How to Tune Up a Chainsaw – Easy Guide

Chainsaws are not unlike other pieces of equipment in that they will need to be maintained every now and then. Over time chainsaws may gradually lose power and cutting efficiency and need to be tuned up or refreshed to get the chainsaw back to optimal performance.

How do you tune up a chainsaw?

Tuning up a chainsaw is a simple process that requires cleaning the fuel system and carburetor, cleaning or replacing the air filter, replacing the spark plug, and sharpening or replacing the chain.

Cleaning the Fuel System

The most common cause of a poorly running chainsaw is old or decayed fuel.

If your chainsaw’s fuel is old and beginning to break down your chainsaw will more than likely run badly, if it runs at all.

In some cases, you can simply pour the old fuel out of your chainsaw and replace it with fresh properly mixed fuel and the chainsaw will run correctly.

In other cases, the carburetor and fuel filter may need to be cleaned manually. This requires removing the carburetor from the chainsaw. Once the carburetor is removed it will need to be disassembled and cleaned with carburetor cleaner, don’t forget to wear eye protection, and blown out with compressed air. Any hardened or damaged carburetor diaphragms and gaskets should also be replaced in the carburetor.

Once the carburetor is cleaned and reassembled it is time to reinstall it back on the chainsaw.

Now the fuel filter needs to be cleaned or replaced. Reach into the fuel tank with a pair of needle-nose pliers or some wire formed into a hook and pull the fuel filter to the tank’s opening.

Once you have the fuel filter in your hand, carefully remove it from the fuel line.

Now is the time to either replace or clean the fuel filter. Once you have made your choice reinstall the cleaned or new fuel filter back onto the fuel line and push it back into the fuel tank. Make sure the fuel line and fuel filter are able to reach the bottom of the fuel tank.

Clean or Replace the Air Filter

Chainsaws have to breathe in order to run correctly. The breathing of a chainsaw is done thru the air filter so that the air being pulled into the chainsaw is as clean as possible. Dirty air can damage the chainsaw internally. A dirty or clogged air filter can change the fuel-air ratio and cause the chainsaw to run improperly.

Clean air is essential to maintaining and having an optimal running chainsaw.

Over time a chainsaw’s air filter will become covered or clogged with dirt and debris. When this happens the air filter either needs to be cleaned or replaced. The good news is that air filters can be cleaned or replaced in about 1 minute. The air filter is usually snapped into place by a clip or a couple of screws. Either way, it takes very little time to remove the air filter to clean or replace it.

Replace the Spark Plug

If a chainsaw does not have an adequate fire it will not run correctly. The fire is provided by the spark plug. Over time spark plugs can begin to foul and developed a weak spark.

The spark plug is very easy to replace. In most cases, the required socket size is 3/4″. Simply remove the spark plug and replace it.

Make sure you get the correct replacement spark plug by matching the spark plugs part number that is printed on the spark plugs side. Just because a spark plug looks the same and will screw into the chainsaw’s head does not mean it’s ok to use it with your chainsaw. Spark Plugs can have different heat ranges and specifications that can damage a chainsaw if the wrong spark plug is used for your chainsaw. Match the part number of the spark plug and avoid any issues.

Another important point is to make sure when reinstalling the spark plug is that you do not cross-thread it. Cross-threading happens when the spark plug is not correctly aligned and screwed into place. The threads on the spark plug and the spark plug hole become “cross-threaded” and can permanently damage your chainsaw’s head. Take your time and you will not have issues.

Sharpen or Replace the Chainsaw Chain

A Chainsaw can be in optimal running condition but if the chain is not in the proper condition it’s all for nothing. A bad or improperly sharpened chain will make a great running chainsaw useless when it comes to cutting wood.

When tuning up your chainsaw make sure that you sharpen or replace your chain.

If you decide that your chain needs replacing make sure you select the correct replacement chain. This is also a good time to inspect your chainsaw’s guide bar.

Here is an article on guide bars and chains that will help you in your replacement efforts.

How often should you tune up your chainsaw?

Tuning up a chainsaw really should be integrated into the normal maintenance of your chainsaw. However, if normal maintenance is not done regularly a chainsaw may need to be tuned up monthly, depending on the amount of usage the chainsaw undergoes.

Keep in mind that you may not need to do every procedure listed above every time you tune up your chainsaw especially if you are maintaining your chainsaw regularly.

How do I know if my chainsaw needs a new spark plug?

A chainsaw can display sluggish and unresponsive behavior when a spark plug is in near-fouled condition. When a spark plug is completely fouled a chainsaw will not start at all.

If you think your spark plug may be fouled simply remove the spark plug from the chainsaw and inspect it. Unscrew the spark plug from the cylinder and look at the electrode end, the part that screws into the chainsaw. If the electrode is pitted or appears to be scalded to a white-hot color it needs to be replaced.

If the spark plug electrode is covered in a dark substance called carbon that means it is fouled and needs to be replaced.

How do you check my spark plug without removing it?

It is possible to check the spark plugs quality of spark without having to remove the spark plug from the chainsaw. This process is very easy and quick to do but you will need to purchase an Inline Spark Plug Tester. They are cheap and easy to get. You can purchase an Inline Spark Plug Tester here.

The process of using the Inline Spark Plug Tester requires you to remove the ignition coil from the spark plug. Once removed snap the Inline Spark Plug Tester in between the ignition coil and spark plug.

Then try to start the chainsaw as normal. As you are pulling the rope the spark plug should be showing spark on the clear part of the Inline Spark Plug Tester. If there is no spark your spark plug is more than likely bad or your ignition coil has gone out.

Replace the spark plug first and if there is still no spark you will more than likely need to replace the ignition coil.

Wrapping Up

Chainsaws need to be maintained like any other piece of power equipment. The more maintained the chainsaw is the fewer repairs and headaches you will have later.

Take the time, at least on a monthly basis to flush out your chainsaw’s fuel system, clean or replace the air filter, replace the spark plug and sharpen or replace your chain. These simple quick tasks will keep your chainsaw running in top-notch condition for years to come.

Be safe out there and happy tuning!

Steven R

I have been part of the chainsaw and outdoor power equipment business in one way or the other for over 35 years. There are not many things that I have not seen in the business. From repairs, sales, equipment operation, and safety I can help you with your questions.

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