Stihl MS 251 Chainsaw Chain Options (Top Picks)

For a common STIHL MS 251 setup, start with a .325-inch-pitch, .063-inch-gauge chain, then match the drive-link count stamped on your bar. STIHL 26RM3 is the practical general-purpose pick; 26RS suits clean wood and experienced users. Common counts are 62 links for a 16-inch bar and 68 for an 18-inch bar, but verify before buying.

A fresh, correctly matched chain helps the MS 251 cut cleanly instead of rubbing and burning wood. Choosing the right chain also helps you keep using the bar and saw you already own, rather than replacing parts that are still serviceable. The key is to check the markings, not guess from bar length.

Choosing a Chain for the STIHL MS 251

A replacement chain must match three details on the installed bar: pitch, gauge and drive-link count. Pitch describes the spacing between chain rivets; gauge is the thickness of the drive links that sit in the bar groove; drive-link count is the number of links that travel around the bar.

STIHL lists the MS 251 with bar lengths that include 16 and 18 inches, though equipment can vary by market and model setup. The saw has a displacement of 45.6 cm³. Those details do not, by themselves, identify the correct chain. Read the bar stamp or check the exact bar part number and the saw’s manual.

STIHL 26RM3: general-purpose choice

A semi-chisel cutter has a more rounded cutting corner than a full-chisel cutter. In my shop, I usually point weekend users toward the 26RM3 when the chain markings fit their bar. Its cutter style tends to handle variable field conditions better than full-chisel chain, and this model is a reduced-kickback option.

“Reduced-kickback” does not mean kickback-proof. Keep the bar nose clear of unintended contact and use the saw’s required protective equipment and operating procedures.

STIHL 26RS: for clean wood

Full-chisel cutters have a sharper, square-cornered profile. The 26RS can be a suitable faster-cutting choice for clean wood and an experienced operator, provided pitch, gauge and link count match. Dirt, grit or contact with the ground can dull its cutters more readily than a semi-chisel chain.

Choose this chain for the conditions you expect, not just for speed. If your wood may be dirty, or you want a chain that is less sensitive to variable conditions, the 26RM3 is often the more practical pick.

Verify fit before purchase

Common MS 251 combinations are .325-inch pitch and .063-inch gauge, with 62 drive links on many 16-inch setups and 68 on many 18-inch setups. Treat those counts as a starting point, not a guarantee. Different bars or replacement parts can change the required count.

Check the bar’s stamped pitch and gauge, then confirm the drive-link count on the chain or in the bar maker’s fit information. Do not substitute .325-inch/.050-inch chain or 3/8-inch low-profile chain unless the bar and sprocket are specifically configured for that system. A chain that seems close is still the wrong chain if one of its dimensions does not match.

Bar, Chain Selection & Safety Preparation

Before fitting a chain, confirm it belongs on the bar and inspect the saw’s safety parts. This short check prevents a mismatch from turning into a poor cut or unsafe start. It also gives you a chance to find a damaged bar, loose fastener or chain that needs service.

Start with the chain brake engaged and the engine off. Wear a helmet with face and eye protection, hearing protection, chainsaw chaps, gloves and protective boots. Check the brake, throttle lockout, chain catcher, fasteners, bar and chain for damage. Set chain tension according to the STIHL manual; the chain should be correctly seated in the bar groove and must not sag below it.

When installing, orient the cutters so their top edges face forward along the top of the bar. Fill the fuel tank and chain-oil tank separately. Use the manual’s cold- or warm-start procedure on stable ground, with the brake engaged. Before cutting, verify that the chain receives oil and that the brake functions as intended. Do not use the saw if a safety part is damaged or does not work.

Plan the work area before starting. Clear your footing and escape route, keep bystanders away, and assess lean, wind, hung limbs and overhead hazards. Upper-quadrant contact at the bar nose can cause rotational kickback, which can lift the bar rapidly toward you. Keep the nose out of unintended contact, do not cut above shoulder height, and never treat the chain brake as a substitute for control.

Field Cutting & Landscaping Operation

A correctly selected chain still needs sound cutting practice. The aim is to let sharp cutters do the work without forcing the saw, while keeping the bar stable and its nose away from contact that could trigger kickback.

Use a two-handed grip and stable footing. Keep the chain sharp and properly tensioned, and do not push a dull chain through wood. Avoid binding the bar in the cut. If a limb is overhead, wood is under tension, or felling conditions are complex, stop and use a qualified arborist. These situations can shift or release wood in ways that are hard to predict.

