Stihl MS 171 Bar & Chain Upgrade (Top Options)
For an MS 171, a compatible 12- or 14-inch bar and chain is usually the practical upgrade for routine property work. A 16-inch setup is the upper listed option on some versions, not a power upgrade. Match the saw’s approved bar mount, 3/8-inch Picco pitch, .043-inch gauge, and required drive-link count, then confirm fit by serial number before buying.
If you are weighing cost, start with the chain and bar already on the saw. A new, correctly sharpened chain may solve slow cutting without replacing a serviceable bar. If the bar rails are worn, the nose sprocket is damaged, or you want a different length, compare a complete bar-and-chain set with separate parts. The least expensive set is not a bargain if its pitch, gauge, mount, or link count is wrong.
Choose a Compatible Bar-and-Chain Upgrade and Prepare the Work Area
A bar-and-chain upgrade means replacing the guide bar, the chain that runs in its groove, or both. On the MS 171, choose by the saw’s exact parts listing, not by bar length alone. Check the saw’s serial number and existing component markings before ordering; model versions and markets can differ.
Which bar length makes sense?
Bar length is the usable cutting length along the guide bar. STIHL lists MS 171 bar options in the 12–16-inch range for some versions, but the approved choices depend on the saw’s specific parts information. A longer bar adds reach, not engine power, and can make the saw less suited to demanding cuts.
For routine pruning and small-diameter wood, 12 or 14 inches is generally the sensible place to compare options. Consider 16 inches only when you need the reach and STIHL’s listing approves that exact setup. Sustained hardwood cutting can place greater demands on this 31.8 cc homeowner saw, so do not treat a longer bar as a way to increase capacity.
| Setup to consider | Best fit | Check before buying |
|---|---|---|
| 12-inch bar and chain | Light work and small cuts where this length is approved | Mount, pitch, gauge, and listed link count |
| 14-inch bar and chain | A practical general-purpose choice for approved MS 171 versions | Exact chain specification and serial-number fit |
| 16-inch bar and chain | Work that needs added reach, where the saw’s listing allows it | Approved application and exact matching components |
Match every fitment detail
Pitch is the spacing between the chain’s drive links, gauge is the thickness of the drive link that sits in the bar groove, and drive-link count is the number of links that travel around the bar. The MS 171 commonly uses 3/8-inch Picco pitch and .043-inch (1.1 mm) gauge. Verify those details on your own parts.
Check the bar stamp, chain markings, drive-link count, sprocket, and bar mount. The same bar length can require a different chain count depending on the bar and chain configuration. A chain that matches the length but not the pitch or gauge is not a compatible upgrade. Do not force it onto the bar or sprocket.
Before purchase, use STIHL’s serial-number-specific parts information or ask a STIHL dealer to confirm the complete assembly. Have the saw’s serial number and current bar markings ready. I would not order from a listing that gives only the bar length and leaves the other fitment details unclear.
Inspect before installation
A new chain will not fix a damaged bar, worn sprocket, or safety fault. With the engine stopped and cool, check the bar rails, nose sprocket, chain, chain catcher, brake, throttle lockout, and guards. If parts are damaged or the chain does not sit correctly, stop and resolve that issue before cutting.
Set up a clear work area with a stable place to work and an escape path for the cutting task. Wear a helmet with face and eye protection, hearing protection, chainsaw-rated leg protection, gloves, and suitable boots. Follow the saw manual and any applicable workplace rules, including ANSI Z133 requirements where they apply.
Install and Test the Replacement Bar and Chain
Installation means fitting the approved bar and chain, setting tension, and checking lubrication and safety controls before cutting. Work with the engine off and cool, and follow the manual for your MS 171 version. Do not substitute a generic tightening value or procedure for STIHL’s instructions.
Step-by-step fit and tension check
- Stop the engine, let the saw cool, and engage the chain brake. Use the manual’s procedure to access the bar and sprocket cover.
- Confirm the replacement parts match the saw’s approved mount, pitch, gauge, and drive-link count. Fit the chain in the direction shown in the manual or on the saw’s markings.
- Seat the bar and chain correctly, then adjust tension using the saw’s specified procedure. Tighten the fasteners as directed in the manual.
- With the engine still off, release the brake only as needed for the check. Wearing gloves, confirm the chain moves by hand and that its drive links stay engaged in the bar groove. The chain should contact the underside of the bar without hanging loose.
- Recheck fasteners and tension using the manual’s steps. A newly fitted chain can need a tension check after its first period of use; stop the saw and follow the manual’s retension procedure.
A chain that is too loose can come off the bar; one that is too tight can add strain and wear. Do not guess at tension by pulling hard on the chain. Use the manual’s check, and never adjust a running chain.
Fill separate tanks and confirm oil delivery
The MS 171 is a two-stroke saw. Use fresh gasoline mixed 50:1 with suitable STIHL two-stroke oil, or the fuel specified in the manual for your version. The fuel and bar-and-chain oil go in separate tanks. Do not put straight gasoline in the fuel tank, and do not use fuel mix in place of chain oil.
Fill the bar-oil tank with STIHL bar-and-chain oil or the oil specified by the manual. Before cutting, check that the saw is delivering oil to the chain according to the manual’s test. Never run the chain dry. If oil delivery is absent or uncertain, stop and inspect the oil supply and passages rather than continuing to cut.
