Husqvarna Chainsaw Repair Manual 445

The Husqvarna Chainsaw 445 is a professional-grade chainsaw featuring a 45.7cc X-Torq engine, Smart Start system, Air Injection centrifugal air cleaning, LowVib anti-vibration system, and inertia-activated chain brake. This manual provides essential information for maintenance, troubleshooting, and repair procedures to ensure optimal performance and safety. Below are key sections covering safety, specifications, maintenance, troubleshooting, and repair instructions.

1. Safety Information 2. Specifications 3. Maintenance Schedule 4. Engine Repair 5. Chain & Bar Maintenance 6. Carburetor Adjustment 7. Ignition System 8. Fuel System 9. Cooling System 10. Troubleshooting 11. Parts Diagram

Safety Information

Always wear protective equipment: helmet, goggles, hearing protection, gloves, and chainsaw chaps. Ensure proper chain tension and sharpness. Never operate a damaged chainsaw.

Safety Component	Description
Chain Brake	Inertia-activated; stops chain within milliseconds during kickback
Right Hand Guard	Protects hand from broken chain
Throttle Lockout	Prevents accidental throttle engagement
Chain Catcher	Catches broken chain to prevent injury
Vibration Dampeners	Reduces vibration to operator's hands

Specifications

Engine Type: 45.7cc X-Torq 2-stroke
Power Output: 2.4 kW (3.2 hp)
Fuel Capacity: 0.5 L (16.9 fl oz)
Oil Capacity: 0.25 L (8.5 fl oz)
Bar Length Options: 13", 15", 18"
Chain Pitch: 3/8"
Chain Gauge: 0.050"
Weight (without bar/chain): 4.9 kg (10.8 lbs)
Ignition System: Electronic, 12V
Spark Plug: NGK BPMR7A (gap 0.5mm)

Maintenance Schedule

Regular maintenance ensures longevity and safe operation.

Daily: Check chain tension and sharpness; clean air filter; inspect bar for wear.
Weekly: Clean cooling fins; check spark plug; inspect fuel lines.
Monthly: Clean carburetor; check clutch and sprocket; inspect anti-vibration elements.
Seasonally: Replace fuel filter; clean exhaust port; check cylinder compression.

WARNING! Always disconnect spark plug before performing maintenance.

Engine Repair

Common engine repairs include piston/cylinder replacement, crankshaft bearing service, and connecting rod inspection.

Remove engine cover and muffler.
Disconnect fuel lines and carburetor.
Remove cylinder head bolts and inspect piston/cylinder for scoring.
Replace piston rings if compression is below 120 psi.
Reassemble with new gaskets; torque cylinder head bolts to 10 Nm.

CAUTION! Use genuine Husqvarna parts for replacements.

Chain & Bar Maintenance

Proper chain maintenance prevents kickback and ensures efficient cutting.

Sharpen chain regularly with 5/32" round file at 30° angle.
Adjust chain tension: loosen bar nuts, adjust tensioning screw until chain snaps back when pulled from bar.
Rotate bar weekly to ensure even wear.
Clean bar groove and oil holes daily.
Replace chain when cutters are worn to 4mm or less.

Tip: Use Husqvarna chain oil for optimal lubrication.

Carburetor Adjustment

The Zama C1M carburetor has three adjustment screws: L (low speed), H (high speed), T (idle).

Start engine and warm up for 5 minutes.
Adjust idle screw (T) until chain just starts to move, then back off 1/4 turn.
Adjust L screw for smooth acceleration from idle.
Adjust H screw for maximum RPM (13,500-14,000 RPM).
Fine-tune L screw after H adjustment.

WARNING! Excessive H screw adjustment can cause engine damage.

Ignition System

The electronic ignition system includes coil, spark plug, and stop switch.

Testing: Check spark plug gap (0.5mm). Test coil resistance: primary 0.2-0.3Ω, secondary 4-6kΩ. Replace if out of specification.

Common Issues: No spark - check stop switch wiring, coil air gap (0.3mm), or replace ignition module.

Fuel System

Components: fuel tank, filter, lines, carburetor, and primer bulb.

Replace fuel filter every 3 months or when clogged.
Inspect fuel lines for cracks; replace if hardened or leaking.
Clean fuel tank vent annually.
Use fresh fuel mix: 50:1 Husqvarna XP+ oil to 89+ octane gasoline.

CAUTION! Never use ethanol-blended fuel above 10%.

Cooling System

The flywheel fan draws air through cooling fins. Keep fins clean for proper engine cooling.

Maintenance: Remove cylinder cover and clean fins with compressed air weekly. Check flywheel fins for damage.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine won't start	No spark, flooded, fuel issue	Check spark plug; dry plug; clean carburetor; fresh fuel.
Engine runs poorly	Dirty air filter, carb adjustment	Clean/replace air filter; adjust carburetor.
Chain won't turn	Clutch worn, sprocket damaged	Inspect clutch springs; replace drive sprocket.
Excessive vibration	Loose parts, worn AV mounts	Tighten all bolts; replace anti-vibration elements.
Overheating	Dirty cooling fins, lean mixture	Clean fins; adjust carburetor richer.

Reset: After repairs, reset maintenance timer if equipped.

Service: Authorized Husqvarna dealers or 1-800-487-5962; www.husqvarna.com