2 Stroke vs 4 Stroke ATV Engines: Which Is Better?

September 16th, 2019 by


In Canada, ATVs are extremely popular; they’re even allowed on lots of roads.

Whether you already have one or are thinking of buying one, one of the things you have to consider is the engine. When it comes to 2 stroke vs 4 stroke engines, there’s a lot of debate as to which is better.

To help you understand the differences between these two ATV engine types so you can make a more informed buying decision, we put together this guide. Keep reading to learn more about these engines.


Understanding ATV Engines

Before we can get into the difference between a 2 stroke and a 4 stroke engine, you first have to understand how an ATV engine works. This is because both of these types of engines work the same way.

ATV engines use strokes to power the engine which turns the wheels. A single stroke is one movement of the piston from the top dead center position to bottom dead center position.

In one power cycle, the fuel is compressed and ignited, and the exhaust gases are expelled from the combustion chamber. The number of strokes required to complete a power cycle is where these engines get their names.


What is a 2 Stroke Engine?

A 2 stroke engine is one that completes the power cycle in just 2 strokes.

The cycle begins with the piston at bottom dead center. There, the rotating crankshaft pushes a mixture of air and fuel into the cylinder. As the piston moves upward for the first half of the stroke, the mixture is compressed.

When the piston reaches the top dead center position, the spark plug ignites the compressed fuel and air mixture which forces the piston back downward.

As it reaches the bottom position again, the exhaust gases are expelled as more fuel and air are brought in.

In this type of engine, the fuel mixture needs to travel through the crankcase. This requires oil to also run through this part of the engine to lubricate it and prevent the crankcase from overheating.

Now let’s take a look at some of the main benefits and drawbacks of a 2 stroke engine.


Higher Power to Displacement Ratio

With a 2 stroke engine, every time the piston completes one complete revolution, it generates power. That makes the engine overall more efficient because you’re constantly burning fuel.

However, this also means lower fuel efficiency, which can cost more money in the long run. It can also require more work to reach higher speeds which is a big drawback if you’re planning on doing a lot of fast driving.


No Oil Reservoir

Because oil has to be mixed with fuel, you don’t have to worry about having an oil reservoir. This creates a lighter engine compared to 4 stroke engines.

On the other hand, it also means you have to do some calculations every time you fill your tank to make sure you’re adding the right ratio of oil to the gasoline to ensure everything works as it should.


Fewer Moving Parts

With a lower number of moving parts to deal with, this can mean less expensive repairs, and you may not even need to visit the mechanic as often since there are fewer things that can break down.

It also means if you’re a beginner ATV owner, you can more easily get in and tinker with on your own. You may even be able to do a lot of repairs yourself to offset any fuel costs.


What is a 4 Stroke Engine?

A 4 stroke engine requires four strokes to complete one power cycle.

The four strokes are:

  • Intake
  • Compression
  • Power
  • Exhaust

The intake stroke starts at the top dead center where an intake valve opens and allows a mixture of fuel and air to enter the piston. When the piston reaches the bottom dead center, the intake valve closes.

As the piston moves back up to its top position, the air and fuel mixture is compressed. At the top, it’s ignited by the spark plug, which is the power stroke. The resulting explosion pushes the piston back down to bottom dead center.

At this point, an exhaust valve opens which pulls the piston back up. On its way, it expels exhaust gases, and the cycle starts again when it reaches the top and draws in more fuel and air.

Here are some of the advantages and disadvantages of a 4 stroke engine:


No Mixing of Oil and Fuel

In a 4 stroke engine, the fuel and air mixture doesn’t travel through the crankshaft as it does in a 2 stroke. This means you don’t have to mix oil into the fuel every time you fill the tank.

Although this means a 4 stroke engine needs an oil reservoir to keep the engine lubricated, it also means less math for you to keep your ATV running. Instead, you’ll just have to schedule regular oil changes as you would a normal vehicle.


More Power Available at Lower RPMs

One of the most significant advantages of choosing a 4 stroke ATV engine is that the engine can generate more power at lower revolutions per minute (RPMs). This makes for an overall more reliable engine compared to a 2 stroke.

It also means better fuel efficiency, which is what attracts many people to this type of engine. Although there are more moving parts which can make it harder to repair yourself, you can save money on fuel costs.


2 Stroke vs 4 Stroke

If you’re looking for a light engine that you can fix yourself and drive fast, a 2 stroke engine may be right for you as long as you don’t mind taking the time to mix gasoline and oil when filling the tank.

If you want a reliable and fuel-efficient ATV which only requires regular oil changes, a 4 stroke engine may be right for you, especially if you don’t plan on trying to fix anything yourself.


Do you Prefer 2-Stroke or 4-Stroke for Your ATV?

Now you have all the information you need to understand 2 stroke vs 4 stroke ATV engines. As you can see, which type you get will depend on your specific needs.

If you’re looking for a new engine or parts for your ATV, fill out our parts order form. We’d be more than happy to provide you with a free estimate so you can get exactly what you need.

Posted in ATV, Polaris, Quadding, Yamaha