What Is the Stihl 023 Spark Plug Gap? (Spec Chart & Gap)

The STIHL 023 spark plug gap is 0.5 mm (0.020 in). Measure between the center and ground electrodes with a feeler gauge, then adjust gently if needed. Check the plug type against the manual for your exact saw, because a correct gap does not make an unsuitable replacement plug safe or compatible.

A spark plug gap is only about half a millimeter, but it is a precise setting, not a visual guess. Too wide or too narrow a gap can affect the spark that ignites the fuel-air mixture. The gap is one thing to check when servicing an 023, but it does not by itself diagnose every starting or running problem.

I use a feeler gauge rather than judging the distance by eye. The measurement is quick, and it helps avoid forcing the electrodes or fitting a plug based on an assumption. Here is the gap specification, how to check it, and what else to confirm before you run the saw.

STIHL 023 spark plug gap and specification chart

The specified spark plug electrode gap for the STIHL 023 is 0.5 mm, or 0.020 in. The inch figure is a rounded equivalent: 0.020 in is about 0.508 mm. Use the metric value or the matching inch blade on a feeler gauge, and verify the plug type in the manual for your saw.

The speed figures are references, not instructions to adjust the carburetor by ear. Use the model-specific manual and the correct tachometer procedure for engine tuning. A spark plug gap is not a substitute for those checks.

The fuel ratio also matters when troubleshooting. Use quality air-cooled two-stroke oil that meets STIHL’s requirements, mix fresh fuel in an approved container, and follow the manual. Do not run straight gasoline in this two-stroke saw.

Key takeaway: Set the plug gap to 0.5 mm (0.020 in), and verify other service details from the manual that matches your 023.

How to measure and set the 023 plug gap

A feeler gauge is a thin metal blade marked with its thickness. To check the gap, place the 0.5 mm blade between the center electrode and the ground electrode. It should pass with light contact, not require force. Work on a cool, switched-off saw with the ignition lead disconnected.

Prepare and inspect the spark plug

Let the engine cool before removing the plug. Disconnect the ignition lead, then use the correct plug tool to remove it. Keep dirt from falling into the cylinder opening; wipe around the plug area before removal if needed.

Look at the plug before adjusting it. Check for a cracked insulator, damaged electrodes, or heavy deposits. A damaged plug should not be treated as serviceable just because its gap can be measured. Confirm that the replacement plug matches the 023 manual or a listing for your exact saw.

Check and adjust the electrode gap

Insert the 0.5 mm feeler gauge between the center electrode and the ground electrode. The fit should be light. If the gauge will not enter, or if it moves through with obvious looseness, adjust the ground electrode a little at a time using a suitable tool.

Do not pry against the center electrode or ceramic insulator. These parts can be damaged by force. Recheck the gap after each small adjustment, and stop if an electrode looks bent, cracked, or loose. Replace a damaged plug instead of trying to correct it.

Refit the plug

After setting the gap, make sure the plug is clean and its threads are not damaged. Start it by hand so it does not cross-thread in the cylinder, then tighten it as directed in the 023 manual. Reconnect the ignition lead securely.

Avoid guessing how tight the plug should be. Tightening instructions can depend on the plug and service guidance, so use the manual rather than adding force. A correctly gapped plug still needs a sound connection and correct installation.

Next step: Once the plug is fitted, follow the manual’s cold- or warm-start procedure. Do not run the saw if you find damage or are unsure the plug is correct.

What a wrong gap can tell you

A gap outside specification is a reason to correct or replace the plug, but it is not proof that the gap caused a starting problem. Ignition trouble can have more than one cause. Check the plug carefully, then use the manual’s troubleshooting steps rather than repeatedly changing the gap.

A plug’s appearance can offer clues, but it does not provide a complete diagnosis on its own. Avoid changing carburetor settings or relying on an approximate idle sound as a substitute for the correct procedure.

Practical examples

These are illustrative service situations, not reports of tests on a specific saw. In one common setup check, a replacement plug’s gap is wider than 0.5 mm. The correct response is to verify that the plug type is approved, adjust carefully if it is serviceable, and measure again before installation.

