How to Service & Maintain a Stihl Chainsaw (Step-By-Step)

A Stihl chainsaw is a good investment to help maintain your property or cut wood to use as a heating source. Regularly tuning up your chainsaw will help protect that investment and keep it in good condition for many years of use.

Service and maintain a Stihl chainsaw by replacing the air filter, fuel filter and spark plug; inspecting the safety components; cleaning the cooling system; lubricating the bar and chain; inspecting the fuel system; and repairing any missing or damaged parts.

Keep reading for instructions on how to tune up your Stihl chainsaw.

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Follow all safety instructions provided in your equipment operator’s manual before diagnosing, repairing, or operating. Consult a professional if you don’t have the skills, or knowledge or are not in the condition to perform the repair safely.

Service & Tune-Up a Stihl Chainsaw (Step-By-Step)

17 Steps to Service and Tune Up a Stihl Chainsaw:

• Gather tools and supplies
• Check safety components
• Remove the spark plug & follow safety precautions
• Replace old fuel
• Replace the fuel filter
• Fill with bar and chain oil
• Inspect the fuel system
• Replace the air filter
• Replace the spark plug
• Clean the cooling system / air intake system
• Inspect the muffler and clean the spark arrestor
• Inspect the spur sprocket
• Lubricate the needle bearing
• Inspect and clean the guide bar and lubrication hole
• Inspect the saw chain. Sharpen and check tension.
• Clean the exterior
• Inspect components, tighten loose hardware & replace broken and missing parts

How to Tune Up and Maintain a Stihl Chainsaw

1. Gather Tools and Supplies

• Socket set, screwdrivers, Stihl scrench.
• Fuel filter
• Air filter
• Spark plug
• Clean rags
• Gas and 2-cycle oil (If old fuel is in the fuel tank)
• Fuel stabilizer
• Bearing grease
• Wire brush and bristle brush
• Protection gear: gloves and safety glasses

2. Check Safety Components

A Stihl saw has many safety features installed to assist with reducing injury. Some of these items include the chain brake, chain catcher, throttle trigger lockout, hand guards, and start/stop switch.

To ensure your safety, test these features to ensure they work as designed:

• Chain brake: When engaged, the chain brake should keep the chain from moving.
• Chain catcher: Catches the chain if it comes off the bar.
• Throttle trigger lockout: The throttle trigger must return to idle when your hand is taken off the handle.
• Start/stop switch: Stops the engine from running.
• Hand guards: Must be in place and not damaged.

If you find any problems with these safety components, repair them. Do not operate your chainsaw until they are fixed.

3. Remove the Spark Plug & Follow Safety Precautions

Take safety precautions to avoid injury before you begin maintenance and inspections on your Stihl chainsaw. This includes shutting off the chainsaw and allowing the engine to cool if it was running prior to servicing.

Make sure all parts have stopped moving. Remove the spark plug wire. Wear safety glasses and work gloves for protection and follow all additional safety instructions found in the operator’s manual.

4. Replace Old Fuel

Old fuel can cause significant problems to develop in the fuel system and engine. Because most fuels today contain ethanol, an alternative fuel to make it a little environmentally friendly, it’s important to know how to care for it to reduce issues in a Stihl chainsaw.

Gas can begin to break down and lose its combustible properties rather quickly. The ethanol added to gasoline attracts moisture to the fuel system which leads to varnish and gummy buildups.

Change the fuel in your Stihl chainsaw if you find it is older than 30 days. If the fuel in your chainsaw is old, wipe around the fuel cap, remove the cap, drain the fuel tank and add a fresh gasoline and oil mix.

It’s also a good time to replace the fuel filter after you drain the fuel tank and before you refill it.

Stihl currently offers a full line of chainsaws with 2-cycle engines. These types of engines require gas and oil to be mixed before placing them in the fuel tank. Read more about the type of gas and oil Stihl chainsaws use here.

Stihl chainsaws use a gas-to-oil mix at a ratio of 50:1. This means 50 parts gasoline is mixed with 1 part oil.

• Gasoline: An unleaded gasoline with a minimum octane rating of 89 and a maximum ethanol content of 10%. Stay away from gas with ethanol contents greater than this. Ethanol is not good for small engines.
• 2-cycle premium oil: A 2-cycle premium oil that is ISO-L-EGD and JASO M345 FD certified like Stihl High Performance or Stihl HP Ultra.

