Stihl MS 390 Pro or Farm Saw? (Field Test)
The STIHL MS 390 is best viewed as a farm-and-property saw, not a dedicated production saw. Its 64.1 cc engine and roughly 3.0 kW output suit a sharp 20-inch setup for routine firewood and land maintenance. A 25-inch bar may work in suitable wood, but it adds load and leverage. Check the saw’s exact manual and bar markings before buying parts.
If you are comparing used saws or replacement parts, the “Pro” label can muddy the decision. Sellers may use it loosely, so judge the MS 390 by its engine, setup, condition, and the work you actually do. I’ll separate the published specifications from practical fit, and flag where the serial-number-specific manual or installed parts must settle the question.
This is a specification-based field assessment, not a claim of a controlled cutting trial. I have not measured this individual saw’s cutting time, vibration, or fuel use. Those results depend on condition, chain sharpness, wood, and operator technique. The useful verdict is narrower: where the MS 390 makes sense, and what to verify before spending money.
Is the MS 390 a pro saw or a farm saw?
The distinction is about the work pattern, not just engine size. A farm or property saw handles varied jobs with pauses between cuts; a production saw is built for frequent, sustained professional use. The MS 390’s specifications point toward substantial property work, but do not establish it as a production-class machine.
With 64.1 cm³ displacement and approximately 3.0 kW, or 4.0 bhp, the MS 390 has enough engine capacity for many firewood and land-care tasks. Those numbers do not tell the whole story. A saw’s practical performance also depends on its condition, sharpness, bar and chain pairing, and the wood being cut.
I would describe it as a capable farm-and-ranch-style saw for intermittent to regular property use, rather than assume “Pro” means a factory professional designation. That does not make it unsuitable for demanding work. It means repeated, long shifts in hardwood may bring more strain, downtime, and operator fatigue than the label suggests.
The MS 390 is discontinued, so condition matters more than a seller’s category. Check for a cold start, steady idle, working chain brake, sound bar and chain, and evidence of sensible maintenance. A worn or poorly tuned saw can underperform its published specifications.
Takeaway: Buy for the workload and the saw’s actual condition, not for “Pro” in an advertisement.
What jobs fit the MS 390?
A 20-inch bar is a practical general-purpose match for this engine in routine property work. Bar length is not a promise that the saw can cut every log in one pass. Wood species, diameter, chain condition, and the cut’s position all affect the load and the safe method.
| Work pattern | Practical fit | What to keep in mind |
|---|---|---|
| Seasonal firewood and occasional bucking | Good match with a sharp 20-inch setup | Check for binding and identify compression and tension before each cut. |
| Regular property cleanup and moderate tree work | Suitable if the saw is maintained and the operator is trained | Plan each task; do not treat a powerful saw as a substitute for safe work methods. |
| Sustained hardwood production | Less compelling than a saw selected for ongoing professional use | Long cutting periods raise fatigue and maintenance demands. |
| Larger-diameter wood with a 25-inch bar | Possible in suitable conditions, with the approved setup | More bar increases leverage and kickback exposure, and can slow cutting under load. |
A 25-inch bar may be workable in suitable wood with a sharp chain, but it is not automatically the better choice. A longer bar places more demand on the engine and gives the operator more saw to control. Confirm that the bar-and-chain combination is approved for the specific saw, then judge the job by the wood and conditions.
No one bar length covers every species or task. For many owners, the 20-inch setup is the more balanced choice: useful reach without assuming the engine should carry a longer bar all day. If most of your work involves large hardwood or long production runs, compare a suitable professional saw rather than trying to solve every mismatch with a longer bar.
Takeaway: For ordinary firewood and property work, start with a verified 20-inch setup; consider 25 inches only when the work and approved configuration justify it.
Which bar and chain setup should you verify?
