Chainsaws are indispensable tools for many homeowners, landscapers, and woodcutters. However, like all machines, chainsaws require regular maintenance to keep them running smoothly.
One essential maintenance task for any gas-powered chainsaw, including Stihl models, is spark plug replacement.
In this article, we’ll guide you through the process of selecting the correct Stihl chainsaw spark plug and spark plug wrench, along with the replacement process. I will also provide some tips on extending the life of your spark plug.
The Correct Spark Plug for a Stihl Chainsaw
Stihl Chainsaws utilize one of two distinct spark plugs, depending on the specific chainsaw model. The two spark plugs used in Stihl chainsaws are the NGK BPMR7A and the NGK CMR6H.
For the Stihl Chainsaws models 017, 019, MS170, MS180, MS191, MS192, 024, MS240, 025, MS250, 026, MS260, MS261, MS270, MS271, 028, MS280, 029, MS290, MS291, 031, MS310, MS311, 039, MS390, MS391, 036, MS360, MS361, 044, MS440, MS441, 046, MS460, MS461, 066, MS660, MS661, 088, MS880, and MS881, the appropriate spark plug is the NGK BPMR7A. AVAILABLE HERE ON AMAZON
For the Stihl Chainsaws models MS171, MS181, MS193, MS194, MS211, MS241, MS251, and MS362, the suitable spark plug is the NGK CMR6H. AVAILABLE HERE ON AMAZON
The SPARK PLUG WRENCH needed for Stihl chainsaws is a T-Wrench 13mm x 19mm AVAILABLE HERE ON AMAZON
- The Correct Spark Plug for a Stihl Chainsaw
- Why Spark Plugs Matter
- Signs of a Bad Spark Plug
- Spark Plug Replacement Process
- The Replacement Process
- Maintenance Tips
- Troubleshooting Spark Plug Issues
- Wrapping Up
Why Spark Plugs Matter
The spark plug is a crucial component of any gas-powered engine, as it’s responsible for igniting the fuel mixture inside the combustion chamber. A properly functioning spark plug ensures optimal engine performance, fuel efficiency, and reduced emissions.
Signs of a Bad Spark Plug
Some common signs that indicate your spark plug might need a replacement include:
- Difficulty starting the chainsaw
- Erratic engine idling
- Decreased power and performance
- Increased fuel consumption
- Noticeable engine misfires
Spark Plug Replacement Process
Preparing for Replacement
Before you start the replacement process, gather the necessary tools and materials:
- A suitable replacement spark plug
- Spark plug wrench or socket
- Clean cloth or rag
- Wire brush (optional)
Safety should always be your top priority when working with power tools. Before starting the replacement process, make sure to:
- Turn off the chainsaw and allow it to cool down
- Disconnect the spark plug wire to prevent accidental ignition
- Wear protective gloves and eyewear
The Replacement Process
Removing the Spark Plug
To remove the old spark plug, follow these steps:
- Locate the spark plug on the engine. It’s typically found on the top of the engine.
- Use the spark plug wrench or socket to gently turn the spark plug counterclockwise until it’s loose.
- Carefully remove the spark plug by hand to avoid damaging the threads.
Inspecting the Spark Plug
Take a close look at the removed spark plug. If it’s covered in deposits, corroded, or damaged, it’s time to replace it.
Choosing the Right Replacement
It’s essential to use the correct replacement spark plug for your specific Stihl chainsaw model. Check your owner’s manual or consult a Stihl dealer to find the right part number.
Installing the New Spark Plug
Before installing the new spark plug, make sure it’s gapped correctly according to your chainsaw’s specifications, which can be found in the owner’s manual.
- Carefully thread the new spark plug into the engine by hand to avoid cross-threading.
- Use the spark plug wrench or socket to tighten the spark plug until it’s snug. Do not overtighten, as this can damage the threads or the spark plug itself.
- Reconnect the spark plug wire, ensuring it’s firmly attached.
Testing the New Spark Plug
Once the new spark plug is installed, start your chainsaw to ensure it’s running smoothly. If there are still issues, further troubleshooting may be necessary.
Maximizing Spark Plug Life
To extend the life of your spark plug, consider the following tips:
- Use the proper fuel mixture for your chainsaw, as specified in the owner’s manual.
- Regularly clean the air filter to prevent debris from entering the engine.
- Avoid using old or contaminated fuel.
- Perform regular maintenance checks on your chainsaw, including checking the spark plug for signs of wear.
Troubleshooting Spark Plug Issues
Common Spark Plug Issues
If you’re still experiencing problems after replacing the spark plug, consider these common issues:
- Incorrect spark plug gap
- A faulty ignition coil or spark plug wire
- Clogged fuel filter or carburetor
- Worn or damaged piston rings or cylinder
To address these issues, you may need to:
- Adjust the spark plug gap according to your chainsaw’s specifications.
- Test and replace the ignition coil or spark plug wire if necessary.
- Clean or replace the fuel filter and clean the carburetor.
- Inspect and replace worn or damaged piston rings or cylinders.
Replacing the spark plug on your Stihl chainsaw is an essential maintenance task that ensures optimal performance and extends the life of your tool. Be sure to purchase the correct replacement spark plug for your chainsaw model, and always follow safety precautions when working with power tools.
For additional help, consult a Stihl dealer or service technician. With the right parts and proper techniques, you can keep your Stihl chainsaw running smoothly for years to come.
By following the steps outlined in this guide, you can keep your chainsaw running smoothly and efficiently for years to come.
How often should I replace the spark plug on my Stihl chainsaw?
It’s recommended to replace the spark plug every 100 hours of operation or annually, whichever comes first. However, it’s a good idea to check the spark plug regularly for signs of wear or damage.
Can I use any spark plug for my Stihl chainsaw?
No, it’s essential to use the correct spark plug specified for your particular Stihl chainsaw model. Using the wrong spark plug can lead to poor performance or damage to your chainsaw.
What should I do if my chainsaw still won’t start after replacing the spark plug?
If your chainsaw still won’t start after replacing the spark plug, consider checking other components, such as the ignition coil, spark plug wire, fuel filter, or carburetor, for issues.
Is it necessary to gap the spark plug before installation?
Yes, it’s essential to ensure the spark plug gap is set according to your chainsaw’s specifications. An incorrect gap can lead to poor performance or even engine damage.
Can I clean and reuse my old spark plug?
Although it’s possible to clean and reuse a spark plug, it’s generally not recommended. Spark plugs are relatively inexpensive, and replacing them regularly ensures optimal chainsaw performance.