Stihl MS 290 to MS 390 Air Filter (Swap Guide)
For an MS 290, MS 310, or MS 390, match the air filter to the saw’s serial number and the installed filter style before ordering. STIHL part number 1127 120 1605 is commonly listed, but styles and superseded numbers can vary. Remove the old element carefully, keep dirt out of the intake, and install a clean filter that seals evenly.
Wear and tear can leave a filter packed with sawdust, misshapen, or unable to seal. A clogged filter may affect how the saw runs, while a poor fit can let abrasive dust reach the engine. I use one rule for this job: confirm the part, protect the intake, and never force a near-match.
Confirm the correct filter before you start
The MS 290, MS 310, and MS 390 belong to the same broad 1127-series platform, but that alone does not prove their filters interchange. The commonly listed standard filter is STIHL 1127 120 1605. Check the parts listing for your saw’s serial number before buying or installing a replacement.
Model displacement can help identify which saw you have, but it does not establish filter fit. The MS 290 is 56.5 cc, the MS 310 is 59.0 cc, and the MS 390 is 64.1 cc. Use the model and serial number together when checking the STIHL parts catalog or asking a dealer.
| Saw model | Displacement | Commonly listed filter | What to verify |
|---|---|---|---|
| MS 290 | 56.5 cc | STIHL 1127 120 1605 | Serial-number listing and filter style |
| MS 310 | 59.0 cc | STIHL 1127 120 1605 | Serial-number listing and filter style |
| MS 390 | 64.1 cc | STIHL 1127 120 1605 | Serial-number listing and filter style |
Treat the table as a starting point, not a guarantee. A replacement number may have been superseded, or the saw may have a different filter style. Do not assume an MS 311 or MS 391 filter fits; those model names do not confirm compatibility with an MS 290, MS 310, or MS 390.
Before installing a part, compare it with the old element. Check its overall shape, attachment, and sealing edge. If the housing or filter differs from the parts listing, stop and confirm the correct part. Do not trim the seal, bend the filter, or press it into place.
Check the installed filter style
The installed element is a useful visual check, but it is not a substitute for serial-number confirmation. A filter can be an old or incorrect replacement. Compare its shape and mounting points with the approved part listing, then make sure the new element’s seal matches the housing.
If the filter that came out does not match the listed part, do not copy its fit by force. Confirm the saw’s model and serial number, then ask a STIHL dealer or consult the parts catalog. That small check can prevent a poor seal and dust entering the intake.
Prepare the saw and work area
Safe filter service starts with a cool, switched-off saw and a clean area around the cover. The chain brake should be engaged, and loose debris should be removed before opening the air-filter compartment. This helps keep dirt out of the intake while you work.
Wear eye protection and gloves. Work in a ventilated area away from ignition sources. Set the saw on a stable surface, switch it off, engage the chain brake, and allow the engine to cool. Brush loose sawdust from around the top cover before removing it.
Have the correct replacement filter ready, along with the operator’s manual for the cover and filter instructions. Use the manual’s method for releasing the filter fastener. Avoid tools or force that could damage the fastener or housing.
I pay close attention to the area around the filter before lifting it out. Dirt on the cover can fall inward once the compartment is open. Cleaning the outside first is easier than trying to keep loose debris out after the filter is removed.
Remove and install the air filter
A careful swap protects the open intake from falling dirt. Remove the top cover as directed in the operator’s manual, release the filter fastener, and lift out the element without disturbing debris. Install only a confirmed, clean filter, seat its seal evenly, secure it, and refit the cover.
Follow this sequence:
- Remove the top cover according to the operator’s manual.
- Release the filter fastener using the manual’s method.
- Lift out the filter carefully. Do not drop dirt into the intake.
- Inspect the filter, its sealing surfaces, and the area around the intake.
- Clean loose debris outward, away from the intake opening.
- Set the correct clean or new filter in place.
- Check that its sealing edge sits evenly all the way around.
- Secure the filter fastener and refit the top cover.
If debris is present near the opening, remove it without pushing it inward. Keep tools and cloths from contacting or leaving material in the intake. If you think dirt has entered, stop and have the saw inspected before continuing to use it.
Before starting, confirm that the filter is seated and the cover is secure. Operate the saw only with the filter installed. A brief run without the filter is not a safe fit test; it can expose the engine to unfiltered dust.
Clean, replace, or investigate a problem
Air-filter cleaning depends on the material and the instructions for the filter fitted to your saw. Follow the operator’s manual for that element. Do not wash a filter unless its manual allows washing, add oil unless instructed, or use high-pressure compressed air that can damage the filter media.
