Husqvarna 440 Chainsaw Service Manual

The Husqvarna 440 is a professional-grade chainsaw featuring a 40.9cc X-Torq engine for reduced emissions and fuel consumption, an air injection system for extended air filter life, a combined choke/stop control, inertia-activated chain brake, LowVib anti-vibration system, and Smart Start for easier starting. This service manual provides detailed instructions for maintenance, troubleshooting, and repair procedures to ensure optimal performance and safety.

1. Safety Precautions 2. Technical Specifications 3. Component Identification 4. Maintenance Schedule 5. Fuel System Service 6. Ignition System 7. Chain & Bar Maintenance 8. Carburetor Adjustment 9. Cooling System 10. Troubleshooting Guide 11. Torque Specifications

Safety Precautions

Always prioritize safety when servicing the Husqvarna 440 chainsaw. Wear appropriate personal protective equipment (PPE).

Precaution	Description
Disconnect Spark Plug	Always disconnect the spark plug boot before performing any maintenance to prevent accidental starting.
Fuel Safety	Drain fuel tank in a well-ventilated area before major service. Use approved fuel containers.
Chain Handling	Wear cut-resistant gloves when handling the chain. Ensure chain brake is engaged when not in use.
Work Area	Service in a clean, well-lit area free from sparks, flames, or ignition sources.
Component Replacement	Use only genuine Husqvarna replacement parts to ensure compatibility and safety.

Technical Specifications

Engine Displacement: 40.9 cc
Engine Type: 2-stroke, X-Torq
Power Output: 2.4 kW (3.2 hp)
Fuel Tank Volume: 0.47 L (0.12 US gal)
Oil Tank Volume: 0.26 L (0.07 US gal)
Recommended Bar Lengths: 13" to 18" (33 cm to 45 cm)
Chain Pitch: 3/8" or .325"
Weight (Powerhead): 4.9 kg (10.8 lbs)
Ignition System: Electronic, SEM
Spark Plug: Champion RCJ7Y or equivalent

Component Identification

Key components: Front Handle, Rear Handle, Throttle Trigger, Throttle Lockout, Combined Choke/Stop Control, Air Filter Cover, Muffler, Chain Brake Handle, Chain Catcher, Chain Tensioner, Fuel Cap, Oil Cap, Decompression Valve (if equipped).

WARNING! Familiarize yourself with all controls and components before disassembly.

Maintenance Schedule

Follow this schedule to maintain performance and longevity.

Before Each Use: Check chain tension, sharpness, and lubrication. Inspect for loose nuts/bolts.
Every 10 Hours: Clean air filter. Check spark plug condition.
Every 20 Hours: Clean spark arrestor screen in muffler (if equipped). Clean cooling fins.
Every 50 Hours: Replace fuel filter. Clean carburetor air intake.
Every 100 Hours: Replace spark plug. Check fuel lines for cracks.
Seasonal: Empty fuel system for long-term storage. Sharpen or replace chain as needed.

Fuel System Service

Includes tank, lines, filter, and carburetor.

Fuel Filter Replacement: Drain tank. Use a wire hook to extract old filter. Install new filter.
Fuel Lines: Inspect for brittleness or cracks. Replace using OEM lines. Ensure proper routing.
Carburetor Removal: Disconnect fuel line, throttle linkage, and choke rod. Remove mounting nuts.
Diaphragm Check: Inspect pump and metering diaphragms for stiffness or holes.

CAUTION! Use fresh, clean fuel mix (50:1 Husqvarna XP+ oil recommended).

Ignition System

Testing and component replacement.

Spark Plug: Gap 0.5 mm (0.020"). Replace if electrodes are worn or ceramic is cracked.
Ignition Coil Air Gap: Set to 0.3 mm (0.012") using a feeler gauge between flywheel and coil legs.
Stop Switch Test: With boot off, check for continuity between switch wire and ground when pressed.
Flywheel: Check for cracks or sheared key. Torque nut to 40-50 Nm (30-37 ft-lb).

Chain & Bar Maintenance

Proper care ensures cutting efficiency and safety.

Chain Tensioning: Loosen bar nuts. Adjust tensioning screw until chain snaps back when pulled from bar.
Sharpening: Use correct round file size. Maintain proper filing angle (typically 30°). File all cutters evenly.
Bar Maintenance: Clean bar groove. Flip bar regularly for even wear. Dress rails with a flat file if burred.
Oil Flow Check: Run saw at high idle over light-colored surface; look for oil sling pattern.

Tip: Always match chain pitch and gauge to the bar and sprocket.

Carburetor Adjustment

Factory settings (H, L, T screws) are typically pre-set. Fine-tuning may be needed for altitude/temperature.

Initial Setting: Turn H and L screws gently clockwise until seated, then back out 1 turn each.
Idle (T) Screw: Adjust so chain does not move at idle, but engine runs smoothly.
Final Tuning: Warm up engine. Adjust L for smooth acceleration. Adjust H for maximum RPM (consult tachometer).
WARNING! Excessive leaning (turning screws out too far) can cause engine damage.

Cooling System

Prevents engine overheating.

Cleaning Fins: Remove cylinder cover. Use a brush and compressed air to clean cylinder fins and flywheel fan.
Air Intake: Ensure intake at rear handle is not blocked.
Muffler Screen: Remove and clean spark arrestor screen with a wire brush. Replace if damaged.

CAUTION! Never operate saw with a dirty cooling system.

Troubleshooting Guide

Symptom	Possible Cause	Corrective Action
Engine will not start	No spark, flooded, fuel issue	Check spark plug, ignition. Use cold start procedure. Check fuel filter/lines.
Engine starts then dies	Clogged fuel filter, carburetor, air leak	Replace fuel filter. Clean carburetor. Check crankcase seals.
Lacks power under load	Clogged air filter, muffler screen, carb adjustment	Clean/replace air filter. Clean spark arrestor. Check H screw setting.
Chain does not oil	Clogged oil port, faulty pump, wrong oil	Clean bar oil holes. Check oil pump drive and diaphragm. Use correct bar oil.
Excessive vibration	Loose components, unbalanced chain, AV mounts	Tighten all fasteners. Balance chain. Inspect anti-vibration mounts.

Torque Specifications

Critical fasteners must be tightened to specified values.

Component	Torque (Nm)	Torque (ft-lb)
Cylinder Cover Nuts	4-5	3.0-3.7
Clutch Drum Nut	35-45	26-33
Flywheel Nut	40-50	30-37
Spark Plug	25-30	18-22
Guide Bar Nuts	9-10	6.5-7.4
Muffler Bolts	8-10	5.9-7.4

Service Support: For technical assistance or parts, contact Husqvarna at 1-800-487-5962 or visit www.husqvarna.com.