Jonsered 621 Chainsaw Manual

The Jonsered 621 is a professional-grade chainsaw designed for demanding forestry and cutting work. It features a powerful two-stroke engine, robust construction, automatic chain oiling, anti-vibration system, and safety features including a chain brake and throttle lockout. Below are key sections for safety, features, assembly, operation, maintenance, and troubleshooting.

Features at a Glance

Key components: Two-stroke engine, guide bar, cutting chain, chain brake, anti-vibration system, automatic oil pump, air filter, spark plug, throttle trigger, and safety lock.

Safety Information

Read all instructions before use. Wear appropriate PPE: helmet, eye protection, hearing protection, gloves, chainsaw chaps, and steel-toed boots.

1. Keep bystanders and pets at least 15 feet away.
2. Inspect chainsaw before each use for damage, loose parts, and chain sharpness.
3. Ensure chain brake is functional and engages properly.
4. Use correct fuel mix (50:1 gasoline to two-stroke oil).
5. Never operate with one hand or above shoulder height.

WARNING! Risk of kickback—always hold saw firmly with both hands. Keep chain sharp and properly tensioned.

Assembly & Preparation

Unpack and inspect contents. Assemble guide bar and chain, fill fuel and oil tanks.

1. Attach guide bar: Loosen bar nuts, position bar over studs, align chain drive links with sprocket.
2. Install chain: Place chain over bar with cutters facing forward on top, adjust tension.
3. Fill fuel: Use 50:1 mix of unleaded gasoline and Jonsered two-stroke oil.
4. Fill chain oil: Use proper bar and chain oil (not used motor oil).
5. Check controls: Ensure throttle trigger, lockout, and chain brake operate smoothly.

CAUTION! Fuel is flammable—refuel outdoors, away from ignition sources, with engine off and cool.

Specifications

• Model: Jonsered 621.
• Engine Displacement: 61 cc (3.7 cu in).
• Power Output: 3.5 kW (4.7 hp) at 9,000 rpm.
• Fuel Consumption: Approx. 560 g/kWh.
• Sound Pressure Level: 112 dB(A).
• Vibration Level: Front handle 4.2 m/s², rear handle 5.8 m/s².
• Spark Plug: Champion RCJ7Y or equivalent.
• Recommended Bar Length: 15", 18", 20".
• Chain Type: 3/8" pitch, .050" gauge, 72 drive links (for 20" bar).
• Warranty: 2 years commercial, 1 year professional.

Controls and Components

Main controls: Front handle with chain brake, rear handle with throttle trigger, throttle lockout, choke, stop switch, decompression valve (if equipped).

Right Side: Chain brake lever, throttle trigger, throttle lockout, choke lever, primer bulb (if equipped). Left Side: Stop switch, decompression valve, air filter cover. Rear: Fuel cap, oil cap, starter grip.

Chain brake: Engages automatically via inertia or manually by pushing front hand guard forward. Anti-vibration: Rubber dampeners in handles reduce operator fatigue.

Starting & Operation

Starting procedure (cold engine):

1. Place saw on flat ground, clear of debris.
2. Engage chain brake by pushing hand guard forward.
3. Set choke to full position, press decompression valve (if equipped).
4. Pull starter rope briskly until engine fires (1-3 pulls).
5. Move choke to half position, pull until engine starts.
6. Blip throttle to disengage fast idle, release chain brake.

Cutting Tips: Let saw reach full speed before cutting. Use lower quadrant of bar for cutting, upper tip for plunging. Avoid cutting with tip to prevent kickback.

Maintenance Schedule

Daily/Before Use: Check chain tension, sharpness, fuel/oil levels, air filter, external fasteners. Weekly: Clean cooling fins, spark arrestor screen, bar groove. Monthly: Replace spark plug, clean fuel filter, check carburetor adjustment. Yearly: Replace fuel lines, inspect piston/cylinder through exhaust port.

Chain Sharpening & Tensioning

Proper chain tension: Chain should snap back when pulled from bar, with drive links not fully out of bar groove.

1. Loosen bar nuts with combination wrench.
2. Adjust tensioning screw until chain fits snugly against bar.
3. Retighten bar nuts, recheck tension.
4. Sharpen chain: Use round file matching chain pitch (5/32" for 3/8" chain). Maintain 30° filing angle, equal strokes per cutter.
5. Check depth gauges with gauge tool, file down if above limit.

WARNING! Always wear gloves when handling chain. Stop engine and disconnect spark plug before maintenance.

Storage Guidelines

For storage over 30 days:

1. Drain fuel tank and run engine until it stops to clear carburetor.
2. Remove chain, clean and soak in oil; clean bar groove and oil hole.
3. Remove spark plug, add 1 tsp of oil through hole, pull starter slowly to coat cylinder.
4. Clean entire saw, store in dry place, cover to prevent dust.

CAUTION! Do not store with fuel in tank—fuel degrades and can damage carburetor components.

Warranty Information

Jonsered 621 warranty: 2 years for commercial use, 1 year for professional use from date of purchase. Covers defects in materials and workmanship. Does not cover normal wear, misuse, improper maintenance, or non-genuine parts. Proof of purchase required. For warranty service, contact authorized Jonsered dealer or Husqvarna Group. For support, visit www.jonsered.com or call 1-800-487-5961.

Troubleshooting

Service: For repairs, use authorized Jonsered service centers. Use only genuine Jonsered parts.

Support: 1-800-487-5961; www.jonsered.com