Stihl MS 250 Maintenance Schedule (Service Guide)
For an MS 250, check the chain, brake, controls, fuel, and bar oil before every use. Mix fresh gasoline and quality air-cooled two-stroke oil at 50:1. Match the chain to the bar’s pitch, gauge, and drive-link count. Clean and inspect after cutting, sharpen to the chain maker’s specifications, and use the operator’s manual for service intervals and adjustments.
A dull chain wastes time, burns wood, and makes the saw work harder. The fastest fix is not filing by guesswork: first identify the chain, then use its specified file and angles. Correct fuel and bar oil matter just as much. Keeping the chain sharp and the saw clean also avoids unnecessary wear and wasted fuel.
I use a short, repeatable check before cutting, then clean and inspect the parts that collect chips and oil after work. That approach suits a quick garage service without replacing the intervals or instructions in the MS 250’s operator’s manual. For a lower-waste routine, maintain the chain and bar rather than discarding them early, but replace damaged parts before use.
Equipment Setup and Safety Preparation
This first check confirms that the saw, cutting attachment, fuel, and safety gear are ready before the engine starts. Use the MS 250 operator’s manual for model-specific controls and starting steps. For the chain, the bar’s markings and the chain’s markings are more reliable than assumptions based on bar length alone.
Before each use, put on a helmet, eye and hearing protection, chainsaw chaps, gloves, and protective boots. Inspect the chain brake, throttle lockout, stop switch, chain catcher, fasteners, and visible fuel or oil leaks. Check that the chain is correctly tensioned and the bar is in good condition. Set a clear work zone and retreat path; assess footing, overhead hazards, the tree or limb’s lean, and bystanders.
Check the cutting attachment, fuel, and oil
The cutting attachment is the guide bar and chain fitted to the saw. These parts must match one another and be approved for the MS 250. Pitch is the chain’s size class, gauge is the drive-link thickness, and drive-link count is the number of links that run in the bar groove.
| Item | Check before use |
|---|---|
| Fuel | Fresh gasoline and air-cooled two-stroke engine oil mixed at 50:1, or 2% oil |
| Chain fit | Match pitch, gauge, and drive-link count to the bar and saw |
| Common MS 250 chain | Many setups use 3/8-inch Picco; gauge may be .050 inch (1.3 mm) or .043 inch (1.1 mm) |
| Bar oil | Dedicated chainsaw bar-and-chain oil; follow its label for temperature guidance |
| Chain tension | Chain moves by hand with suitable resistance, while drive links remain engaged in the bar groove |
Do not choose a chain from bar length alone. Read the bar stamp, check the chain marking, and confirm the specified drive-link count in the manual or parts information for that exact bar. A chain with the wrong gauge or link count will not fit or run correctly.
The MS 250 requires a 50:1 fuel mix. Measure both liquids rather than estimating. Fill the fuel and bar-oil tanks before starting; the automatic oil pump supplies the chain, but output varies with conditions. Follow the manual’s oil-delivery check and keep hands clear of the moving chain.
Start safely and verify idle
Engage the chain brake and follow the MS 250’s cold- or warm-start procedure. Secure the saw on the ground, or hold it exactly as the operator’s manual directs. Never drop-start it. After starting, confirm that the engine idles steadily and the chain stays still at idle. If it moves, stop and have the idle setting checked before cutting.
Field Cutting and Landscaping Operation
During cutting, the key maintenance checks are sharpness, chain tension, lubrication, and safe control. Recheck the chain after initial operation and as conditions require; a new or recently adjusted chain may need attention sooner. Stop the engine before adjusting tension, clearing an obstruction, or handling the chain.
Use a sharp chain and compatible bar. Keep both hands on the saw and maintain a stable stance. Keep the bar nose clear of wood and other objects: contact at the upper part of the bar tip can cause kickback, driving the saw rapidly up and back toward you. The chain brake and safety devices must work, but they do not replace kickback prevention. Do not cut above shoulder height or force a dull chain through wood.
If the chain cuts slowly, produces fine dust instead of clear chips, or needs excess pressure, stop and inspect it. These signs can point to a dull chain, but do not rule out other issues. Check tension, damage, and lubrication before deciding whether sharpening is enough. If the chain or bar is damaged, replace or service it as directed.
A simple lubrication check helps catch a dry-running chain. Follow the operator’s manual’s procedure and keep the bar tip pointed away from people and objects. Do not touch the chain or bring it close to a surface to test oil delivery. If oiling appears absent, stop and inspect the oil level, bar groove, and outlet; consult the manual or a qualified service shop if the cause is not clear.
