How Do Petrol Lawn Mowers Work?

A petrol mower is a type of mower that’s powered by petrol rather than electricity or manual pushing.


Read this guide before you buy a new petrol lawnmower for your lawn. I’ve shared everything you should know about how petrol mowers work, including how to start and use a petrol mower, the various parts of this mower, and how petrol mowers compare to other mower types.

✅ Key Takeaways:

  • A petrol mower (or a gasoline lawn mower) is a type of cordless mower that’s powered by petrol.

  • There are a few kinds of petrol mowers. Most petrol mowers use rotary cutting blades.

  • Petrol lawn mowers are a powerful, convenient, cord-free mowing solution, ideal for large lawns. However, they’re louder, more difficult to use, and less environmentally friendly than electric and battery-operated models.

Table of Contents

❓ How Does A Petrol Lawn Mower Work? Quick Overview

A petrol lawnmower works by powering the mower blades with an internal combustion engine, like the engine in a car. Combustion in the engine forces down a piston in the cylinder, causing the crankshaft to rotate and the blade to spin. The rotating blade cuts your grass as you push the mower along your lawn.

🤔 What Is A Petrol Lawn Mower?

A petrol lawn mower is a powerful fuel-operated mower that you can use to quickly cut a large lawn.


Petrol mowers are decreasing in popularity because there are other easier-to-use and more convenient options, like battery-powered mowers and robotic lawn mowers.


However, petrol lawn mowers are still popular amongst folks with big gardens who want a quick, powerful mowing option that can run for hours, or people who want a reliable mower for commercial use.


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  • Brand: Murray
  • Price: £££

  • Power source: Petrol

  • Cutting width: 51cm

  • Cut height range: 25-75mm
  • Weight: 28.8 kilograms

  • Grass box capacity: 75 litres

  • Dimensions (DxWxH): 162 x 54 x 98cm

  • Power: 2.06 kW/2900 rpm

🔍 Types of Petrol Lawn Mowers

There are two types of petrol lawn mowers that you’ll find for home grass cutting: rotary lawn mowers and cylinder mowers.

♻️ Petrol Rotary Lawn Mowers

Most petrol mowers for home gardening are rotary mowers, meaning that they use a single horizontally-rotating blade to cut grass.


A petrol rotary lawn mower is cheaper than a cylinder mower, but doesn’t offer quite the same cut quality and can’t be used to produce a very close-cropped cut.

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✂️ Petrol Cylinder Mowers

Petrol-powered cylinder mowers, otherwise known as reel mowers, use vertically-spinning blades to snip the ends of grass with a scissor-like action.


A petrol cylinder mower is more expensive and is more commonly used for certain sports turf (such as golf courses) as well as certain situations where a manicured or ornamental look is desired.


For home gardening, petrol-powered push mower models are the most commonly used. These mowers walk-behind models that you push along your lawn.


Petrol commercial mowers for large spaces might be push mowers or riding lawn mowers, depending on the use.


There are also self-propelled models that use petrol, which are motorized and drive themselves forward, rather than requiring pushing. Petrol-powered hover mowers, which float on a cushion of air, are less common but also available.

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🔬 How Does A Petrol Mower Work?

A petrol mower works by powering a rotating blade with a small engine inside the mower chassis. This type of engine is known as a combustion engine because it runs on the explosive reaction between spark and fuel.


When you switch the mower on, the engine creates combustion with fuel (petrol) and a spark, which causes the piston in the cylinder to be forced down. This rotates the crankshaft and causes the mower’s blades to turn.


This rotating blade spins at a high speed, ripping the ends off the grass. These grass clippings are blown into the grass box, which needs to be emptied periodically when it gets full.


🏁 How Do You Start A Petrol Mower?

To start a petrol mower, first check the petrol level to make sure there’s enough fuel in the machine to run. Next, pull the throttle to starter position and pull the starter cord (or pull cord) to kick the mower into action.


Starting a petrol mower takes a bit of practice. It can be difficult to get the mower running if it’s your first time using it or if it’s been sitting in storage all winter.


If your mower isn’t starting, there are a few things you can try:

  • Replace the fuel – Petrol goes stale after about 30 days, so you might need new fuel.

  • Press the fuel button – If your mower has been standing for a long period, you might need to pump petrol into the engine by pressing the fuel button 3-5 times.

  • Check the spark plug – If the spark plug is wet, it’ll stop the mower from switching on. Use a carburetor cleaner cloth to dry the spark plug, then try again.

  • Top up the oil – Check the oil level and add more oil if it’s too low. This should encourage the mower to kick into gear.

More of a visual learner? Check out the video below for how to start a petrol mower.

🧾 How To Use A Petrol Mower: Step-By-Step

To use a petrol mower on your lawn, follow these easy steps:

  1. Position the mower on your lawn. A good starting point is the corner of your lawn, pointing in the direction of the longest section of your garden.

  2. Conduct a visual inspection. Before you start the mower, check the mower’s fuel and oil levels, then check the spark plug and the chassis for damp or damage.

  3. Start the mower. Pull the throttle to starter position and swiftly pull the starter cord (pull cord). You will hear the sound of the engine switching on.

  4. Mow your lawn. Some petrol lawn mowers have a throttle that should be set to “run” position before you start mowing. If you have a self-propelled mower, press the second lever on the handle, which will cause it to start moving forward.

  5. Cleanup & put away. When you’ve finished mowing, empty out the grass box and clean down the entire mower before returning it to storage.

