Stihl 039 Chainsaw (Field Test & Specs)
The STIHL 039 is a 64.1 cm³, two-cycle saw built for substantial cutting jobs, but a used example’s condition matters more than its badge. A sound 16–20-inch setup suits many ground-level tasks. Before cutting, confirm bar and chain match, safety controls work, fuel is fresh at 50:1, and the saw idles without chain movement.
The quick fix for many 039 problems is not a carburetor adjustment: first check the chain, fuel, air filter, and safety controls. That simple order can prevent a minor setup issue from becoming engine damage or an unsafe cut.
This guide is a practical field-use assessment based on the model’s published specifications and checks to make before and after work. It is not a claim of a controlled performance test on every 039. Older saws may have different bars, sprockets, parts, and service histories, so verify the exact configuration on the saw in front of you.
STIHL 039 specs and what they mean
The 039 is a 64.1 cm³ two-cycle chainsaw. Displacement describes the volume swept by the piston, not the saw’s cutting speed by itself. Bar choice, chain condition, wood, and engine health all affect results, so treat the model’s specs as a starting point for inspection.
| Item | Field reference | What to check |
|---|---|---|
| Engine | 64.1 cm³, two-cycle | Confirm the model marking and consult the correct manual |
| Fuel mix | 50:1 | Use fresh gasoline and suitable air-cooled two-cycle oil |
| Oil per litre of gasoline | 20 mL | Measure accurately; do not estimate |
| General bar range | 16–20 in | Use only a length suitable for the saw, chain, wood, and operator |
| Common chain pitch | 3/8 in | Confirm the bar and drive sprocket; configurations can vary |
| Chain gauge | .050 or .063 in are found | Match the bar stamp and chain |
| Published speed references | About 2,800 rpm idle; 12,500 rpm maximum no-load | Verify the exact manual and use a tachometer for tuning |
A saw’s pitch is the spacing of the chain drive links and cutters. Gauge is the thickness of the drive links where they sit in the bar groove. Both must match the bar, and pitch must also match the sprocket. A chain can look close and still be wrong.
Engine speed figures are not instructions to adjust by ear. The published references commonly associated with the 039 are approximate, and service details can differ by version or market. Use the correct STIHL service information and a tachometer. Never tune above the manual’s limit.
Equipment setup, bar and chain fit, and safety preparation
This section defines the checks that make the saw ready for work. A 16–20-inch bar is a practical general-purpose range for many 039 users, not a promise that every saw or job can handle it. Confirm the bar, chain, and sprocket fit, then inspect the controls and work area before starting.
Read the bar stamp before ordering a replacement chain. It should identify the pitch and gauge; the chain also needs the correct number of drive links for that bar. Do not assume that “3/8” means low-profile chain. The 039 is commonly set up for 3/8-inch chain, but its parts and configurations vary.
For many users, a 16- or 18-inch bar is easier to manage than a longer one. A 20-inch bar can suit some work, but extra bar length increases load. Do not fit a longer bar just because the powerhead accepts it. The wood, chain, saw condition, and operator’s skill all matter.
Before each use, check:
- Chain brake, throttle interlock, stop switch, and chain catcher.
- Handles, chain tension, bar rails, drive sprocket, and oil delivery.
- Chain sharpness and cutter condition; replace damaged parts.
- Helmet with face and eye protection, hearing protection, gloves, leg protection, and boots.
- Overhead hazards, footing, tree lean, wind, escape routes, and where people will stand.
For felling, keep people at least two tree lengths away and follow site rules. Plan the cut and escape route before starting. Felling requires training and a sound tree assessment; if the tree, lean, or surroundings make the fall uncertain, stop and use a qualified sawyer.
Rotational kickback is the sudden movement that can occur if the upper part of the bar nose hits wood or another object. Keep that area clear, maintain a two-handed grip, and do not rely on the chain brake to prevent kickback. Stop if you cannot see or control the nose.
Field cutting and practical setup cases
A field check looks at how the saw starts, idles, oils, and cuts with a correctly matched setup. It cannot prove that an unknown used saw is sound inside. Test only in a safe work area, with stable footing and suitable wood, and stop if the saw behaves unpredictably.
Start on firm ground with the chain brake engaged and the bar clear of people and objects. Follow the manual’s cold- or warm-start steps. At idle, the chain must remain still. Check that the stop switch works and that the chain receives oil before cutting.
Keep two hands on the saw and avoid cutting above shoulder height. Keep the bar nose away from the wood, and do not force the chain through a cut. Hardwood often cuts more slowly and loads the engine more than similar softwood; there is no single hardwood rating that applies to every species, log, and chain.
| Work scenario | Sensible starting point | What the field check should confirm |
|---|---|---|
| Firewood bucking in manageable logs | 16–18 in bar, if correctly matched | Stable idle, sharp chain, sound oiling, controlled cuts |
| Mixed ground-level cutting | 18 in bar, if the powerhead and setup are sound | No chain movement at idle; no bogging from a dull chain |
| Larger wood or longer reach | Consider 20 in only when the full setup supports it | More load and careful technique; stop if the bar pinches |
| Suspected poor cut | Check chain sharpness, tension, and bar condition first | Do not compensate by leaning on the saw or changing tune |
These are setup examples, not test results or a claim that every 039 will cut at the same rate. A dull or mismatched chain can make a healthy saw seem weak. A saw that bogs should be checked for chain condition, air supply, fuel, and service issues before anyone raises engine speed.
