Types of Motorcycle Engines
Buying a motorcycle involves more than meets the eye. The power plants in motorcycles vary widely. There are benefits and drawbacks to each of these systems. The terrain and riding style you prefer will determine the best engine for your needs.
Learn the differences between motorcycle categories with our comprehensive guide and set out on your next adventure with the perfect bike and powerplant.
Various Motorcycle Engine Designs
A motorcycle’s engine is typically one of eight types:
- Single Cylinder Engine.
- Parallel Twin Engine.
- V-Twin or L-Twin Engines
- Boxer Engines.
- V4 (Or V5) Engines
- Flat-Twin Engine
- Rotary Engines
- Electric Engines
#1. Single-Cylinder Engine
The single-cylinder nature of this engine type is reflected in the name. It could be standing upright, lying flat, or leaning at an angle.
Since the engine’s power comes from the cylinder, having more of them results in a more potent engine. There, fuel is converted into mechanical energy that drives your motorcycle’s wheels.
A piston is present in each cylinder to compress the air and fuel. One-cylinder engines are simple, cheap, and easy to maintain. They can be easily removed, cleaned, or replaced due to their simplistic designs. There is, however, a drawback: the engine only has one piston.
You will have to work hard to maintain your engine, so it may eventually need to be replaced or fixed. Having a one-cylinder engine means less bulk, which helps you keep your bike light.
We use cubic centimeters to describe the engine capacity. How hard the engine is sucking in air and gasoline is what this term alludes to.
Most single-cylinder motors have a displacement of between 50 and 250 cc, making them significantly smaller than multi-cylinder motors of the same power. However, some “huge singles,” or single-cylinder, engines can be as large as 700cc. For most single-cylinder motors, that’s the upper limit.
More power would mean more vibration if the engine were any bigger. Sometimes, especially in older models, driving at high speeds causes the car to vibrate excessively, making it difficult to keep your balance.
#2. Parallel Twin Engine
There are two pistons and two valves in a parallel twin engine; however, they share a cylinder block. This means that they frequently collaborate with one another. They can be stacked in the engine either vertically or horizontally and even sometimes arranged one after the other.
When compared to other types of two-cylinder engines, parallel twins are more compact. This design is typical on dirt bikes, sport bikes, and even some commuter motorbikes.
In comparison to single-cylinder engines, they are more powerful and reliable, although they still experience excessive vibrations when traveling at high speeds.
They are simple in design, and like their single-cylinder siblings, they don’t cost too much to make or keep running smoothly. One common effect of adding a cylinder to an engine is to make it bulkier overall. Motorcycles with engine sizes as large as 1,000cc are readily available.
#3. V-Twin or L-Twin Engines
To get this “V” or “L” shape, the two cylinders are set at an angle to one another. Each cylinder is housed in its own block, making the engine bigger and more powerful than a parallel pair. The cylinders range in size and arrangement from one model to the next.
The moniker “L-Twin” comes from the fact that the engine’s cylinders may be angled at either 45 or 90 degrees. The cylinders in a bike with a “V-Twin Trans” are aligned perpendicular to the bike’s frame, ensuring a relatively small footprint. Cylinders are typically long and skinny to prevent excess weight.
They produce a distinctive rumble from the tailpipe and have high levels of torque. The greater power and stability of these bikes compared to parallel twins comes without the added hassle of a heavier or more difficult-to-maintain bike.
The V-Twin design is the standard in the business sector since it combines the advantages of two different types of engines.
#4. Inline Motorcycle Engines
You can find inline engines with four or six cylinders in various models. In most cases, a single-cylinder block will serve as housing. Although having the cylinders laid out transversely helps keep the engine relatively narrow, adding more cylinders does make it wider.
When compared to inline-four engines, inline-six engines are more potent, but at the expense of fuel economy. Despite being substantially heavier and more expensive to maintain, these motorcycles offer more power and stability than smaller engines, with little vibrations even at high speeds.
They are notorious for their high fuel consumption and lackluster torque output. This style is common among high-performance motorcycles, especially those produced in Japan.
