Husqvarna 55 Rancher Service Manual

The Husqvarna 55 Rancher is a professional-grade chainsaw designed for demanding forestry and ranch work. This service manual provides comprehensive information for maintenance, troubleshooting, and repair of the 55 Rancher model, covering the engine, fuel system, ignition, chain brake, clutch, guide bar, chain, and all other major components. It is intended for qualified service technicians.

1. Safety Precautions 2. Specifications & Identification 3. Maintenance Schedule 4. Engine Service 5. Fuel System 6. Ignition System 7. Chain Brake & Clutch 8. Guide Bar & Chain 9. Carburetor Adjustment 10. Electrical System 11. Troubleshooting & Repair

Safety Precautions

Before performing any service, disconnect the spark plug wire to prevent accidental starting. Always wear appropriate personal protective equipment (PPE) including gloves and safety glasses. Work in a clean, well-ventilated area. Use only Husqvarna-approved tools and replacement parts.

Hazard	Precaution
Fuel Fire/Explosion	Drain fuel tank in a safe area; no smoking or open flames.
Sharp Components	Handle chain, guide bar, and cutting attachments with extreme care.
Hot Surfaces	Allow engine and muffler to cool completely before servicing.
Spring Tension	Be aware of stored energy in clutch springs and chain brake mechanism.
Chemical Exposure	Use gloves when handling fuel, oil, and cleaning solvents.

Specifications & Identification

Key identifiers and technical data for the Husqvarna 55 Rancher.

Engine Type: 2-stroke, single cylinder, air-cooled.
Displacement: 55 cc (3.4 cu in).
Power Output: Approx. 3.3 kW (4.4 hp).
Fuel Tank Capacity: 0.5 L (0.13 US gal).
Oil Tank Capacity: 0.25 L (0.07 US gal).
Ignition System: Electronic, SEM or equivalent.
Carburetor: Walbro or Zama diaphragm type.
Idle Speed: 2700 RPM.
Max Power Speed: 9600 RPM.
Spark Plug: Champion RCJ7Y or equivalent, gap 0.5 mm (0.020").
Serial Number Location: Stamped on crankcase or starter housing.

Maintenance Schedule

Regular maintenance is critical for performance, safety, and longevity.

Before Each Use: Check chain tension, sharpness, and lubrication. Inspect for loose nuts/bolts. Check throttle trigger and lockout function.
Every 10 Operating Hours: Clean air filter. Check spark plug condition and gap.
Every 20 Operating Hours: Clean cooling fins and cylinder cover. Check fuel filter in tank.
Every 50 Operating Hours: Clean spark arrestor screen in muffler (if equipped). Check clutch drum and sprocket wear.
Every 100 Operating Hours: Replace fuel filter. Inspect and clean carburetor. Check anti-vibration mounts.
Annually or Every 300 Hours: Replace spark plug. Clean fuel tank and lines. Inspect piston through exhaust port.

WARNING! Failure to maintain proper chain tension and lubrication can result in severe injury or damage.

Engine Service

Procedures for cylinder, piston, crankshaft, and bearings.

Cylinder & Piston Inspection: Remove muffler to inspect piston and cylinder for scoring, wear, or carbon buildup.
Compression Test: Use compression gauge. Minimum acceptable compression is typically 110 psi (7.6 bar). Low compression indicates worn piston rings, cylinder, or leaking crank seals.
Crankcase Disassembly: Split crankcase halves using a puller tool. Inspect crankshaft, main bearings, and seals for wear or damage.
Reassembly: Use new gaskets and seals. Apply sealant as specified. Ensure proper alignment of crankshaft and connecting rod.

CAUTION! Mark all components for correct reassembly. Torque all fasteners to specified values.

Fuel System

Servicing the fuel tank, lines, filter, and pump.

Fuel Line Replacement: Drain tank. Remove old lines from tank grommet, filter, and carburetor. Install new lines, ensuring they are routed correctly and not kinked.
Fuel Filter: Replace filter attached to the pickup line inside the tank.
Tank Vent: Check the tank vent for blockage. Clean or replace if fuel flow is restricted.
Fuel Cap: Ensure cap seal is intact and vent is clear.

Tip: Use only fresh, high-quality 2-stroke engine oil mixed with unleaded gasoline at a 50:1 ratio (or as specified for your model year).

