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HOME » VINTAGE BIKES & MOTORCYCLE HISTORY » The Group of Seven : Picking the Great Motorcycle Engines

The Group of Seven : Picking the Great Motorcycle Engines


Singles. Doubles. Triples. Multis. Parallel. Opposed. Inline. The history books are full of engine choices. Picking the “most important”—or even the top seven—is a thankless task. Consequently then, we won’t bother thanking Rick Epp who weighs in with his personal short list of most significant platforms ever. We do admire his pluck though.

I was flipping through a stack of old motorcycle magazines recently when I came upon a tattered old 1975 issue that caught my eye. It contained an article featuring the most significant bikes of the last 25 years. Those two and a half decades were certainly witness to some legendary machinery, and the writer detailed such stalwarts as the BSA Gold Star, the Triumph Bonneville, the Harley-Davidson Sportster and the Norton Commando among his selections for top honours. I enjoyed the nostalgic reading and then moved on down the stack but later I couldn’t help thinking about his choices. Firstly, how odd that so few on that august list are still around today. Secondly, what influence did they have on the showroom floors of today? Granted, the British industry all but left the field but the game goes on, and each player is owing something to his predecessors. Motorcycles are a wonderful example of evolutionary engineering where the single disc brake begat the twin disc, which begat the triple disc, which begat the linked brakes, etc.

It would seem that the writer had chosen his favourites based on their ability to produce remarkable numbers on dynos and stopwatches. He was clearly biased in favour of power and speed. Fair enough—it was his article—but the more I thought about it the more I came to think that it was a most arbitrary list. Well, if he could compose one, then so would I. A problem quickly arose though: every list is necessarily subjective and therefore arbitrary. Even if you have hard numbers to back up your choices, those choices are based on criteria you have selected. I decided to disregard any era and to try and list the most influential motorcycles to date.

To frame these choices I used the industry’s penchant for focusing on engine capacity. After all, models are often named after their engine size, such as a “Harley 45” or a “Moto Guzzi 750S.” To further bolster my argument, race competitions are often grouped according to engine size so it seemed reasonable to talk about, for example, the most significant 50cc motorcycle.

That has to be a Honda. No other machine rolling upon any number of wheels has exerted the same influence this little bike has. More people around the globe have been introduced to internal combustion and mechanized transport by a Honda Cub than anything else. First built in 1958 this design has remained basically unchanged to this day. You just don’t mess with success. Honda managed in 1959 what the Japanese Imperial army failed to do in 1941—it conquered America. The bike has since been built in 11 different countries and production is well in excess of 20 million units.

Its clean, quiet and frugal four-stroke engine has carried people and goods to office and farm, to market and factory, to worship or frolic, and then taken them home again. We have all seen pictures of people in other lands using their bike to haul the whole family and perhaps a bit of livestock. Chances are that under all those legs sticking this way and that was a Honda 50 just going about its business. There have been faster and slicker 50s but none has had the impact of the humble Honda.

Check out the models from the latest countries to be exporting motorcycles. The profile of that new little four-stroke engine will certainly look familiar to anyone who has had a Honda. This is not a bad track record for a design now 50 years old.

Few of us have ever seen a DKW RT125, but it has been described as the most copied motorcycle in the world. It wasn’t really steam-powered as the name “Dampf Kraft Wagen” implies, but it was built by a steam engineering company in Germany. By 1930 DKW was the largest producer of motorcycles in the world and kept getting bigger by merging with other manufacturers to create the Auto Union in 1932.

Though by 1938 the Reich was imposing frugal rationalization on much of Germany’s industrial variety, the little DKW was left alone. The military acquired huge numbers of them and while they didn’t haul sidecars and machine guns like the BMW and Zundapp Twins did, they proved invaluable in scouting and communications work.

The two-stroke engine used a flat topped piston with Schnurle loop technology to move the fuel about, and was efficient, reliable and light. It was easy to push, pull or drag through spots where the road had given way to a bomb and served its rider very well. In fact its success was noticed by soldiers from other countries at war’s end in 1945.

