McCulloch MAC 120 Chainsaw Owner's Manual

The McCulloch MAC 120 is a lightweight, gas-powered chainsaw designed for general homeowner use, featuring a 38cc 2-stroke engine, 16-inch Oregon bar and chain, automatic oiler, tool-free chain tensioning, inertia-activated chain brake, anti-vibration system, and easy-start technology. Below are key sections for safety, features, assembly, operation, maintenance, and troubleshooting.

Features at a Glance

Key components: 38cc 2-stroke engine, 16-inch guide bar and chain, automatic chain oiler, inertia chain brake, anti-vibration handles, combined choke/stop control, translucent fuel tank.

Safety Information

Read all instructions before use. Always wear appropriate PPE.

1. Personal Protective Equipment (PPE): Always wear safety glasses, hearing protection, gloves, chainsaw chaps/pants, and sturdy boots.
2. Work Area Safety: Keep bystanders and pets at least 15 feet away. Ensure secure footing.
3. Kickback Zone: Avoid contact with the upper quadrant of the bar tip.
4. Chain Brake: Test before each use. