonishing motorcycle engines ever produced, with a seamless spread of power and torque (160 horsepower and 129 foot pounds of torque) which was needed to propel the 768 pounds of weight the K160GTL touring model carried. If it’s a large motorcycle, you’d never guess it from the rider’s seat, with seriously impressive dynamics, even when the going gets twisty. Beautifully executed, if there are touring models in the BMW range that do the same job for less money, then none of them do it with such style and performance.

Say ‘six-cylinder motorcycle’ to anyone, and it is very likely that this is the one they will reference. Six cylinders and six carburetors equaled 105 horsepower which doesn’t sound like a lot today, but, in 1978, it was very respectable. It was visually one of the most exciting six-cylinder motorcycles, with the six chromed exhaust headers and largely exposed - and very wide - engine. However, even though it was widely admired, there were other, simpler motorcycles that did everything a motorcycle should do, but better. The Suzuki GS1000, for example, was just as fast, handled better, stopped better and was cheaper. But for sheer presence, the CBX1000 takes the crown.

Related: Honda CBX1000: How Honda Won the Motorcycle Power War

More pot-stirring from Honda, the F6B (Flat-Six Bagger) sits in between the full-house Gold Wing and the stripped-down F6C Valkyrie. The Panniers give it some practicality, although your pillion passenger might not appreciate the lack of a back rest. Up front, the screen is a lot smaller and the overall style is much lower and sleeker. The F6B might just be the best Gold Wing variant, still with excellent wind and weather protection giving good touring ability, while being lighter and carrying a little less weight. The chassis and engine remain the same, which can only be described as a good thing.

Absolutely bonkers creation from Honda, designed to showcase Honda’s technical prowess as a manufacturer but ending up costing Honda at least $225 million, a figure that includes around $75,000 lost on every one sold, mostly due to the fact that besides the engine, all remaining parts were custom made by Honda exclusively for the Rune. To quote the project leader, Masanari Aoki, there were “no performance goals, no distinct function, purchase price [was] not a consideration.” Impractical, arguably irrelevant, stupendously ugly but utterly fascinating, around 3,000 were built before Honda saw sense. But where would motorcycling be today without some of the flights of fancy the manufacturers committed to production?

Harry has been writing and talking about motorcycles for 15 years, although he's been riding them for 45 years! After a long career in music, he turned his hand to writing and television work, concentrating on his passion for all things petrol-powered. Harry has written for all major publications in South Africa, both print and digital and produced and presented his own TV show called, imaginatively, The Bike Show, for seven years. He held the position of editor of South Africa's largest circulation motorcycling magazine before devoting his time to freelance writing on motoring and motorcycling. Born and raised in England, he has lived in South Africa with his family since 2002. Harry has owned examples of Triumph, Norton, BSA, MV Agusta, Honda, BMW, Ducati, Harley Davidson, Kawasaki and Moto Morini motorcycles. He regrets selling all of them.