This is the second part about motorcycle engines. This time I'd like to consider the layout.
Engines have a "number of cylinders" and a "line up"
In my last column, I talked about how a motorcycle's ride is determined by its engine. And I mentioned that displacement is a big part of that, but there is one more important thing to consider There is. It's the layout of the engine.
Layout is a matter of placement. It is largely dependent on the "number of cylinders" and the way they are arranged. For example, the terms "4-cylinder in parallel" and "V-twin" that often appear in motorcycle catalogs are used to describe the layout of an engine. In parallel, the cylinders are arranged in a single row, also known as a series. Parallel means that the cylinders are arranged in a single row, also known as a series.
Therefore, a parallel four-cylinder engine is an engine with four cylinders lined up horizontally in a row, which is also called a two-cylinder engine. In the case of the V-twin cylinder, the two cylinders have a V-shaped opening.
In terms of "number of cylinders", the current typical layout is single, two, three, four, and six cylinders. Common and "lined up" include parallel, V-shaped, and horizontally opposed. In the past, V8s (Moto Guzzi's GP racers) and rotary engines (Suzuki RE-5) Or, in the old days, the star-shaped engine (with cylinders arranged in a radial pattern) of an aircraft. There were a lot of strange machines that I didn't understand. Come to think of it, Honda's first MotoGP machine, the RC211V was a V5, wasn't it?
The number of cylinders makes a big difference in character.
To put it simply, the single-cylinder has a clear throbbing sensation and is often described as "tasteful" or "idyllic", and is often used in classic models, small-displacement cars, and off-road models because they are lighter.
The two-cylinder models are unequally spaced with thumping and thumping, or have a grainy feel to them, and are often used to "kick out the road". It is said to have "feel" and "excellent traction". It is hard to say it in general because the feeling changes greatly with the ignition order and ignition interval, but for example The 270-degree crankshaft, which is popular with the recent parallel twin, is daringly made to explode at unequal intervals. The V-twin V-twin V8 engine provides a sense of excitement and traction (the sensation of the tires catching the road surface) It is said to have enhanced performance.
The four-cylinder has a high-pitched, siren-like exhaust sound of a four-cylinder and a "heart-pounding rise It is easy to gain power at the highest rpm, and high performance machines such as the Supersports use almost all four cylinders. . This is an area where Japanese motorcycles have traditionally been strong, but it's also an area where parallel four-cylinder (straight four) and V-4 (V4) The V4 has a very different feeling. Roughly speaking, the straight 4 is said to have more power at high RPMs and the V4 is said to have superior mid-range torque. The V4 also has the advantage of being able to slim down the width of the body.
The three-cylinder is essentially a middle ground between two and four cylinders, with flat power output characteristics and a smooth sound. The type that also has a sense of pulse in the It's used by Triumph, Yamaha MT-09, and others.
The six-cylinder is called the silky-six, and its rotating feel is smoother and smoother than the four-cylinder. That's why large-displacement tourers such as BMW's K series, the former Z1300 and CBX1000 They are often employed by.
"Horizontal" or "Vertical"?
Another thing to remember is that the engine can be placed on the body of the car, either horizontally or vertically. . This is based on the orientation of the crankshaft and the direction of the crankshaft intersecting with the body of the vehicle. It is placed horizontally, and similarly, vertically, facing the direction of travel of the body.
As far as current models are concerned, the horizontally opposed two-cylinder engine used by the BMW R series (commonly known as a "flat twin"), the V-twin of the Moto Guzzi, the horizontally opposed six-cylinder of the Honda Goldwing, etc., with the cylinders protruding horizontally are mounted vertically, and most of the other bikes are mounted horizontally.
Most other bikes are mounted horizontally. Although it is a minority of longitudinal engines, the crankshaft faces the same direction as the body, so it can be tilted left and right. It has a handling characteristic of light engagement. In addition, the recoil of crank rotation (so-called torque reaction) causes the body to move to the right or to the left when the accelerator is turned on. It has a tendency to lean to the left, and the maniacal nature of it has become an attraction. However, this has been reduced recently by the balancer equipment.
Even if the displacement is the same, the ride quality changes greatly depending on the number of cylinders and the layout. It is. In addition to this, there are 4-stroke and 2-stroke, water-cooled and air-cooled, bore and stroke, fire order (combustion (spacing and order), pulp format, etc., to name but a few details, but these reciprocating engines It's a fun way to enjoy the unique character, feeling and taste of a bike! .
Why don't you think about the engine, which is the fruit of 150 years of human invention, development and evolution?