The Americans took some home and the design reappeared as the Harley-Davidson Hummer, first in the original 125cc capacity and later as a 165cc machine. A final production of 175cc bikes was called the “Bobcat” for one year before H-D began bringing in Aermacchis from Italy in 1960.

In the Soviet Union the bike was built variously as the “Kovrov,” the “Moska” or the “MMZ.”
Japan saw an Asian DKW in a model that Yamaha offered early in its motorcycle production. The most successful theft of the little German happened in Britain. Somebody brought one around to the BSA works and for once sense prevailed over precedent. The chain and gear change lever were on the wrong sides of course but the BSA people quickly put that right by reversing everything below the cylinder base. The Bantam was initially offered as the D-1 in the original 125cc capacity, but grew to 150cc and then 175cc before its end in 1971. Along the way it gained rear suspension and a fourth cog in the gear box but its origins were always very plain to see.

Many people first learned to ride on a Bantam and what’s more the Royal Mail bought thousands of them and letters and parcels everywhere in Britain were delivered by lads riding red BSA Bantams. That was likely not what the design team in Zschopau had in mind in 1930, but their little RT125 has secured a spot as one of the most imitated bikes ever built.

There was a time when a manufacturer could double the models in his lineup by taking each one and adding a skid plate, some knobby tires, and running the exhaust pipes higher up. You now had a “scrambler” model to complement the street version. It worked too. Triumph “C” models, and Honda “SL” bikes could be found grunting through the woods accompanied by AMC products powered by the same 750 twin the Norton Atlas was chugging down the road with. Yamaha had a successful high-pipe 250 Twin called the YDS3C Big Bear and played the game as well as anyone. So would have thought they would spoil it all in 1968 with a little something called simply DT1? They turned it all upside down with that little bike. It had a purpose-built frame and suspension meant for thrashing through the brush, and carried a lightweight single cylinder engine complete with gearbox whose ratios were meant for exactly this sort of fun. It could be legally ridden anywhere you wanted to go and then behaved like a competent off-roader when you got there.

Yes, it seems kind of obvious now with everybody building dualsport bikes these days and the Motard thing raging on, but there was a time when this one little bike with the white tank and black exhaust sent designers everywhere scurrying to their drafting tables to try and catch it. I think it is fair to say that the entire dualsport market owes its DNA to this one bike. Wouldn’t the ultimate irony be Yamaha “scrambling” to get its Big Bear back into production!

This is the most difficult category to name a leader in. The 350s it seemed were usually upsized 250s or down sized 500s , yet roadracing in this class produced some thrilling events. There have been many brilliant bikes built with this engine capacity. The racing “cammy” Norton and Velocette were one approach. Victoria’s Bergmeister was sheer elegance. Ducati’s Desmo 350 and Moto Morini’s 3 1/2 portrayed another two approaches. Each of these machines is highly desirable both new and now, but each of them is a standalone example of a fine bike. Not one of them inspired a lineage of bikes descended of their genius. I cast my vote in favour of the Matchless G3L. This almost prosaic offering from Plumstead, England could boast no features unique unto itself yet it too earned a place in history.

While many Canadian military motorcycle riders were issued a Harley-Davidson WLC in 1939, the British and many Commonwealth troops likely received a Norton 16H or BSA M20. These half-litre side valve engines and girder front ends were the tried and true stuff of two-wheeled tractors. They were slow, ungainly and utterly reliable. A fortunate few troops received the Matchless 350.

The little bike gave away 150cc in capacity yet proved quicker and faster with its perky overhead valve single cylinder. If the speed alone wasn’t enough to leave its heavier brethren behind, the Teledraulic forks up front gave it agility the other two couldn’t match either. Up until the 1940s, overhead valves were reserved for sporting and racing machinery. The dutiful man going to work each day had no use for such extravagance. Come the weekend, you undid the head, decoked the hole and buttoned it all up again. One wrench. One scraper. Done. As for telescopic forks, well, who has time for more leaky seals? The Matchless tested these themes under the worst of circumstances and proved itself worthy. The lessons were not wasted on the other manufacturers and post-war virtually all factories were building mostly OHV motors while the girder front end all but disappeared.

