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Are Lawn Mower Engines 4 Cycle? Find Out Here!

Written by William
Last Updated on April 1, 2021

We understand that most people are not professionals when it comes to engine types. If you are unsure what a 4 cycle engine lawnmower is, look no further.

While not all lawnmowers are powered by a 4 cycle engine, they are typically the better type of mowers to buy.

But why are 4 cycle engines so common in lawnmowers and why are top mower brands keen to use these types of engines? Let us explain.

How does a 4 cycle engine work?

As can be guessed from the name alone, a 4 cycle engine completes 4 cycles but of what exactly?

Almost always, these types of engines are internal combustion engine meaning that instead of the petrol being burnt elsewhere in the lawnmower, it is burnt within the engine.

This burning of the fuel creates hot air which pushes on a piston which then turns the crankshaft.

Everytime that the piston completes a 4 step stroke, one cycle is complete.

These steps are:

  • Intake - the air produced by the fuel moved into the combustion chamber
  • Compression - once in the chamber, the air becomes compressed. This is a key step in accessing more energy stored in the fuel's air
  • Ignition - the now compressed air is combusted by rapidly mixing oxygen with the air, resulting in the release of energy in the form of hot air
  • Exhaust - now that the energy is released, it is moved from the combustion chamber into the air

Once all of these steps have been complete then 1 cycle has finished.

However, just 1 cycle on its own does not produce the level of power expected from a top of the range lawnmower. Nor enough power to cleanly cut through grass.

That is why engines with more than 1 cycle engines are used.

What is the difference between a 4 cycle engine and a 2 cycle engine?

Unlike a 4 cycle engine, a 2 cycle engine does not require as many strokes of the piston to work. But that is not the only difference.

Different types of cycle engines require different types of fuel or power sources to operate and produce the most energy they can.

A 2 cycle engine needs to have a mix of fuel and oil so that the engine parts can be well oiled continuously during combustion.

One the other hand, a 4 cycle engine does not need its oil and fuel mixed.

It is this key difference that makes it easier for you to identify if you have a 2 cycle or a 4 cycle lawnmower.

Simply find where you fill-up the fuel on your mower and look for the little sign that will indicate what type of engine it uses.

Why do lawnmowers use 4 cycle engines?

The biggest attraction to a 4-stroke engine system is the environmentally friendly design.

When comparing 2 cycle and 4 cycle engines, a 2 cycle engine produces just as much power as a 4 cycle and is lighter.

This is why a 2 cycle engine is most often used for self propelled lawn mowers.

However, manufacturers are trying to move away from 2 cycle engines due to the oil and fuel mix that they require.

Every time combustion happens, a little bit of oil is burnt at the same time, releasing extra pollution into the atmosphere.

4 cycle engines keep their oil and fuel separate. Therefore, no oil is being burnt while the engine is completing its cycles.

That is why you will find top lawnmower brands like Bosch using a 4 cycle engine, as they are committed to reducing air pollution.

There is also the fact that a 2 cycle engine has to work twice as hard as a 4 cycle engine to produce the same amount of power meaning that it will have to be replaced more regularly.

Therefore, not only do 4 cycle engines burn less oil but they are also saving you money in the long run as they will not wear out as fast.

About the author
Written by William
I have always had a passion for gardening and that with a background in selling lawn mowers for the past 10 years, I have become very knowledgeable in all types of gardening tools. The site TheBestMowers.co.uk was created as a hub where I can review and write about all of the tips around gardening.
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