Husqvarna Chainsaw Workshop Manual 450

The Husqvarna Chainsaw Workshop Manual 450 provides comprehensive technical information for the Husqvarna 450 chainsaw model, covering safety procedures, specifications, maintenance, troubleshooting, and repair. This manual is intended for professional technicians and experienced users. Below are key sections for safety, features, maintenance, operation, and repair procedures.

1. Features at a Glance 2. Safety Information 3. Specifications 4. Maintenance Schedule 5. Engine System 6. Fuel System 7. Ignition System 8. Chain & Bar Assembly 9. Troubleshooting 10. Disassembly & Assembly 11. Torque Specifications

Features at a Glance

Key components: X-Torq engine technology, Smart Start system, Air Injection centrifugal air cleaning, LowVib anti-vibration system, combined choke/stop control, inertia activated chain brake.

Feature	Description
Engine Type	2-stroke, single cylinder, X-Torq technology
Displacement	50.2 cm³ (3.06 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 Length	40-45 cm (16-18 in)
Chain Pitch	3/8" or .325"
Weight (without bar & chain)	4.9 kg (10.8 lbs)
Ignition System	Electronic, capacitor discharge
Vibration Dampening	LowVib system with rubber dampeners

Safety Information

Always wear appropriate personal protective equipment (PPE) including safety glasses, hearing protection, gloves, chainsaw chaps, and steel-toed boots.

Pre-operation inspection: Check chain tension, bar condition, fuel/oil levels, and all fasteners.
Starting procedure: Place on flat ground, engage chain brake, use decompression valve if equipped.
Operation: Maintain secure footing, keep bystanders at safe distance, avoid kickback zone.
Transport: Always engage chain brake and install scabbard over bar.

WARNING! Chainsaws are dangerous tools. Never operate with damaged or missing safety devices. Always follow manufacturer safety guidelines.

Specifications

Model: Husqvarna 450
Engine: 2-stroke, air-cooled, X-Torq
Cylinder Bore: 42 mm (1.65 in)
Stroke: 36.3 mm (1.43 in)
Compression Ratio: 9.5:1
Maximum Power Speed: 9000 rpm
Idle Speed: 2700 rpm
Spark Plug: NGK BPMR7A (Champion RCJ7Y)
Gap: 0.5 mm (0.020 in)
Fuel Mix: 50:1 (2% oil) Husqvarna XP+ or equivalent
Carburetor: Zama C1Q-EL28 or Walbro WT-215

Maintenance Schedule

Access maintenance points via appropriate covers and panels.

Daily: Clean air filter, check chain tension, inspect bar for wear, check fuel/oil levels.

Weekly: Clean cooling fins, check spark plug condition, inspect chain brake function, clean fuel filter.

Monthly: Clean carburetor air intake, check anti-vibration elements, inspect clutch and sprocket, clean spark arrestor screen.

Seasonal: Replace fuel filter, check fuel lines, inspect ignition system, replace bar and chain if worn.

Engine System

Cylinder and Piston: Inspect for scoring, measure wear. Crankshaft: Check bearings and seals. Decompression Valve: Test operation. Muffler: Clean regularly to prevent carbon buildup.

Compression test: Should be 120-150 psi (8.3-10.3 bar).
Crankcase pressure test: Check for air leaks.
Piston ring gap: 0.3-0.5 mm (0.012-0.020 in).
Cylinder bore wear limit: 0.08 mm (0.003 in) out of round.

Tip: Always use genuine Husqvarna replacement parts for engine components.

Fuel System

Carburetor adjustment: Use tachometer for precise settings.

Initial settings: L screw 1 turn out, H screw 1 turn out, T screw 1 turn out.
Warm up engine for 5-10 minutes before adjustment.
Adjust idle speed: 2700 rpm (chain should not rotate).
Adjust H screw for maximum speed: 12500-13000 rpm (no load).
Adjust L screw for smooth acceleration from idle.
Fuel lines: Replace if cracked or hardened.
Fuel filter: Replace annually or when clogged.

WARNING! Use fresh fuel mixture (less than 30 days old). Stale fuel causes starting and performance issues.

Ignition System

Spark plug: Clean with wire brush, check gap (0.5 mm/0.020 in). Ignition coil: Air gap 0.3 mm (0.012 in). Stop switch: Test continuity. Flywheel: Check key and magnets.

Chain & Bar Assembly

Chain tension: Proper when snug against bar but can be pulled around by hand. Bar maintenance: Clean groove weekly, flip monthly for even wear. Sprocket: Replace when worn (teeth rounded).

CAUTION! Always stop engine and engage chain brake before adjusting chain tension. Wear protective gloves.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine won't start	No spark, fuel issues, flooded	Check spark, clean plug, fresh fuel, clear flood.
Engine starts then dies	Fuel filter clogged, carb adjustment	Replace filter, adjust carburetor.
Poor performance	Clogged air filter, exhaust screen	Clean air filter, clean spark arrestor.
Chain won't turn	Clutch worn, sprocket damaged	Inspect clutch springs, replace sprocket.
Excessive vibration	AV mounts worn, unbalanced parts	Replace anti-vibration elements, balance clutch.
Oil not feeding	Oil pump failure, clogged ports	Check pump drive, clean oil passages.

Disassembly & Assembly

Use proper tools: Torx drivers, socket set, piston stop, flywheel puller, clutch tool.

Remove top cover, air filter cover, and filter.
Remove starter assembly and fuel tank.
Remove cylinder cover and muffler.
Remove cylinder and piston assembly.
Remove clutch and flywheel for crankshaft access.
Reassembly in reverse order with new gaskets.

Note: Take photos during disassembly for reference during reassembly.

Torque Specifications

Cylinder nuts: 10 Nm (88 in.lb)
Spark plug: 25 Nm (18 ft.lb)
Clutch: 40 Nm (30 ft.lb) - left-hand thread
Flywheel: 40 Nm (30 ft.lb)
Bar nuts: 9-10 Nm (80-88 in.lb)
Muffler bolts: 8 Nm (71 in.lb)
Carburetor screws: 1.5-2 Nm (13-18 in.lb)
Handlebar bolts: 12 Nm (106 in.lb)

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