Husqvarna 440 Chainsaw Service Manual

The Husqvarna 440 is a professional-grade chainsaw designed for demanding forestry and arborist work. This service manual provides comprehensive instructions for maintenance, troubleshooting, and repair of the Husqvarna 440 chainsaw, covering the engine, fuel system, ignition, chain brake, cutting equipment, and electrical system. It is intended for qualified service technicians. Below are key sections for safety, specifications, maintenance procedures, troubleshooting, and parts information.

Safety Information & Warnings

Before performing any service, read and understand all safety warnings. Always wear appropriate personal protective equipment (PPE).

WARNING! Failure to follow safety instructions can result in serious injury or death. This manual is for trained technicians only.

Technical Specifications

• Model: Husqvarna 440
• Engine Type: 2-stroke, single cylinder, air-cooled
• Displacement: 40.9 cm³ (2.5 cu. in.)
• Power Output: 2.2 kW (3.0 hp)
• Fuel Tank Volume: 0.5 L (16.9 fl. oz.)
• Oil Tank Volume: 0.25 L (8.5 fl. oz.)
• Recommended Bar Lengths: 13" to 18" (33 cm to 45 cm)
• Chain Pitch/Gauge: 3/8" LP / .050" (1.3 mm)
• Ignition System: Electronic, SEM
• Carburetor: Zama C1Q-S
• Spark Plug: NGK BPMR7A (gap 0.5 mm / 0.020")

Maintenance Schedule

Regular maintenance is critical for performance, longevity, and safety.

1. Daily/Before Use: Check chain tension, sharpness, and lubrication. Inspect for loose nuts/bolts. Check throttle trigger and lockout function.
2. Weekly/Every 10 Hours: Clean air filter. Check spark plug condition and gap. Clean external surfaces and cooling fins.
3. Monthly/Every 50 Hours: Clean fuel filter. Check fuel lines for cracks. Inspect clutch, drum, and sprocket for wear.
4. Annually/Every 100 Hours: Clean carburetor and adjust (if necessary). Check cylinder and piston through exhaust port. Replace spark plug.
5. As Needed: Replace worn guide bar, chain, or sprocket. Service chain brake mechanism.

CAUTION! Use only genuine Husqvarna replacement parts and lubricants.

Engine Service

Procedures for cylinder, piston, crankshaft, and bearings.

1. Cylinder & Piston Inspection: Remove muffler to inspect cylinder walls and piston skirt for scoring. Measure piston ring end-gap.
2. Decompression Valve: Test by pressing; should spring back. Replace if stuck or leaking.
3. Crankcase Seals: Check for leaks using pressure/vacuum test. Replace if test fails.
4. Engine Mounts: Inspect for cracks or deterioration. Tighten or replace as needed.

Note: Major engine disassembly requires special tools (puller, installer, torque wrench).

Fuel System

Carburetor adjustment, fuel line, and filter service.

1. Carburetor Adjustment (Zama C1Q-S): Factory settings: L=1 turn out, H=1 turn out. Fine-tune at operating temperature for smooth acceleration and max RPM of 13,500 (under load).
2. Fuel Filter: Replace by disconnecting fuel line at carburetor and pulling filter out of tank with wire hook.
3. Fuel Lines: Inspect for hardening, cracks, or leaks. Replace in sets.
4. Fuel Tank Vent: Clean to prevent vacuum lock or flooding.

WARNING! Use fresh, high-quality 2-stroke mix (50:1 Husqvarna XP+ oil with 90+ octane gasoline).

Ignition System

Testing and replacement of ignition module, spark plug, and stop switch.

Spark Test: Remove spark plug, reconnect cap, ground plug base against cylinder. Pull starter; look for strong blue spark.

Ignition Module (SEM) Test: Check primary resistance (approx. 0.2-0.4 Ω) and secondary resistance (approx. 4-6 kΩ). Replace if out of spec or no spark.

Stop Switch: Test for continuity between switch wire and ground when pressed. Should be open circuit when released.

Chain Brake & Clutch

Service of the inertia-activated chain brake and centrifugal clutch.

1. Chain Brake Band Inspection: Check for wear, glazing, or cracking. Replace if thickness is below minimum.
2. Brake Spring Tension: Manual release should be smooth. Replace spring if brake feels weak or does not engage fully.
3. Clutch Inspection: Remove drum. Check clutch shoes for wear and springs for fatigue or breakage.
4. Sprocket: Inspect spur or rim sprocket for wear. Replace rim sprocket if teeth are hooked or worn unevenly.

CAUTION! The brake spring is under high tension. Use a brake spring tool for safe removal/installation.

Cutting Equipment

Guide bar, chain, and lubrication system maintenance.

1. Guide Bar: Clean bar groove and oil holes. Dress bar rails with flat file if burred. Flip bar regularly for even wear.
2. Chain Sharpening: Use correct round file size (4.0 mm / 5/32"). Maintain correct filing angle (30°). Ensure depth gauges are properly lowered.
3. Oil Pump Adjustment/Test: Run saw at full throttle pointed at light surface; should see oil sling from chain. Adjust pump screw if necessary.
4. Chain Tension: Correct when chain snaps back after pulling away from bar nose. Adjust with bar nuts loose, then retighten.

Electrical System

Includes starter, flywheel, and wiring harness.

Starter Assembly: Inspect rewind spring for damage. Check pawls for wear and free movement. Clean and lubricate.

Flywheel & Key: Check for sheared woodruff key if ignition timing is suspect. Inspect magnets for cracks.

Wiring Harness: Check all connections for corrosion or looseness. Inspect wires for pinches or cuts, especially near handle and tank.

Troubleshooting Guide

Exploded Views & Parts List

Refer to official Husqvarna parts catalog for complete exploded diagrams and part numbers for the 440 model. Key assembly groups include:

• Engine Assembly (Cylinder, Piston, Crankshaft)
• Carburetor & Fuel System
• Ignition & Electrical
• Chain Brake & Handle
• Clutch & Sprocket
• Guide Bar & Chain
• Covers & Housing

Ordering Parts: Always use the saw's serial number when ordering. Contact an authorized Husqvarna dealer or visit www.husqvarna.com.

Service Support: For technical assistance, contact Husqvarna Technical Support at 1-800-487-5962 or your local authorized service dealer.