Stihl MS 271 Frequent Problems (Causes & Fixes)
When an STIHL MS 271 will not start, runs poorly, cuts slowly, or fails to oil its chain, check the basics before buying parts. Use fresh 50:1 fuel, inspect the air filter and spark plug, and check chain condition and oil delivery. Work through spark, fuel, and compression in order; stop if a safety part is damaged.
The MS 271 is a 50.2 cc, two-stroke chainsaw. Its rated output is 2.6 kW; the listed idle speed is 2,800 rpm, and maximum engine speed is 13,000 rpm. Confirm limits and service steps in the manual for your saw. When I diagnose a no-start, I avoid replacing parts until a test points to the fault.
Set up the saw and troubleshoot safely
Start with the model’s manual and a safe work area. The MS 271’s bar, chain, and sprocket setup can vary, so check the identification label and approved combinations before service. Shut the engine off before inspecting or cleaning parts, keep the chain brake in working order, and wear proper chainsaw protective gear.
Before testing, put on eye and hearing protection, gloves, chainsaw leg protection, and protective footwear. Use a helmet where the work calls for one. Keep bystanders clear. Check the chain brake, throttle interlock, stop switch, chain catcher, handles, chain tension, and bar for damage. Do not use the saw if a safety part is broken or does not work.
Match the chain’s pitch and gauge to the bar and sprocket. Match its drive-link count to the bar. Do not assume every MS 271 takes the same chain. Use only a bar-and-chain combination listed for your saw, and set depth gauges using the instructions for that chain. A longer bar increases engine load, so do not oversize.
For a basic no-start check, park the saw on stable ground and use the cold- or warm-start steps in its manual. Engage the chain brake. If it still will not start after a few correct attempts, stop pulling and check for flooding rather than repeating the same start cycle. Shut the saw down before servicing it, and let hot parts cool.
Diagnose an MS 271 that will not start or stay running
A two-stroke engine needs fuel, spark, and compression to run. Check simple causes first, then test each system in order. A plug that is wet after repeated pulls can point to flooding, but it does not prove the carburetor is faulty. Look for evidence before changing parts or adjusting the carburetor.
Start with these checks:
- Fuel: Use fresh gasoline mixed 50:1 with quality air-cooled two-stroke oil. Do not use straight gasoline. If fuel has been stored for a long time, drain it and follow the manual’s fuel-system instructions.
- Controls: Check that the stop switch is in the run position and the starting controls are set as the manual directs.
- Air filter: Remove and inspect it as described in the manual. Clean or replace it if dirty or damaged.
- Spark plug: Check for damage, heavy deposits, or a wet tip. Clean or replace it only as the manual allows, and use the specified plug and gap.
- Fuel supply: A blocked filter or line can restrict fuel. If the line is cracked or fuel flow remains poor, have the system inspected.
A plug that looks wet may be the result of repeated starting attempts. Follow the manual’s flooded-engine procedure; do not keep choking the engine. For a spark check, use an in-line spark tester and follow its directions. Do not hold a plug lead near an exposed spark while fuel vapor may be present.
If fuel and spark checks do not explain the failure, compression may be low. A compression gauge can help, but do not rely on a universal pressure cutoff: gauge type, test method, and engine condition affect the reading. Persistent low compression, unusual mechanical noise, or a saw that starts only briefly needs further diagnosis. Carburetor faults may also require dealer service. Do not defeat limiter caps or guess at high-speed settings.
| Symptom | First checks | Next step |
|---|---|---|
| No start; plug wet | Flooding procedure, fresh fuel, air filter | Test spark safely; seek service if unresolved |
| No start; plug dry | Fuel level, fuel condition, filter and line | Have the fuel system checked if supply remains poor |
| Starts, then stalls | Fuel freshness, filter, vent or carburetor symptoms | Stop guessing at carburetor settings; get diagnosis |
| Runs but lacks power | Air filter, chain sharpness, fuel quality | Check compression if basic checks pass |
A clogged filter, stale fuel, and a worn part can cause similar symptoms. If your checks do not isolate the cause, stop replacing parts at random. A technician can test fuel delivery, ignition, and engine sealing more directly.
Fix poor cutting, bogging, chain trouble, and oiling faults
A saw that runs but cuts badly may have a sharpness or bar problem, not an engine problem. A dull chain makes the engine work harder and can bog the saw. Chain tension, depth gauges, the guide bar, and lubrication all affect safe cutting, so inspect them before blaming the carburetor.
If the saw bogs in wood, first inspect the chain. A sharp chain should cut without forcing the saw. Use the correct file and filing gauge for the installed chain, following the chain’s specified angles and depth-gauge setting. Do not file depth gauges to a general clearance; the correct setting depends on the chain. Replace a cracked, damaged, or badly worn chain.
