Husqvarna Chainsaw 235 Repair Manual

The Husqvarna Chainsaw 235 is a lightweight, professional-grade chainsaw designed for demanding cutting tasks. This repair manual covers essential maintenance, troubleshooting, and repair procedures for the engine, fuel system, ignition, chain brake, guide bar, chain, and other critical components. Below are key sections for safety, specifications, maintenance schedules, disassembly, repair, and reassembly.

Safety Precautions

Before performing any repair or maintenance, ensure the chainsaw is turned off, the spark plug wire is disconnected, and all moving parts have stopped. Wear appropriate personal protective equipment (PPE).

Specifications

• Model: Husqvarna 235
• Engine Type: 2-stroke, single cylinder
• Displacement: 38.2 cc
• Power Output: 1.8 kW (2.4 hp)
• Fuel Tank Capacity: 0.33 L
• Oil Tank Capacity: 0.2 L
• Guide Bar Length: 40 cm (16 inches) standard
• Chain Pitch: 3/8" low profile
• Chain Gauge: 0.050" (1.3 mm)
• Ignition System: Electronic, air gap 0.3 mm
• Spark Plug: Champion RCJ7Y or equivalent, gap 0.5 mm
• Idle Speed: 2700 RPM
• Max Power Speed: 9000 RPM

Maintenance Schedule

Regular maintenance ensures optimal performance and longevity.

1. Daily (Before Use): Check chain tension, sharpness, and lubrication. Inspect for loose nuts/bolts. Check fuel and oil levels.
2. Weekly (or every 10 hours): Clean air filter. Check spark plug condition and gap. Clean cooling fins and external surfaces.
3. Monthly (or every 50 hours): Replace fuel filter. Clean spark arrestor screen (if equipped). Inspect chain brake function.
4. Annually (or every 100 hours): Replace spark plug. Clean carburetor and fuel lines. Check clutch and sprocket wear.
5. As Needed: Replace worn chain, guide bar, or sprocket. Sharpen chain.

WARNING! Never operate a chainsaw with a damaged or malfunctioning safety device, such as the chain brake.

Tools Required

Basic and specialized tools needed for repair.

Engine Repair

Procedures for cylinder, piston, crankshaft, and bearings.

1. Compression Check: Use compression tester. Reading below 110 psi indicates worn piston/rings or cylinder.
2. Cylinder & Piston Inspection: Remove muffler to inspect cylinder walls and piston skirt for scoring.
3. Piston Ring Replacement: Remove cylinder head. Expand rings carefully and slide off piston. Install new rings with gaps aligned with piston pin.
4. Crankshaft Seal Replacement: Remove clutch and flywheel. Pry out old seals. Lubricate new seals and press in flush.
5. Bearings: Check for play or roughness. Replace by pressing out old bearings and pressing in new ones.

CAUTION! Label and organize all parts during disassembly. Use a service manual for specific torque values.

Fuel System

Carburetor, fuel lines, filter, and tank.

1. Carburetor Removal: Disconnect fuel lines and throttle linkage. Remove mounting nuts.
2. Cleaning & Rebuild: Disassemble carburetor. Soak metal parts in solvent. Replace diaphragms, gaskets, and needle valve if kit is available.
3. Adjustment (Standard Settings): Initial settings: L screw 1 turn open, H screw 1 turn open, T screw 1 turn open. Fine-tune for smooth idle and acceleration.
4. Fuel Line Replacement: Replace cracked or stiff lines. Ensure proper routing to avoid kinks.
5. Fuel Filter: Replace by pulling from tank with a wire hook.

Tip: Always use fresh, properly mixed fuel (50:1 Husqvarna XP+ oil ratio recommended).

Ignition System

Spark plug, coil, and flywheel.

1. Spark Plug: Check for fouling, cracks, or incorrect gap. Replace if necessary.
2. Ignition Coil Air Gap: Set to 0.3 mm (0.012") using a feeler gauge between coil legs and flywheel magnets.
3. Testing Coil: Use an ohmmeter. Primary winding: 0.5-2.0 Ω. Secondary (spark plug lead to ground): 5-15 kΩ. Replace if out of spec.
4. Flywheel Removal: Use a puller. Do not hammer. Inspect key and keyway for damage.

WARNING! A weak spark can cause hard starting and poor performance.

Chain & Guide Bar

Maintenance, repair, and replacement.

1. Chain Tension: Adjust so chain snaps back when pulled from guide bar. It should not sag from the bar's underside.
2. Sharpening: Use correct file size. Maintain 30° cutting angle and 10° top plate angle. File all cutters evenly.
3. Depth Gauge (Raker) Filing: Use depth gauge tool to maintain 0.025" (0.65 mm) below cutting edge.
4. Guide Bar Inspection: Check for uneven wear, "rail" wear, and straightness. Flip bar regularly for even wear.
5. Sprocket Inspection: Replace if teeth are hooked or worn. A worn sprocket accelerates chain wear.

CAUTION! A dull or improperly tensioned chain increases kickback risk and operator fatigue.

Chain Brake System

Inspection, testing, and band replacement.

1. Functional Test: With engine off, engage brake by pushing handle forward. It should lock chain securely.
2. Band Inspection: Remove side cover. Check brake band for wear, cracks, or glazing. Thickness below 1.5 mm requires replacement.
3. Band Replacement: Remove clutch drum and sprocket. Unhook spring, remove old band, install new one, and reattach spring.
4. Spring & Mechanism: Ensure return spring is intact and mechanism moves freely without binding.
5. Handle Position: Adjust if necessary so brake engages fully when handle is pushed forward.

WARNING! Never operate the chainsaw if the chain brake does not function correctly.

Troubleshooting

Reset: For electronic ignition modules, disconnect spark plug wire for 30 seconds to reset.

Service: For genuine Husqvarna parts and technical support, visit www.husqvarna.com or contact your local authorized dealer.

Parts Diagram

Refer to the official Husqvarna 235 Parts Manual (Part No. 590 60 01-02) for exploded views and part numbers. Key assembly groups include:

• Engine Assembly (Cylinder, Piston, Crankshaft)
• Carburetor & Air Filter Assembly
• Ignition System (Flywheel, Coil)
• Clutch & Sprocket Assembly
• Chain Brake Assembly
• Guide Bar & Chain
• Handle & Control Assembly
• Fuel & Oil Tanks

Note: Always use genuine Husqvarna replacement parts to ensure compatibility, performance, and safety.