Stihl MS 441 Service Manual

The Stihl MS 441 is a professional-grade chainsaw featuring a powerful engine with advanced anti-vibration system, electronic ignition, quickstop chain brake, decompression valve, and STIHL Ematic lubrication system. This service manual provides comprehensive information for maintenance, repair, and troubleshooting. Below are key sections covering safety, specifications, maintenance procedures, engine service, fuel system, ignition system, troubleshooting, and parts diagrams.

Features at a Glance

Key components: Professional engine with decompression valve, Quickstop chain brake, STIHL Ematic lubrication system, Anti-vibration system, Electronic ignition module, Side-access chain tensioner, Tool-free fuel and oil caps.

Feature	Description
Engine Type	2-stroke, single cylinder, air-cooled
Displacement	70.7 cc (4.3 cu. in.)
Power Output	4.4 kW (6.0 bhp)
Fuel System	Diaphragm carburetor with manual choke
Ignition System	Electronic, capacitor discharge
Starting System	STIHL ErgoStart or standard recoil
Chain Brake	Quickstop inertia-activated
Vibration Damping	Advanced anti-vibration system
Lubrication	STIHL Ematic system (adjustable)
Weight (powerhead)	Approx. 6.7 kg (14.8 lbs)

Safety Information

Always wear proper protective equipment including eye protection, hearing protection, gloves, chainsaw chaps, and sturdy boots.

1. Read and understand the operator's manual before use.
2. Inspect chainsaw before each use for loose parts, damage, or leaks.
3. Ensure chain brake is functioning properly.
4. Use proper fuel mixture (50:1 gasoline to 2-cycle oil).
5. Never operate chainsaw with damaged or missing safety devices.

WARNING! Chainsaws are dangerous tools that can cause serious injury or death. Always follow safety procedures and use proper protective equipment.

Specifications

• Engine: 2-stroke, single cylinder, 70.7 cc displacement
• Power Output: 4.4 kW (6.0 bhp) at 9,000 rpm
• Idle Speed: 2,800 rpm
• Maximum Power Speed: 9,000 rpm
• Fuel Tank Capacity: 750 ml (25.4 fl. oz.)
• Oil Tank Capacity: 300 ml (10.1 fl. oz.)
• Fuel/Oil Ratio: 50:1 (gasoline:2-cycle oil)
• Spark Plug: Bosch WSR 6 F or equivalent, gap 0.5 mm (0.020 in.)
• Bar Lengths: 16" to 25" (40 cm to 63 cm)
• Chain Pitch: 3/8" or .325"
• Chain Gauge: 0.050" or 0.063"

Maintenance Schedule

Regular maintenance is essential for safe operation and long service life.

Daily/Before Each Use: Check chain tension, sharpness, and lubrication; inspect for loose fasteners; check fuel and oil levels; test chain brake function.

Weekly/Every 10 Operating Hours: Clean air filter; check spark plug condition; clean cooling fins; inspect anti-vibration elements.

Monthly/Every 50 Operating Hours: Clean fuel filter; check carburetor adjustment; inspect clutch and sprocket; clean spark arrestor screen.

Annually/Every 100 Operating Hours: Replace fuel filter; replace spark plug; check ignition timing; inspect piston through exhaust port.

Engine Service

Engine disassembly requires special tools and mechanical experience.

1. Cylinder and Piston: Remove muffler to inspect piston and cylinder; check for scoring or excessive wear.
2. Crankshaft Seals: Replace if leaking (common cause of lean running condition).
3. Bearings: Check main bearings for play or roughness.
4. Decompression Valve: Test operation; replace if leaking compression.
5. Cooling System: Keep fins clean for proper heat dissipation.

Note: Use genuine STIHL parts for all engine repairs. Torque all fasteners to specifications.

Fuel System

Proper fuel mixture and system maintenance are critical for engine performance and longevity.

1. Fuel: Use fresh unleaded gasoline (minimum 89 octane) mixed with STIHL HP Ultra or equivalent 2-cycle oil at 50:1 ratio.
2. Carburetor Adjustment: Three adjustment screws (L, H, LA). Initial settings: L=1 turn open, H=1 turn open, LA=1 turn open.
3. Fuel Filter: Replace annually or when clogged.
4. Fuel Lines: Inspect for cracks or deterioration; replace if necessary.
5. Fuel Tank Vent: Ensure vent is clear; clean if clogged.

Tip: Always use fresh fuel mixture. Stale fuel (older than 30 days) can cause starting and performance issues.

Ignition System

Electronic ignition provides reliable spark with no points to adjust.

1. Spark Plug: Use Bosch WSR 6 F or equivalent; gap 0.5 mm (0.020 in.).
2. Ignition Module: Fixed timing; no adjustment available. Test with spark tester.
3. Stop Switch: Test continuity; should be open when switch is in RUN position.
4. Wiring: Inspect for damaged insulation or loose connections.
5. Flywheel: Check key and keyway for damage; ensure proper torque (40 Nm/30 ft-lbs).

WARNING! Never crank engine with spark plug removed and wire grounded against cylinder. Fuel vapor could ignite.

Chain & Bar Maintenance

Proper chain maintenance ensures cutting efficiency and safety.

1. Chain Tension: Adjust when chain sags from bar rails. Proper tension: chain should snap back when pulled from bar.
2. Sharpening: Use proper round file size (typically 5.5 mm for 3/8" chain). Maintain correct filing angle (30°).
3. Bar Maintenance: Clean bar groove regularly; flip bar weekly for even wear; dress bar rails as needed.
4. Sprocket: Check for wear; replace if teeth are hooked or excessively worn.
5. Lubrication: Ensure oiler is working; adjust flow as needed for conditions.

CAUTION! Always wear gloves when handling chain. A sharp chain is safer than a dull one.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine won't start	Fuel issues, spark, compression	Check fuel freshness, spark plug, compression (should be 120+ psi).
Engine starts then dies	Fuel system, carburetor	Clean fuel filter, check fuel lines, adjust carburetor.
Poor performance	Air filter, exhaust, carburetor	Clean air filter and spark arrestor; check carburetor adjustment.
Excessive vibration	AV mounts, balance	Inspect anti-vibration mounts; check clutch balance.
Chain won't oil	Oil system, bar groove	Check oil tank vent, oil pump, clean bar groove and oil holes.
Chain brake not working	Mechanism, band	Clean and lubricate mechanism; check brake band for wear.

Compression Test: Minimum 120 psi for proper operation.

Parts Diagrams

Refer to STIHL parts catalog for complete illustrated parts breakdown. Key assemblies:

1. Cylinder and Piston Assembly (including rings, wrist pin, bearings)
2. Crankshaft and Crankcase Assembly
3. Carburetor and Fuel System Assembly
4. Ignition and Electrical Assembly
5. Clutch and Sprocket Assembly
6. Chain Brake Assembly
7. Anti-Vibration System Assembly
8. Bar and Chain Assembly

Note: Always use STIHL part numbers when ordering replacement parts.

Warranty Information

STIHL MS 441 carries a limited warranty for professional use. Warranty period and coverage vary by region. Contact authorized STIHL dealer for specific warranty details.

Warranty Requirements: Proper maintenance using genuine STIHL parts and lubricants; proof of purchase from authorized dealer; professional use registration (if applicable).

Service Support: For technical assistance, contact authorized STIHL servicing dealer or visit www.stihlusa.com. Always refer to the latest version of this service manual for updated information.