With the engine off, check chain tension, drive links, sprocket, and bar rails. A chain that repeatedly loosens, binds, or derails needs more than a quick adjustment. Stop using the saw until you identify the cause. Inspect the bar groove and oil hole for packed debris, and clean them as the manual directs.
If the chain does not appear to receive oil, stop cutting. Check the oil reservoir and use purpose-made bar-and-chain oil, not used oil. Clean the bar oil hole and groove, and inspect the oil pickup area for contamination. Follow the manual’s method to verify delivery. If oil still does not reach the chain, the oil line or pump may need service. Never run the chain dry.
Poor cutting can also come from a bar-and-chain mismatch or a bar that is worn or damaged. Confirm pitch, gauge, and drive-link count against the bar and sprocket. Check that the fitted combination is approved for the MS 271. Do not force a dull chain through wood or use a chain with damaged cutters.
Common repair scenarios, upkeep, and storage
These examples show how to use the checks above without treating a guess as a diagnosis. They are illustrative troubleshooting scenarios, not reports of specific customer repairs. Note when the problem occurs, what you found, and whether the symptom changes after a basic correction. That record helps avoid repeated, unnecessary part changes.
- The saw will not start after sitting: Check fuel age and the manual’s storage instructions first. Drain or replace questionable fuel as directed, then inspect the filter and plug. If it still will not start, move on to safe spark and compression checks.
- The saw starts but cuts slowly: Inspect the chain and bar before tuning the engine. A dull chain, poor tension, or damaged bar can explain slow cutting. Sharpen to the chain specification or replace damaged parts.
- The chain is dry after cutting: Stop the saw. Check oil level and clear visible debris from the bar groove and oil hole. If correct oil still does not reach the chain, arrange service for the oil system.
For routine care, clean the air filter, cooling-air passages, starter area, and bar groove at the intervals in the manual. Inspect the sprocket, anti-vibration mounts, fasteners, chain brake, and chain catcher. Check fuel and bar oil before work, and confirm the chain is properly tensioned.
For extended storage, follow the STIHL manual’s fuel-system instructions. Stale fuel, including ethanol-containing fuel left too long, can contribute to hard starting and deposits. Store fuel in an approved container away from ignition sources. Before returning the saw to work, inspect the fuel lines, filter, plug, bar, chain, brake, and oil delivery.
Before cutting, assess footing, overhead hazards, tree condition, lean, and nearby targets. Keep the bar nose’s upper quadrant away from wood and obstructions; contact there can cause kickback. Hold the saw with both hands, keep cuts below shoulder height, and use a suitable cutting plan. Do not fell near power lines without qualified utility coordination. Follow applicable workplace rules and tree-work procedures.
Frequently asked questions
These quick answers cover common MS 271 symptoms, but the manual for your exact saw remains the authority for starting, service, and approved parts. If a fault involves the chain brake, oil system, fuel system, or engine internals, stop work when the basic checks do not resolve it.
Why won’t my STIHL MS 271 start?
Check fresh 50:1 fuel, starting controls, air filter, and spark plug. A flooded engine, blocked fuel filter, ignition fault, or low compression can also prevent starting.
What fuel mix does the MS 271 use?
Use a 50:1 gasoline-to-two-stroke-oil mix with quality oil made for air-cooled engines. Follow the manual for fuel requirements and storage.
Why does my MS 271 start and then stall?
Stale fuel, a dirty filter, restricted fuel flow, or a carburetor problem may cause stalling. Check basic service items first; avoid guessing at carburetor settings.
Why is the spark plug wet?
Repeated starting attempts can flood the engine. Follow the manual’s flooded-engine procedure, then check fuel quality and the starting steps.
Why does the saw bog down in a cut?
Check chain sharpness, tension, depth gauges, air filter, and fuel quality. A dull chain can load the engine heavily.
Why is the chain not getting oil?
Check oil level and type, then inspect the bar groove and oil hole for blockage. Stop cutting until oil delivery is restored.
Why does my chain keep loosening?
Check tension, drive links, sprocket, and bar condition with the saw off. Repeated loosening or derailment calls for inspection before further use.
Can I use any bar and chain on an MS 271?
No. Use a listed combination and match chain pitch, gauge, and drive-link count to the bar and sprocket.
What should I check before using the saw after storage?
Inspect fuel lines, filter, plug, bar, chain, chain brake, and oil delivery. Use fresh correctly mixed fuel and confirm lubrication before cutting.
(This article was written by one of our staff writers, Robert Callahan. Visit our Meet the Team page.)
