Stihl 051 Chainsaw Chains (Fitment Specs)
The STIHL 051 is an approximately 89 cm³ saw, but its name alone does not identify the right chain. Match chain pitch to the installed sprocket, gauge to the guide-bar groove, and drive-link count to the exact bar. .404-inch pitch and .063-inch gauge are common, not guaranteed. Check the saw, bar, and chain markings before ordering or fitting parts.
Will a chain that looks close enough run safely, or will it bind, track poorly, or come off? The dependable answer comes from checking three measurements on your saw and bar, not guessing from the model name. Below, I’ll show you how to identify them, confirm fit, and check the setup before cutting.
STIHL 051 Chain, Bar, and Safety Setup
A chain fits only when its pitch, gauge, and drive-link count match the saw’s drive sprocket and the installed bar. The 051 is an air-cooled, two-stroke saw of about 89 cm³. That engine size does not set the bar length or chain size; parts on the saw do.
| Fitment detail | What to match | What to know |
|---|---|---|
| Chain pitch | Chain to drive sprocket | .404 inch is common on 051 setups, but confirm the sprocket and chain markings. |
| Chain gauge | Chain to bar groove | .063 inch (1.6 mm) is common on 051 bars, but read the bar stamp. |
| Drive links | Chain to the exact bar | There is no one count for every 051. Count the old chain or check the bar maker’s chart. |
| Bar length | Bar approved for the saw | Use the bar maker’s fitment information and consider saw condition, lubrication, and your skill. |
How to identify the three fitment measurements
Pitch is the spacing of the chain’s rivets, stated as a fraction of an inch. It must match the sprocket. Do not put a 3/8-inch chain on a .404-inch sprocket, even if the chain seems to sit near the teeth.
Gauge is the thickness of the chain’s drive links, which run inside the bar groove. A chain that is too thick will not fit the groove. One that is too thin may not track as intended. Read the bar stamp, often found near the mounting end, and match the gauge exactly.
Drive links are the teeth that extend into the bar groove and engage the sprocket. Count every drive link on the old chain, including the links around the full loop. If that chain is missing, use the bar manufacturer’s fitment chart for the exact bar model and length. Do not rely on a seller’s “fits 051” label alone.
Check the saw and bar before ordering
First confirm the model identification on the powerhead. An 051, 051 AV, and another STIHL model may have different manuals or parts. Use the manual for the saw you actually own rather than transferring specifications from a similar model.
Next, inspect the sprocket and bar. Look for clear pitch and gauge markings. If a marking is worn away, have a qualified dealer identify the part before ordering. Also check that the sprocket teeth are not badly worn and that the bar rails and nose are in usable condition. A new chain will not correct a damaged sprocket or bar.
Workshop-style fitment examples
These examples show how I approach common fitment puzzles; they are not claims about one standard 051 configuration.
- The bar says .063, but the old chain is unreadable: I use the bar stamp to identify gauge, then confirm pitch at the sprocket and get the drive-link count from the bar maker’s chart. Gauge alone is not enough to choose a chain.
- A seller lists a 3/8-inch chain for an 051: I do not buy it based on the model name. I check the sprocket first. If the installed sprocket is marked .404, I need a chain that matches that pitch.
- The replacement chain is the right pitch and gauge but too long: I check the drive-link count against the bar chart. I do not force the chain onto the bar or assume the tensioner will take up any length.
These checks save time and help prevent a mismatch that can cause poor tracking, derailment, or damage.
Field Cutting: Wood Support, Cut Planning, and Controlled Operation
A correctly matched chain is only one part of a safe cutting setup. Before starting, inspect the chain, bar, sprocket, chain catcher, throttle lockout, brake, and oiling system. Wear chainsaw protective equipment and set a clear work zone, escape route, and way to communicate with anyone nearby.
Fit and tension the chain
With the engine off and cool, follow the 051 manual’s bar and chain installation steps. Check that the cutters face the correct direction: on the top run, their cutting edges point toward the bar nose. Set tension as the manual directs. The chain should sit in the groove and move by hand while you wear gloves, without hanging loose from the bar.
Do not start the saw if the chain, brake, or other safety parts are damaged or missing. Start only as the manual directs, on stable ground, with the brake engaged when specified. At idle, the chain must not move. If it moves, stop and have the idle setting checked against the manual.
Verify oiling before cutting
Use proper bar-and-chain oil. Check the oil level and confirm delivery using the procedure in the saw manual. Oil flow can be adjustable and depends on the model; there is no universal fixed flow rate for every 051. If oil delivery is poor, stop and check the oil passages and bar ports rather than continuing to cut dry.
