Husqvarna Model 51 Chainsaw Owners Manual

The Husqvarna Model 51 is a professional-grade chainsaw designed for demanding cutting tasks. It features a powerful 2-stroke engine, automatic chain oiling, anti-vibration system, inertia-activated chain brake, and easy-start technology. Below are key sections for safety, features, assembly, operation, maintenance, troubleshooting, and specifications.

1. Features at a Glance 2. Safety Information 3. Assembly & Preparation 4. Specifications 5. Controls and Components 6. Starting & Stopping 7. Operating Instructions 8. Maintenance Schedule 9. Chain & Bar Care 10. Storage Guidelines 11. Troubleshooting

Features at a Glance

Key components: 2-stroke engine, guide bar, cutting chain, chain brake, throttle trigger, choke control, fuel tank, oil tank, and anti-vibration handles.

Feature	Description
Engine Type	2-stroke, air-cooled gasoline engine
Displacement	51.7 cc (3.15 cu. in.)
Power Output	3.1 kW (4.2 hp)
Fuel Tank Volume	0.55 L (18.6 fl. oz.)
Oil Tank Volume	0.26 L (8.8 fl. oz.)
Guide Bar Length	15-20 inches (38-51 cm) options
Chain Pitch	3/8" or .325" (depending on configuration)
Weight (dry)	5.5 kg (12.1 lbs) without bar and chain
Ignition System	Electronic, capacitor discharge
Chain Brake	Inertia-activated, manual release

Safety Information

Read and understand all safety instructions before operation.

Personal Protective Equipment (PPE): Always wear safety helmet, hearing protection, eye protection, gloves, chainsaw chaps/pants, and sturdy boots.
Work Area Safety: Keep bystanders and pets at least 15 meters away. Ensure secure footing and clear escape path.
Fuel Safety: Refuel outdoors, with engine off and cool. Use clean, unleaded gasoline mixed with 2-stroke oil (50:1 ratio).
Kickback Danger: Be aware of kickback zone (upper quadrant of bar nose). Never cut with this area. Maintain firm grip.

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

Assembly & Preparation

Unpack and inspect contents. Assemble guide bar and chain.

Attach guide bar: Place bar onto drive sprocket, align with mounting studs, install bar nuts finger-tight.
Install chain: Place chain over bar sprocket, ensuring cutting teeth face forward on top of bar. Adjust tension.
Fill tanks: Add fuel mix to fuel tank. Add bar and chain oil to oil tank. Use recommended oils only.
Check controls: Ensure throttle trigger, throttle lockout, and chain brake function correctly.

CAUTION! Chain must be properly tensioned. Too loose can derail; too tight can damage bar and engine.

Specifications

Model: Husqvarna 51
Engine Displacement: 51.7 cc
Power Output: 3.1 kW (4.2 hp) @ 9000 rpm
Max Recommended Bar Length: 20" (51 cm)
Fuel/Oil Ratio: 50:1 (Husqvarna HP or equivalent 2-stroke oil)
Idle Speed: 2700 rpm
Spark Plug: Champion RCJ7Y or NGK BPMR7A (gap 0.5 mm / .020")
Sound Pressure Level: 106 dB(A) at operator's ear
Vibration Level (front/rear handle): 4.5/2.5 m/s²
Warranty: 2 years consumer, 1 year professional

Controls and Components

Front Handle: Contains throttle trigger, throttle lockout, and choke control. Rear Handle: Contains master control lever (combines choke/stop control), ignition switch, and rear hand guard.

Master Control Lever Positions: STOP (engine off), RUN (normal operation), CHOKE (cold start).

Other Components: Chain brake handle, chain catcher, muffler, spark arrestor screen, air filter cover, decompression valve (optional), primer bulb (optional on some models).

Starting & Stopping

Cold Start:

Place saw on firm, level ground. Engage chain brake.
Set master control lever to CHOKE position.
Press decompression valve (if equipped).
Pull starter handle until engine fires (1-2 pulls).
Move master control lever to RUN position.
Pull starter handle again until engine starts.

Warm Start: Master control lever in RUN position. No choke.

Stopping: Release throttle. Move master control lever to STOP position.

Operating Instructions

Basic Cutting Techniques:

Felling: Plan escape path (45° behind fall direction). Make notch cut (1/3 tree diameter). Make felling cut (horizontal, leaving hinge).
Limbing: Stand uphill. Cut branches from trunk using pulling chain (bottom of bar).
Bucking: Support log. Cut from top, avoid pinching bar. Use wedges if needed.
Maintain Chain Speed: Apply full throttle before contacting wood.
Chain Brake Test: Before each use, test by pulling brake handle forward with engine off. Should engage with a click.

Tip: Let saw do the work. Don't force it. Keep chain sharp.

Maintenance Schedule

Interval	Task
Daily / Before Use	Check chain tension, sharpness, and lubrication. Check fuel/oil levels. Inspect for loose parts/damage. Clean air filter.
Every 10 Hours	Clean spark arrestor screen. Check bar for wear, clean bar groove and oil holes.
Every 20 Hours	Replace air filter (more often in dusty conditions). Check spark plug.
Every 50 Hours	Clean cooling fins. Check fuel filter. Clean carburetor air intake.
Every 100 Hours	Replace spark plug. Check clutch, drum, and sprocket for wear.
Annually / End of Season	Full service: Clean fuel tank, check all hoses and connections, check anti-vibration elements.

Chain & Bar Care

Sharpening: Use correct round file size (typically 4.0mm / 5/32" for 3/8" chain). Maintain 30° filing angle. File all cutters to equal length. File depth gauges with gauge tool.

Tensioning: Chain should be snug against bar but pull freely by hand. Re-tension when warm. Adjust via side tensioning screw.

Bar Maintenance: Flip bar weekly for even wear. Clean oil holes and groove. Dress rails with flat file if burred.

CAUTION! Always wear gloves when handling chain. A sharp chain is safer and more efficient.

Storage Guidelines

For storage longer than 30 days:

Drain fuel tank and run engine until it stops to empty carburetor.
Remove spark plug, add 1 teaspoon of 2-stroke oil into cylinder, pull starter 2-3 times, reinstall plug.
Clean entire saw, especially cooling fins and air filter.
Remove chain, clean and soak in oil. Store bar and chain in oiled paper.
Store in cool, dry place, protected from dust and moisture.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine won't start	No spark, flooded, stale fuel, clogged filter	Check spark plug, use fresh fuel mix, clean air/fuel filter, avoid over-choking.
Engine starts then dies	Clogged fuel filter, carburetor issues, vent blocked	Replace fuel filter, clean carburetor, check tank vent.
Poor performance/loss of power	Dirty air filter, clogged spark arrestor, dull chain	Clean/replace air filter, clean spark arrestor screen, sharpen chain.
Chain doesn't turn	Chain brake engaged, clutch worn, sprocket damaged	Disengage chain brake, inspect clutch and sprocket, replace if worn.
Excessive vibration	Loose components, unbalanced chain, damaged AV mounts	Tighten all nuts/bolts, balance chain, inspect anti-vibration mounts.
Chain not oiling	Empty oil tank, clogged oil holes, faulty pump	Fill tank, clean bar oil holes, check oil pump and lines.

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

Customer Support: Husqvarna USA: 1-800-487-5962; www.husqvarna.com/us