#5. V4 (Or V5) Engines
The V4 engine is essentially two V-Twins joined together and stacked on top of each other. They have four cylinders in an oblique configuration. For this reason, there must be more room on the bike, which in turn increases its overall mass and necessitates more frequent servicing.
Their power is comparable to that of Inline-Four engines, if not greater. Compared to an Inline-Four, this engine is more compact due to its narrower dimensions. No major bumps or jolts are to be anticipated.
#6. Flat-Twin Engine
An unusual engine design, the Flat-Twin (or Boxer engine) has its cylinders aligned horizontally on either side of the crankshaft. Once again, the number of cylinders directly correlates to the engine’s power.
The improved cooling potential and decreased center of gravity are two key advantages of this design. Due to the rarity of the design, cylinder and piston parts may be difficult to find and replace.
#7. Rotary Engines
Rotor blades in rotary engines (or “Wankels”) do the work of pistons in conventional internal combustion engines by compressing air and fuel.
Angular momentum is generated by doing this. Although this style is incredibly uncommon nowadays, some producers are working to bring it back into fashion.
They are typically smooth and silent, with few moving components, so they require little in the way of upkeep. They feature higher RPMs than standard pistons, which translates to more force.
The downside is that rotary engines are notorious gas hogs, so be prepared to spend extra money at the pump. They also need to be serviced and fixed on a regular basis.
#8. Electric Engines
Electrification of the motorcycle market is happening gradually. Electric engines, which can be powered by renewable energy, are generally more eco-friendly.
Because they are not powered by fossil fuels, they produce fewer greenhouse gas emissions. The air and fuel are not compressed by cylinders, pistons, or rotaries.
It’s the same as charging a smartphone, laptop, or another electrical device. Those who live in cities and have access to reliable, cheap energy have sparked a surge in interest in electric bikes among customers.
These motorcycles are touted as being as powerful as conventional ones, but they require a lengthy charging process. If your neighborhood auto shop doesn’t offer services for this sophisticated engine, keeping it running can be difficult.
Even though they are slightly more expensive than standard motorcycles, you won’t have to spend nearly as much on petrol, especially if you get a solar power system installed at your house.
How Does a Motorcycle Engine Work?
Motorcycle engines function similarly to automobile engines. Pistons, a cylinder block, and a head with the valve train are the main components. Pistons rise and fall in the cylinder block as a result of explosions caused by the ignition of a fuel-air mixture.
The fuel-air combination is let into the combustion chamber by opening and closing valves. The up-and-down motion of the pistons turns a crankshaft, which in turn generates rotational motion.
Motorcycles’ back wheels are driven by the crankshaft’s rotational force, which is communicated to the wheel via the transmission. There are three main ways to categorize motorcycle engines: the number of cylinders, the size of the combustion chambers, and the number of power strokes.
Cylinders of Motorcycle Engine
The number of cylinders in a motorcycle’s engine can range from one to six. For many years, motorcycle engineers in the United States, Europe, and Japan all preferred V-twin designs for their bikes’ power plants.
The two cylinders of a V-twin engine, like the original Harley-Davidson V-twin shown below, create a V, hence the name. Take note of the V-twin angle of 45 degrees in Harley-Davidson motorcycles; other manufacturers may use different angles to cut down on vibration.
Although the V-twin configuration is common, it is not the only option for housing two cylinders. A configuration known as an “opposed-twin” is created when the cylinders are arranged so that the pistons are at right angles to one another.
Engines with twin cylinders that are parallel to one another have their pistons aligned vertically. Nowadays, four-cylinder designs dominate the market, as they are more efficient than twins and can reach higher speeds and RPMs without sacrificing performance.
The four cylinders can be set up in a straight line, or they can be organized in a V form, with two cylinders on each side of the V.
The Capacity of Motorcycle Engine
The efficiency of a motorbike engine is proportional to the volume of its combustion chamber. There is a roughly 1500 cc upper restriction and a 50 cc lower limit.
