Husqvarna Model 51 Chainsaw Manual

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

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

Features at a Glance

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

Feature	Description
Engine Type	2-stroke, air-cooled
Displacement	50.1 cc
Power Output	3.0 hp
Guide Bar Length	15-20 inches (standard)
Chain Pitch	3/8" or .325"
Chain Brake	Inertia-activated, manual release
Anti-Vibration System	Reduced vibration handles
Automatic Oiling	Adjustable chain lubrication
Air Filtration	Centrifugal air cleaning system
Fuel Tank Capacity	0.55 US quarts

Safety Instructions

Read all instructions before use. Wear protective equipment.

Personal Protective Equipment: Always wear safety glasses, hearing protection, gloves, chainsaw chaps, and sturdy boots.
Work Area Safety: Keep bystanders and pets at least 15 feet away. Ensure secure footing.
Kickback Prevention: Hold saw firmly with both hands. Do not cut with tip of bar. Use reduced-kickback chain.
Chain Brake: Test brake before each use. Ensure it engages properly.

WARNING! Chainsaw kickback can cause severe injury or death. Never operate when tired or under influence.

Assembly & Preparation

Unpack and inspect contents. Assemble on clean, flat surface.

Attach Guide Bar & Chain: Place bar on mounting studs. Fit chain over sprocket and bar groove. Adjust tension.
Fill Fuel: Use fresh 50:1 gasoline/oil mix (2-stroke oil). Do not use automotive oil.
Fill Chain Oil: Use proper bar and chain oil. Check oiler function.
Check Controls: Ensure throttle trigger, choke, and stop switch work smoothly.

CAUTION! Fuel is flammable. Refuel outdoors, away from sparks. Wipe spills immediately.

Specifications

Model: Husqvarna 51
Engine Displacement: 50.1 cc
Power Output: 3.0 hp at 9,000 rpm
Fuel Consumption: Approx. 560 g/kWh
Sound Pressure Level: 106 dB(A)
Vibration Levels: Front handle 4.2 m/s², rear handle 4.8 m/s²
Weight (dry): 11.2 lbs (5.1 kg) without bar and chain
Recommended Bar Length: 15", 18", 20"
Ignition System: Electronic, air gap 0.3 mm
Spark Plug: Champion RCJ7Y or equivalent, gap 0.020"

Controls and Components

Front Handle: Throttle trigger, throttle lockout, choke control. Rear Handle: Stop switch, primer bulb (if equipped).

Main Components: Chain brake handle, chain catcher, front hand guard, muffler, spark arrestor, air filter cover, fuel cap, oil cap, decompression valve (if equipped).

Chain Tensioning: Side-mounted adjuster. Oiling: Adjustable via screw near oil cap. Starting: Combined choke/stop control, decompression valve to reduce pulling force.

Starting & Stopping

Cold Start: Place on flat ground. Engage chain brake. Set choke to full. Press primer 4-6 times. Pull starter cord until engine fires. Move choke to half position. Pull to start. Warm Start: Choke off. Pull to start.

Engage chain brake before starting.
Hold saw firmly with foot in rear handle.
Pull starter cord smoothly; do not yank.
After starting, disengage chain brake before cutting.
To stop: Release throttle, press stop switch.

Tip: If flooded, move choke to off, open throttle fully, pull starter 10-15 times to clear.

Operation Guidelines

Cutting Techniques: Use full throttle when cutting. Let chain do the work.

Felling: Plan escape path. Make notch cut, then felling cut. Use wedges if needed.
Limbing: Stand uphill. Cut from top of log. Beware of springback.
Bucking: Support log. Cut from top. Avoid ground contact with chain.
Kickback Zone: Never let upper quarter of bar tip contact wood.
Chain Brake: If kickback occurs, inertia should activate brake. Test regularly.

WARNING! Do not operate above shoulder height. Do not cut with one hand.

Maintenance Schedule

Daily: Check chain tension, sharpness, brake function. Clean air filter. Check fuel/oil levels.

Weekly: Clean cooling fins, spark arrestor. Inspect spark plug. Check all nuts/bolts.

Monthly: Clean fuel filter. Replace air filter if needed. Check carburetor adjustments.

Seasonally: Replace spark plug. Clean fuel tank. Inspect anti-vibration mounts.

Chain & Bar Care

Sharpening: Use round file and guide. Maintain correct filing angle (typically 30°). Depth gauges must be filed periodically.

Bar Maintenance: Clean bar groove weekly. Flip bar monthly for even wear. Lubricate sprocket tip.

CAUTION! Always wear gloves when handling chain. Chain is extremely sharp.

Storage

Long-term: Empty fuel tank. Run engine until it stops to clear carburetor. Remove chain, clean and oil it. Store in dry place.

CAUTION! Fuel left in tank can degrade and damage engine. Use fuel stabilizer if storing less than 30 days.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine won't start	No spark, fuel, or compression	Check spark plug, fuel mix, choke setting. Clean air filter.
Engine runs poorly	Dirty air/fuel filter, carb adjustment	Clean filters. Adjust carburetor (H/L screws).
Chain doesn't oil	Empty oil tank, clogged oiler	Fill oil. Clean oil holes in bar. Check oil pump.
Chain comes off bar	Loose chain, worn bar, damaged drive links	Tension chain properly. Replace bar or chain if worn.
Excessive vibration	Loose parts, unbalanced chain, worn mounts	Tighten all fasteners. Balance chain. Replace anti-vibration mounts.

Service: For repairs, contact authorized Husqvarna service center.

Support: 1-800-487-5962; www.husqvarna.com