How much compression should a chainsaw have – 2 Best Methods to know

how much compression should a chainsaw have

Do you ever feel like your chainsaw isn’t performing at its peak and that something must be wrong? It could be the compression.

As a chainsaw user, I know the importance of good engine compression. After all, compression is responsible for producing the power and torque you need to get through any task you might have. If a chainsaw has too much compression, it can be overly powerful and cause damage.

Unfortunately, knowing the best compression level can be difficult without some knowledge and experience.

So, I will break down exactly how much compression a chainsaw should have, so you can decide when choosing your chainsaw.

How Much Compression Should a Chainsaw Have- Ideal Limit and Depending Factors

Ideal Limit

Most chainsaw engines are designed to run within a certain compression range. A good range would be between 90 and 160 psi, average around 100-110 psi. This is considered the ideal pressure for most two-stroke engines, and if your engine falls within this range, it’s probably running just fine.

Depending Factors- 3 Common Factors

However, the ideal compression for your engine may vary depending on a few factors.

  • Type of Fuel

One of these is the type of fuel you’re using. If you use a lower-grade fuel, then your engine’s compression will be slightly lower than what it would be with higher-quality fuel. Also, if your chainsaw has been running for a while, the compression may decrease as it wears down.

  • Type of Engines/Motor

Ideally, the compression on your chainsaw should be between 160 and 180 PSI (pounds per square inch). This range is generally considered optimal for most operations you may want to do with a chainsaw.

However, The compression varies according to the model and brand of each chainsaw. For instance, two-stroke engines typically have higher compression than four-stroke ones.

  • Type of Wood

Furthermore, the type of wood you cut and how often you use it can also affect things. If cutting hardwood or using your chainsaw a lot, you should consider having a slightly higher compression for better performance.

In contrast, a slightly lower compression will do if you mostly cut softwood and don’t use your chainsaw too often.

Does Temperature Affect Chainsaw Compression?

Yes, like a motorcycle, its engine is affected by high and low temperatures. Also, the compression of a chainsaw will be affected. The engine will produce less power in colder temperatures due to lower pressure levels. This is because cold air has a higher density than hot air, meaning the engine takes more effort to suck in air and create the necessary compression level.

Generally, chainsaws run at high temperatures but can overheat. Cold chainsaws use about 85 to 100 PSI. Hot chainsaws might use about 160 PSI.

If you use your chainsaw in cold temperatures, allowing the engine to warm up before use is recommended, as this will help keep the compression within the optimal range.

How Can You Perform The Chainsaw Compression Test – 2 Best Methods

Method 1: Pressure Test Gauge – Easy Guiding Steps in Detail

  • Gather The Tools You Need

    First, you must gather a few tools, including a compression tester kit, a spark plug, a wrench or socket set, and a torque wrench.
  • Engage the Brake

    Next, you must ensure the chainsaw is off and disengage the brake. This will ensure no power is transferred through the saw while you test the compression.
  • Locate The Chainsaw Spark Plug

    Next, you will need to locate the spark plug on your chainsaw. Most chainsaws have a removable cover that can be accessed by unscrewing from the engine. Once the cover is removed, you should be able to see the spark plug clearly.
  • Remove The Chainsaw Spark Plug

    Once the spark plug is visible, you must remove it from the engine. This can usually be done using a spark plug wrench or socket set.
  • Attach The Pressure Test Gauge

    After removing the spark plug, you must attach a pressure test gauge to the opening where the spark plug was located. This can be done by screwing the pressure gauge into the spark plug hole. Make sure that it is properly installed and secure before continuing.
  • Start The Chainsaw

    Once the pressure gauge is in place, start your chainsaw and let it run for a few seconds. Ensure the engine is idling or running at low speed so that you can get accurate readings from the pressure gauge.
  • Check The Pressure Gauge Reading

    Now that your chainsaw is running, you must check the pressure gauge reading. The pressure gauge should display a number in PSI (pounds per square inch). This is the current compression level of your chainsaw engine.
  • Compare To Normal Compression Levels

    Once you have taken the pressure gauge reading, compare it to the normal compression levels for your particular chainsaw model. If the reading is close to or within the normal range, then your chainsaw engine is in good condition and should be able to provide adequate power for your operations. If the reading is significantly lower than the normal range, then you may need to take steps to increase the compression level of your engine.
  • Resetting the Chainsaw’s Spark Plug

    After you have completed the compression test, don’t forget to reset the spark plug. This can be done by simply unscrewing the pressure gauge and screwing the spark plug back into its place.

