Husqvarna 3120 Chainsaw Manual

The Husqvarna 3120 is a professional-grade, high-powered chainsaw designed for demanding forestry and logging applications. It features a large displacement engine, robust construction, advanced safety systems, and professional-grade components for maximum durability and performance. Below are key sections for safety, features, assembly, operation, maintenance, and troubleshooting.

Features at a Glance

Key components: High-torque engine, Anti-Vibration System (AVS), Air Injection cleaning system, Quick-release air filter, Combined choke/stop control, Inertia-activated chain brake, Side-mounted chain tensioner.

Safety Information

Read and understand all instructions before operation. Wear appropriate PPE.

1. Personal Protective Equipment (PPE): Always wear chainsaw chaps, helmet with face shield and hearing protection, gloves, and steel-toe boots.
2. Work Area Safety: Clear work area of obstacles and ensure secure footing. Keep bystanders at a safe distance.
3. Fuel Safety: Refuel in a well-ventilated area with engine off and cool. Use approved fuel containers.
4. Kickback Awareness: Understand kickback zone (upper quadrant of bar tip). Maintain secure grip and proper stance.
5. Chain Brake: Test chain brake function before each use.

WARNING! Failure to follow safety instructions can result in serious injury or death. This is a professional-grade tool requiring proper training.

Assembly & Preparation

Unpack and inspect contents. Assemble on a clean, stable surface.

1. Attach guide bar and chain: Place bar over studs, loop chain over sprocket and bar, adjust tension with side screw.
2. Fill fluids: Add high-quality 2-stroke engine oil mixed with gasoline (ratio 1:50) to fuel tank. Fill bar and chain oil reservoir with specified oil.
3. Install air filter: Ensure filter is clean and properly seated in housing.
4. Check controls: Verify throttle trigger, throttle lockout, stop switch, and chain brake operate smoothly.

CAUTION! Ensure chain is installed with cutting teeth facing forward on top of bar. Chain must move freely when pulled by hand.

Specifications

• Engine Type: 2-stroke, single cylinder.
• Displacement: 118.8 cc (7.25 cu. in.).
• Power Output: High torque for demanding cuts.
• Fuel/Oil Ratio: 1:50 (2% mix) with Husqvarna 2-stroke oil or equivalent.
• Recommended Bar Lengths: 24" to 42" (60 cm to 106 cm).
• Chain Pitch/Gauge: .404" pitch, .063" gauge (standard).
• Ignition System: Electronic, capacitor discharge (CDI).
• Weight (powerhead only): Approximately 9.5 kg (20.9 lbs).
• Sound Pressure Level: Exceeds 100 dB(A). Hearing protection required.

Controls and Functions

Right Side: Throttle trigger, Throttle lockout, Front hand guard/chain brake, Stop switch. Left Side: Choke/stop control, Decompression valve, Rear handle with AV mounts.

Top/Back: Combined choke/stop control, Air filter cover, Fuel cap, Oil cap. Bottom: Muffler, Spark plug access.

Operation: Throttle lockout must be depressed before throttle trigger can be engaged. Pull back front hand guard to activate chain brake; push forward to disengage. Choke control has three positions: Run, Half-throttle/choke, Full choke.

Starting & Stopping Procedure

Cold Start: Place saw on firm ground. Activate chain brake. Set choke control to full choke. Press decompression valve. Pull starter cord sharply until engine fires. Move choke to half-throttle position. Pull starter cord again until engine starts. Briefly blip throttle to return choke to run position. Release chain brake.

1. Warm Start: Follow procedure but start from half-throttle position, not full choke.
2. Stopping: Release throttle and allow engine to idle. Push stop switch to "0" or "STOP" position.

Tip: Always engage chain brake before starting. Never drop-start the saw.

Operation Guidelines

Use proper cutting techniques to maintain control and reduce fatigue.

1. Felling: Plan escape path. Use proper notch and back cut techniques. Never cut above shoulder height.
2. Limbing: Stand on left side of trunk. Use the bumper spike for leverage. Beware of spring-loaded branches.
3. Bucking: Support log properly. Cut from top unless pinching is a risk, then use undercut.
4. Kickback Prevention: Keep saw at full throttle during cut. Do not let the upper quadrant of the bar tip contact wood or other objects.
5. Pushing/Pulling: If chain stops in cut, do not force it. Stop engine, release tension (e.g., with a wedge), and restart.

WARNING! Always cut at full throttle. Never operate with one hand. Be aware of reactive forces (kickback, pushback, pull-in).

Maintenance Schedule

Daily (Before Use): Check chain tension and sharpness, check fluid levels, inspect air filter, test chain brake and throttle lockout, check for loose nuts/bolts.

Weekly/Every 10 Hours: Clean air filter, clean cooling fins, check spark plug condition, clean external surfaces, inspect guide bar for wear and groove condition.

Monthly/Every 50 Hours: Clean fuel filter, replace spark plug, clean carburetor air intake, check fuel lines for cracks, clean spark arrestor screen in muffler (if equipped).

Annually/Seasonal: Professional servicing recommended. Check clutch, sprocket, and AV mounts for wear.

Chain Sharpening & Tensioning

Sharpening: Use correct round file size for chain (.404 pitch typically uses a 7/32" file). Maintain correct filing angle (typically 30°). File all cutters to equal length. Check and adjust depth gauges (rakers) with a flat file and gauge.

1. Tensioning: Loosen bar nuts. Use side tensioner to adjust until chain fits snugly against bar but can be pulled around by hand. Tighten bar nuts while lifting tip of bar. Re-check tension.

CAUTION! Always wear gloves when handling chain. A dull or improperly tensioned chain is dangerous and inefficient.

Storage Guidelines

Long-Term Storage (Over 30 Days): Drain fuel tank and run engine until it stops to clear carburetor. Drain bar and chain oil tank. Remove chain, clean it and the guide bar, and coat with oil. Clean entire saw. Store in a dry, cool place, covered.

CAUTION! Never store with fuel in the tank for extended periods. Old fuel can cause starting problems and damage the engine.

Troubleshooting

Service: For repairs beyond basic maintenance, contact an authorized Husqvarna service dealer.

Support: Husqvarna AB, SE-561 82 Huskvarna, Sweden. For your local dealer, visit www.husqvarna.com.