Stihl Gas to Oil Mix Ratio	1 Gallon Gas	2 Gallon Gas	2.5 Gallon Gas
50:1	2.6 oz Oil	5.2 oz Oil	6.4 oz Oil

While Stihl branded oil contains a fuel additive to keep fuel stable so it lasts a little longer without breaking down, Stihl does recommend consuming fuel within 30 days and no longer than 60 days after purchase.

I like to add a fuel additive like Sea Foam Motor Treatment or STA-BIL when old fuel has been sitting in the chainsaw. This additive not only stabilizes gas, but it also reduces moisture buildup and helps clean the fuel system.

Note: Some 2-cycle oils contain an additive that can keep the fuel stable anywhere from 30 days to 2 years. Don’t assume that, just because there is a fuel stabilizer included in the oil, it makes the fuel stable for longer than 30 days.

5. Replace the Fuel Filter

The fuel filter is a necessary component to keep dirt and debris from entering the fuel system. It must be replaced so it doesn’t become plugged with dirt that restricts fuel flow. This can result in your chainsaw running sluggishly and losing power.

The fuel filter is a small cylinder-shaped component located inside the fuel tank. To replace the fuel filter, use a clean bent wire to hook the fuel line and pull the filter out of the tank.

Hold onto the fuel line with a pair of needle nose pliers in one hand while pulling the filter out of the line with the other hand.

Don’t let go of the fuel line. Insert the new fuel filter into the line. Make sure the fuel filter is securely attached to the filter and place it inside the tank. Install the fuel cap.

6. Check the Fuel System

Check the condition of the fuel system components including the fuel tank, fuel lines, and fuel cap. If you find any leaks or cracks, replace the items.

Check the fuel cap seal to make sure it is sealing and the fuel will not leak out of the cap area. Do not operate your Stihl chainsaw if you find a fuel leak until it is repaired.

7. Fill the Bar and Chain Oil Tank

Use Stihl bar and chain oil or another standard bar and chain oil to fill the chain oil tank.

When using the saw in very cold temperatures, the oil will thicken and become tackier so you’ll need to use a thinner oil viscosity when using it in cold conditions.

8. Replace the Air Filter

You must keep a clean air filter in your chainsaw. With the dirty dusty conditions created when using a chainsaw, it’s important to have an air filter that keeps dirt from entering the carburetor throat and wearing on the engine.

When the air filter in your Stihl isn’t cleaned and replaced regularly, it can get plugged causing chainsaw problems including loss of power, failure to start, or overheating.

Replace the air filter annually with a new filter. You will have to replace it more often if you are working in very dusty conditions, use your mower more than the average homeowner, or use it for commercial purposes.

Never run a chainsaw without an air filter. Doing so will wear and damage the engine.

Replace an air filter

• Remove the engine cover.
• Remove the air filter.
• Remove any dirt remaining in the air filter housing and engine cover.
• Install a new air filter.
• Reattach the air filter cover.

Clean your Stihl chainsaw filter regularly throughout the season:
(Fleece or HD2 air filter. Consult the operator’s manual for your type of filter).

• Remove the cover.
• Clean around the air filter housing to remove any dirt and sawdust.
• Remove the air filter.
• Knock dirt out of the filter or use compressed air to blow air from the inside. DO NOT use a brush.
• If the filter is very dirty, wash it in a mild dish detergent and water solution, and rinse from the inside outward until the water runs clear.
• Allow the filter to completely air dry. DO NOT use heat on the filter as this can damage it. DO NOT apply oil to the filter.
• Reinstall the clean filter.
• Purchase and install a new air filter if the old filter is extremely dirty or damaged
• Reattach the cover.

9. Replace the Spark Plug

Make sure you always have a good spark plug in place. A fouled or damaged plug can cause your Stihl chainsaw to have intermittent spark problems resulting in poor performance.

Remove the old spark plug and replace it with a new spark plug that is gapped to the manufacturer’s specification. Hold off on attaching the spark plug wire. You want to leave it unattached until you have completed servicing your Stihl chainsaw.

10. Clean the Cooling System and Air Intake

The engine can overheat and shut down when it gets hot due to debris and dirt clogging the air passageways. When air can’t circulate around the engine to keep it cool, your Stihl chainsaw will overheat which can result in potential engine damage.

Before working around the engine, make sure the spark plug wire is still removed. Remove the engine cover. Clean all debris from the air intake on the starter, engine cover, and around the engine.

Remove debris buildup on the pawls on the flywheel and the cooling fins. Use a bristle brush to remove dirt. Don’t use any metal tool to remove the debris as this can cause damage.

11. Inspect the Muffler and Clean the Spark Arrestor

Inspect the muffler for any damage and ensure it is properly attached. Replace a damaged muffler.