Method 2: Do The Thumb Test – 3 Simple Rules

Most chainsaw users don’t have access to pressure testers, so they prefer to do the thumb test. This is an easy way of testing a chainsaw engine’s compression.

  • Engage the Brake

    To perform the thumb test, ensure the chainsaw is off and the brake is engaged so no power is transferred through the chainsaw while you test compression.

    Place Your Thumb Over The Spark Plug Hole

    Next, thumb over the spark plug hole while pulling the starter cord. If there is enough compression in your engine, you should feel a strong resistance with your thumb and hear a distinct “pop” sound. This indicates that the compression is adequate and that you won’t need to adjust.
  • Check for Compression Level

    However, you should feel a strong resistance and hear a distinct “pop” if compression is adequate. This is an easy way to check for compression without using tools or gauges. If you don’t feel any resistance or hear the “pop” sound, it may be time to adjust your chainsaw’s compression levels or replace the spark plug.

What Are The Problems Caused By The Low Or High Compression?

Low Compression

  • Misfire

    If there is not enough compression or pressure, the chainsaw’s spark plug may not start the chainsaw properly and may cause it to misfire
  • Poor Starting

    Low compression can also cause the chainsaw to take longer and may even prevent it from starting. This is because the air-fuel mixture inside the combustion chamber will not be able to ignite properly if there isn’t enough pressure.
  • Low Power Output

    Another reason for low compression is decreased power output. This means that the chainsaw may not be able to cut through materials as quickly or efficiently as it should.

High Compression

  • Poor Performance

    High compression can cause the chainsaw to run hotter, leading to poor performance. The heat inside the engine may also cause damage to the spark plug and other components.
  • Difficulty In Starting

    High compression can also make it difficult for the chainsaw to start. The air-fuel mixture may be too rich, making pulling on the starter cord hard.

How much compression does a 2-stroke chainsaw need to run?

For most 2-stroke chainsaws, the ideal compression should be between 110 and 130 psi. This range of compression allows for optimal power and combustion efficiency in the engine. Anything lower could decrease power output, while anything higher may cause damage to internal components over time.

It is also important to note that different chainsaw models may require different compression levels depending on their design. Therefore, check the manufacturer’s specifications for your particular model before adjusting or replacing any components.

How Can You Fix The Chainsaw Compression Problems?

If you find that your chainsaw is not running at the optimal level of compression, then there are a few things that you can do to try and fix the problem.

Fix 1: Air Leaks in Gasket

Firstly, check whether air leaks have developed in the cylinder head or gasket. If there are any leaks, then it will be necessary to replace these parts to restore the proper compression.

Fix 2: Adjust the Valve Clearance

Sometimes, you may also need to replace the spark plug or adjust the valve clearance on your chainsaw. This can help improve the air-fuel mixture inside the combustion chamber and restore optimal compression levels.

Fix 3: Qualified Technician

Finally, if all else fails, then it is recommended that you take your chainsaw to a qualified technician for professional inspection and repair.


In conclusion, how much compression should a chainsaw have is an important question to answer and an essential factor for maintaining the performance of a chainsaw. It’s not only related to the type of fuel, engines/motors, and wood used but also can be affected by the temperature.

The ideal compression level depends on the size and type of engine or motor installed in your chainsaw. It is best to measure the compression level by using a pressure test gauge or doing the ‘thumb test.’

Once you have established if there are problems with either low or high compression in your chainsaw, repair steps should be taken as soon as possible.

With these considerations in mind, you can start evaluating what kind of tools you need and methods you should use when considering how much compression should a chainsaw have to run its optimum performance.


How Much Compression Should A Small 2-Stroke Engine Have?

A small two-stroke engine should typically have between 90 and 110 psi of compression. However, checking the manufacturer’s specifications for your particular model is important.

What Is The Minimum Compression For A Stihl Chainsaw?

The minimum compression for a Stihl chainsaw is between 110 and 130 psi. However, checking the manufacturer’s specifications for your particular model is important.

How Many CC Is The Chainsaw?

The size of the engine or motor installed in your chainsaw will determine how many CC it is. This information can usually be found on the manufacturer’s website or in your user manual.

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