Overview of the Types of Motorcycle Engine – The Big Bang Theory
Don’t worry, you’re not going to read somewhere that Richard the Lionheart led the Third Crusade to Jerusalem on the back of a steam powered iron horse. I know 12th Century Europe was in the grip of the Renaissance, which led to unprecedented growth in knowledge, philosophy and trade, but they weren’t that advanced.
No, our interest in that time period is down to a guy called Al-Jazari. He was the Chief Engineer at a palace in Eastern Turkey and wrote the first DIY book. It was called the Book of Knowledge of Ingenious Mechanical Devices and inside were plans for a device that exists inside every modern-day motorcycle on the showroom floor.
The basic idea for a crank had been around since pre-Roman times. But what Al did was build a crankshaft fitted with a con-rod to work his twin-cylinder water pump. This allowed the crank to move in a circular motion and the con-rod to move back and forth in a straight line. Which in other words, converts rotary motion into linear motion. And right there we have the very origins of the engine.
Motorcycle Engine Types: Camshaft
Oh yes, I forgot to mention Al-Jazari also invented the camshaft, for use in his water clocks but that’s no big deal is it? Anyway, it’s now safe to jump on 500 years. All over Europe and America scientists and inventors were going crazy, designing various internal combustion engines that used everything from gas to gasoline. But the first to reach commercial standard and resemble the modern internal combustion engine we recognize today, was created in 1876 by Nikolaus Otto.
This was a four-stroke engine, which in other words, produced power by four distinct operations. These being; induction (air/fuel going in), compression (mixture is compressed in the combustion chamber), ignition (spark introduced to ignite the gasses) and exhaust (expulsion of spent gas).
I can hear all you Yamaha and Suzuki fans shouting, ‘what about the two-stroke engine.’ Developed along a similar timeline, the two- stroke devotees obviously took a separate path, believing that their method of power delivery was far superior.
As the name suggests, combustion is produced twice for every rotation of the crank. This means that it doesn’t rely on overhead valves. Engines can be smaller, lighter and give a better power to weight ratio. Perfectly demonstrated by engine designer and two-stroke devotee, Alfred Angas Scott.
Scott’s brother had designed and built a two-stroke engine to drive the machinery in his workshop and its reliability and power led Angas to develop his own version for use in small boats. On the back of its success, he did the next obvious thing and strapped one onto a bicycle frame.
Motorcycle Engine Types: Twin Cylinder
In 1904, he registered the patent for his twin cylinder two-stroke engine and a few years later designed a purpose-built frame to cope with its power. Scott’s 450cc two-stroke engine bikes with innovative two-speed chain driven transmission, were so successful they dominated the hill climb circuit to such a degree, that the governing body handicapped them just to give the four-stroke bikes a chance. Three years later a Scott, ridden by Frank Phillip, smashed the Isle of Man lap record at 50.11mph and went on to be the fastest bike at the event for the next three years.
To close our chapter on Alfred Angas Scott, we need to know two further things. Firstly, he produced a bike with one of the coolest names ever, namely the Scott Flying Squirrel and secondly, in 1935 he manufactured the first water-cooled 750 cc triple cylinder two-stroke motorcycle. Something that would take both Suzuki and Kawasaki a further 37 years to duplicate.
But whilst we are on the subject of Japanese motorcycle manufacturers and the whole two-stroke, four-stroke divide, it’s a good time to look at how bike makers more or less dived into their separate camps.
With the exception of Scott who specialized in them, most British manufacturers had at least one two-stroke in their line-ups, such as the Enfield Flying Flea and the BSA Bantam, but predominantly bikes leaving the factories were four-stroke. These generally came in configurations of singles and parallel twins.
Motorcycle Engine Types: Triple
In a joint effort, Triumph and BSA developed the triple, Trident/Rocket Three and although a four- cylinder bike reached the prototype stage (the Quadrant) it never made it to production.
It was the same story in America. Both Indian and Harley Davidson started off with single cylinder four- stroke engines. With Indian first to launch their V-twin racer in 1904, followed a couple of years later by the road going version and Harley’s V making its first appearance in 1909.
Both manufacturers exclusively stuck to V-twin engines from that moment on, as did a plethora of other short-lived US bike manufacturers such as Crocker, Thor, and Excelsior. It was left to the more obscure bookmarks in American Motorcycle manufacturing history such as Henderson, Cleveland, Pierce, and Ace to break the mold with their inline four-cylinder bikes.
In mainland Europe, primarily Italy and Germany, things progressed along conventional lines. Most manufacturers started off on small capacity two-stroke and four-stroke singles. But as motorcycles became more popular and sales increased. R and D departments came up with some interesting configurations.
Moto Guzzi produced the transverse V-twin and Ducati kept with desmodromic singles until introducing their 90 degree V-twins. Laverda kept to parallel twins until developing the mighty three cylinder Jota. Benelli was slightly different, in as much as they transitioned from small two-strokes to inline fours and then to inline six cylinders.
Moto Morini stayed with 350cc and 500cc V-twins, whilst MV Augusta tried everything from two, three, four and six cylinder engines in their efforts to dominate motorsports.
Motorcycle Engine Types: Wankel
Once Germany’s largest producer of bikes, DKW stuck to two-strokes with over 20 models ranging from 175cc to 600cc. Interestingly, they also had a hand in producing one of the first Wankel-engined bikes, the W-2000 that went into production for four years.
As for the Bayerische Motoren Werke, small four-stroke singles and twins were the order of the day until the coming of the horizontally opposed Boxer twin engine that rocked the world. They went on to produce such adventurous configurations as an inline four, across the frame four and six cylinder bikes.
The arrival of the Japanese onto the motorcycle scene was subtle at first, but once they got a foothold, they made the rest of the industry sit-up and take notice.
Honda was first with the 1949 single cylinder two-stroke. The company continued to make a name for itself manufacturing small capacity four-stroke commuters and their C100, which was also introduced to the United States, became the best-selling motorcycle of all time.
Motorcycle Engine Types: Four Stroke
The introduction of the Honda 750-4 in 1969 was a game-changer and set the stage for an invasion of Japanese engine layouts in every shape and size. Honda became famous for four-stroke singles, parallel twins, fours and sixes, as well as V-twin, V4, and flat 4/6 cylinder engines. Whilst Kawasaki favored triple cylinder two-strokes, with four and six cylinder bikes in four-stroke format and V-twin cruiser engines.
Suzuki was another company that initially made their name with two-strokes in single, twin and triple formats. Launching into big bore four-cylinder bikes with the GS750 in 1976. They also manufactured a rotary engine model, the RE-5 and a range of V-twins. The same can be said of Yamaha whose single cylinder dirt bikes were legendary. They also went on to produce twins and triples, with four-stroke singles, twins and fours and a popular range of V-twins.
As emission laws get more and more stringent, strangling output and drowning out exhaust noise, motorcycle manufacturers have no choice but to conform. Have we already seen the golden age of engine design, or will technology reveal that the best is yet to come?