Before you begin. This procedure is general reference information, not professional advice. Equipment varies by manufacturer, model, and year. Always follow the documentation supplied with your equipment — where it differs from this page, follow the manufacturer. Verify that you have the tools, the working conditions, and the ability to do this task safely. If anything is unclear, if the equipment is damaged, or if the task exceeds your experience, stop and use a qualified professional. You are responsible for your own safety and for the outcome. This site accepts no liability for any loss, damage, or injury arising from the use of this information.
Specifications marked unverified could not be traced to a manufacturer source. Do not rely on them — obtain the value from your equipment documentation.
Summary
A new guide bar must match your saw and chain specifications. Before you install the new bar, check the drive sprocket for wear. A worn sprocket will damage a new chain. This procedure covers bar removal, sprocket inspection, and component replacement using manufacturer specifications.
Necessary equipment
| Item | Note |
|---|---|
| Socket set or wrench set | Metric or US SAE as required by your saw model. |
| Screwdriver set | Phillips or flathead, as required by your saw model. |
| Spark plug socket | Optional, use if you have one. Otherwise the wrench set is sufficient. |
| Work gloves | Protect hands from sharp chain and sprocket teeth. |
| Replacement guide bar material | Must match your saw model. Note the length, mount pattern, and sprocket type. |
| Replacement drive sprocket material | Required if wear marks exceed the limit in your manual. Must match chain pitch. |
| Replacement chain material | Must match the gauge, pitch and drive link count. Consult your manual or old chain. |
Specifications
No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.
No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.
No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.
No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.
Prepare the saw
Estimated 12 min
Stop the engine and let it cool before you work on the chainsaw.
A burn injury can result.
- Stop the engine and allow the saw to cool for at least 10 minutes.10mReport a problem with step 1, Prepare the saw
Disconnect the spark plug wire from the spark plug.
The engine could start if the wire remains connected and a control moves.
- Disconnect the spark plug wire from the spark plug to prevent accidental starting.<1mReport a problem with step 2, Prepare the saw
- Place the saw on a flat work surface with the guide bar extending away from you.<1mReport a problem with step 3, Prepare the saw
- Find your saw model and locate the operator manual.1mReport a problem with step 4, Prepare the saw
Remove the guide bar and chain
Estimated 4 min
The guide bar, sprocket and chain have sharp edges and teeth.
Wear work gloves and handle these parts with care to prevent cuts.
- Locate the side cover nuts or bolts that hold the guide bar. Refer to your manual for their location.<1mReport a problem with step 1, Remove the guide bar and chain
- Remove the side cover fasteners using the right wrench or socket.1mReport a problem with step 2, Remove the guide bar and chain
- Lift the side cover. Set it on your work surface.<1mReport a problem with step 3, Remove the guide bar and chain
- Turn each bar bolt counterclockwise until loose.1mReport a problem with step 4, Remove the guide bar and chain
- Lift the guide bar. Pull it away from the engine.<1mReport a problem with step 5, Remove the guide bar and chain
- Lift the chain free from the bar. Remove it.<1mReport a problem with step 6, Remove the guide bar and chain
Inspect the sprocket
Estimated 3 min
The sprocket has sharp teeth.
Do not run your finger across the teeth. A sharp edge can cause a laceration.
- Examine the sprocket teeth on the engine drive. Look for wear marks (small arrows stamped into the sprocket).1mReport a problem with step 1, Inspect the sprocket
- Refer to your saw manual to find the maximum wear depth for your sprocket model.<1mReport a problem with step 2, Inspect the sprocket
- Place a wear gauge or the edge of a feeler gauge into the deepest wear mark if you have one.1mReport a problem with step 3, Inspect the sprocket
- If wear marks exceed the manual specification, you must replace the sprocket along with the bar.<1mReport a problem with step 4, Inspect the sprocket
- If wear marks are within limits, the old sprocket can be reused with a new chain.<1mReport a problem with step 5, Inspect the sprocket
Install the replacement bar and sprocket
Estimated 6 min
- If you must replace the sprocket, consult your manual. Read the removal method. Some sprockets press-fit. Others screw in.<1mReport a problem with step 1, Install the replacement bar and sprocket
- Install the new sprocket following the exact procedure in your manual for your saw model.2mReport a problem with step 2, Install the replacement bar and sprocket
- The bar must meet compatibility requirements. Model, length, mount pattern and sprocket type must all match.1mReport a problem with step 3, Install the replacement bar and sprocket
- The chain must have the right gauge, pitch and drive link count from your manual.<1mReport a problem with step 4, Install the replacement bar and sprocket
- Slide the new guide bar into position with the sprocket nose aligned to the drive sprocket.<1mReport a problem with step 5, Install the replacement bar and sprocket
- Wrap the chain around the bar and sprocket. Keep the teeth in the cutting direction.1mReport a problem with step 6, Install the replacement bar and sprocket
- Position the side cover and reinstall the nuts or bolts. Tighten them by hand until snug but not tight.1mReport a problem with step 7, Install the replacement bar and sprocket
Tension the new chain
Estimated 3 min
- Locate the chain tension adjuster. Refer to your manual for its exact location (often on the side cover).<1mReport a problem with step 1, Tension the new chain
- Turn the adjuster clockwise to increase tension. Tighten the bar bolts as you go.2mReport a problem with step 2, Tension the new chain
- When the chain hangs loosely by one link, stop. Secure the bolts firmly.<1mReport a problem with step 3, Tension the new chain
Operation test
Estimated 2 min
- Reconnect the spark plug wire to the spark plug.<1mReport a problem with step 1, Operation test
- Start the engine and allow it to idle for 30 seconds.<1mReport a problem with step 2, Operation test
- Do a test. The chain must not move when the engine idles at normal speed.<1mReport a problem with step 3, Operation test
- Stop the engine. Allow the saw to cool and tension the chain again if needed.1mReport a problem with step 4, Operation test
Terminology
This page uses one term for each item and holds it throughout, as ASD-STE100 requires. Equipment sellers and other guides use the names below for the same parts.