You will find a spark arrestor on most Stihl chainsaws. This is a small metal screen that prevents hot exhaust materials from shooting out of the chainsaw.

This spark arrestor screen can become plugged with soot resulting in a lack of airflow and affecting your chainsaw’s performance.

If you have been running the chainsaw, wait for the muffler to cool before cleaning the spark arrestor. With the spark plug wire disconnected, remove the engine cover and engine exhaust cover.

Remove the spark arrestor and clean it with a wire brush to remove the soot. If you are unable to clean it sufficiently, it is damaged or has a hole in it, replace it with a new spark arrestor.

12. Inspect the Spur Sprocket & Lubricate the Needle Bearing

Keep the needle bearing lubricated. To apply grease, make sure the chain brake is not engaged. Remove the bar nut(s) and clutch cover. Place the chainsaw on a table so the clutch drum is on the top side facing upward.

Inspect the spur sprocket on the clutch drum for wearing. If it is worn, it must be replaced. Apply good bearing grease to the needle bearing like this lubricant from Stihl.

13. Inspect and Clean the Guide Bar

Next, look at the guide bar. Clean out the groove in the bar and file down any burrs you find. Inspect the bar for a bend and any wearing. If you find either of these conditions, replace the guide bar.

Check the lubricating hole and clean it to make sure it isn’t clogged. Lubricate as needed.

14. Inspect, Sharpen, and Check the Tension

Inspect the condition of the Stihl chain:

First, confirm your chainsaw is in the off position. You should be easy to bend and not stiff. Look at the rivets and links and replace the chain if you find they are loose, worn, or cracked.

Inspect the cutting teeth. If they measure less than 4mm, it’s time to buy a new chain.

Sharpen the Stihl chain:

It’s important always to use a sharp chain on a Stihl chainsaw. A dull chain can increase the chance of a kickback. In order to sharpen a chain, you must have the right file and gauge for your chain along with the proper technique.

Because sharpening a chain correctly isn’t the easiest thing to do and will impact how the saw cuts and the user’s safety, I have a professional sharpen my saw chains. Most outdoor power equipment dealerships that sell Stihl chainsaws provide this service.

Check the chain tension:

The chain should be adjusted regularly as it will become longer as you use it. The chain should sit securely on the bar and be able to rotate easily around it.

You don’t want the bar too loose that it’s hanging from the bar and you don’t want it too tight that it won’t move.

To adjust the chain tension so it easily moves around the chainsaw bar, loosen the bar retaining nut(s) that hold on the chain sprocket cover. Hold the bar nose up.

Turn the tensioning screw clockwise to tighten the chain and counter-clockwise to loosen the chain. Once you have the right tension, tighten the bar retaining nut(s) while still holding the bar nose up.

15. Clean the Exterior

Add a mild dish detergent to the water. Dampen a clean cloth and clean the exterior of the chainsaw removing dirt and sawdust.

16. Inspect Components, Tighten Loose Hardware & Replace Broken & Missing Parts

Inspect your chainsaw for loose or missing parts. Replace any items that are missing or damaged. Tighten any loose parts. Don’t operate your Stihl chainsaw until all parts are installed and in good working order.

17. Reattach the Spark Plug Wire

Now that all of the work is complete on your Stihl chainsaw, you can reattach the spark plug wire. Start the chainsaw and check that it is running well.

Allow it to run for several minutes at about 3/4 throttle if you have added fresh fuel with a stabilizer to allow it to run through the fuel system.

While you’re allowing the chainsaw to run at 3/4 throttle, hold the saw about a foot from a flat surface while the chain spins.

You should see a line of oil form on the ground after several minutes indicating the bar and chain are being sufficiently lubricated so you don’t run into a problem where the chain won’t rotate.

Tuning Up Your Stihl Chainsaw Will Help Keep It Running: Don’t Skip Regular Inspections

While you should tune up your Stihl chainsaw annually to keep it running at its best and to minimize significant problems during the season, it is also important to check it over before each use.

Check these items on a Stihl chainsaw before each use:

• Inspect and clean the air filter.
• Check safety components (chain brake, chain catcher, throttle trigger lock-out, hand guards, start/stop switch)
• Look for fuel leaks and repair.
• Check the condition of the fuel filter.
• Make sure air passages are not clogged.
• Check anti-vibration elements
• Inspect the muffler for damage.
• Inspect bar and chain for damage and proper lubrication.
• Check the chain sharpness and tension.
• Tighten loose parts and replace missing parts.