Stihl 034 AV Chain Replacement (Fitment Guide)
The STIHL 034 AV does not have one universal replacement chain. Match chain pitch to the bar and drive sprocket, gauge to the bar groove, and drive-link count to the bar. Read the bar stamp and count the old chain’s drive links; a common 20-inch setup may use 72 links, but verify it. Then install, tension, and lubricate the chain according to the saw’s manual.
A chain that burns wood or needs force is a poor choice for a quick cut, but replacing it by bar length alone can create a worse problem. The 034 AV is an older saw, and its current bar or sprocket may not be the original equipment. I treat the parts actually fitted to the saw as the starting point, then confirm each chain dimension before installation.
Equipment Setup, Chain Fitment & Safety Preparation
Chain fitment means matching three measurements to the parts on your saw: pitch, gauge, and drive-link count. A chain can appear to fit while still being wrong for the sprocket or bar groove. Check the bar stamp and old chain before buying or fitting a replacement; do not rely on bar length alone.
Identify the correct chain
Pitch is the size of the chain’s drive system. It must match both the drive sprocket and the bar tip sprocket. Gauge is the thickness of the chain’s drive links, which must fit the bar groove. Drive-link count is the number of links that sit inside that groove. All three must agree.
Start with the bar stamp, usually found near the bar’s mounting end. It may show bar length, pitch, and gauge. If the stamp is worn or incomplete, check the bar manufacturer’s markings or documentation. Count the old chain’s drive links by marking one link and counting around the chain. Do not guess from the bar’s stated length.
| What to match | Where to check | Why it matters |
|---|---|---|
| Pitch | Bar stamp and drive sprocket | Chain must engage both sprockets correctly |
| Gauge | Bar stamp or confirmed bar specification | Drive links must fit the bar groove |
| Drive-link count | Count the old chain or verify bar specification | Chain must fit the bar length and tension range |
| Cutter type and chain family | Chain packaging or manufacturer chart | Helps identify the correct sharpening method and file |
A common 034 AV setup is 3/8-inch pitch with .063-inch (1.6 mm) gauge. A 20-inch bar may use 72 drive links in that setup. These are examples, not universal specifications. Replacement bars, sprockets, and chain configurations vary, so confirm the actual parts on your saw.
Illustrative fitment checks
These examples show how I would resolve two common fitment questions. They are not claims about every 034 AV; the correct answer comes from the installed bar, sprocket, and chain.
- The bar says 20 inches, but the old chain is missing: The bar length alone does not identify the chain. Find the bar’s pitch and gauge markings, confirm the sprocket pitch, then use the bar maker’s fitment information to confirm drive-link count.
- The old chain’s links fit the bar, but the pitch marking differs from the sprocket: Do not install it. A chain must match the sprocket as well as the bar. Confirm the sprocket and bar specifications before choosing a chain.
Prepare the saw and work area
Wear a chainsaw helmet with face and eye protection, hearing protection, chainsaw-rated leg protection, gloves, and sturdy boots. Before work, inspect the chain brake, throttle lockout, chain catcher, bar, and chain. Clear bystanders and escape routes, and check footing, overhead hazards, and wood tension before cutting. Follow applicable ANSI Z133 requirements; OSHA 1910.266 applies where its logging-work scope covers the job.
With the engine off and cool, secure the saw so it cannot move. Follow the 034 AV manual for chain-brake position during cover removal. On some saws, removing the sprocket cover with the brake engaged can damage the brake mechanism; never force the cover. Keep the engine off while fitting or adjusting the chain.
Field Cutting Operation & Worksite Controls
A safe first start confirms that the replacement chain is seated, tensioned, and receiving oil before the saw meets wood. Use the starting and chain-brake procedures in the STIHL manual. Start in a clear area, check chain movement and lubrication as directed, and stop if the chain binds, runs dry, or behaves unexpectedly.
Fit and tension the replacement chain
- Confirm the replacement chain’s pitch, gauge, and drive-link count against the bar and sprocket.
- Remove the sprocket cover according to the saw’s manual. Lift the bar slightly and place the chain around the drive sprocket.
- Set the chain onto the bar, with the cutters on the top run pointing toward the bar nose. Seat every drive link in the bar groove and around the tip sprocket.
- Refit the cover without forcing it. Keep the bar nose raised while adjusting tension, if the manual calls for that method.
- Adjust the tension to the 034 AV manual’s instructions. The chain should be seated in the groove and should move by hand with suitable gloves, without sagging away from the bar. Do not use a generic tension measurement when the manual specifies a different check.
- Tighten the bar nuts to the model-specific manual instruction. There is no safe generic torque figure to substitute.
A chain that is too loose can come off the bar. One that is too tight can increase wear and strain parts. After initial running, stop the engine and recheck tension as the manual directs. A hot chain expands; if you adjust it while warm, account for its contraction as it cools so it does not end up overtight.
