Husqvarna Model 51 Chainsaw Owners Manual

The Husqvarna Model 51 is a professional-grade chainsaw designed for demanding forestry and cutting applications. It features a high-performance 2-stroke engine, X-Torq technology for reduced emissions and fuel consumption, an inertia-activated chain brake, LowVib anti-vibration system, and an ergonomic design for operator comfort and control. Below are key sections for safety, features, assembly, operation, maintenance, and troubleshooting.

Features at a Glance

Key components: High-performance 2-stroke engine, X-Torq technology, Inertia-activated chain brake, LowVib anti-vibration system, Combined choke/stop control, Air Injection centrifugal air cleaning system.

Safety Information

Read and understand all safety warnings before operation.

1. Personal Protective Equipment (PPE): Always wear chainsaw protective pants, safety boots, gloves, eye protection, and hearing protection.
2. Work Area Safety: Keep bystanders and pets at least 15 meters away. Ensure secure footing.
3. Chain Brake: Test chain brake function before each use. Use front hand guard to activate.
4. Kickback Zone: Avoid contact with the upper quadrant of the bar tip.
5. Fuel Safety: Refuel outdoors, away from ignition sources. Use fuel mix of 50:1 (2% oil).

WARNING! Chainsaws are dangerous tools. Failure to follow safety instructions can result in serious injury or death.

Assembly & Preparation

Unpack and inspect contents. Assemble bar and chain.

1. Attach guide bar: Place bar on studs, align chain tensioning pin.
2. Install chain: Ensure cutting teeth face forward on top of bar. Fit chain over sprocket.
3. Install bar nut and cover: Hand-tighten nuts, then tighten with tool.
4. Tension chain: Adjust tensioning screw until chain snaps back when pulled from bar.
5. Fill fuel and oil: Use Husqvarna XP 2-stroke oil (or equivalent JASO FD rated) mixed with unleaded gasoline (min 89 octane). Fill chain oil with Husqvarna chain oil.

CAUTION! Ensure chain is properly tensioned. A loose chain can derail; an overtightened chain can damage the engine.

Specifications

• Model: Husqvarna 51.
• Engine Displacement: 50.1 cc.
• Power Output: 2.8 kW (3.8 hp).
• Fuel/Oil Ratio: 50:1 (2% oil).
• Idle Speed: 2700 RPM.
• Maximum Power Speed: 9000 RPM.
• Sound Pressure Level: 106 dB(A).
• Vibration Level (front/rear handle): 3.5/4.5 m/s².
• Spark Plug: Champion RCJ7Y or NGK BPMR7A (gap 0.5 mm).
• Carburetor: Walbro HDA.

Controls and Components

Front Handle: Contains throttle trigger and throttle trigger lockout. Rear Handle: Contains master control lever (choke/stop), start/stop switch.

Master Control Lever Positions: - STOP (0): Engine off. - CHOKE (full left): For cold start. - RUN (middle): Normal operation. - FAST IDLE/HALF CHOKE (between CHOKE and RUN): For warm start or after flooding.

Other Controls: Chain brake lever/hand guard, chain tensioning screw, fuel and oil tank caps, decompression valve (if equipped), primer bulb (if equipped).

Starting & Stopping

Cold Start: 1. Engage chain brake. Place on firm ground. 2. Press decompression valve (if equipped). 3. Set master control lever to CHOKE. 4. Pull starter handle until engine fires (1-4 pulls). 5. Move lever to FAST IDLE/HALF CHOKE position. 6. Pull starter handle to start. Allow to idle for 10 seconds. 7. Squeeze throttle trigger to disengage fast idle.

Warm Start: Set lever to FAST IDLE/HALF CHOKE and pull starter.

Stopping: Release throttle, let engine idle, move master control lever to STOP (0).

Tip: Always engage chain brake when starting or carrying the saw.

Operation Guidelines

Proper cutting techniques ensure safety and efficiency.

1. Felling: Plan escape path (45° behind tree). Make notch cut (1/3 diameter), then felling cut. Use wedges if needed.
2. Limbing: Stand on left side of trunk. Cut branches from top down. Beware of spring-loaded branches.
3. Bucking: Support log. Cut from top, avoid pinching bar. Use undercut if needed.
4. Throttle Control: Apply full throttle during cuts. Allow chain to reach full speed before contacting wood.
5. Kickback Prevention: Maintain secure grip, do not cut with bar tip, keep chain sharp and tensioned.

WARNING! Never operate chainsaw above shoulder height or with one hand.

Maintenance Schedule

CAUTION! Always disconnect spark plug wire before performing maintenance.

Chain & Bar Care

Proper care extends life and improves performance.

1. Sharpening: Use round file matching chain pitch (5/32" for 3/8" pitch). Maintain 30° cutting angle, 10° top plate filing angle. File all cutters to equal length.
2. Depth Gauges: File down with flat file when sharpening. Maintain 0.025" (0.65 mm) below cutting edge.
3. Bar Maintenance: Clean bar groove weekly. Flip bar monthly for even wear. Dress bar rails with flat file if burred.
4. Lubrication: Always use quality chain oil. Check oil flow by pointing bar at light surface—oil streak should appear.

Tip: A sharp chain reduces operator fatigue and increases cutting efficiency.

Storage

Prepare chainsaw for extended storage.

1. Empty fuel tank and run engine until it stops to clear carburetor.
2. Remove chain, clean, and soak in oil. Clean bar and store separately.
3. Clean entire saw, especially cooling fins and air filter.
4. Store in dry, cool place, protected from dust and moisture.
5. For storage over 30 days, remove spark plug and add 1 teaspoon of engine oil through spark plug hole. Pull starter cord slowly to distribute oil, then reinstall plug.

CAUTION! Never store with fuel in tank for more than 30 days. Fuel can deteriorate and damage engine components.

Troubleshooting

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

Support: Husqvarna AB, SE-561 82 Huskvarna, Sweden. In USA: Husqvarna Forest & Garden Company, 9006 Perimeter Woods Drive, Charlotte, NC 28216. Phone: 1-800-487-5962. www.husqvarna.com