These later motors are typically found in mopeds, which are small motorcycles with speeds of between 30 and 35 miles per hour with a fuel economy of 100 miles per gallon.
Transmission of Motorcycle
- Gearset
- Clutch
- Drive Systems
Massive amounts of power generated by a motorbike engine need to be sent to the wheels in a manageable fashion. The gearset, clutch, and drive system are all components of the motorcycle gearbox that work together to send power to the rear wheel.
#1. Gearset
Riders using a gearset can go from a full halt to a comfortable cruising speed. Motorcycles normally have four to six gears in the transmission, while some smaller bikes may only have two. Lever movement activates shifting fork motion within the transmission, allowing for the selection of gears.
#2. Clutch
A clutch’s function is to connect the engine’s crankshaft to the transmission and to disconnect the two when necessary. Stopping the wheels from turning without using the clutch is an unfeasible approach in any motorized vehicle.
A clutch consists of a set of plates with springs between them; when the plates are forced together, they link the transmission to the crankshaft.
To change gears, a rider detaches the transmission from the crankshaft via the clutch. He shifts into the new gear and then engages the clutch to reconnect the mechanism.
#3. Drive Systems
Transmission of engine power to the motorcycle’s back wheel can be accomplished in three primary ways: chain, belt, and shaft.
It’s extremely typical for a vehicle’s final-drive system to be a chain. A metal chain runs from a sprocket on the motorcycle’s output shaft to another one on the sprocket on the rear wheel.
Power is carried from the transmission to the front sprocket, which in turn turns the chain and, ultimately, the back sprocket and wheel. The chain and sprockets in such a setup will stretch and wear with time, necessitating periodic replacement. Instead of using a chain, you might use a belt drive.
Commonly seen on early motorbikes was a leather belt with a spring-loaded pulley and a hand lever to adjust the belt’s tension and hence the bike’s traction. Because of the difficulty in maintaining a firm grip on the belt in wet conditions, leather belts have given way to alternative materials and styles.
Belt final-drive systems were once again practical by the 1980s because of developments in materials. Nowadays, belts are typically made of cogged rubber and function similarly to metal chains.
They don’t need lubrication or cleaning solutions like metal chains to do. Final-drive systems that employ a shaft are not uncommon. The drive shaft in this setup is what really transfers the power to the back wheels.
Drives that use shafts rather than chains are increasingly common because of their ease of use and low maintenance requirements.
Shaft drives are an option, but they add weight and might result in “shaft jacking” or a jerking action at the back of the motorcycle. The chassis houses the rest of the essential parts that give a motorcycle its unique character.
Motorcycle Engine Parts
- Cylinder Head
- Cylinder
- Pistons
- Piston Rods
- Crankshaft
- Spark Plugs
- Engine Valves
- Cooling System
- Air Cooling System
- Refrigeration by Means of a Liquid
- Battery
#1. Cylinder Head
Motorcycles use internal combustion engines, just like conventional automobiles. This means that the car’s moving parts are propelled by the combustion of fuel (often gasoline or diesel).
The cylinder head is a component of an engine that, depending on the model, may be made of cast iron or aluminum alloy. Sealing the top of the engine cylinders is what the cylinder head is for. The cylinders of an engine serve as the chamber where combustion takes place.
Simply called “the head” or “engine heads,” these parts play crucial roles in the operation of vehicles. Besides being the engine’s combustion chamber, this is also where the shafts and valves are located. Overhead or side valves are common in motorcycle engines.
The performance of motorcycles can be affected by the design of the motorcycle’s head, which can provide more or less room for combustion depending on the design.
Enthusiasts have learned to recognize the various head shapes because of their visual impact. Additionally, the head will be elevated on the front of the motorcycle, which was not previously the case. In the earliest iteration of motorbikes, the steam engine was mounted in the rear.
If there are issues with the cylinder heads, the engine as a whole is probably malfunctioning as well. It will also have an impact on the processes that take place after combustion, like the removal of smoke and pollutants through the exhaust. This is a common cause of exhaust smoke issues.
