Husqvarna 445 Chainsaw Repair Manual

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

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

Safety Precautions

Always prioritize safety when operating or repairing the Husqvarna 445 chainsaw.

Safety Item	Description
Personal Protective Equipment (PPE)	Always wear safety glasses, hearing protection, gloves, chainsaw chaps, and steel-toed boots.
Work Area	Ensure a clean, well-lit, and ventilated area free from flammable materials.
Fuel Safety	Refuel only when engine is cool, outdoors, and away from ignition sources.
Chain Brake Check	Test the chain brake functionality before each use.
Disconnect Spark Plug	Always disconnect the spark plug wire before performing any repairs or maintenance.
Sharp Chain	Use only a sharp chain to prevent kickback and ensure efficient cutting.
Proper Handling	Hold chainsaw firmly with both hands, right hand on rear handle, left hand on front handle.
Emergency Stop	Familiarize yourself with the location and operation of the stop switch.

Specifications

Engine Type: 2-stroke, single cylinder, X-Torq.
Displacement: 45.7 cc.
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 Length: 13" to 18" (33 cm to 45 cm).
Chain Pitch: 3/8" or .325".
Chain Gauge: 0.050" (1.3 mm).
Weight (Powerhead): 4.9 kg (10.8 lbs).
Ignition System: Electronic, semi-transistorized.
Starting System: Smart Start with combined choke/stop control.

Maintenance Schedule

Regular maintenance is crucial for optimal performance and longevity.

Before Each Use: Check chain tension, sharpness, and lubrication. Inspect for loose nuts/bolts. Test chain brake and throttle lock.
After Each Use: Clean air filter, cooling fins, and external surfaces. Check for damage.
Every 10 Hours: Clean or replace spark plug. Check fuel filter.
Every 20 Hours: Clean or replace air filter. Check carburetor settings.
Every 50 Hours: Replace fuel filter. Clean spark arrestor screen (if equipped).
Every 100 Hours: Check cylinder and piston for carbon deposits. Inspect clutch and sprocket.
Annually: Replace bar and chain if worn. Full inspection of all components.

WARNING! Use only genuine Husqvarna replacement parts and recommended lubricants.

Engine Repair

Procedures for common engine-related repairs.

Cylinder & Piston: Remove muffler, cylinder cover, and cylinder bolts. Inspect piston rings and cylinder walls for scoring. Replace if worn.
Crankcase Seals: Check for air leaks. Replace seals if engine runs lean or has difficulty starting.
Muffler: Remove to clean carbon deposits from spark arrestor screen.
Decompression Valve: Test for proper sealing. Replace if leaking.

CAUTION! Mark all parts during disassembly for correct reassembly. Use a torque wrench for critical fasteners.

Fuel System

Maintenance and repair of fuel tank, lines, and filter.

Drain fuel tank before any service.
Replace fuel filter by pulling old filter out with a wire hook. Insert new filter.
Inspect fuel lines for cracks, brittleness, or leaks. Replace if necessary.
Clean fuel tank cap vent.

Tip: Use fresh, high-quality 2-stroke oil mixed at 50:1 ratio (Husqvarna XP+ recommended).

Ignition System

Troubleshooting and replacing ignition components.

Spark Plug: Gap: 0.020" (0.5 mm). Type: Champion RCJ7Y or equivalent.
Ignition Coil: Check resistance: Primary 0.2-0.4 Ω, Secondary 8-12 kΩ. Replace if out of spec.
Stop Switch: Test for continuity. Ensure wire is not pinched or damaged.
Flywheel & Magneto: Check for cracks and secure key. Air gap should be 0.010" (0.25 mm).

Chain & Bar Assembly

Proper installation, tensioning, and maintenance of the cutting assembly.

Ensure bar is clean and groove is free of debris.
Install chain with cutting teeth facing forward on top of bar.
Tension chain so it snaps back when pulled from middle of bar.
Lubricate chain oiler and check oil flow by running saw briefly near a light surface.
Rotate bar regularly to ensure even wear.
File chain at 30° angle with a round file matching chain gauge.

WARNING! A loose chain can derail and cause serious injury. Always re-tension chain after initial warm-up.

Carburetor Adjustment

Adjusting the H, L, and T screws on the Zama C1Q-S carburetor.

Start with factory settings: L screw - 1 turn open, H screw - 1 turn open, T (idle) screw - 1 turn open.
Warm up engine fully.
Idle Speed (T): Adjust so chain does not move and engine runs smoothly.
Low Speed (L): Turn in until engine speed drops, then out for peak RPM, then in 1/4 turn.
High Speed (H): NEVER exceed 13,500 RPM. Adjust for maximum power without over-revving.
Re-check idle speed after adjusting L and H screws.

CAUTION! Improper carburetor adjustment can cause engine damage. Use a tachometer for precise H screw adjustment.

Troubleshooting Guide

Symptom	Possible Cause	Corrective Action
Engine will not start	No spark, flooded, fuel issue	Check spark plug, air filter, fuel lines. Use cold start procedure.
Engine starts then dies	Clogged fuel filter, carburetor adjustment	Replace fuel filter. Clean carburetor. Check tank vent.
Loss of power	Clogged air filter, spark arrestor, carburetor	Clean/replace air filter. Clean spark arrestor screen. Adjust carburetor.
Chain does not oil	Empty oil tank, clogged oil passages	Fill oil tank. Clean oil holes in bar. Check oil pump drive.
Excessive vibration	Loose components, unbalanced chain, damaged AV mounts	Tighten all fasteners. Balance chain. Inspect anti-vibration mounts.
Chain rotates at idle	Idle speed too high, clutch springs worn	Adjust idle screw (T). Inspect clutch drum and springs.

Parts Diagram

Refer to official Husqvarna parts catalog (Part No. 545 25 41-01) for exploded views and part numbers for the 445 model. Key assembly groups include:

Handle & Control Assembly
Cylinder & Piston Assembly
Crankcase & Crankshaft
Clutch & Sprocket Assembly
Fuel Tank & Carburetor Assembly
Chain Brake & Throttle Lock Assembly
Starter Assembly

Always use the serial number of your saw when ordering parts.

Warranty Information

Husqvarna 445 chainsaws are covered by a limited warranty for residential use. Warranty period and terms vary by region. For warranty service, contact an authorized Husqvarna servicing dealer with proof of purchase.

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

Disclaimer: This manual is for informational purposes. Repairs should be performed by qualified personnel. Husqvarna is a registered trademark of Husqvarna AB.