owners manual stihl ms 250

The STIHL MS 250 is a professional-grade, lightweight chainsaw designed for demanding forestry, landscaping, and property maintenance work. It features a powerful 45.4 cc engine with STIHL anti-vibration system, Quickstop® inertia chain brake, Ematic™ lubrication system, and side-access chain tensioner for easy maintenance. Below are key sections for safety, features, operation, maintenance, and troubleshooting.

Features at a Glance

Key components: Engine with decompression valve, anti-vibration system, Quickstop® chain brake, side-access chain tensioner, Ematic™ lubrication, and tool-free fuel and oil caps.

Safety Information

Read and understand all safety warnings before operation.

1. Personal Protective Equipment (PPE): Always wear chainsaw chaps or pants, safety glasses, hearing protection, gloves, and sturdy boots.
2. Pre-Operation Check: Inspect chain tension, sharpness, and lubrication. Ensure all guards are in place.
3. Safe Operation Zone: Keep bystanders and pets at least 15 feet (5 meters) away.
4. Kickback Awareness: Understand kickback zone (upper quadrant of bar tip). Use reduced-kickback chain and maintain firm grip.

WARNING! Chainsaw operation is inherently dangerous. Failure to follow safety instructions can result in serious injury or death. Never operate when tired or under the influence.

Assembly & First-Time Setup

Assemble your MS 250 before first use.

1. Attach Guide Bar and Chain: Place bar on studs, loop chain over sprocket and bar with cutters facing forward. Install bar nut and adjust tension.
2. Fill Fluids: Use STIHL HP Ultra 2-stroke oil mixed 50:1 with unleaded gasoline (min. 89 octane). Fill chain oil reservoir with STIHL chain oil.
3. Check Chain Brake: Ensure brake functions by pulling hand guard forward; it should snap back when released.
4. Break-in Period: Operate at varying speeds (not full throttle) for first 3-5 tanks to seat engine components.

CAUTION! Use only STIHL-approved oils and fuels. Improper mix can cause engine damage.

Specifications

• Engine Type: 2-stroke, single cylinder, air-cooled.
• Displacement: 45.4 cc.
• Power Output: 2.6 kW (3.5 bhp).
• Fuel/Oil Mix: 50:1 (STIHL HP Ultra).
• Fuel Tank Capacity: 14.9 fl oz (0.44 L).
• Oil Tank Capacity: 8.5 fl oz (0.25 L).
• Idle Speed: 2,800 RPM.
• Max Engine Speed: 13,500 RPM.
• Weight (powerhead only): 10.1 lbs (4.6 kg).
• Sound Pressure Level: 106 dB(A).
• Vibration Levels (front/rear): 4.5/2.5 m/s².

Controls and Components

Master Control Lever: Combines choke, throttle lock, and stop switch. Throttle Trigger: Controls engine speed. Throttle Lockout: Must be depressed to engage throttle. Chain Brake Hand Guard: Activates brake when pushed forward. Decompression Valve: Reduces cylinder pressure for easier starting. Fuel and Oil Caps: Tool-free design. Chain Tensioner: Side-mounted, adjustable with scrench.

Maintenance Points: Air filter cover, spark plug, muffler, chain catcher, and bar studs.

Starting & Operating Procedures

Cold Start:

1. Set chain brake to ON (hand guard forward).
2. Press decompression valve (if equipped).
3. Move Master Control to choke position (full down).
4. Pump primer bulb 5-7 times until fuel is visible.
5. Place saw on ground, hold front handle with left hand, place right foot through rear handle.
6. Pull starter rope sharply until engine fires (1-3 pulls).
7. Move Master Control to half-throttle position (mid-notch).
8. Pull starter rope again until engine starts.
9. Blip throttle to set Master Control to run position.
10. Release chain brake before cutting.

Warm Start: Master Control to run position, no choke. Follow steps 5-6 and 9-10.

Cutting Techniques: Use lower quadrant of bar for felling and bucking. Let saw do the work; avoid forcing. Maintain secure footing.

Chain & Bar Maintenance

Proper maintenance ensures performance and safety.

1. Chain Tension: Adjust when chain sags from bar rails. Loosen bar nuts, turn tensioning screw until chain snaps back when pulled from bar. Tighten bar nuts.
2. Sharpening: Use round file and guide matching chain pitch. File each cutter at 30° angle, maintaining equal length on all cutters.
3. Bar Maintenance: Clean bar grooves weekly. Flip bar monthly for even wear. Dress rails with flat file if burred.
4. Lubrication: Check oil flow by running saw at high speed near light surface; fine oil line should appear.

CAUTION! Always wear gloves when handling chain. A dull chain increases kickback risk.

Engine Maintenance

Regular maintenance schedule:

• Daily: Clean air filter (tap out debris, wash in soapy water if very dirty). Check spark arrestor screen.
• Weekly: Clean cooling fins and cylinder area. Check fuel filter.
• Monthly: Replace spark plug (NGK BPMR7A). Check fuel lines for cracks.
• Seasonally: Clean carburetor and muffler. Check anti-vibration elements.

Fuel System: Use fresh fuel (mixed within 30 days). Empty tank for storage over 30 days.

Storage Guidelines

For storage over 30 days:

1. Drain fuel tank and run engine until it stops.
2. Drain chain oil tank.
3. Remove chain, clean, and soak in oil. Store bar coated in oil.
4. Clean entire saw, especially cooling fins.
5. Store in dry, cool place, protected from dust.

CAUTION! Never store with fuel in tank; old fuel can damage carburetor.

Regulatory Information

EPA and CARB compliant for emissions. Meets ANSI B175.1 safety standards. Manufactured by STIHL Incorporated. Copyright © STIHL. All rights reserved. For genuine parts and accessories, visit an authorized STIHL servicing dealer. For support, contact STIHL USA at 1-800-467-8445 or visit www.stihlusa.com.

Troubleshooting

Service: For repairs beyond basic maintenance, contact an authorized STIHL servicing dealer.

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