- guide bar
- Also called: no common alternatives
- chain pitch
- Also called: no common alternatives
- chain gauge
- Also called: no common alternatives
- drive link
- Also called: no common alternatives
- drive sprocket
- Also called: no common alternatives
- sprocket wear
- Also called: no common alternatives
When to use a professional
If you are uncertain about bar compatibility, consult your manual. If you are uncertain about chain specifications, consult your manual. If sprocket installation is unsafe, contact a dealer.
Common questions
How do I know what chain pitch my chainsaw uses?
The simplest method is to read the stamped markings on the drive link of your old chain. If the chain is worn out, consult your saw's operator manual, which lists all compatible chains by model. You can also contact an authorized dealer with your saw model number.
What does chain gauge mean?
Gauge is the thickness of the drive link where it fits into the guide bar groove. Common gauges are 0.043 inch, 0.050 inch, 0.058 inch and 0.063 inch. A chain that is too thick will not fit in the bar groove; a chain that is too thin will fit loosely and operate unsafely. Always match the gauge to your guide bar.
How do I count the drive links on my chain?
Place a piece of tape on the first drive link (the tooth-like link underneath the chain). Count each drive link as you go around the chain back to the tape. This count must match the bar length and saw model for the chain to fit correctly.
Why does the sprocket condition matter when I replace the chain?
A worn sprocket has shallow tooth engagement with the chain. Installing a new chain on a worn sprocket creates stress points that cause rapid chain and sprocket wear and can lead to chain failure. Replacing a worn sprocket at the same time as the bar prevents this problem.
What if I cannot tell whether my sprocket is worn?
Your saw's operator manual defines the wear specification, usually the maximum depth of the wear marks stamped into the sprocket. If you do not have the manual, contact an authorized dealer or the equipment manufacturer with your saw model number. If you are uncertain, it is safer to replace the sprocket as a precaution.
Can I reuse an old chain on a new bar?
Not reliably. Old chains wear and develop loose links over time. Reusing an old chain increases the risk of chain breakage or slippage. Replace the chain whenever you replace the bar for safety and predictable performance.
Related procedures
- How to tell if a chainsaw chain is too loose, and how to tighten it
- Sharpen a chainsaw chain with a round file and a depth gauge, and know when to stop filing
- What chain fits my chainsaw? How to check pitch, gauge, and drive link count
Sources
Every specification on this page is traced to one of these sources. Tier 1 is a manufacturer document, a published standard, or a government safety authority. See Standards for the full tiering rule.
- Tier 1When to Replace Your Chainsaw Chain, Sprocket or Guide Bar
- Tier 1How to: adjust the tension of the saw chain — Petrol Chainsaw support
- Tier 1Tightening Chainsaw Chain
- Tier 1How to tighten your chainsaw chain
- Tier 1QuickCard: Chainsaw Safety (OSHA 3269-04R 2013)
Revision history
Current version 1 · updated 2026-08-03 · next review due 2027-08-03
- v1 · 2026-08-03First publication.
Corrections to this page are listed in the public corrections log. Reports that are credible and not yet verified are listed in the public errata register, and an open one renders above the step it concerns.
Comments and corrections
Found an error? A correction with a manufacturer source is applied and logged publicly. You can also write to corrections@fixchecklist.com.
Every step above carries its own report control, which tags the report with that step so a correction reaches the right place. For anything about the procedure as a whole — the order of the sections, a step that is missing, something that did not match your equipment — use this: report something about this whole procedure.