Husqvarna 51 Chainsaw Parts Manual

The Husqvarna 51 is a professional-grade chainsaw designed for demanding forestry and cutting work. This parts manual provides detailed diagrams, part numbers, and descriptions for all components of the Husqvarna 51 chainsaw, including the engine, cutting equipment, fuel system, ignition system, and housing. Below are key sections for identification, engine parts, cutting attachments, fuel system, ignition system, and ordering information.

Model Identification & Specifications

Key identifiers: Model 51, serial number location on crankcase. Engine type: 2-stroke, air-cooled.

Engine Assembly & Components

Major engine components: Crankcase, crankshaft, connecting rod, bearings, seals.

1. Crankcase Assembly: Includes halves, screws, and gaskets.
2. Crankshaft: Part number for complete assembly with bearings.
3. Connecting Rod: Attached to piston with wrist pin and circlips.
4. Main Bearings & Seals: Crankcase and clutch side.

WARNING! Engine disassembly requires specialized tools. Mark components for correct reassembly.

Cylinder & Piston Assembly

Cylinder: Chrome-plated bore. Piston: Aluminum with two piston rings.

1. Cylinder: Includes cooling fins and transfer ports.
2. Piston: Complete with rings, wrist pin, and circlips.
3. Cylinder Gasket: Between cylinder and crankcase.
4. Decompression Valve: Optional part for easier starting.

CAUTION! Measure piston and cylinder for wear before replacement.

Fuel System & Carburetor

• Fuel Tank: Polyethylene with integrated filter.
• Carburetor: Walbro HDA or Zama C1M.
• Fuel Lines: Supply and return lines with clamps.
• Fuel Filter: In-tank filter element.
• Air Filter: Foam or felt element with cover.
• Impulse Line: Connects crankcase to carburetor pump.
• Throttle Linkage: Throttle rod, springs, and lock.
• Choke/Kill Switch: Integrated control lever.

Ignition System & Electronics

Ignition coil (SEM), spark plug, stop switch, wiring harness.

Components: Ignition coil, spark plug cap, high-tension wire, stop switch, wiring, flywheel, flywheel key.

Testing: Check for spark with plug grounded. Ensure flywheel key is not sheared. Stop switch must break ground connection.

Cutting Equipment & Bar/Chain

Guide bar, saw chain, drive sprocket, chain tensioner, clutch.

1. Guide Bar: Various lengths, .325" or 3/8" pitch.
2. Saw Chain: Matching pitch and gauge (e.g., .058").
3. Drive Sprocket: Rim or spur type.
4. Clutch Assembly: Centrifugal clutch with drum.
5. Chain Tensioner: Screw adjustment with pin.
6. Bar Nuts & Cover: Side cover with nuts.

Tip: Always match chain pitch and gauge to bar and sprocket.

Starter Assembly & Recoil

Recoil starter housing, rope, pulley, spring, pawls.

1. Starter Housing: Plastic assembly with handle.
2. Starter Rope: Specific length and diameter.
3. Recoil Spring: Clock spring inside pulley.
4. Pawl Assembly: Engaging dogs with springs.
5. Starter Handle: Grip with knot.

WARNING! Recoil spring is under tension. Use caution during disassembly.

Housing & External Covers

Top cover, rear handle, anti-vibration mounts, muffler cover, chain brake (if equipped).

Maintenance & Service Intervals

Regular maintenance parts: Air filter, spark plug, fuel filter, chain, bar, sprocket.

CAUTION! Use only genuine Husqvarna parts for optimal performance and safety.

Safety Parts & Features

Chain brake components (band, lever, spring), throttle lockout, right hand guard, front handle.

Parts Ordering & Exploded Views

Ordering: Use part numbers with your serial number. Contact authorized Husqvarna dealer.

Support: Husqvarna Forest & Garden Company; www.husqvarna.com; 1-800-487-5962