Ignition System

Testing and replacing the ignition coil (flywheel magneto), spark plug, and stop switch.

Testing Ignition Coil: Use an ohmmeter. Check primary and secondary winding resistance against specifications. Typical primary resistance: 0.2-0.4 ohms. Secondary (with plug cap): 8-15 kOhms.

Air Gap: Set gap between ignition coil legs and flywheel magnets to 0.2-0.3 mm (0.008-0.012").

Stop Switch: Test for continuity. The switch should be open (no continuity) in RUN position and closed (continuity) in STOP position.

Chain Brake & Clutch

Service procedures for the centrifugal clutch and inertia-activated chain brake.

Clutch Removal: Hold piston with a stopper through spark plug hole. Remove clutch nut (left-hand thread). Inspect clutch shoes, springs, and drum for wear.
Chain Brake Band: Inspect brake band for wear or glazing. Replace if thickness is below specification.
Hand Guard/Trigger Linkage: Check that the hand guard moves freely and engages the brake mechanism correctly when activated.
Function Test: With saw secured and chain brake disengaged, start the engine at idle. A sharp forward motion of the front hand guard should instantly engage the brake and stop the chain.

WARNING! Never operate a chainsaw with a defective or inoperative chain brake.

Guide Bar & Chain

Maintenance of the cutting attachment.

Bar Maintenance: Clean bar groove regularly. Flip bar weekly for even wear. Dress bar rails with a flat file if burred.
Chain Sharpening: Use correct round file size (typically 4.0 mm or 5/32"). Maintain correct filing angle (usually 30°). Ensure all cutters are filed to equal length.
Depth Gauge Setting: File down depth gauges (rakers) to maintain proper height (approx. 0.025" / 0.65 mm below cutter tip). Use a depth gauge tool.
Sprocket: Inspect drive sprocket (clutch drum) for wear. Replace if teeth are hooked or excessively worn. Use spur or rim sprocket as applicable.

Carburetor Adjustment

Procedure for adjusting the H (High), L (Low), and T (Idle) screws. Engine must be at operating temperature.

Initial Settings: Turn H and L screws gently clockwise until seated, then back out 1 turn each as a starting point.
Idle Speed (T): Adjust so chain does not move at idle, but engine runs smoothly.
L-Screw (Low Speed): Adjust for smooth acceleration from idle without hesitation.
H-Screw (High Speed): Adjust for maximum RPM, then richen slightly (turn counter-clockwise) to achieve specified max no-load RPM (9600 RPM). NEVER LEANER THAN MAX RPM SETTING.
Final Check: Re-check idle and acceleration. Chain must remain stationary at idle.

CAUTION! An improperly adjusted carburetor can cause severe engine damage from lean running.

Electrical System

Overview of wiring, stop switch, and ignition components.

Component	Test/Service
Stop Switch	Continuity test. Replace if faulty.
Wiring Harness	Inspect for cracks, chafing, or broken connections, especially near handles and mounts.
Spark Plug Cap	Check internal resistor (approx. 5 kOhms). Ensure tight connection on plug.
Flywheel & Key	Inspect for cracks. Check woodruff key for shear; ensures correct ignition timing.

Troubleshooting & Repair

Symptom	Possible Cause	Corrective Action
Engine will not start	No spark, flooded, fuel issue	Check spark, plug condition. Dry plug if flooded. Check fuel flow, filter, and carburetor.
Engine starts but dies	Clogged fuel filter, tank vent, carburetor	Replace fuel filter. Clean tank vent. Service carburetor diaphragm and gaskets.
Lacks power under load	Clogged air filter, exhaust screen, carb adjustment, low compression	Clean air filter and spark arrestor. Adjust carburetor. Perform compression test.
Chain does not stop with brake	Worn brake band, sticky mechanism	Inspect and replace brake band. Clean and lubricate pivot points.
Excessive vibration	Loose components, worn AV mounts, unbalanced clutch/flywheel	Tighten all fasteners. Check and replace anti-vibration mounts. Inspect clutch for damage.
Chain oil not flowing	Empty oil tank, clogged oil passages, defective pump	Fill tank. Clean bar oil holes and tank pickup filter. Test/replace oil pump.

Service Support: For technical assistance and genuine Husqvarna parts, contact an authorized Husqvarna service dealer or visit www.husqvarna.com.