#2. Cylinder
Motorcycles’ iron-cast engines can include as many as six cylinders. Because of the high temperatures they will be subjected to, it is imperative that they be constructed from a robust material. The cylinders allow the pistons to move in a sealed environment.
The word “engine block” is commonly used to refer to the cylinders, and the size of the cylinders is directly related to the amount of power the engine produces. One of the most basic types of internal combustion engines is a one-cylinder engine.
There are benefits to using them, but they also have some downsides. A single-cylinder engine is easy on the wallet and can be maintained by even the most inexperienced mechanic. They can’t reach high speeds or accelerate quickly, but they cool down a lot faster than conventional engines.
Disadvantages include increased vibration and noise from single cylinders. For this reason, riding one might be unpleasant, and running one late at night can be an annoyance to the neighbors. The majority of motorcycles sold in the UK have engines with two cylinders.
Their configurations range from the conventional “straight-twin” to “v-twin,” “flat-twin,” and “tandem-twin.” The names are symbolic representations of the cylinders’ shapes and locations within the engine.
Changing to one of these alternative positions can improve performance and lessen vibration. A motorcycle’s efficiency increases with the number of its cylinders. The capacity to handle larger motorcycles could help with this.
V8 and V10 engines have eight and ten cylinders, respectively, in a V shape, yet they appear as if they belong on a Batmobile.
#3. Pistons
Within the cylinders, the up-and-down motion of the pistons is what drives the connecting rod. Pistons can only travel upwards and downwards; therefore, energy is transferred to the transmission when the connecting rod swings from left to right as the pistons rise and fall.
Materials such as cast iron, steel alloys containing aluminum or nickel, and cast iron are used to make pistons. The energy released from the combustion of gases is transferred to the connecting rod through the motion of the pistons.
These pistons will be moving at high speeds and need to be in good condition so as not to cause an accident. Learn more about this topic by reading about how to recognize worn piston rings.
#4. Piston Rods
Meanwhile, the pistons are connected to the crankshaft through the connecting or piston rod. The rod is built to transform the reciprocating motion of the pistons into a rotational motion. To put it another way, it transfers the energy of the piston’s motion into the rotation of the crankshaft.
To make a connecting or piston rod, manufacturers typically turn to steel, aluminum, or titanium. Big difficulty could arise if the connecting rod breaks.
What causes this to occur? Failure of the rod bearings will cause the crankshaft to wear out prematurely, necessitating a complete disassembly of the motorcycle in order to get to the worn components. Diagnosing piston rod issues can be challenging; if in doubt, see an expert technician.
#5. Crankshaft
As was previously mentioned, the crankshaft is a connecting rod-attached shaft that spins and moves in time with the engine’s pistons.
The motorcycle’s chain and wheels are placed in motion by the crankshaft’s rotation. The crankshaft is shaped in a way that causes the pistons to move at irregular intervals.
Mistiming one of these intervals can have disastrous consequences. They must be regulated by this timing chain or belt, with chains being more prevalent. In contrast, timing belts have been increasingly commonplace in automobiles since the 1970s.
#6. Spark Plugs
One component of your motorcycle’s ignition and combustion system is the spark plugs. They generate a spark that ignites the fuel-air combination in the cylinders. This is the process through which the combustion engine transforms the potential energy stored in chemical fuel into mechanical motion.
Without spark plugs, your motorcycle won’t start, but don’t worry—they’re simple to replace. Because a spark plug requires electricity to spark and ignite the fuel, a dead battery could be to blame if your engine won’t start.
#7. Engine Valves
The engine valves are a crucial component of your motorcycle. They play a significant role in regulating the flow of air and fuel into and out of the combustion chamber, as well as the gas produced by the combustion process. By inspecting their state, you can see if the combustion is going well.
Engine valves should be adjusted routinely to prevent costly damage. Injecting fuel directly into the combustion chamber is another method for managing fuel flow. Although not always present in older models, they are becoming increasingly common.
In a similar vein, turbochargers are becoming increasingly common, though primarily on racing motorcycles. It’s feasible that they will become standard fare in motorcycle engines in the future, although for now, they aren’t widely used.