🧰 Parts Of A Petrol Lawn Mower

The main parts of a petrol mower are:

🪒 Blades

A petrol mower’s blades cut the grass by rotating rapidly as you mow. A petrol rotary mower uses a single horizontally-rotating blade, while a cylinder or reel mower uses multiple vertically-rotating blades.

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🏎 Engine

The combustion engine inside a petrol mower is what powers the blades to spin. The engine produces mechanical energy due to explosions between fuel and sparks.

⛽️ Fuel Tank

The fuel tank, as the name suggests, stores the fuel for the mower. This tank keeps the fuel clean and secure, and is easily accessible for fuel changes and top-ups.

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spark, plug, lawn, mower, engine, maintenance,

⚡️ Spark Plug

The spark plug is an essential petrol mower feature that produces sparks that trigger combustion inside the mower engine.

💪 Handle

The handle gives you a comfortable means of pushing your mower, and you can often adjust it to make it longer or shorter depending on your height. You’ll also find the throttle and starter cord on the handle.

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🔵 Wheels

Most petrol mowers (excluding hover mowers) have four wheels: two at the front and two at the back. These allow the mower to glide easily over grassy surfaces.

📦 Grass Box/Bag

Unless you have a dedicated mulching mower, your petrol mower should have a grass box or bag to collect the grass clippings as you mow.

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📊 Petrol Mowers Vs Electric Mowers

Petrol mowers have been used for home lawn mowing since they were first manufactured over 100 years ago – but they’re not the only option for cutting your grass.


Another popular mower is the electric lawn mower, which came about after electricity became commonplace in our homes.


The main difference between petrol mowers and electric mowers is the power source: petrol mowers are powered by fuel and use a combustion engine, while electric mowers are powered by electricity and need to be plugged into a power outlet.


Electric mowers are cheaper, quieter, and better for the environment than petrol mowers, but they’re not as powerful and they’re tethered by a cord. So, while an electric mower is typically the best option for small-to-medium lawns, a petrol mower is the faster and more convenient option to cut a large lawn.

📊 Pros & Cons Of Petrol Mowers – Chart

Pros of Petrol Mowers Cons of Petrol Mowers
Better for large gardens More difficult to start
Can handle a variety of terrains High noise levels
Lots of features to choose from Need more maintenance
Reliable and tough
Pros of Petrol Mowers Cons of Petrol Mowers
Better for large gardens More difficult to start
Can handle a variety of terrains High noise levels
Lots of features to choose from Need more maintenance
Reliable and tough

✅ Petrol Mower Pros

🟩 Better For Large gardens

Petrol mowers have more powerful engines than the small engines found in electric mowers. That means they’re the better choice for large gardens because they do a better and faster job of cutting grass.


⛰ Can Handle A Variety Of Terrains

Another benefit of the powerful petrol mower engine is its ability to handle a variety of terrains, including rough surfaces, leaf-littered lawns, and taller grass. You can mow straight over a difficult surface without worrying about the blades getting caught or the engine struggling to cope.


📡 Lots Of Features To Choose From

Petrol lawn mowers tend to have more features than conventional electric mowers, and it’s easy to find two-in-one mowers that can be used as bagging mowers (where the grass is collected in a bag) and mulching mowers (where the grass is dispersed over your lawn as you cut). You can also find plenty of riding mowers and self-propelled mowers that are petrol powered.


🔨 Reliable And Tough

Petrol mowers are the most reliable and durable mower types that exist today. These mowers can easily last beyond 15 years with the right maintenance, and if a part breaks, you can probably fix it yourself.

❌ Petrol Mower Cons

🏁 More Difficult To Start

The older petrol mower models are more difficult to start than other mower types. You have to put the throttle in the start position and pull the starter cord, which can sometimes take a few tries. It’s much easier to start an electric mower, which just has a single push-button, and some mower types (like manual reel mower models) don’t need starting at all.


🎧 High Noise Levels

Most rotary lawn mowers with petrol engines are very loud – so much so that manufacturers recommend wearing hearing protection when using a petrol-powered mower. There’s not a lot you can do about the sound of the engine, and you might disturb your neighbours if they live in close proximity.


🧰 Need More Maintenance

Petrol mowers need more maintenance than any other type of mower to use at home. You need to service the mower annually, including regularly changing the fuel and topping up the engine oil, so a petrol mower isn’t right for you if you want a low-maintenance option.

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🛠 How To Maintain A Petrol Mower’s Performance

Petrol lawn mowers require more maintenance than electric rotary mowers and battery-operated mowers.


The main maintenance tasks for a petrol-powered lawn mower are:

  • Change/top up the engine oil

  • Change/top up the fuel

  • Keep the mower clean

  • Sharpen the mower blades

  • Replace the spark plug

  • Lubricate the parts

  • Inspect and change the air filters

Mower maintenance is essential, especially for a petrol mower. The mower can only continue to run properly if you keep it clean, lubricated, and topped up with fuel and oil.

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💰 Are Petrol Mowers Worth It?

Petrol mowers are worth it for you if you have a budget of at least £200 and you prefer a powerful lawnmower that will do an exceptional job of cutting grass across a variety of terrains and can quickly cut a large lawn.


If you have a smaller garden and you just want a quality mower, you don’t necessarily need a petrol mower.


Consider an electric rotary lawn mower, which costs less than half the price of a petrol mower and offers a similarly powerful performance, just with an electric cord to consider. Or, to avoid the cord altogether, consider a cordless battery-powered mower, which isn’t as powerful but still does a good job on smaller lawns.


Whatever mower you decide on, make sure to do your research and invest smartly in a mower that has plenty of positive customer feedback and great reviews from industry experts.