In both two-stroke and four-stroke form, the half-litre engine has been a popular size right from the beginning of motorcycle production. Prior to WWII, two cylinder engines were usually arranged in a Vee. At the Triumph works a young Edward Turner thought differently. He would place two pistons alongside each other vertically and parallel. Admittedly this wasn’t the first time it had been done. Even Triumph had had a 650 model a few years earlier with this arrangement, but it hadn’t been very successful. Turner’s Speed Twin first saw the light of day in 1937 and was an immediate hit with its light weight, smooth power and compact design. The fact that it looked good too was no accident as it was an exercise in symmetry.

The motor was essentially two single cylinder motors cast as one, and running side-by-side. The crankshaft, the light alloy connecting rods shared, was a built-up affair with no central bearing, thus making the Twin hardly wider than a single. The motor also responded well to tuning and a sporting Tiger 100 model was soon on offer which boasted a top speed of 100 mph.

The Speed Twin came just as the industry was gearing up for war and civilian products were being stopped. The Triumph facilities were damaged early in the war by bombing and for the duration of hostilities their major contribution consisted of basically this same Speed Twin motor set up to run generators for the RAF. Civilian consumer production resumed in 1946 and Triumph was first out of the gate with a parallel Twin. The following year BSA introduced the A7 which too had a vertical Twin and displaced 500cc.

Norton’s model 7 came in 1948 and soon a motorcycle of this description could be had from almost every British manufacturer. By 1950 Triumph and BSA increased capacity to 650cc while Royal Enfield went straight to 700cc. As the 1950s and ‘60s rolled by the vertical Twin simply dominated motorcycle production. Models were available in all sorts of guises and capacities. Norton’s last Twin displaced 828cc with little that was fundamentally changed. The little Speed Twin simply set a bench mark that lasted some three decades. In 1969, Yamaha’s new XS1 was still being compared to Triumph’s Twin rather than to the other Japanese four-strokes. Bikes are often discussed as being pre- or post-war. It is likely just as accurate to say “pre- or post-Speed Twin.”

Its a no-brainer. Honda’s four-cylinder CB750 of 1969 simply rocked the industry. It had plenty of competition mind you. The Triumph/BSA triple was still fairly fresh. Norton’s Commando still had lots of admirers. Kawasaki had just released their ferocious Mach III that could catch anybody. So why the Honda then? Well, at the end of the day while the British lads were adding oil, checking valve clearance and point gap, and the Kawasaki clan were kicking over their nervous and twitchy triples, the Honda rider simply thumbed the start button, and with all the drama of an electric motor silently and smoothly rode away. Everyone knew that they had seen the future. The CB750 did what the Speed Twin had done 32 years earlier. It redefined the motorcycle. No, Honda wasn’t the first to build a four-cylinder motor. MV Augusta screamed around the tracks of Europe all through the1950s and ‘60s with four-cylinder power and Indian’s last four was made in 1942 marking the end of an era when many American manufacturers made fours.

Just like the Speed Twin inspired copies from everyone else, so did the Honda. Yamaha soon had an in-line OHC four and Kawasaki, who were rumoured to be only a step behind Honda, paused for a breath before unleashing the awesome Z-1. The fact that these bikes were bigger than 750cc fooled nobody. Honda had already called the tune that everyone would dance to.
Suzuki brought out its four-cylinder in 1977 and it was the first four-stroke offering from them as well. This was also the dawn of the UJM or the “Universal Japanese Motorcycle.” It seemed that every model absolutely had to have four cylinders arrayed across the frame. There were big ones and little ones. There were fast ones and not so fast ones. Even Italy got into the game with Benelli producing fours in 350 and even 250cc sizes. Aside from that dazzling display of exhaust pipes the other eye-catching device the Honda sported was a front disc brake. Curiously the single disc brake didn’t make for obviously shorter braking distances, but what it did do was add to the air of exotica the Honda flaunted. It was simply a very well made motorcycle offering the stuff that hitherto only racers got, but at an affordable price.

I would dearly love to say Vincent. I would also wish to say Crocker, but of course these hand-built and expensive gems didn’t sire a legacy. They were truly built of unobtanium as far as the budgets of most riders were concerned. No, the litre bike that made the biggest impact in the market place came along in 1975 and was monikered “GL 1000.” Yes, the first Gold Wing displaced only 999cc divided among only four cylinders. A rather different quartet of pistons though.

