The STIHL MS250 is a professional-grade, lightweight chainsaw designed for demanding homeowners and occasional users. This parts manual provides detailed diagrams, part numbers, and ordering information for the complete assembly, engine, fuel system, cutting attachment, and safety components. Below are key sections for identification, major assemblies, ordering, maintenance, and safety.
Locate the model number (MS250) and serial number on the crankcase. Key specifications for parts identification.
| Feature | Description |
|---|---|
| Engine Type | STIHL 2-MIX engine, single cylinder, 2-stroke |
| Displacement | 45.4 cc (2.77 cu. in.) |
| Power Output | 2.6 kW (3.5 bhp) |
| Fuel Tank Capacity | 0.47 L (15.9 fl. oz.) |
| Oil Tank Capacity | 0.26 L (8.8 fl. oz.) |
| Recommended Bar Lengths | 16" (40 cm), 18" (45 cm) |
| Chain Pitch/Gauge | .325" / .063" (1.6 mm) or .325" / .058" (1.5 mm) |
| Weight (powerhead) | 5.2 kg (11.5 lbs) |
| Ignition System | Electronic, capacitor discharge (CDI) |
| Spark Plug | Bosch WSR6F or equivalent |
Key component groups for disassembly and parts lookup.
WARNING! Always disconnect the spark plug boot before performing any maintenance or parts replacement.
Detailed parts list for the power unit.
CAUTION! Use only STIHL-approved 2-stroke engine oil mixed at 50:1 ratio with unleaded gasoline (min. 89 octane).
Components for the cutting system.
| Part | Part Number (Example) | Description |
|---|---|---|
| Guide Bar, 16" | 3003 000 7218 | .325" pitch, .063" gauge, 72 drive links |
| Saw Chain, 16" | 3635 005 0085 | Oregon 91PX series, 72 drive links |
| Drive Sprocket | 1128 640 2003 | Rim sprocket, 7-tooth |
| Clutch Assembly | 1128 160 0600 | Centrifugal clutch, drum, springs |
| Chain Tensioner | 1128 312 0600 | Adjustment screw, worm gear |
| Bar Nuts | 9006 003 1020 | M8 x 1.25, 2 required |
| Chain Catcher | 1128 650 0600 | Safety component |
| Clutch Cover | 1128 791 0600 | Plastic side cover with chain brake |
Electrical and control components.
Ignition Module: Part # 1128 400 0601. Includes ignition coil, spark advance.
Stop Switch: Part # 1128 962 0600. Grounds ignition to stop engine.
Throttle Control: Throttle trigger (1128 131 0600), Throttle lockout (1128 131 0700), Throttle cable (1128 421 0600).
Choke/Start Lever: Part # 1128 131 0800. Controls carburetor choke plate.
Wiring Harness: Part # 1128 431 0600. Connects switch to ignition module.
Internal drive and support parts.
Tip: Inspect AV mounts regularly for wear to reduce operator fatigue and vibration.
Parts for the manual recoil starter.
WARNING! The rewind spring is under tension. Use proper tools and follow service manual procedures to avoid injury.
Critical safety components and identification decals.
Chain Brake Assembly: Brake band (1128 790 0800), activation lever, inertia mechanism.
Hand Guard: Part # 1128 790 0900. Front right-hand guard.
Safety Labels: Warning decals (e.g., 1128 991 0601, 1128 991 0602). Replace if damaged or illegible.
Throttle Lockout: Must function properly to prevent accidental throttle engagement.
Recommended service schedule for key wear parts.
| Component | Inspection Interval | Replacement Criteria |
|---|---|---|
| Air Filter | Every 10 operating hours | When dirty or damaged; clean with soap/water |
| Spark Plug | Every 50 hours | Gap 0.5 mm (0.020"); replace if electrodes worn |
| Fuel Filter | Every 3 months or 50 hours | Replace annually or if clogged |
| Saw Chain | Before each use | Sharpen when dull; replace when cutters worn to line |
| Guide Bar | Before each use | Replace if rails worn unevenly, damaged, or grooved |
| Drive Sprocket | Every 2-3 chains | Replace if teeth hooked or worn |
| Chain Brake | Before each use | Test function; replace band if worn or damaged |
| Anti-Vibration Elements | Annually | Replace if cracked, hardened, or compressed |
Critical fastener torque values (Nm / in-lbs). Use a calibrated torque wrench.
CAUTION! Overtightening can strip threads; undertightening can cause loose parts and failure.
Use official STIHL diagrams for accurate part identification.
| Symptom / Need | Reference Document | Corrective Action |
|---|---|---|
| Identify a specific part | Exploded View Diagram (1128 791 0601) | Match component to numbered diagram; note item number. |
| Order parts | STIHL Parts Price List / Microfiche | Provide model, serial number, and part number to authorized dealer. |
| Assembly procedure | STIHL MS250 Service Manual | Follow step-by-step instructions for complex assemblies. |
| Part not available | Dealer Parts System | Check for superseded part numbers or kit alternatives. |
| Warranty claim | Proof of Purchase & Warranty Card | Contact selling dealer with serial number and receipt. |
Reset: For electronic ignition issues, ensure spark plug boot is fully seated.
Service: For genuine STIHL parts and service, locate an authorized dealer at www.stihlusa.com or call 1-800-467-8445.