A Basic Guide to Motorcycle Engines
It is the engine in your motorbike that makes it so much fun. Compact and lightweight, it is the power and thrust of your motorbike engine that gives it the edge over four wheeled road users.
There are a wide range of motorcycle engines to choose from, and a lot of techie stuff to take in when choosing one, But as a general rule of thumb more cylinders equals more revs per minute which equals more horsepower. The higher the horsepower – the faster the bike – in theory! If you are looking at a new bike, but aren’t sure about the type of engine it has, or how the power and performance is delivered, be sure to do your research before you buy.
As a starting point, here is a basic overview of the different kind of motorbike engines available today:
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With one big cylinder providing all the power to your bike, these simple engines are easy to repair and maintain, while still being able to kick up some exciting speeds.
Often found in cheaper motorcycles and scooters, these types of engine are also popular with those who enjoy the unbridled thrill of dirt riding.
Lightweight and compact, the simple mechanics of single cylinder engines means they are often also round in dual-sports bikes where weight is important and the grunt is focused around torque vs horsepower.
On the downside, these types of engine require a larger flywheel and the use of balancers to counteract it and will almost always create a lower power to weight ratio.
A standard in some of the world’s most iconic cruisers including the Triumph Bonneville, these two-cylinder piston engines have cylinders arranged side by side and its pistons connected to a common crankshaft.
Chock full of fast revving power, these types of engine also offer high-performance power to some of the sportier bikes on the market made by manufacturing giants such as Kawasaki and Yamaha. Small in size and incredibly lightweight, these types of engine are incredibly responsive, cheap to repair and maintain and make a good workhorse for everyday riding and commuting.
The only real downside to a bike with a parallel twin engine is the noticeable vibration that can deflect from the fun of your riding experience.
As the most iconic and easily recognisable of all motorbike engines, the V-Twin can really pack a punch. Sometimes referred to as a V2, this type is a two-cylinder piston engine where the cylinders share a common crankshaft, and are arranged in a V configuration.
With a thick powerband, off-the-line torque, a low centre of gravity and that gorgeous sounding V-twin roar, these types of engines are often found on American and Japanese cruising bikes as they produce a lot of torque at lower revs, making it easier to maintain momentum.
V-Twin engines are also able to be incredibly fast. Ducati for example, famously, performance tune their V-Twin engines to crank out higher levels of horsepower in their high-performance racing bikes. Italian manufacturers Moto Guzzi is also famous for mounting V-Twin engines transversely to give their bikes those gorgeous European good looks.
Because no engine is perfect, even the much loved V-Twin has some downsides including ongoing vibration issues and some difficulty in cooling the rear cylinder. They can also create less power per unit of displacement than 3 or 4-cylinder engines.
Boxer Twin Engines
Most usually found in BMW bikes, the boxer-twin engine is designed to be perfectly-balanced and incredibly smooth. With horizontally opposed cylinders that benefit from air cooling, these types of engines are recognised for having the power to motor through the roughest terrain.
With a linear powerband to smooth, even delivery, these torquey engines are perfectly suited to shaft-drive motorcycles. Prolific across the BMW range there are other manufacturers such as Honda that also appreciate the awesome power of the boxer.
Unlike some of the more traditional engines however, boxers can be wide and unwieldy with a limited lean angle on some models of motorcycle.
These reciprocating piston internal combustion engines have three cylinders arranged in a straight line or plane, side by side. They are a good mid point engine that sits between the torquey nature of twin engines and the rev fuelled power of the fours. Triple engines are most notably found in Triumph motorbikes, although they are becoming more popular in certain Yamaha models too. There potent power paired with perfect balance make them a popular choice for everything from daily commuting to weekend track riding.
Incredibly versatile, triple engines work well in lots of ride settings. They’re narrow and compact and they have their very own unique exhaust sound.
No real downsides to owning a bike with a triple engine, unless of course, you are after a bike with a V4.
Smooth, fast-revving and packing a powerful punch, inline-4 engines are extremely popular and usually found in sports bikes. First introduced in the iconic Honda CB750 in the 1960’s, Japanese manufacturers are fond of the ease of performance, reliability and excellent performance that can be found with inline-4 engines.
Delivering smooth power, high revs and an exhilarating rush, these engines can be found in any supersport or superbike class in the world.
With a simple engine architecture that cranks out amazing horsepower, especially at high RPM, these engines really are the bee’s knees! The only downsides (if you even consider them to be) is that these engines can be screamingly loud, and torque is not their strong point.
These high end engines are often found in sport and sport-touring models as well as world glass MotoGP machines. Not cheap to produce, and complex in their architecture, these are usually only available in top of the range models where riders pay for the privilege of smooth power delivery, high performance and sleek, narrow profiles.
The V-4 engine is a four-cylinder piston engine where the cylinders share a common crankshaft and are arranged in a V configuration – a bit like the V-Twin engines but with those all important extra cylinders. Putting performance aside, one of the very best reasons to own a V-4 machine is the awesome, guttural growl of the engine that is instantly recognisable and endlessly impressive.
The downsides to these monster engines is that as well as being more complex and expensive to manufacture, they are often heavier than comparable inline-4 engines.
This cheeky little number is currently only used by BMW, so not one to worry about unless you are thinking of buying one. Providing a silky-smooth ride and plenty of free-revving horsepower, these machines have plenty of pulling power.
Horizontally opposed six-cylinder
Another niche engine, these are used in the awesome and enormous Gold Wing tourer bikes. Sometimes referred to as a flat-six. Great if you are buying one – unnecessary on other types of bikes.
Have we missed any? Add a comment below if you’ve spotted a motorcycle engine layout we’ve not included in this guide.
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