Two practical inspection cases
When I assess an older 039 for a buyer, I first compare the chain and bar markings with the sprocket setup. A chain that fits the bar but not the sprocket is not a usable match. I then check the brake, throttle interlock, stop switch, idle, and oiling before judging cutting behavior.
For a firewood setup, begin with a sound 16- or 18-inch bar and the correct chain. Make a controlled cut in suitable wood. If the saw cuts poorly, stop and inspect sharpness, tension, and oiling before concluding that the engine is weak. This avoids blaming the powerhead for a chain problem.
During felling, use a planned notch, back cut, and hinge only if trained and conditions allow. Do not use a generic hinge dimension as a substitute for judgment or model-specific instruction. If the bar is trapped, do not pull the saw free while it is running; secure the situation and use a safe method to release it.
Maintenance, chain sharpening, and carburetor tuning
Maintenance keeps the 039 predictable and helps reveal faults before they become failures. A depth gauge, sometimes called a raker, controls how much wood each cutter takes. Its height must follow the chain maker’s instructions; a common full-size-chain reference is 0.025 inch (0.65 mm), not a setting for every chain.
Sharpen cutters evenly and preserve their specified profile. Use the correct file size and guide for the chain. Set depth gauges with the proper tool, following the chain maker’s direction. If the cutters have uneven damage or the chain’s identity is unclear, identify it before filing or ask a qualified service shop.
A field maintenance sequence:
- Stop the engine and engage the brake before handling the chain.
- Check tension and inspect the cutters, drive links, bar groove, and rails.
- Clean the bar groove and oil ports; clear debris from the clutch-cover area.
- Clean the air filter as the manual directs.
- Confirm chain oil delivery before cutting.
- After work, inspect for loose, damaged, or unusually worn parts.
Fuel matters. Use fresh gasoline mixed 50:1 with quality two-cycle oil specified for air-cooled STIHL engines. That equals 20 mL of oil per 1 L of gasoline. Never use straight gasoline or an unknown mix. Too little lubrication can seize the piston and cylinder.
Carburetor tuning should follow the correct service data, not sound alone. Published references commonly list about 2,800 rpm at idle and 12,500 rpm maximum no-load speed, but verify the manual for the exact version. Use a tachometer where the manual calls for it. If the chain moves at idle, correct the fault before using the saw.
Storage, fuel handling, and buying a used 039
Used-saw checks help separate a worn but serviceable 039 from a risky purchase. A serial number can support identification, but it does not by itself prove age, country of manufacture, or authenticity. Confirm the saw’s identity and condition through its markings, parts, records, and a knowledgeable STIHL dealer.
Ask the seller for the model and serial information, service history, and any records for major repairs. Compare the identifying marks with STIHL documentation or ask a dealer to check them. Serial-number formats and locations can vary, so do not rely on a web chart that claims one simple decoding rule applies to every saw.
Look closely for inconsistent markings, damaged fasteners, mismatched parts, or a seller who will not allow a cold start and basic safety checks. None of those details alone proves a counterfeit. A used saw may have legitimate replacement parts, but an unexplained mix of parts deserves careful review.
For storage, follow the owner’s manual for the fuel system and storage period. Keep fuel in an approved container away from heat and ignition sources. Stop the engine and let hot parts cool before refueling or servicing. Clean the saw after use, protect the bar and chain, and repair safety faults before the next job.
The safest purchase is not always the cleanest-looking saw. I give more weight to a working chain brake, sound controls, correct bar-and-chain fit, reliable starting, and a clear service story than to cosmetic condition. If a seller will not permit a reasonable inspection, walk away.
Frequently asked questions
How much displacement does the STIHL 039 have?
It has a 64.1 cm³ two-cycle engine.
What fuel mix does an 039 use?
Use a 50:1 gasoline-to-two-cycle-oil mix with suitable air-cooled engine oil. That is 20 mL of oil per litre of gasoline.
What bar length works well on an 039?
A 16–20-inch bar is a practical general-purpose range, if the saw and cutting setup support it. A shorter bar is often easier to manage; longer bars add load.
What chain pitch does the 039 use?
Many setups use 3/8-inch chain, but verify the bar and drive sprocket. Pitch, gauge, and drive-link count must all match.
Can I use .050- or .063-inch gauge chain?
Both gauges occur in 039 configurations. Use only the gauge stamped on the bar and matched to the chain.
What should the chain do at idle?
It should remain still. If it moves, stop and correct the problem before cutting.
What is the 039’s maximum engine speed?
Published service references commonly give about 12,500 rpm maximum no-load speed. Check the exact manual and use a tachometer for tuning.
Does a serial number show the saw’s age and origin?
Not reliably by itself. Have STIHL documentation or a dealer help verify the model and serial details.
Can I use a longer bar to cut larger wood?
Only if the saw, bar, chain, wood, and operator can safely support it. A longer bar increases load and does not replace proper cutting technique.
What is the first check if the saw cuts slowly?
Check chain sharpness, tension, and bar condition first. Do not force a dull chain or tune the carburetor by ear.
The 039 remains a substantial 64.1 cm³ saw, but age and setup decide whether a particular example is ready for work. Confirm the bar and chain match, use fresh 50:1 fuel, test every safety control, and stop if anything behaves abnormally. For repairs or tuning, use the manual for the exact saw version or a qualified STIHL dealer.
(This article was written by one of our staff writers, Elliott Fowler. Visit our Meet the Team page.)
