Craftsman 20 Chainsaw Manual

The Craftsman 20 Chainsaw is a powerful 20-inch gas-powered chainsaw designed for demanding cutting tasks. It features a robust 50cc 2-stroke engine, automatic oiling system, inertia-activated chain brake, anti-vibration handles, tool-free chain tensioning, and a quick-start system. Below are key sections for safety, features, assembly, operation, maintenance, and troubleshooting.

1. Features at a Glance 2. Assembly & Setup 3. Safety Instructions 4. Specifications 5. Controls and Components 6. Fuel & Oil Mixing 7. Starting & Operation 8. Maintenance Schedule 9. Chain Sharpening 10. Storage 11. Troubleshooting

Features at a Glance

Key components: 50cc 2-stroke engine, 20-inch Oregon bar and chain, automatic chain oiler, inertia-activated chain brake, anti-vibration system, side-access chain tensioner, and quick-start primer bulb.

Feature	Description
Engine	50cc 2-stroke air-cooled engine
Bar Length	20 inches (Oregon)
Chain	.325" pitch, 72 drive links
Chain Brake	Inertia-activated for kickback protection
Oiling System	Automatic with manual override
Anti-Vibration	Rubber-mounted handles
Chain Tensioning	Side-access, tool-free adjustment
Starting System	Primer bulb and decompression valve
Fuel Tank	Capacity: 16.9 fl oz (500 ml)
Oil Tank	Capacity: 10.1 fl oz (300 ml)

Assembly & Setup

Unpack and inspect all parts. Assemble on a clean, flat surface.

Attach the guide bar: Place bar onto mounting studs, align chain with drive sprocket.
Install chain: Ensure cutting teeth face forward on top of bar.
Tension chain: Use side knob to adjust tension until chain snaps back when pulled.
Fill tanks: Add proper fuel/oil mix to fuel tank and bar & chain oil to oil tank.

WARNING! Always wear cut-resistant gloves during assembly. Ensure chain is properly tensioned before use.

Safety Instructions

Read all instructions before operation. Always wear proper PPE.

Personal Protective Equipment: Wear safety glasses, hearing protection, gloves, steel-toe boots, and chainsaw chaps.
Clear work area: Remove tripping hazards and ensure bystanders are at least 15 feet away.
Check controls: Verify chain brake, throttle lock, and stop switch function properly.
Fuel safely: Refuel outdoors, away from ignition sources. Wipe spills immediately.

CAUTION! Never operate a chainsaw from a ladder or unstable surface. Beware of kickback.

Specifications

Engine Displacement: 50cc
Power Output: 3.2 HP
Fuel Type: 50:1 gasoline to 2-stroke oil mix
Bar Length: 20 inches
Chain Pitch: .325"
Chain Gauge: 0.050"
Drive Links: 72
Weight (dry): 12.8 lbs (5.8 kg)
Sound Level: 105 dB(A) at operator's ear
Vibration Level: Front handle: 4.2 m/s², Rear handle: 5.1 m/s²

Controls and Components

Main Controls: Front handle with chain brake, rear handle with throttle trigger, throttle lockout, stop switch, choke, primer bulb, and decompression valve.

Components: Chain brake lever, chain catcher, muffler, spark arrestor, fuel cap, oil cap, air filter cover, and spark plug.

Operation: Pull chain brake back towards front handle to engage brake. Push forward to disengage. Press throttle lockout while squeezing trigger to operate. Use choke for cold starts.

Fuel & Oil Mixing

Use fresh unleaded gasoline (minimum 89 octane) mixed with high-quality 2-stroke engine oil at 50:1 ratio.

In a approved fuel container, add 2.6 fl oz (77 ml) of 2-stroke oil to 1 gallon (3.8 L) of gasoline.
Shake container thoroughly before filling chainsaw fuel tank.
Use bar & chain oil specifically designed for chainsaws in the oil tank.

Tip: Never use automotive motor oil, diesel fuel, or old gasoline. Mix only what you'll use in 30 days.

Starting & Operation

Supports both cold and warm starting procedures.

Cold Start: Set chain brake. Move choke to FULL position. Press primer bulb 5-6 times. Pull starter rope until engine fires. Move choke to HALF. Pull rope to start.
Warm Start: Set chain brake. Choke in OFF position. Pull starter rope.
Cutting: Disengage chain brake. Apply light pressure, let chain do the work. Avoid tip contact to prevent kickback.
Stopping: Release throttle, allow chain to stop. Engage chain brake. Press stop switch.

WARNING! Always engage chain brake when starting or carrying saw. Never drop-start the chainsaw.

Maintenance Schedule

Daily: Check chain tension, sharpness, and lubrication. Clean air filter. Inspect for loose parts.

Weekly: Clean spark arrestor screen. Check fuel filter. Inspect bar for wear and groove damage.

Monthly: Clean cooling fins. Check spark plug gap (0.025"). Replace fuel filter if clogged.

Seasonally: Replace spark plug. Clean carburetor air passage. Grease clutch bearing.

Chain Sharpening

Use round file (5/32" or 4.0mm) and file guide. Maintain 30° cutting angle and 10° top plate angle.

Secure bar in vise. Identify shortest cutter to match all others.
Place file guide on chain. File from inside out with consistent strokes.
File each cutter equally (3-5 strokes typically).
Check depth gauges with gauge tool; file down if above recommended height.

CAUTION! Always wear gloves. File in one direction only. Keep chain properly tensioned during sharpening.

Storage

For storage over 30 days: Run engine dry of fuel. Remove chain, clean and oil it. Clean entire saw. Store in dry, cool place with bar cover installed.

CAUTION! Never store with fuel in tank for extended periods. Fuel can degrade and damage carburetor.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine won't start	Old fuel, clogged filter, flooded	Use fresh fuel mix. Clean/replace air filter. Wait 15 min if flooded.
Engine runs poorly	Dirty air filter, spark arrestor	Clean air filter and spark arrestor screen.
Chain doesn't turn	Brake engaged, clutch worn	Disengage chain brake. Inspect clutch springs and drum.
Chain throws oil	Over-oiling, wrong oil	Adjust oil flow screw. Use correct bar & chain oil.
Excessive vibration	Loose parts, unbalanced chain	Tighten all fasteners. Sharpen chain evenly.
Chain dulls quickly	Hitting dirt, improper filing	Avoid ground contact. Maintain proper filing angles.

Service: For repairs beyond basic maintenance, contact authorized Craftsman service center at 1-888-331-4569 or visit www.craftsman.com.