2013 Honda CB1100 Development

    American Honda
    Jan 24, 2013

When Mitsuyoshi Kohama was designated Chief Designer of what would eventually become the new Honda CB1100, he set out to create a motorcycle in a very different way than most of us could imagine. For starters, this bike didn’t fit into any existing category. This was not to be a new generation of supersport bike or a more comfortable touring machine or a way-out cruiser. Instead, this would be something very different.

This was to be a thoroughly modern motorcycle, yet one that paid homage to the history of Honda. This would be a touchstone motorcycle that resonated with Honda’s landmark CB750 Four, a two-wheeled icon, while also providing the performance, reliability and quality of contemporary Honda motorcycles. This would be a modern reincarnation of a timeless form, a purist’s kind of motorcycle, if you will. And to please the eye of the discerning purist, this motorcycle had to be a thing of beauty and grace.

How to bridge the many, broad gaps in time, space and functional differences between past and future designs? Let’s examine some of the ideas Kohama worked through along the way: “Instant acceleration has its appeal, as does modern styling that conveys the swiftness of the bike. But there’s a lot more to the path of motorcycle evolution. I found myself thinking along these lines for the first time when I returned to Japan, after several years in Europe. It was also at this time that I grabbed a pencil and quickly started sketching.

“Tires. Engine. Frame. Tank. Seat. I thought about how to craft all the necessary elements beautifully and combine them in a perfect whole. A simple and efficient double-cradle frame embraces the air-cooled inline-four engine that secured Honda's status as the four-cylinder pioneer and the creator of the CB750 Four. Building on this proud tradition, the approach to the new bike strives for beauty, craftsmanship, ease. In other words, I wanted to create a beautiful motorcycle with artisan-level handiwork that's also approachable and easy to ride. Based on my sketch, this ‘bike that defies logic and just demands to be ridden’ became a reality.”

Even as you begin to see things through the eyes of the designer, you’re likely still wondering why Kohama chose to give the CB1100 an air-cooled engine—a very natural question that he explains in very simple terms: “My only reason is that a lot of customers like air-cooled engines. I like the metallic sound the engine makes as it cools. Just looking at the cooling fins inspires me. There is something about an air-cooled engine—a feeling you simply can't get from the liquid-cooled engine in a high-performance bike. To me, as a bike rider and a bike fan, a future without air-cooled engines just didn't seem right. And I was certain I wasn't the only one who felt this way!”

That choice of an air-cooled design notwithstanding, the CB1100 engine incorporates many up-to-date engineering features. Dual overhead camshafts with a central chain drive and a narrow included valve angle of 26.5 degrees for an open combustion chamber that promotes good flame propagation for a clean and efficient burn. Four valves per cylinder; 27mm intakes and 24mm exhausts, with light and narrow 2.5mm valve stems. Honda’s modern PGM-FI fuel injection system for superior fuel metering under widely varying conditions. Moreover, with bore and stroke dimensions of 73.5mm by 67.2mm, the engine displaces a full 1140cc for loads of smooth, instantly accessible power that translates to effortless, big-time pull. Journalists who have enjoyed a brief, early ride rave about how fun and accommodating the CB1100 is to ride. Yet achieving a just-right look as well required uncounted hours of design time.

As an example, the cooling fins that cover the surface of the CB1100's engine not only had to play a functional role in aiding engine cooling, they also had to look just right. Kohama explains, “Fulfilling the requirements of beauty and function resulted in cooling fins that were just 2mm thick—the thinnest of any model in the Honda lineup. Commercially producing such fins is difficult, and at first the factory told us it was impossible. But we developed a new production process to make the fins possible, and they became a part of the bike of which we are extremely proud. Beauty is a subjective thing that can't be expressed in numbers or explained with logic. While valuing the way that air passed over the fins so that they could perform their crucial function of carrying heat away from the engine, we also greatly valued—as fans of bikes and guys who love machinery—the excitement that the appearance of the fins could produce, and we shaped them with appropriate care.”
That kind of extreme attention to detail in pursuit of beauty can be found in almost every visible element on the CB1100, as Kohama explained: “In taking on the design of the CB1100, the team and I agreed that our mission was design—not styling. These words tend to get confused with one another, but at base they mean two totally different things. ‘Styling’ refers to establishing the look the vehicle needs to have, adding motifs, and otherwise enhancing its appearance. On the other hand, the elements of ‘design’ are mostly to be found in the actual drawings of the machine, serving as the true origins of the form of the vehicle.
“Unlike an automobile, a motorcycle is not covered with a body, so there is no clear division between exterior and interior. Rather, the visible mechanical parts serve as the exterior decoration. For these reasons, we needed to keep our focus on the pure design elements, making each mechanical part as beautiful in form as possible. To create parts that were both beautiful and functional, we utilized the characteristics of many different materials, including metal, plastic, leather and rubber. This approach is what design is all about and lets designers show what they can really do.”
Fuel tank. Taillight. Camshaft location and spacing. Footpeg brackets. Part after part, detail upon detail, all carefully shaped as an individual part, and then integrated into a whole to create a beautiful silhouette. “Had the objective been horsepower, there would have been no problem whatsoever,” Kohama said. “In striving to bring true joy to CB1100 customers, there were things more important to us than horsepower. So freed from the necessity of maximizing power output, the designers came together and created an air-cooled engine offering not a superficial, decorative appearance, but instead true beauty based on the essence of the molded form. I believe that this was a huge accomplishment.
“Honda motorcycle designers will continue the search for new possibilities in performance and design. At the same time, by building our bikes on Honda's motorcycle origins and polishing them to perfection, we'll seek to offer true joy to bike fans and riders everywhere.”

Honda Powersports
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