Start the saw using its cold- or warm-start instructions, on stable ground, with the brake engaged until you are ready to cut. Check brake function and controls before work. The manual’s common specifications are about 2,800 rpm at idle and 10,000 rpm maximum engine speed, but confirm the figures for your version. Do not tune maximum speed by ear; that requires qualified service equipment.
Three common upgrade cases
These are fitment-planning examples, not claims about a particular serial-numbered saw. In each case, the exact parts still need approval in STIHL’s listing.
- The chain is dull, but the bar is sound: Keep the bar if its rails and nose are serviceable. Buy a matching replacement chain by pitch, gauge, and drive-link count, or sharpen the existing chain if it is in good condition.
- The bar is worn, and the current length works: Compare a complete same-length bar-and-chain set with separate replacements. Confirm the mount and chain count; changing the bar can change the required chain.
- You want more reach: Check whether a 16-inch assembly is listed for your saw’s serial number. If it is approved, choose the exact matching chain and recognize that extra reach does not add power or make the saw suitable for heavier work.
Operate the MS 171 Safely for Property-Maintenance Cutting
Safe operation means keeping control of the saw, using an appropriate cutting position, and stopping when the work can pinch the bar or exceed the saw’s capacity. A new bar does not change kickback risk or make an unsafe cut safe. Follow the operator’s manual and use qualified help for hazardous tree work.
Keep a firm two-handed grip and a stable stance. Where practical, cut with the lower portion of the bar and keep the bar nose clear of wood and other objects. Rotational kickback can occur if the upper quadrant near the bar nose contacts wood; a sudden pinch can also drive the saw. Do not cut above shoulder height.
Keep the chain clear of soil and debris. Dirt can quickly damage cutting parts and dull the chain. If the workpiece may shift or close on the bar, stop and reassess the cut. Do not force a dull chain through wood; stop, inspect, and sharpen or replace it as needed.
Maintain the Bar, Chain, Lubrication, and Sharpening
Maintenance keeps the approved setup working as intended. Check chain tension, oil delivery, and bar condition during use according to the manual. Sharpening angle and depth-gauge settings depend on the exact chain, so identify its markings and use that chain maker’s instructions and the matching gauge tool.
After cutting, stop the engine, engage the brake, and allow the saw to cool before inspection. Check the chain and bar for damage, clean the bar groove and oil passages as directed, and clear debris from the sprocket cover and air intake. Turn the bar periodically if the manual recommends it for that bar.
Use a file size and filing angle only when they match the chain’s markings or manufacturer instructions. Do not apply a generic depth-gauge clearance to an unidentified chain. If cutters are damaged, uneven, or beyond the chain maker’s limits, have the chain assessed or replace it with the exact approved specification.
Store and Prepare the Saw for Seasonal Use
Seasonal storage means protecting the chain and saw while following the fuel instructions in the manual. Clean the bar, chain, and cover before storage, and fit a chain guard. Handle or drain fuel only as the manual directs; storage steps can depend on the fuel used and expected storage period.
Before the next outing, confirm the chain is the correct one for the bar, tension it by the manual, and check oil delivery. Inspect the bar, chain, brake, catcher, and controls. If the saw has been stored with fuel, follow the manual before starting it. Do not head out until the chain lubricates and the safety controls work.
Frequently Asked Questions
What bar lengths fit a STIHL MS 171?
Some MS 171 versions list 12- to 16-inch bars. Confirm the approved length for your saw’s serial number before buying, since market and version differences can affect fitment.
What chain pitch does an MS 171 commonly use?
Common configurations use 3/8-inch Picco pitch. Check the chain and bar markings and your saw-specific parts listing before ordering a replacement.
What chain gauge does it commonly use?
Common configurations use .043-inch (1.1 mm) gauge. Match the gauge to the bar groove; do not assume another gauge will fit.
Can I install a 16-inch bar?
Only if STIHL’s parts information approves that bar-and-chain setup for your exact saw. A longer bar adds reach, not engine power.
How do I know the correct chain drive-link count?
Read the existing chain marking or count its drive links, then confirm the count against the approved bar and chain listing. Bar length alone is not enough.
Is a new chain enough if the old bar is worn?
Not necessarily. Inspect the bar rails and nose sprocket. If they are worn or damaged, replacing or servicing the bar may be needed as well.
What fuel mix does the MS 171 use?
Use fresh gasoline mixed 50:1 with suitable STIHL two-stroke oil, or follow the fuel specification in the manual for your saw.
Can I run the saw without bar oil to test it?
No. Fill the separate bar-oil tank and confirm chain lubrication using the manual’s procedure. Running without adequate lubrication can damage the cutting system.
What should chain tension feel like?
Use the manual’s check. With the engine stopped, the chain should contact the bar underside, move by hand with gloves, and keep its drive links engaged in the groove.
Can a longer bar reduce kickback risk?
No. Bar length does not remove kickback risk. Keep the nose clear, use a two-handed grip, and avoid cuts above shoulder height.
(This article was written by one of our staff writers, David Hensley. Visit our Meet the Team page.)
