Stihl MS250C Parts Manual

The Stihl MS250C is a lightweight, professional-grade chainsaw featuring a powerful engine, easy-start system, anti-vibration handles, and STIHL Quickstop® inertia chain brake. This parts manual provides detailed diagrams, part numbers, and ordering information for maintenance, repair, and replacement of components. Below are key sections for identification, engine components, cutting attachments, fuel system, ignition, and ordering.

1. Features at a Glance 2. Identification & Serial Numbers 3. Engine Assembly & Components 4. Cutting Attachment Parts 5. Fuel System Parts 6. Ignition System Parts 7. Anti-Vibration System 8. Maintenance Schedule 9. Safety Components 10. Ordering Parts 11. Troubleshooting Parts Issues

Features at a Glance

Key components: Engine cylinder, piston, carburetor, air filter, spark plug, fuel tank, oil tank, guide bar, saw chain, chain brake, anti-vibration system, starter assembly.

Feature	Description
Engine Cylinder	Bore 40mm, displacement 45.4 cc
Piston	Forged aluminum with two piston rings
Carburetor	Zama C1Q-S189 diaphragm carburetor
Air Filter	Two-stage foam/fleece filter element
Spark Plug	Bosch WSR6F or equivalent, 0.020" gap
Fuel Tank	Capacity 16.9 fl oz (0.5 L)
Oil Tank	Capacity 11.8 fl oz (0.35 L)
Guide Bar	STIHL Rollomatic® E, lengths 16" or 18"
Saw Chain	STIHL Picco™ 3/8" PM3, 0.050" gauge
Chain Brake	STIHL Quickstop® inertia-activated

Identification & Serial Numbers

Locate serial number on engine housing for parts ordering.

Serial number: Stamped on right side of engine housing near rear handle.
Model number: MS250C printed on left side of housing.
Date code: First two digits of serial indicate year/week of manufacture.
Parts diagrams: Refer to section numbers (e.g., 1110 for cylinder group).

WARNING! Always provide serial number when ordering parts to ensure correct fit.

Engine Assembly & Components

Engine group includes cylinder, piston, crankshaft, bearings, seals.

Cylinder group (1110): Cylinder, decompression valve, cylinder bolts.
Piston group (1120): Piston, piston rings, wrist pin, circlips.
Crankshaft group (1130): Crankshaft, main bearings, oil seals.
Connecting rod: Forged steel, needle bearing small end.
Crankcase: Two-piece magnesium housing with intake and exhaust ports.

CAUTION! Use torque wrench for cylinder bolts (12 Nm). Replace gaskets during reassembly.

Cutting Attachment Parts

Guide Bar: STIHL Rollomatic® E, part numbers 3005 000 4816 (16") or 3005 000 4818 (18").
Saw Chain: STIHL Picco™ PM3, 63 drive links (16") or 72 drive links (18").
Sprocket: Spur sprocket 7-tooth, part number 0000 642 2007.
Clutch: Centrifugal clutch assembly, drum, springs.
Chain Tensioner: Screw-type adjuster with worm gear.
Bar Nuts: M8 flange nuts with washers.
Chain Catcher: Metal guard to prevent chain derailment.

Fuel System Parts

Carburetor, fuel lines, filter, tank cap, primer bulb.

Carburetor: Zama C1Q-S189, includes diaphragm kit, metering lever, inlet needle.

Fuel lines: 3.5mm ID black line (tank to carb), 4.0mm ID clear line (carb to primer). Fuel filter: STIHL 0000 350 3500 in-tank filter. Tank cap: Venting cap with O-ring seal. Primer bulb: Rubber bulb with check valves.

Ignition System Parts

Ignition module, spark plug, stop switch, wiring harness.

Turn off engine before servicing ignition components.
Match part numbers: Ignition module 0000 400 1300 for MS250C.
Check spark plug boot and wire for cracks or damage.
Select input via stop switch continuity test (open/closed).

Tip: Disconnect spark plug wire before working on ignition system.

Anti-Vibration System

Reduces vibration to handles for operator comfort.

Front AV springs: Two rubber springs between engine and front handle.
Rear AV buffers: Rubber mounts at rear handle attachment points.
Inspection: Check for cracks, hardening, or compression set annually.
Replacement: Part numbers 1128 030 0800 (springs), 1128 030 0900 (buffers).
Torque: Handle bolts 10 Nm after AV component replacement.
Alignment: Ensure handles are parallel after reassembly.
Wear indicators: Replace if rubber shows signs of deterioration.

WARNING! Worn AV components increase vibration; replace promptly.

Maintenance Schedule

Regular parts replacement intervals for optimal performance.

Safety Components

Chain brake band, trigger interlock, chain catcher, right hand guard.

CAUTION! Replace safety parts immediately if damaged; do not operate with defective safety components.

Ordering Parts

Use genuine STIHL parts; order through authorized dealers with serial number. Parts diagrams available at www.stihlusa.com. Warranty: 1-year limited warranty on parts. For support, contact STIHL at 1-800-467-8445 or visit dealer locator online.

Troubleshooting Parts Issues

Symptom	Possible Cause	Corrective Action
Engine won't start	Spark plug/fuel filter	Replace spark plug; check/replace fuel filter and lines.
Loss of power	Air filter/piston rings	Clean/replace air filter; inspect piston/cylinder for scoring.
Chain won't oil	Oil pump/oil lines	Check oil lines for cracks; replace oil pump if defective.
Excessive vibration	AV components	Inspect and replace worn AV springs/buffers.
Chain brake not engaging	Brake band/spring	Replace worn brake band (part 0000 350 3500) or return spring.

Reset: None required for mechanical parts.

Service: 1-800-467-8445; www.stihlusa.com