Different Motorcycle Engine Parts and Their Functions

By Max. D Gray. Updated: May 25, 2017
Different Motorcycle Engine Parts and Their Functions

If you have a motorbike and use it as your usual mean of transport, you'll understand how important keeping good maintenance of your bike is for your safety on the road. If you don't know the ins and outs of motorbike maintenance, it's best to leave it in the hands of a professional. Yet you may want to get more involved or are considering purchasing a bike for the first time. If this is the case, you may want to know some general basics of the motorcycle engine so you don't sound like a complete noob. If you want to quench your thirst for knowledge, and provide more of an insight into how your beloved motorcycle works, read this informative oneHOWTO article on what are the different parts of a motorbike engine and their functions.

You may also be interested in: How to Adjust Motorcycle Engine Valves

Cylinder head

Like most non-electric cars, motorcycles are powered by an internal combustion engine. This means that fuel (usually gasoline or diesel) is burned or combusted to make the parts of the car move which propel it along. The cylinder head is an engine part which is constructed of various materials, depending on the model: often cast iron or aluminium alloy. The function of the cylinder head is to seal the top of the engine cylinders. These engine cylinders are what form the combustion chamber. It is also referred to as an engine head or the head.

It is not only the combustion chamber, but shafts and valves are also found here. In motorcycles the valves for the head tend to be side valve or overhead. Different motorbikes have different head shapes, which often affect performance as some allow more space for combustion than others. Aficionados have come to identify each type of head shape, as they can be pretty striking. The head will also be up on the front of the motorbike, something which was not always the case. The first motorcycles developed were steam powered and had the engine on the back.

Different Motorcycle Engine Parts and Their Functions - Cylinder head


The engine of a motorcycle may have up to six cylinders which are cast from iron. They need to be made from such a strong material so they can be capable of withstanding very high temperatures. The purpose of the cylinders is to provide a sealed space for the movement of the pistons. Commonly, the cylinders are referred to as the engine block, and is also used as a way to measure the engine's power to determine of the size of the cylinders.

Single cylinder engines are one of the simplest combustion engines out there. While they have their use, they also have certain drawbacks. A single cylinder engine is cheap to run and shouldn't tax even the most amateur mechanic too hard. They do not have very high speeds nor is their acceleration particularly good, but they cool much quicker than most other engines. On of the inconveniences is the vibration and noise which single cylinders emit. They can be uncomfortable to ride for this reason and can annoy neighbors when ridden at night.

Twin cylinders are the most common type of motorbike engine in the UK. Their types include the straight-twin, v-twin (pictured below), flat-twin and tandem-twin. The names represent the shape and position of the cylinders in the engine. The different positions can affect performance as well as reduce vibration. The more cylinders the motorbike has, the better the performance should be. This may be mitigated by the ability to control bigger bikes. There are even V8 and V10 (8 and 10 cylinder engines in a V-shape), but these tend to look like something the Dark Knight might ride.

Different Motorcycle Engine Parts and Their Functions - Cylinders


The pistons drive the movements of the connecting rod, moving up and down inside the cylinders. They can move up and down only, so the connecting rod moves from left to right as the pistons rise and fall, transferring energy to the drive train. Pistons are made from materials like cast iron, steel alloys with aluminium or nickel and cast iron. Through the movement of the pistons, the energy of the combustion of gases is transferred to the connecting rod. These pistons will move at tremendous speeds and need to be in good nick as they can cause an accident if broken. Take a look at how to know if your piston rings are bad for more information on the subject.

Different Motorcycle Engine Parts and Their Functions - Pistons

The Connecting/Piston Rod

The connecting or piston rod, Meanwhile, is the link between the pistons and the crankshaft. While the pistons move up and down, the rod is designed to convert this reciprocating motion into a rotating motion. In other words, it converts the movement of the piston into the rotation of the crankshaft. Normally, the material use for manufacturing the connecting or piston rod is steel, aluminium or titanium.

If there is a problem with the connecting rod, there could be big trouble. Why does this happen? If you have rod bearing failure (where the crankshaft wears out prematurely), you will have to take all of the motorbike apart to reach the parts which need replacing. It can be difficult to diagnose problems with the piston rod, so make sure to get professional mechanical advice if you are unsure.

The Crankshaft

The crankshaft is a shaft connects to the connecting rod, which rotates and moves in coordination the pistons, as explained above. The rotary motion of the crankshaft is what sets the motorcycle chain and ultimately the wheels of the motorbike into motion. The special shapes of the crankshaft mean that the different pistons move at different intervals. The timing of these intervals is very precise and if there is a mis-timing, it can cause a lot of trouble. They will need to be controlled by this timing chain or belt, although chains are most common. This is unlike cars which have used timing belts more since the 1970's.

Different Motorcycle Engine Parts and Their Functions - The Crankshaft

The Spark Plugs

The spark plugs are one of the parts in the ignition/combustion system in your motorbike engine. They produce a spark, which subsequently ignites the fuel-air mixture in the engine cylinders. This is how the combustion engine converts chemical fuel energy into kinetic energy. Spark plugs are easy to replace, but are very important as without them your motorcycle won't be able to move. If the spark plug does not seem to be working, there may be a problem with your battery, as you need electricity to make the spark plug spark and thereby ignite the fuel.

Different Motorcycle Engine Parts and Their Functions - The Spark Plugs

The Engine Valves

Some other important parts of your motorbike engine are the Engine valves. They are important because they control the passage of air and fuel to and from the combustion chamber as well as the gas that the combustion generates. Checking their condition will allow you to monitor if the combustion process is happening correctly and efficiently. You should also adjust engine valves regularly to avoid serious and costly problems.

Maintenance care of a motorbike engine

These are the basic parts at the heart of your motorbike engine. To find out how to keep them in good condition, we recommend the following oneHOWTO article on how to maintain your motorbike engine.

If you want to read similar articles to Different Motorcycle Engine Parts and Their Functions, we recommend you visit our Motorbike Maintance and Repair category.

Write a comment about Different Motorcycle Engine Parts and Their Functions

What did you think of this article?
Total engin parts
what did you leak gearbox ?
David Martin
Much for a service honda crf 250
michael pasinabo
thanks for more info.. i need a schematic diagram electrical wiring of honda xrm 125.
please. send me a full article how to maintain motor bike. a nd it will far better if it is support ed with animation, thanks

to ride motor bike
joseph gitonga
am a motorcycle mechanic and a require to be boosted by companies or dealers
Boffah Bismark
resign for motorcycle repairs
dear sir/madam
i have few doubts in regular observation
1.why engine getting bore?
2.why sometimes black smoke realising? to control fuel efficiency and Courbet cleaning process?

How many bike parts r there

Different Motorcycle Engine Parts and Their Functions
1 of 6
Different Motorcycle Engine Parts and Their Functions

Back to top