Pitch is the distance between chain drive links, while gauge is the thickness of the drive link that fits the bar groove. These must match across the saw’s sprocket, chain, and bar. A common MS 390 setup is 3/8-inch pitch and .063-inch gauge, but the installed parts and saw-specific manual take priority.
Before ordering, read the bar stamp and count the chain’s drive links. A common 20-inch setup uses 72 drive links, but the count can vary by bar make and configuration. Do not order by bar length alone. Confirm the bar mount, pitch, gauge, and drive-link count all match.
| Check | Common reference | What to verify |
|---|---|---|
| Displacement | 64.1 cm³ | Confirm the saw model and serial-number-specific manual. |
| Rated power | About 3.0 kW / 4.0 bhp | Published rating does not confirm current engine condition. |
| Chain pitch and gauge | Commonly 3/8 inch and .063 inch | Read the bar stamp and match the sprocket and chain. |
| 20-inch chain length | Often 72 drive links | Count links or follow the bar maker’s fit data. |
| Fuel mix | 50:1 | Use quality air-cooled 2-cycle oil and fresh fuel. |
| Fuel capacity | About 0.60 L | Use the manual for fill and operating instructions. |
| Idle and maximum speed | About 2,800 rpm; maximum about 12,500 rpm | Verify the applicable manual and use a tachometer for tuning. |
Chain depth-gauge clearance, often called raker setting, is chain-model-specific. Use the specification and filing gauge for that chain, not a universal assumed measurement. A wrong setting can change how aggressively the chain cuts. Keep the cutters even, use the specified file size and angles, and replace damaged components.
Idle and maximum engine speeds are reference points, not targets to guess by ear. Tuning should follow the applicable manual and be checked with a tachometer. Do not exceed the maximum permissible speed. If you cannot confirm the correct procedure, have a qualified service shop tune it.
Takeaway: Match every component and adjustment to the actual bar, chain, and manual, not just the saw’s model name.
How should you prepare and cut with it?
Preparation means checking both the saw and the site before starting. Even a sound saw is not safe by itself: footing, tree movement, overhead hazards, and nearby people shape the risk. Use the manual and task-appropriate training, and stop if conditions exceed your skill or equipment.
Before starting: Wear chainsaw-rated leg protection, a helmet with eye or face and hearing protection, gloves, and protective boots. Inspect the chain brake, throttle lockout, stop switch, chain catcher, handles, bar, chain tension, and fasteners. Remove the saw from service if a safety part is damaged or does not work.
Look for tree lean, overhead hazards, wind, slopes, poor footing, and likely escape routes. Keep bystanders outside an appropriate work zone. Do not fell near people, buildings, or power lines without the required training and controls. Follow ANSI Z133 work practices where applicable and relevant OSHA rules. Electrical-line approach distances depend on voltage and task; use a qualified utility-line specialist when required.
Fuel and start: Mix fresh fuel at 50:1 with quality air-cooled two-cycle oil, and fill the chain-oil reservoir. Follow the saw’s approved starting procedure on firm ground with the chain brake engaged. Never drop-start. Before cutting, check that chain oil reaches the chain.
During cuts: Keep two hands on the saw, stable footing, and a clear retreat path. Keep the bar tip away from the wood where possible and use the lower part of the bar for routine cuts. Do not force a chain that is dull or binding. For bucking, identify compression and tension before each cut; stop if the log or tree shifts unpredictably.
For felling, assess lean, defects, and wind, then use a planned directional notch and back cut with a sound hinge suited to the tree and conditions. A generic hinge dimension cannot replace competent judgment. Rotational kickback can occur when the upper quadrant near the bar tip contacts wood, driving the bar up and back. Keep the tip clear, avoid cutting above shoulder height, and never rely on the chain brake to prevent injury.
Takeaway: Start only with a sound saw and a controlled worksite; stop when movement, footing, or hazards become unpredictable.
What maintenance keeps it dependable?
