The STIHL MS 261 is a professional-grade chainsaw featuring a high-performance engine with STIHL M-Tronic engine management for automatic adjustment to fuel quality and operating conditions. It offers reduced-emission engine technology, an anti-vibration system, a QuickStop chain brake, and an ergonomic design for demanding forestry and arborist work. Below are key sections for safety, features, operation, maintenance, and troubleshooting.
Key components: M-Tronic engine control unit, Decompression valve, QuickStop chain brake, Side-access chain tensioner, Ergonomic front and rear handles with anti-vibration system.
| Feature | Description |
|---|---|
| Engine | STIHL M-Tronic controlled 2-stroke engine |
| Displacement | 50.2 cm³ (3.06 cu. in.) |
| Power Output | 3.0 kW (4.0 bhp) |
| Fuel System | M-Tronic automatic adjustment |
| Guide Bar Lengths | Typically 16" (40 cm) to 20" (50 cm) |
| Chain Brake | QuickStop inertia-activated |
| Anti-Vibration | STIHL anti-vibration system |
| Weight (powerhead) | Approx. 5.2 kg (11.5 lbs) |
| Emissions | Meets EPA Phase III and EU Stage III standards |
| Starter | STIHL ElastoStart |
Read and understand all instructions before operation. Always wear appropriate PPE.
WARNING! Risk of severe injury or death from kickback, cutting, or thrown objects. Never operate a chainsaw without proper training and safety gear.
Unpack and inspect contents. Assemble guide bar and chain.
CAUTION! Ensure chain brake is engaged when starting. Keep hands away from chain at all times.
Master Control Lever: Combines stop switch, choke, and run positions. Throttle Trigger: With interlock. Throttle Trigger Lockout: Must be pressed to engage throttle. Chain Brake Lever: Front hand guard. Decompression Valve: Reduces pulling force for starting. Side-Access Chain Tensioner: For easy adjustment. M-Tronic Calibration Button: For resetting engine management (if needed).
Maintenance Points: Air filter, Spark plug (SR4E), Fuel filter, Chain catcher, Sprocket cover.
Starting, cutting techniques, and shutdown.
Tip: Keep chain sharp and properly tensioned. Lubricate chain continuously during operation.
Daily or before each use: Check chain tension, sharpness, and lubrication. Check all nuts and bolts. Clean air filter. Check chain brake function. Weekly or every 10 operating hours: Clean spark arrestor screen (if equipped). Check fuel filter. Clean cooling fins. Monthly or every 50 operating hours: Replace spark plug. Clean or replace air filter more thoroughly. Check anti-vibration elements. Annually or every 100 operating hours: Have saw inspected by an authorized STIHL servicing dealer.
WARNING! Perform maintenance only with engine off, spark plug disconnected, and chain brake engaged.
Sharpening: Use correct round file size for chain pitch. Maintain correct filing angle (typically 30°). Ensure all cutters are uniform. Tensioning: Chain should be snug against bar but pull freely by hand. Re-tension when chain is warm. Bar Maintenance: Clean bar groove regularly. Flip bar periodically for even wear. Lubrication: Always use STIHL chain oil. Check oil flow by running saw at speed over light surface; oil line should appear.
Long-term storage (over 30 days): Empty fuel tank and run engine until it stops to clear carburetor. Remove chain, clean and oil it. Clean entire saw. Store in a dry, secure place, away from children.
CAUTION! Do not store with fuel in the tank for extended periods. Fuel can degrade and damage engine components.
STIHL Limited Warranty applies. This product complies with relevant EPA and EU emissions regulations. The STIHL M-Tronic system is covered by software copyright. Use only STIHL-approved replacement parts and accessories to maintain warranty and safety. For service, contact an authorized STIHL dealer. For support, visit www.stihl.com.
| Symptom | Possible Cause | Corrective Action |
|---|---|---|
| Engine will not start | No fuel, flooded, spark plug faulty | Check fuel, dry plug, check spark, use decompression valve. |
| Engine runs poorly/dies | Clogged air filter, fuel filter, carburetor adjustment | Clean/replace air filter, replace fuel filter. M-Tronic should self-adjust. |
| Chain does not turn | Chain brake engaged, clutch/sprocket worn | Disengage chain brake, inspect clutch drum and sprocket. |
| Excessive vibration | Loose components, damaged anti-vibration mounts | Tighten all fasteners, inspect anti-vibration elements. |
| Chain throws oil | Oil output too high | Adjust oil pump (if adjustable on model). |
| M-Tronic malfunction | System requires reset | Run at full throttle for 1 minute under load. If problem persists, see dealer. |
Reset M-Tronic: Start engine, run at full throttle under load for 1 minute to allow recalibration.
Service: Authorized STIHL dealers only. Do not attempt major repairs yourself.