Plan each cut around how the wood is supported and where it is under compression or tension. Keep the guide-bar nose clear of the wood. Contact at the upper quadrant of the nose can cause rapid rotational kickback toward you. Hold the saw with both hands, use a functioning chain brake, and never cut above shoulder height.
A longer bar is not automatically a better choice. Use only a bar approved for the saw, and consider the powerhead’s condition, oil delivery, the work, and your ability to control the saw. Felling or work aloft calls for suitable training, planning, and qualified help; do not improvise a felling plan.
Chain Sharpening, Depth-Gauge Checks, and Saw Maintenance
A sharp chain cuts without needing you to force it. The correct file size and sharpening angles depend on the chain’s exact design, not only on the saw model or the .404-inch pitch. Check the chain markings or the chain maker’s chart before filing; do not guess at a file size or angle.
Find the file size and angles
Look for a chain identification code stamped on the cutter or packaging. Use that code to find the maker’s filing instructions, including file diameter, top-plate angle, and any specified side-plate angle. If the code is missing, identify the chain through a dealer or its maker before sharpening. Two chains that fit the same bar can have different sharpening requirements.
Keep cutters even in length and file each one to the specified angles. A file guide can help hold the correct position. Avoid changing the cutter shape to make a dull chain “cut faster.” If cutters are badly damaged or uneven, have the chain assessed or replaced.
Depth gauges control how much wood each cutter can take. Check and set them to the chain maker’s specification, using the correct gauge tool. Clearance varies by chain design and pitch, so a single universal depth-gauge number is not reliable. Cutting that feels slow can also point to a dull cutter, poor oiling, or a fitment problem, not just depth-gauge height.
Match chain type to the work
Chain type affects cutting behavior, but it does not make a saw safe to force through wood. Choose a chain approved for the bar and saw, and follow the chain maker’s instructions. A chain marketed for hardwood is not permission to lean on the saw. If a sharp, correctly fitted chain is not cutting well, stop and check the setup and wood before continuing.
Fuel, Operating Settings, and Shutdown
The 051 is a two-stroke saw, but the model name alone is not enough to choose a fuel ratio or engine speed. Use the exact manual for your model and the oil maker’s instructions. Do not use straight gasoline, copy a generic modern-saw setting, or tune the saw by ear.
Use the correct fuel and settings
Confirm the required fuel mix in the applicable STIHL manual and use two-stroke oil suitable for that instruction. If the manual is missing or unclear, ask a STIHL dealer to verify the requirement for your saw. For idle and maximum speed, follow the manual and use a tachometer; do not guess at a setting from another model.
Before service or adjustment, shut the saw down. Let it cool, then check chain tension, damage, and fuel or oil leaks. Clean the bar groove and oil ports as directed by the bar maker. Maintain the chain, bar, and sprocket according to their manufacturers’ instructions. For work covered by logging rules, OSHA 29 CFR 1910.266 applies; use ANSI Z133 work practices where relevant.
Frequently Asked Questions
What chain pitch is common on a STIHL 051?
.404-inch pitch is common, but it is not universal. Check the installed sprocket and match the chain pitch to it.
Is .063-inch gauge correct for every 051 bar?
No. Many 051 bars use .063-inch (1.6 mm) gauge, but the bar stamp or maker’s fitment chart is the authority for your bar.
How many drive links does an 051 chain need?
There is no single count for every 051. Count the old chain’s drive links or use the fitment chart for the exact bar.
Can I use a 3/8-inch chain on an 051?
Only if the installed sprocket and bar are made for that chain pitch. Do not use a 3/8-inch chain with a .404-inch sprocket.
Does the 051 model number tell me which bar length to buy?
No. Use a bar approved for the saw and suitable for the work. Confirm fitment with the bar maker or a STIHL dealer.
What file size and angle should I use?
Check the chain’s identification code and the chain maker’s sharpening chart. File size and angles can differ between chain designs, even when the chains fit the same saw.
What fuel ratio does the 051 need?
Use the ratio in the manual for your exact model and the instructions for the two-stroke oil you use. Do not assume a ratio from another saw.
Why does my chain move at idle?
Stop using the saw and check the idle setting against the manual. The chain must not move at idle. Have the saw serviced if the issue persists.
How can I confirm that the chain is getting oil?
Follow the oil-delivery check in the saw manual. Check the oil level, bar ports, and oil passages if delivery seems poor. Stop cutting until the oiling issue is resolved.
What should I check if a new chain does not fit?
Recheck pitch, gauge, and drive-link count against the sprocket, bar stamp, and bar maker’s chart. Do not force the chain onto the bar.
(This article was written by one of our staff writers, David Hensley. Visit our Meet the Team page.)