Replace the filter if it is torn, distorted, persistently clogged, or no longer seals. A filter that looks clean but does not sit flat is not ready for service. The seal matters because it helps keep dust from passing around the element.
If the saw runs poorly after a swap, check the filter fit and intake sealing first. Make sure the correct element is installed, the fastener is secure, and the cover is seated. Do not turn carburetor screws to compensate for a restricted, damaged, or incorrectly fitted filter. Use an authorized service procedure if the issue remains.
If you see dust beyond the filter or suspect that dirt passed through, stop using the saw and arrange an inspection. Abrasive debris can wear internal engine parts and may lead to serious damage. A filter swap does not call for a change to carburetor settings.
Practical fitment scenarios
These examples show how to make a decision when the old filter or saw details do not match at first glance. They are service scenarios, not claims about a specific customer’s saw. In each case, the safe step is to verify the part and seal rather than make the filter fit by force.
| What you find | What to do | Avoid |
|---|---|---|
| Old filter matches the catalog listing and is damaged | Replace it with the confirmed filter number and check the seal | Reusing a torn or distorted element |
| New filter looks close but has a different edge or attachment | Stop and verify the serial-number listing with a dealer | Trimming, bending, or forcing it |
| Old element differs from the catalog listing | Confirm the saw identity and correct filter style | Assuming the old part was correct |
| Dust is visible near or beyond the intake | Stop and arrange an inspection before further use | Starting the saw to see if it runs normally |
A common point of confusion is a filter number that differs from the one printed on an old package or element. A superseded number may be valid, but confirm that through the parts catalog or a dealer for the saw’s serial number. Do not rely on appearance or displacement alone.
After the swap and between uses
A completed filter swap should leave the element seated, the fastener secure, and the top cover properly fitted. Store spare filters clean and dry in a sealed bag, away from fuel, oil, and shop dust. Before seasonal use, inspect the filter and seal again.
Start and operate the saw only after confirming that the filter is installed and the cover is secure. If it still runs poorly, revisit the fit and inspect the intake area before considering other causes. Do not change the fuel mixture or chain setup just because you changed the air filter.
Fuel mix is a separate service item. STIHL specifies a 50:1 mix when using STIHL two-stroke oil; if using another oil, follow the saw manual and oil maker’s instructions. Filter fitment does not determine fuel ratio.
Air-filter swap FAQ
These short answers cover common questions about choosing, fitting, and caring for an MS 290, MS 310, or MS 390 air filter. When a filter style or part number is uncertain, use the saw’s serial number in the STIHL parts catalog or confirm it with a dealer.
Does the MS 290 use filter 1127 120 1605?
STIHL 1127 120 1605 is commonly listed for this model family, including the MS 290. Confirm the current part number and filter style against your saw’s serial number before ordering, since listings may vary or show a superseding number.
Do MS 290, MS 310, and MS 390 filters interchange?
They may share a commonly listed filter, but the model family alone does not confirm fit. Check the serial-number parts listing and compare the filter’s shape, attachment, and sealing edge. Do not force a filter that differs from the approved part.
Does an MS 311 or MS 391 filter fit these saws?
Do not assume it does. An MS 311 or MS 391 filter must not be treated as compatible based only on the similar model name. Confirm the correct filter for the MS 290, MS 310, or MS 390 by serial number.
How do I know if the new filter is seated correctly?
The filter should match the housing, sit evenly on its sealing surface, and stay in place when secured with the correct fastener. If its edge lifts, its shape differs, or it needs force to fit, stop and verify the part.
Can I run the saw briefly without the filter to test it?
No. Run the saw only with the correct filter installed. Operating without a filter can let abrasive dust enter the engine. If the saw runs poorly after service, check fitment and sealing without removing the filter for a test run.
Can I wash the MS 290-series air filter?
Only if the instructions for the installed filter material and the saw’s manual allow it. Filter materials need different care. Do not wash a non-washable element, oil it without instruction, or use high-pressure compressed air.
When should I replace the filter instead of cleaning it?
Replace it if it is torn, distorted, stays clogged after approved cleaning, or no longer seals. If debris may have passed into the intake, stop using the saw and arrange an inspection before continuing.
Does replacing the air filter change the fuel mix?
No. Air-filter fitment does not change the fuel ratio. STIHL specifies 50:1 when using STIHL two-stroke oil; follow the saw manual and oil maker’s instructions when using another oil.
(This article was written by one of our staff writers, David Hensley. Visit our Meet the Team page.)