Just six years earlier Honda had set the style with the CB750 and now they introduced a flat four with water cooling! Much of the world didn’t know just what to make of it. Initial sales were slow in many markets, but not in North America. Here in the land of long, wide and straight highways we embraced it immediately. Aftermarket manufacturers of fairings and luggage had never been so busy. The touring bike had moved up a notch.

Prior to the Gold Wing only Harley-Davidson was fitting large capacity motors behind huge windshields to whisk us from Toronto to L.A. True, BMW also built bikes with touring style equipment but had only recently built a 750, their biggest bike since the military orders had dried up 30 years earlier. Honda forged ahead, and as other marques began to dabble in this market too, they increased capacity to 1100 and then 1200 all the while making the machine more opulent and luxurious with every year.

People who had never considered a motorcycle before were attracted to the silent yet powerful machine that could carry a passenger in automobile comfort. The touring bike sector had suddenly become more than an afterthought at the factories. Harley-Davidson managed to update its specifications. BMW offered a 900, then 1000cc Twin before leaping into the liquid-cooled, four-cylinder genre themselves with the “K” bike. Meanwhile Suzuki had a Cavalcade to offer while Yamaha and Kawasaki beckoned with a Venture and a Voyager respectively. All these machines featured large engines and plush suspension. The bodywork was either standard or available and the options list ran on and on. This is likely the most lucrative segment of the market the industry has ever seen.

This summer you will be passed by six-cylinder Gold Wings with engines bigger than many of Honda’s cars. The riders and passengers will sit on seats that are heated in cooler weather and listen to satellite radio as the world slides silently by beneath them. Other bikes with other names will emulate the Honda style and do it very well too, but everybody knows that it was all begun by an upstart one-litre curiosity in 1975. If Phil Vincent and Al Crocker were around to consider the market’s high-end motorcycles today I have to wonder what they might have built.

More than a litre
Sportbike riders will be very disappointed with me. I know of the Hayabusa and its friends but they are but a leaf on the limb of the tree Honda planted with its venerable first four-cylinder bike. Currently this turf is dominated by cruisers with pistons as big as milk pails. The rumble should be low as must the seat height be, and the bars, if not high, should be wide. We all know the formula but where did it come from? Check Harley-Davidson’s catalogue for 1941.

There it is; the 74FL.
Harley’s knucklehead motor first appeared in 1936 and its overhead valves made it the liveliest Harley yet. But soon, police forces were calling for even more power from the 988cc Twin. In true American style Harley just upped the cubes and the 1213cc, or 74-incher, was born. It was the ultimate American machine: big, fast, and plush. The fact that you wanted the proverbial 40 acres to turn this rig around wasn’t a problem. America had 40 acres anywhere you needed them. And there was style. It was long, low and had whitewall tires. What do you want to call it? Presence? Panache? Swagger? The Harley had it and bequeathed it to those which followed. Time passed and the Hydra Glide begat the Duo Glide, which begat the Electra Glide, which begat the Super Glide, or some such sequence of head-turners.

Today of course the Harley has a lot of company. Everybody, it seems, is making a cruiser. They come in all sorts of capacities, from 49cc to well over 2000cc. They come from every place that motorcycles are made. But it doesn’t matter whether it wants a half-inch wrench or a 13mm, it is paying homage to a long gone patriarch: the great grandfather FL.

WELL THAT IS MY LIST. IF YOU’VE been reading between the lines you have probably picked up on the fact that I didn’t pick my own and personal favourites in each category. That would be a different list. What I hope this list does show is that a good and sound design transcends barriers of nationality, geography, style and even size. I think that the list also hints at how related all our machines are no matter what badge is on the tank. I hope that you are bursting with indignation right now and want to correct me on at least one of my choices here. Perhaps you’d like to take me to task for the entire roster. Great! Diversity within this narrow theme is what makes motorcycling so very interesting. If you and I and everyone else agreed, we would all be riding the same bike, and what a thin magazine Canadian Biker would be.

By Rick Epp (from March 2011)

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