#8. Cooling System
Motorcycle engines, like automobile engines, may get very hot after being in use for a while. The fuel is being consumed to produce motion.
Overheating the engine can cause it to malfunction, cause the engine to break down, or make the vehicle too hot to ride. A motorcycle’s engine can be cooled in two primary ways:
#9. Air Cooling System
Unlike in most automobiles, the motorcycle engine is often open to the elements. The engine can contain a mechanism that harnesses the air that flows past the motorcycle as it moves.
Different engine components aid in the process of distributing air around the engine. Fans are sometimes used to aid in heat dissipation, but fins and other air-guiding mechanisms are typically employed.
Motorcycles with engines that rely on airflow for cooling are at risk of overheating if the rider leaves the bike idling.
#10. Refrigeration by Means of a Liquid
A radiator may be installed on a motorcycle in place of the radiator seen in most automobiles. To keep the engine from overheating, liquid coolant must circulate through the various components.
They’re gaining traction and might one day become the norm in the market. They’re especially vital on fairing-equipped racing bikes (a shell placed over the engine). Fairings keep things aerodynamic, but they also block air from getting to the engine.
The oil used in certain engines doubles as a coolant in others. Due to the oil system’s dual usage, this is a highly effective method. However, this is not as frequent.
#11. Battery
The battery is crucial to the operation of any motorbike, which may seem like an obvious statement. These days’ motorcycles are particularly guilty of this. For starters, they rely on electricity to power the ignition system and other crucial components like the lights.
The degree of compatibility between the bikes’ electrical and mechanical components varies widely. Some may contain a variety of extra features that can only be used with a battery.
Motorcycle Functions
A motorcycle is a motor vehicle that can have either two or three wheels, depending on its design. Motorcycles come in a wide range of styles and configurations to accommodate various uses, such as long-distance touring, daily commuting, leisurely cruising, competitive racing, and off-roading.
Taking part in the social scene around motorcycling includes not just riding motorcycles but also activities like joining motorcycle clubs and going to motorcycle rallies.
FAQs about Motorcycle Engines
What are the main types of motorcycle engines?
Motorcycle engines can be categorized into several types, including single-cylinder, parallel twin, V-twin or L-twin, inline, V4 or V5, flat-twin, rotary, and electric engines.
What is the advantage of a single-cylinder engine?
Single-cylinder engines are known for their simplicity, low cost, and ease of maintenance. They are lightweight and ideal for certain types of riding.
How does a V-twin engine differ from other twin-cylinder designs?
V-twin engines have two cylinders set in a V-shape, offering more power and torque compared to parallel twins. They also produce a distinctive exhaust note.
What is unique about a rotary engine in motorcycles?
Rotary engines, also known as Wankel engines, operate with rotor blades instead of pistons. They are known for their smooth operation but can be fuel-intensive and require specific maintenance.
Are electric motorcycles practical for everyday use?
Electric motorcycles are gaining popularity due to their eco-friendliness and quiet operation. They require charging but offer instant torque and minimal maintenance.
How do motorcycle transmissions work?
Motorcycle transmissions typically have four to six gears and utilize a clutch to engage and disengage power from the engine to the wheels. Final drive systems include chain, belt, or shaft drives.
What are some key maintenance tips for motorcycle engines?
Regular maintenance includes checking spark plugs, engine valves, cooling systems (air or liquid), and ensuring proper lubrication and adjustment of drive systems.
Which type of engine is best for touring versus racing?
Touring bikes often benefit from larger displacement engines like V4s or flat-twins for smooth power delivery and stability. Racing bikes may use inline engines for high performance and responsiveness.
How does engine configuration affect motorcycle handling?
Engine placement and configuration can influence a motorcycle’s center of gravity, weight distribution, and overall handling characteristics, impacting rider comfort and control.
What trends are shaping the future of motorcycle engines?
Trends include increased adoption of electric powertrains, advancements in fuel efficiency, and the development of hybrid technologies blending traditional combustion engines with electric motors.