Maintenance, Sharpening, and Carburetor Service
The schedule below separates checks by when they are useful, not by an invented hour count. Clean and inspect more often when cutting dusty or resinous wood. For intervals not stated here, use the manual for your saw’s serial-number range and follow its replacement and service instructions.
| When | Maintenance task |
|---|---|
| Before each use | Inspect safety controls, chain brake, catcher, fasteners, bar, chain tension, and leaks; fill correct fuel and bar oil |
| During work | Check chain tension and oiling as conditions require; stop the engine before adjustments |
| After each use | Let the saw cool; clean chips and debris around the sprocket cover, oil outlet, and bar groove; inspect chain and bar |
| As needed | Clean the air filter; sharpen the chain; correct tension; inspect the bar rails and sprocket |
| At manual-specified intervals | Check or replace parts and carry out service listed for the saw |
Sharpen with the chain’s specifications
A file angle is the angle used to sharpen each cutter. It depends on the exact chain model, so check the chain marking and its sharpening instructions before filing. Many 3/8-inch Picco chains use a 4.0 mm (5/32-inch) round file and a 30-degree filing angle, but do not treat those as universal MS 250 settings. STIHL’s common 3/8-inch Picco depth-gauge setting is 0.65 mm (0.026 inch); verify your chain model and use its specified filing gauge.
- Stop the engine, let hot parts cool, engage the chain brake as appropriate, and secure the saw. Wear gloves when handling the chain.
- Identify the chain model and confirm the file size, filing angle, and depth-gauge specification. Keep the file level and follow the chain maker’s filing guide.
- File cutters consistently, using the same number of strokes where practical. Check cutter condition and length; a cracked or badly damaged chain needs replacement, not routine filing.
- Check depth gauges with the correct gauge tool. Lower them only as the chain maker specifies; setting them too low can make the chain cut aggressively.
- After filing, check chain tension and lubrication before restarting.
After cutting, clear packed debris from the sprocket-cover area, oil outlet, and bar groove. Inspect the bar rails for uneven wear or damage, check the chain and drive sprocket, and rotate the bar periodically if the bar maker and manual allow it. Clean the air filter as needed using the manual’s method; avoid damaging the filter during cleaning.
Know when carburetor service is needed
The manual’s model-specific service data controls engine settings. The nominal idle speed is approximately 2,800 rpm, and maximum engine speed without the cutting attachment is approximately 14,000 rpm. These figures are service references, not targets to adjust by ear. If the chain moves at idle, the engine will not idle steadily, or cutting performance remains poor after basic checks, have the saw inspected. Do not exceed the specified maximum speed.
Two common service-bench scenarios show why diagnosis matters. If a saw leaves rough, dusty cuts, I check chain sharpness and depth gauges before blaming the engine. If the chain appears dry, I check oil level, outlet, and bar groove before assuming the pump has failed. These are troubleshooting examples, not proof of a single cause; inspect the saw and follow its manual.
Storage and Seasonal Care
Storage care protects the saw between jobs and helps prevent stale fuel or trapped debris from complicating the next start. Let the engine cool, stop it, and clean the saw before putting it away. Follow the operator’s manual and fuel manufacturer’s directions for fuel storage and longer periods without use.
Wipe away sawdust and oil. Clean the bar groove and oil outlet, then inspect the chain, bar, and fasteners. Store the saw in a dry, secure place, away from children and ignition sources. For extended storage, use the manual’s instructions for fuel handling rather than guessing whether to leave fuel in the tank.
Before the next use, repeat the pre-use checks: inspect the safety devices and cutting attachment, confirm chain tension, and fill with fresh 50:1 mix and bar oil. If the saw was stored with fuel, check its condition according to the fuel maker’s guidance. A short inspection is safer than assuming it is ready because it ran well last time.
Frequently Asked Questions
These quick answers cover common MS 250 service questions. The exact chain model and bar markings still matter, and the operator’s manual controls model-specific procedures. When a chain, bar, or engine problem is unclear, stop and get qualified service rather than relying on a generic setting.
What fuel mix does a STIHL MS 250 use?
Use fresh gasoline mixed 50:1 with quality air-cooled two-stroke engine oil, equal to 2% oil. Measure the mix accurately.
What file size does an MS 250 chain need?
It depends on the chain. Many 3/8-inch Picco chains use a 4.0 mm (5/32-inch) round file, but confirm the chain marking before filing.
What angle should I use to sharpen the chain?
Follow the exact chain maker’s instructions. Many 3/8-inch Picco chains use a 30-degree filing angle, but this is not universal.
What is the depth-gauge setting for 3/8-inch Picco chain?
STIHL’s common specification is 0.65 mm (0.026 inch). Verify the chain model and use its specified depth-gauge tool.
Can I use any 3/8-inch chain on the saw?
No. Match chain pitch, gauge, and drive-link count to the approved bar and saw combination. Check the markings and manual.
How often should I clean the air filter?
Clean it as needed, especially when dirty, and follow the manual’s cleaning method. Avoid damaging the filter.
What oil goes in the chain-oil tank?
Use dedicated chainsaw bar-and-chain oil. Follow the oil maker’s temperature guidance and the saw manual’s directions.
What should I do if the chain moves at idle?
Stop cutting and have the idle setting checked. The chain should remain stationary at idle; do not continue using the saw in this condition.
When should I rotate the guide bar?
Inspect the bar during routine cleaning and rotate it periodically if allowed by the bar maker and operator’s manual. Replace or service damaged parts.
(This article was written by one of our staff writers, David Hensley. Visit our Meet the Team page.)
