Husqvarna 340 Chainsaw Workshop Manual

The Husqvarna 340 is a professional-grade chainsaw featuring a 40.9cc engine, X-Torq technology for reduced emissions and fuel consumption, Air Injection air filtration, LowVib anti-vibration system, combined choke/stop control, and inertia-activated chain brake. This workshop manual provides detailed technical information for maintenance, troubleshooting, repair, and overhaul procedures. Below are key sections covering specifications, safety, operation, maintenance, disassembly, assembly, and troubleshooting.

Specifications & Technical Data

Key technical specifications for the Husqvarna 340 chainsaw.

Safety Instructions

Essential safety precautions for workshop handling and repair.

1. Personal Protective Equipment (PPE): Always wear safety glasses, gloves, and hearing protection when working.
2. Work Area: Ensure adequate ventilation. Keep workspace clean, dry, and free of flammable materials.
3. Fuel Safety: Drain fuel tank before any repair. No smoking or open flames nearby.
4. Sharp Edges: Handle cutting components (chain, bar) with extreme care. Use protective gloves.
5. Disconnect Spark Plug: Always disconnect the spark plug cap before starting any repair to prevent accidental starting.
6. Lifting: The unit is heavy; use proper lifting techniques or assistance.

WARNING! Failure to follow safety instructions can result in serious injury or death. This manual is for qualified technicians.

Component Identification

Key components and their locations on the Husqvarna 340.

Maintenance Schedule

Recommended maintenance intervals for optimal performance and longevity.

• Daily/Before Use: Check chain tension, sharpness, and lubrication. Inspect for loose nuts/bolts. Check air filter cleanliness.
• Every 10 Operating Hours: Clean air filter. Check spark plug condition and gap (0.5 mm / 0.020").
• Every 20 Operating Hours: Clean cooling fins on cylinder. Clean spark arrestor screen in muffler. Check fuel filter in tank.
• Every 50 Operating Hours: Clean carburetor fuel filter (if equipped). Check clutch drum and sprocket for wear. Inspect anti-vibration mounts.
• Every 100 Operating Hours: Replace fuel filter. Clean/replace air filter. Check piston through exhaust port for scoring.
• Annually/Off-Season: Drain all fuel from tank and carburetor. Perform full inspection. Grease clutch bearing.

Fuel System

Procedures for servicing the fuel tank, lines, filter, and cap.

1. Draining Fuel: Use a syringe or drain plug (if equipped). Dispose of fuel properly.
2. Fuel Filter Replacement: Remove tank cap. Use a wire hook to extract the filter and fuel line. Replace filter and reattach line securely.
3. Fuel Line Inspection: Check lines for cracks, brittleness, or leaks. Replace if damaged.
4. Fuel Tank Vent: Check the small vent in the fuel cap. Clean with a pin if clogged.
5. Pressure/Vacuum Test: After reassembly, test system for leaks using pressure pump.

CAUTION! Use only fresh, high-quality 2-stroke oil mixed with unleaded gasoline (50:1 ratio for Husqvarna XP+ oil).

Ignition System

Testing and replacing the ignition coil, spark plug, and stop switch.

1. Spark Plug Test: Remove plug, reconnect cap, ground electrode against cylinder. Pull starter - look for strong blue spark.
2. Ignition Coil Air Gap: Correct gap between coil legs and flywheel is 0.2-0.3 mm. Adjust by loosening coil screws.
3. Coil Resistance Test: Primary winding: 0.2-0.4 ohms. Secondary winding: 8-12 kOhms. Replace if out of spec.
4. Stop Switch Test: Disconnect wire from coil. Check continuity between switch terminal and ground - should be open circuit when switch is OFF, closed when ON.
5. Flywheel Key: Inspect key on crankshaft for shearing if timing is incorrect.

Cylinder & Piston

Inspection, measurement, and replacement procedures.

1. Remove Muffler: Provides view of piston and cylinder exhaust port.
2. Visual Inspection: Look for scoring, scratches, or aluminum transfer on piston skirt and cylinder walls.
3. Measurement: Use a dial gauge or micrometer to measure piston diameter and cylinder bore. Compare to service limits (wear limit typically 0.1 mm oversize).
4. Decarbonizing: Remove carbon deposits from piston crown and exhaust port with a plastic scraper.
5. Ring Gap: Insert ring into cylinder, square with piston. Measure end gap (service limit approx. 1.0 mm).
6. Reassembly: Lubricate piston and rings with 2-stroke oil. Ensure ring end gaps are aligned with locating pins.

WARNING! Never start the engine without the muffler attached.

Clutch & Chain Drive

Servicing the centrifugal clutch, drum, sprocket, and oil pump.

1. Clutch Removal: Use a clutch holding tool to counterhold. Turn clutch nut clockwise (left-hand thread) to remove.
2. Clutch Inspection: Check shoes for wear, cracking, or glazing. Check springs for fatigue or stretching.
3. Sprocket/Drum: Inspect sprocket teeth for hooking or excessive wear. Replace if worn. Check drum bearing for smooth rotation.
4. Oil Pump:Test oil flow by running saw at idle with bar tip pointed at a piece of cardboard. Adjust flow via screw near pump. Clean oil passages in bar. Engine runs but dies under loadFuel filter/clogged tank vent/ carburetorReplace fuel filter; clean tank vent; clean/rebuild carburetor; check fuel line. Excessive vibrationLoose components/ worn AV mounts/ unbalanced chainTighten all nuts/bolts; inspect and replace anti-vibration mounts; balance or replace chain. Chain does not stop when brake engagedWorn brake band/ contaminated mechanismInspect brake band for wear; clean brake mechanism of oil and sawdust; replace if necessary. Hard starting or no start (spark present)Fuel delivery/ compression/ air leakCheck fuel lines, filter, carburetor; perform compression test (should be >120 psi); pressure test crankcase for leaks.

   Special Tools: Clutch holding tool, flywheel puller, piston stop, compression tester, pressure/vacuum tester.

   Service: For genuine Husqvarna parts and technical support, contact an authorized Husqvarna service dealer.

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