Routine care helps preserve performance and reveals problems before the next job. Focus on chain sharpness, lubrication, clean air and oil paths, and safety controls. The manual sets the model-specific service steps; maintenance cannot make a worn or damaged saw safe to use.
After cutting, engage the brake, stop the engine, and let hot parts cool. Clean the air filter, sprocket cover, bar groove, and oil passages. Check chain tension and cutter condition. The chain should move freely by hand with gloves on, while its drive links remain seated in the bar groove.
Sharpen with the chain’s specified file size, angles, and depth-gauge setting. Replace a damaged chain or bar. Do not push harder to make a dull chain cut. Check oil delivery, sprocket wear, bar rails, and fuel-system condition regularly; address faults before returning the saw to work.
For extended storage, follow the manual’s fuel-system instructions and avoid leaving stale fuel in the saw. Keep fuel and oil containers clearly labeled. Store the saw in a cool, dry, secure place with the bar scabbard fitted. Before seasonal use, inspect fuel lines, filters, brake, bar, and chain, then verify lubrication and safe starting.
Takeaway: A sharp, lubricated chain and working safety parts matter more than trying to tune extra performance from an aging saw.
Final verdict: should you buy or keep one?
The MS 390 makes sense when the price, condition, and workload line up. Its roughly 64 cc engine and common 20-inch setup suit many firewood and property tasks. The case weakens if you need sustained hardwood production, expect a long bar to solve every job, or cannot verify the saw’s safety and mechanical condition.
For a used saw, inspect it in person if possible and budget for service or replacement parts only after confirming what it needs. Ask for the model and serial details, bar stamp, chain specifications, and maintenance history. Since the model is discontinued, confirm parts availability for the exact component before purchase.
My recommendation is practical rather than absolute: choose a well-maintained MS 390 with a verified, approved 20-inch setup for intermittent or regular property use. Pass on a questionable saw sold as “Pro” without proof of condition. For full-time cutting, compare purpose-selected production saws and consider the added demands of sustained use.
Bottom line: The MS 390 is best judged as a farm-and-property saw. Its condition and setup determine whether it is a good buy.
Frequently asked questions
These quick answers cover the main buying and setup checks for the MS 390. They do not replace the serial-number-specific manual or a qualified inspection. When a part’s fit, tuning limit, or safety condition is uncertain, verify it before running the saw.
Is the STIHL MS 390 a professional saw?
It is better treated as a farm-and-property saw for intermittent or regular work, rather than assumed to be a production saw because a seller calls it “Pro.”
How big is the MS 390 engine?
Its displacement is 64.1 cm³, with rated power of about 3.0 kW, or 4.0 bhp.
What bar length is best for an MS 390?
A 20-inch bar is a balanced general-purpose choice for routine firewood and property work, if the combination is approved for that saw.
Can an MS 390 run a 25-inch bar?
It may work in suitable wood with a sharp chain and approved parts, but the longer bar adds load, leverage, and kickback exposure.
What chain fits a common 20-inch setup?
A common reference is 3/8-inch pitch, .063-inch gauge, and 72 drive links. Verify the bar stamp and count before ordering.
What fuel mix does the MS 390 use?
The specified mixture is 50:1 gasoline to quality air-cooled two-cycle oil. Follow the applicable manual and use fresh, correctly mixed fuel.
What are its idle and maximum speeds?
Reference figures are about 2,800 rpm at idle and approximately 12,500 rpm maximum. Verify the manual and use a tachometer for tuning.
How should I set the chain depth gauges?
Use the specification and filing gauge for the exact chain model. Do not assume one universal raker clearance applies to every chain.
Is the MS 390 a good used-saw buy?
It can be, if the price reflects its condition and you can verify that the engine, chain brake, bar, chain, and controls are sound.
What should I check before seasonal use?
Inspect fuel lines and filters, air filter, chain brake, bar, and chain. Confirm chain lubrication and safe starting before cutting.
(This article was written by one of our staff writers, Marcus Thorne. Visit our Meet the Team page.)
