It was to be the King of Motorcycles. It would set new standards of smoothness, comfort, speed and quality. It led to the creation of the greatest touring-motorcycle dynasty ever. Its influence continues to be felt to this day. And it was never meant to be seen outside of Honda R&D.
The project was known only by its code: M1. Created some 42 years ago as an outrageous experiment to push the boundaries of what was then possible in motorcycle design, the liquid-cooled, six-cylinder, shaft-drive prototype was an internal exercise, the answer to a question that has inspired some of Honda’s greatest designs: What if?
To understand the M1’s significance, you have to understand motorcycling’s landscape in the early ’70s, and Honda’s philosophy. Then, multi-cylinder motorcycle engines were still a rarity, with Honda’s CB750 the exception to the rule. Plus, the prevailing orthodoxy of the day made air-cooling and chain drive almost universal for motorcycles. In addition, Soichiro Honda always pushed for creation first, then the process of reconsidering and revising. This way of thinking encouraged engineers to push the limits of possibility, without the limitations of practical application. Honda also had a policy of rotating engineers between motorcycle and automotive design departments. Not that they were separate; back then, all of Honda’s engineers worked in the same large room. As a result, there was a vast cross-pollination of ideas and concepts. The M1’s project leader was Shoichiro Irimajiri, who had led the design of Honda’s classic five- and six-cylinder Grand Prix engines of the ’60s, and then gone on to assist Honda’s transition to car manufacturing. With that background, the M1’s creation, and its use of both Grand Prix racing and automotive features, seem logical, even inevitable.
The M1 was a leap of faith, and it delivered Honda into new areas. Although it sprang from the limitless ambition to make a flagship, engineers at first had no idea what form it would take. And that was the point behind the M1, to explore possibility. What’s more, as the exploration went on, it split the engineers on the M1’s basic direction, whether it was to be a Grand Touring machine or an ultra-high-performance bike. In the end, the GT direction won out, with an engine designed for a broad powerband and flat torque curve, not the highest peak power. At a time when every other manufacturer pursued peak performance as the key to sales, the M1’s broad-power approach was a bold new direction.
While it was never originally intended as a prototype for the Gold Wing®, it’s easy to see how the M1 influenced the creation of the original Gold Wing. The six-cylinder M1 was an example of blue-sky thinking at its best, but the Gold Wing had to be mass-produced, marketed and sold. The sheer size and complexity of the M1’s six-cylinder engine made production impractical at the time, but the opposed cylinder configuration was carried into the original four-cylinder GL1000.
The M1’s influence far exceeded what the original design team envisioned. In fact, when Honda engineers began developing the current six-cylinder Gold Wing GL1500 introduced in 1988, engineers spooned the M1’s six-cylinder engine into a GL1200 chassis to evaluate the merits of a six- versus a four-cylinder. That engine, almost 20 years old at the time, became Honda’s oldest test mule.
Today, the M1 is still around at Honda R&D. It now wears a complete front end from a GL1100, replacing the CB750 front end it originally wore. The rest of it’s the same, though, from the bread-loaf-like gas tank, to the black, slab-sided rocker covers and the car-like distributor poking up from the left bank of cylinders. Look at it now and you can see back to the future of motorcycling.
The M1 helped pave the way for the current generation of motorcycles, where low maintenance, high torque, and smooth, quiet running remain marketable design characteristics. These common traits were once a radical idea that came together in a small R&D facility in Japan, in a motorcycle called the M1.