Example: choosing for mixed firewood

Consider a weekend operator cutting clean rounds alongside logs that have dirt on the bark. If both chains fit the bar, the 26RM3 is generally the more forgiving option for that mix. The 26RS may suit the clean rounds, but its cutters can lose sharpness sooner if they meet dirt or the ground.

This is a selection example, not a claim that either chain will remain sharp in every condition. The best choice depends on the wood and the operator’s ability to keep the chain clean and maintained.

Chain Sharpening, Tensioning & Saw Maintenance

Sharpening restores the cutting edges; tensioning keeps the chain seated and moving as intended. Use the chain maker’s specified file, filing angle and depth-gauge setting for the exact chain. Do not assume one setting fits every chain, even when two chains share the same pitch.

I check the chain markings or the maker’s sharpening instructions before filing. A file that is too large or small, or an incorrect angle, can change the cutter shape. Use a guide suited to the chain, file each cutter consistently, and keep the left and right cutters even. Set depth gauges only with the specified tool and setting; guessing can affect cutting performance and control.

Check tension with the engine off and follow the MS 251 manual for adjustment. A chain that is too loose can come off the bar; one that is too tight adds strain and can wear parts. Recheck after the chain has run and again after it cools, since tension can change with use and temperature. Do not tune engine speed by ear or alter limiter settings. Use the model-specific manual for idle and maximum speed limits, and for oil-system checks.

Shutdown, Cleaning & Seasonal Storage

Care after cutting helps you spot wear before the next job. A short shutdown routine also keeps chips and debris from hiding problems around the bar, chain and oiling parts.

Engage the brake, switch off the saw and allow it to cool before cleaning or service. Remove chips and inspect the chain and bar. Check for damage, unusual wear and a blocked oil path, following the manual’s cleaning guidance. Recheck chain tension after cooling, then sharpen the chain or set its depth gauges only to the chain maker’s instructions.

For storage, follow the STIHL manual for the saw and fuel system. Do not leave stale or incorrectly mixed fuel in the saw. Use fresh fuel mixed at 50:1 gasoline to STIHL two-stroke oil, and keep the fuel and bar oil in their separate tanks. The manual gives the model-specific steps for storage and return to service.

Quick Fit and Use Checklist

Frequently Asked Questions

Which chain is best for a STIHL MS 251?
The 26RM3 is a practical general-purpose choice when its pitch, gauge and drive-link count match your bar. The 26RS is an option for clean wood and experienced users.

Does every MS 251 use the same chain?
No. Bar and equipment configurations can vary. Match the replacement chain to the installed bar’s pitch, gauge and drive-link count.

What chain size does a 16-inch MS 251 bar use?
Many common setups use .325-inch pitch, .063-inch gauge and 62 drive links. Check the bar markings and part number before buying.

What chain size does an 18-inch MS 251 bar use?
A common setup is .325-inch pitch, .063-inch gauge and 68 drive links. Verify the actual bar because length alone does not prove fit.

Can I use a .325-inch/.050-inch chain instead?
Not unless the bar and sprocket are configured for that chain gauge. The chain must match the bar groove and the saw’s chain system.

Can I use 3/8-inch low-profile chain on an MS 251?
Only if the bar and sprocket are specifically set up for it. Do not substitute it based on appearance or bar length.

Is the 26RS faster than the 26RM3?
The 26RS is a full-chisel option suited to clean wood and may cut faster in the right conditions. Its cutters can dull sooner in dirty wood.

What fuel mix does the MS 251 need?
Use fresh fuel at a 50:1 gasoline-to-STIHL two-stroke-oil ratio. Keep fuel and bar oil in separate tanks.

What file size and angle should I use?
Use the file size and filing angle specified for the exact chain. Check its markings or the chain maker’s instructions rather than relying on a setting for another chain.

How do I know whether the chain is getting oil?
Follow the MS 251 manual’s oil-system check before cutting. If the chain is not receiving oil, stop and diagnose the system rather than continuing to run it.

Can I sharpen a chain while it is on the saw?
Yes, if the saw is switched off and secured, the chain brake is managed as the manual directs, and you use the correct guide and file. Keep hands clear of sharp cutters.

When should I replace the chain instead of sharpening it?
Replace it if it is damaged or worn beyond the limits in the chain maker’s instructions. If you cannot confirm its condition, have a qualified dealer inspect it.

(This article was written by one of our staff writers, David Hensley. Visit our Meet the Team page.)