Check before making a cut
Check fuel and fill the oil tank with bar-and-chain oil. Start the saw only in a clear area and use the manual’s procedure. Verify lubrication using the method specified by STIHL, and confirm the chain brake works before cutting. If oil delivery is in doubt, stop and inspect the oil outlet, bar groove, and oiling system rather than continuing to cut.
Rotational kickback can occur when the upper quadrant of the bar nose contacts wood or another object. The saw can be thrown toward the operator. Keep the nose clear, hold the saw with both hands, and do not cut with the nose quadrant. Never cut above shoulder height, and do not force a dull chain through wood.
Chain Sharpening, Bar Care & Saw Tuning
Sharpening and adjustment depend on the exact chain fitted, not just the saw model. Cutter angles, file diameter, and depth-gauge settings vary by chain type. Read the chain markings and use the chain maker’s sharpening chart and tools; do not apply a familiar file size or angle unless it matches that chain.
Use the chain’s own sharpening specification
Look for identification on the chain or its packaging, then check the chain maker’s chart for file diameter and filing angles. If markings are hard to read, match the chain to a reliable parts listing or ask a qualified dealer to identify it. A wrong file can alter the cutter shape and cutting performance, even when the chain appears sharp.
Depth gauges, sometimes called rakers, control how much wood each cutter takes. Set them to the chain maker’s specification with the specified gauge tool. A setting of 0.025 inch (0.65 mm) is common, but it is not universal. Do not lower every depth gauge by guesswork or file it to match a different chain.
| Service item | Correct check | Avoid |
|---|---|---|
| File diameter and cutter angle | Chain maker’s specification | Assuming every 3/8-inch chain takes the same file |
| Depth gauge | Chain maker’s value and gauge tool | Lowering rakers indiscriminately |
| Bar groove and oil outlet | Clean and unobstructed | Running with packed debris or poor oil flow |
| Sprocket | Check for wear and chain fit | Pairing a new chain with a damaged sprocket |
Use bar-and-chain oil, not fuel or engine oil in the oil tank. No single oil viscosity or oil-flow rate applies to every oil and temperature. If lubrication is poor, stop and inspect the outlet, bar, and oiling system. Set idle and maximum engine speed only to the 034 AV service-manual values; do not tune by sound or use a generic RPM figure.
Shutdown, Storage & Seasonal Fuel Care
After cutting, switch off the saw and let it cool before cleaning or inspection. Remove debris from the sprocket cover, bar groove, oil outlet, and air intake. Check chain tension, cutter condition, depth gauges, bar-rail wear, and sprocket wear; repair or replace damaged parts before the next job.
The 034 AV’s engine displacement is 56.5 cm³. Use a 50:1 fuel mix with suitable two-cycle engine oil: 100 mL of oil per 5 L of gasoline. Use fresh fuel and follow the applicable STIHL manual, especially if it specifies a particular oil or fuel procedure. Never run straight gasoline.
Before storing the saw, clean it and inspect the chain and bar. If the chain was adjusted warm, check its tension again after it cools. Keep the chain protected from damage, and follow the manual’s instructions for fuel storage and return to service.
Conclusion
The reliable replacement-chain choice comes from the installed parts, not the 034 AV name or bar length by itself. Confirm pitch, gauge, and drive-link count; install the cutters in the correct direction; then tension and lubricate the chain by the saw’s manual. If any marking conflicts or remains unclear, pause and verify before starting.
Frequently asked questions
What chain size does a STIHL 034 AV use?
There is no single size for every saw. Match pitch to the bar and sprocket, gauge to the bar groove, and drive-link count to the bar.
Can I order a chain using only the bar length?
No. Bar length does not confirm pitch, gauge, or drive-link count. Check the bar stamp and count the old chain’s drive links.
Does a 20-inch bar always take 72 drive links?
No. A 20-inch bar may use 72 links in a common 3/8-inch, .063-inch setup, but verify the specific bar and chain.
Is 3/8-inch pitch and .063-inch gauge common on the 034 AV?
Yes, it is a commonly encountered setup, but it is not universal. Check the parts fitted to your saw.
Which way should the cutters face?
On the top run of the bar, the cutters point toward the bar nose. Check every link before tightening the bar nuts.
What file size should I use?
Use the file diameter and angles specified for the exact chain. The saw model or pitch alone does not identify the correct file.
Is a 0.025-inch depth-gauge setting right for every chain?
No. It is common, but follow the chain maker’s specification and use the specified depth-gauge tool.
What fuel mix does the 034 AV use?
Use a 50:1 mix with suitable two-cycle oil: 100 mL oil per 5 L gasoline. Follow the applicable STIHL manual and use fresh fuel.
Can I keep cutting if the chain is not oiling properly?
No. Stop the saw and check the oil outlet, bar groove, and lubrication system before cutting again.
Why should I avoid contact with the bar nose?
Contact with the upper nose quadrant can cause rotational kickback, throwing the saw toward the operator. Keep it clear and use a firm two-handed grip.
(This article was written by one of our staff writers, David Hensley. Visit our Meet the Team page.)