In another situation, the gauge shows 0.5 mm, but the plug has a damaged insulator. The measurement does not make that plug acceptable; replace it with the specified type. If the saw still has trouble after a sound plug is installed, continue diagnosis using the manual instead of assuming the gap is at fault.

Key takeaway: The gap is a measurable setting, not a complete diagnosis. Check the plug’s condition and compatibility as well.

Safety checks before starting the STIHL 023

Spark-plug service is done with the engine off and cool. Before starting the saw afterward, check that the machine and work area are ready. Wear a helmet with face and eye protection, hearing protection, chainsaw-rated leg protection, gloves, and boots. Keep bystanders clear and follow the manual.

Inspect the chain brake, throttle interlock, chain catcher, and chain tension. Confirm that the bar and chain are an approved combination for that particular 023. Match the bar’s stamped pitch and gauge to the chain, and verify the chain’s drive-link count against the bar. Bar length alone does not identify the correct chain.

Start the saw on stable ground using the manual’s procedure. Confirm that the chain does not move at idle and that the brake functions. Do not cut if the chain moves at idle or a safety part does not work. If the chain brake or idle behavior needs repair, have the saw checked before use.

During cutting, keep the guide-bar nose clear of the cut and nearby material. Contact with the nose’s upper quadrant can cause rotational kickback, which can throw the saw toward the operator. The chain brake is a safety device, but do not rely on it to prevent kickback.

Key takeaway: A correctly gapped plug does not make an unsafe saw safe. Check the controls, chain, bar fit, and work area before cutting.

Maintenance and storage after checking the gap

The spark plug should be checked as part of maintenance intervals and troubleshooting, not adjusted by guesswork each time the saw is used. Follow the 023 manual for inspection, cleaning, and replacement guidance. After work, switch off the saw, let it cool, engage the chain brake, and clean the air intake, bar groove, and sprocket area.

Recheck chain tension as the manual directs. Keep fuel fresh and store it in an approved container. For seasonal storage, follow the saw’s instructions for fuel and cleaning; do not assume one storage method fits every manual or fuel product.

If the plug gap changes again or the electrodes appear damaged, replace the plug with one confirmed for the exact saw. Record the installed plug type and the measured gap if you maintain the saw yourself. That simple note can prevent uncertainty during the next check.

Next step: Keep the manual with your maintenance notes, and use it to confirm both plug replacement details and service intervals.

STIHL 023 spark plug gap FAQ

The direct answer is 0.5 mm (0.020 in), measured between the center electrode and ground electrode. These quick answers cover common questions about measuring, adjusting, replacing, and troubleshooting the 023 spark plug. Always check the manual for the exact saw and replacement plug.

What is the spark plug gap on a STIHL 023?

The gap is 0.5 mm (0.020 in). Measure it with a feeler gauge.

Is 0.020 inch the same as 0.5 mm?

It is the rounded inch equivalent. Exactly, 0.020 in is about 0.508 mm, so use the specified 0.5 mm setting.

What tool should I use to check the gap?

Use a feeler gauge with a 0.5 mm blade or a matching 0.020 in blade. Avoid judging the gap by eye.

How do I adjust the spark plug gap?

Move the ground electrode gently, a little at a time, then measure again. Do not pry against the center electrode or insulator.

Should I adjust a damaged spark plug?

No. Replace a plug with a cracked insulator or damaged electrode, using a type confirmed for the 023.

Can the wrong gap cause starting trouble?

An incorrect gap can affect ignition, but it is not the only possible cause of a starting problem. Check the plug and follow the manual’s troubleshooting steps.

Does every STIHL 023 use the same replacement plug?

Do not assume so. Confirm the plug type against the manual or a parts listing for your exact saw.

What fuel mix does the STIHL 023 use?

The specification is 50:1 gasoline to suitable air-cooled two-stroke oil. Use fresh fuel and follow STIHL’s oil requirements and the manual.

What should I check before using the saw after plug service?

Check the ignition lead, chain tension, chain brake, throttle interlock, and chain catcher. Start by the manual’s procedure and confirm the chain does not move at idle.

Can I use the chain brake to stop kickback?

Do not rely on the chain brake to prevent kickback. Keep the guide-bar nose’s upper quadrant away from the cut and surrounding material.

(This article was written by one of our staff writers, Evan Bradley. Visit our Meet the Team page.)