Stihl 041 Farm Boss Service Manual

The Stihl 041 Farm Boss is a professional-grade chainsaw known for its durability and power, designed for demanding forestry and farm work. This service manual provides comprehensive information for maintenance, troubleshooting, and repair. Below are key sections covering safety, specifications, maintenance procedures, engine service, fuel system, ignition system, cutting equipment, and troubleshooting guidelines.

1. Features at a Glance 2. Safety Precautions 3. Specifications 4. Maintenance Schedule 5. Engine Service 6. Fuel System 7. Ignition System 8. Cutting Equipment 9. Carburetor Adjustment 10. Disassembly & Assembly 11. Troubleshooting

Features at a Glance

Key components: Two-stroke engine, anti-vibration system, chain brake, decompression valve, automatic oiler, and manual oil pump.

Feature	Description
Engine Type	Single cylinder, two-stroke, air-cooled
Displacement	61 cc (3.7 cu. in.)
Power Output	Approx. 3.5 kW (4.7 hp)
Fuel System	Diaphragm carburetor (Bing or Tillotson)
Ignition System	Electronic, breakerless
Starter	Rewind starter with decompression valve
Chain Brake	Inertia-activated for kickback protection
Bar Lengths	Typically 16" to 20" (40-50 cm)
Weight (powerhead)	Approx. 6.6 kg (14.5 lbs)
Anti-Vibration	Spring-mounted handles

Safety Precautions

Always prioritize safety when servicing the chainsaw. Wear appropriate PPE.

Disconnect spark plug wire before any service to prevent accidental starting.
Work in a clean, well-ventilated area away from ignition sources.
Use only STIHL-approved replacement parts and tools.
Handle fuel and oil with care; wipe up spills immediately.
Secure the saw in a vise when working on cutting equipment.

WARNING! Failure to follow safety procedures can result in serious injury or death. The chainsaw must not be operated if any safety device is defective or removed.

Specifications

Model: STIHL 041 Farm Boss
Engine: 61 cc two-stroke
Fuel: Gasoline-oil mixture (50:1 with STIHL HP Ultra oil)
Fuel Tank Capacity: 0.55 L (18.6 fl. oz)
Oil Tank Capacity: 0.26 L (8.8 fl. oz)
Idle Speed: 2,800 - 3,200 rpm
Maximum Power Speed: Approx. 9,000 rpm
Ignition Air Gap: 0.3 - 0.4 mm (0.012 - 0.016 in)
Spark Plug: Bosch WSR6F or equivalent, gap 0.5 mm (0.020 in)
Chain Pitch/Gauge: 3/8" or .404", .063" gauge

Maintenance Schedule

Access OSD via TV MENU or SETUP (DVD). Front Panel: POWER, OPEN/CLOSE, AUTO/DPMS, MUTE.

Daily/Before Use: Check chain tension, sharpness, and lubrication. Check for loose fasteners. Inspect air filter. Every 10 Hours: Clean air filter. Check spark plug. Every 20 Hours: Clean spark arrestor screen (if equipped). Check fuel filter. Every 50 Hours: Clean cooling fins. Check carburetor adjustment. Annually/As Needed: Replace fuel filter, spark plug. Check piston/cylinder through exhaust port. Grease clutch bearing.

Engine Service

Top end inspection, cylinder/piston assessment, crankcase seals.

Remove muffler to inspect piston and cylinder for scoring.
Check compression: Should be above 120 psi (8.3 bar).
Inspect crankcase seals for leaks using pressure/vacuum test.
Check connecting rod for side play; should be minimal.

Tip: Always use a piston stop when removing the flywheel or clutch.

Fuel System

Includes fuel tank, lines, filter, and carburetor.

Drain fuel before servicing.
Replace fuel filter annually or if clogged.
Inspect fuel lines for cracks, stiffness, or leaks.
Clean carburetor with compressed air; rebuild kit if necessary.
Ensure tank vent is clear.

WARNING! Use only fresh, properly mixed fuel. Old fuel can cause starting and performance issues.

Ignition System

Electronic ignition module, spark plug, stop switch, and wiring.

Test for spark: Remove plug, ground it to cylinder, pull starter.
Check ignition module air gap (0.3-0.4 mm).
Inspect wiring for breaks or shorts, especially at the stop switch.
Replace spark plug annually or if electrode is worn.

CAUTION! Do not crank engine with spark plug removed at high speed without grounding the ignition wire, as it can damage the module.

Cutting Equipment

Guide bar, chain, sprocket, clutch, and oiler system.

Chain Tension: Adjust so chain snaps back when pulled from bar.
Bar Maintenance: Clean bar groove and oil holes. Flip bar regularly.
Sprocket: Check for wear; replace if hooked.
Clutch: Inspect shoes for wear and springs for integrity.
Oiler: Test output. Clean oil passages and filter screen.

WARNING! Always use matched chain, bar, and sprocket (same pitch/gauge). A worn sprocket will rapidly wear a new chain.

Carburetor Adjustment

Standard settings: L (low speed) - 1 turn out; H (high speed) - 1 turn out; LA (idle) - 1 turn out. Fine-tune with saw warmed up.

Start with standard settings.
Adjust L jet for smooth acceleration from idle.
Adjust H jet for maximum RPM without 4-stroking excessively under load.
Set idle speed so chain does not move.

CAUTION! Over-leaning the H jet can cause engine seizure. Use a tachometer for precise adjustment (Max RPM approx. 12,500-13,500 no-load).

Disassembly & Assembly

General sequence for major service.

Remove top cover, air filter, and carburetor.
Remove starter assembly, flywheel, and ignition module.
Remove cylinder cover, cylinder, and piston.
Remove clutch, oil pump, and drive sprocket.
Separate crankcase halves (requires special tool).
Reverse sequence for assembly using new gaskets and seals.

Tip: Take photos during disassembly and organize parts. Use a service manual with torque specifications.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine will not start	No spark, flooded, fuel issue	Check spark, plug condition. Dry plug if flooded. Check fuel flow, filter, lines.
Engine starts then dies	Fuel starvation, air leak	Check fuel filter, tank vent, carburetor. Perform crankcase pressure test.
Loss of power	Clogged air filter, exhaust screen, carb adjustment	Clean air filter and spark arrestor. Check carburetor settings and compression.
Chain does not oil	Clogged oil passages, faulty pump	Clean bar oil holes and tank filter. Check oil pump drive and diaphragm.
Excessive vibration	Loose components, unbalanced clutch	Tighten all fasteners. Inspect clutch shoes and anti-vibration mounts.
Chain turns at idle	Idle speed too high, clutch sticking	Adjust idle speed screw. Clean clutch drum and bearing.

Reset: For electronic ignition issues, ensure all connections are clean and tight.

Service: For genuine STIHL parts and technical support, contact an authorized STIHL servicing dealer.