How Do You Perform A Chainsaw Compression Test?

Checking that your chainsaw has the correct compression is vital to having a well-maintained and powerful chainsaw. To do this, you need to conduct compression tests on your chainsaw. So, how do you perform a chainsaw compression test?

To perform a chainsaw compression test, seal a compression test gauge on the spark plug hole, then gently pull the chainsaw starter rope. Pull the starter rope multiple times until the needle on the gauge stops flicking. Where this stops indicates the level of compression your chainsaw is producing.

It’s important to learn how to properly perform your chainsaw compression test. This helps with your chainsaw maintenance and to get the most out of your chainsaw use.

How to perform a chainsaw compression test

A chainsaw compression test should be conducted if you have noticed less power from your chainsaw or the engine shutting down. The compression test is conducted usually using a compression test gauge. This gauge gives the best reading of the compression in your chainsaw. Below we’re going to walk you through how to do a chainsaw compression test.

Using a chainsaw compression test gauge

Using a compression test gauge is a more reliable method to get an accurate reading of PSI on your chainsaw. Here is a step-by-step procedure on how to do it:

Engage the chainsaw brake

Chainsaws are fitted with breaks to ensure that the blade of the chainsaw remains in place when not in use to minimize the risk of injury. So, the first thing to do before completing a chainsaw compression test is to engage the chainsaw brake. It’s important to do this when conducting any chainsaw maintenance.

Find and remove the spark plug

The second step is to locate your chainsaw spark plug. Consult your chainsaw manual if you’re not sure where to find it. Once you have found the spark plug, use a wrench or ratchet to turn it in a clockwise direction. This will loosen it and allow you to remove it.

How to check chainsaw compression with compression test gauge

Fix your chainsaw compression test gauge

Grab your chainsaw compression test gauge and fasten it in the hole where the spark plug goes. Ensure that the seal is tight, and that no air can escape. If the seal isn’t secure, there’s a chance that the gauge will give you a wrong reading. To prevent this from happening, make sure that you get the right-sized compression gauge for your chainsaw.

Pull on your chainsaw’s starter rope

Now that the compression test gauge is in position, gently pull on the chainsaw starter rope. You will notice that the needle of the gauge will start to move. Repeat the process until the needle no longer moves. Where the needle stops on the gauge is the PSI reading of your chainsaw.

The size and model of your chainsaw will determine what PSI reading you want for the chainsaw compression. This should be written in your chainsaw manual. Otherwise, you can contact a chainsaw maintenance service for advice. If your chainsaw’s compression levels are too high or low, it’s recommended to take it to a professional to be fixed.

Reattach the chainsaw’s spark plug

Once you’ve completed your chainsaw compression test, remove the compression test gauge, and put the spark plug back in place. To ensure that the chainsaw functions as it should start it up for a small test run. Don’t forget to disengage the chainsaw brake.

The chainsaw compression thumb test

If you don’t have access to a chainsaw compression test gauge, you can attempt the chainsaw compression thumb test. This method doesn’t provide a proper, accurate reading, but can be an indication of whether the chainsaw has compression issues.

To complete the chainsaw compression thumb test, follow these steps:

  • Remove the spark plug by rotating it clockwise, then pulling it from the hole.
  • Place your thumb over the hole that the spark plug initially filled.
  • Gently pull on the chainsaw starter rope. When you do this, there should be enough air to push your thumb out of the hole. If this happens, your chainsaw has an adequate amount of compression. If this doesn’t happen, your chainsaw compression level is low.

This method is just an indication of the chainsaw compression levels and should be conducted with extreme caution. Make sure you have engaged the chainsaw break and are practising chainsaw safety at all times.

How much compression should a chainsaw have?

It’s hard to specify how much compression your individual chainsaw should have because it varies from make and model. One of the most common chainsaw compression levels is around 110 PSI. But you should always consult your specific chainsaw’s manual to be sure.

How much compression a chainsaw should have

A bigger chainsaw engine could require a compression reading of 160 PSI, whereas a smaller one might only need 90 PSI. If you buy a petrol chainsaw, it will have a different compression level than some battery chainsaws. The range of compression levels across chainsaws is very wide. If you’re not sure, always contact a professional to check out the chainsaw. They will be able to tell you exactly what PSI you need, conduct the compression test, and make adjustments to compression levels.

Problems caused by incorrect chainsaw compression levels

It’s important for chainsaws to have the right level of compression, otherwise, this can cause problems for the engine. The chainsaw might not produce enough energy to function properly. Let’s talk about the specific problems related to high and low compression levels.

Poor chainsaw performance

A chainsaw with too much compression will always have an untidy finish. The chainsaw could saw too fast, making it hard to control. The pressure can cause the chain to jump. This risks chainsaw kickback injury and puts you in danger.

If your chainsaw’s compression levels are too low, the chainsaw won’t have much power. This will make sawing a lot more difficult and time-consuming.

Difficulty starting the chainsaw  

A chainsaw with high compression will constantly have a hard time starting. If not treated right away, there’s a chance that the chainsaw won’t start at all. This can cause lots of damage to the chainsaw engine.

If the compression levels in your chainsaw are too low, your chainsaw could struggle to start at all. The spark plugs won’t fire the way needed to start the chainsaw.

How to solve a chainsaw compression problem

Solving a chainsaw compression problem

To avoid compression problems, you need to conduct regular chainsaw maintenance. However, if compression issues do arise, you will need to correct the problem. There are several reasons as to why your chainsaw could be experiencing high or low compression.

Low compression is usually a sign of an air leak on either the gasket, engine parts, or the crankshaft seal. Once you locate the leak, you can either fix it or replace the part. Alternatively, you can have a professional fix the chainsaw for you.

High compression is often a problem caused by a faulty spark plug. Your spark plug might be dirty. Often, a good cleaning can solve this problem. However, if the spark plug has a crack, you will need to replace it.

We recommend always approaching a professional if you don’t have much experience with fixing chainsaw compression levels. This is the best way to be sure that your chainsaw gets the care and attention needed. You can always pop into our Canberra Diamond Blade Supplies store, where we offer gardening and construction tools maintenance. We’re always happy to help out!

In the market for a new chainsaw? Check out our quality Husqvarna chainsaws for sale! Seeking more chainsaw advice? Check out our Canberra Diamond Blade resources. We cover topics such as what to do when your chainsaw doesn’t cut straight.

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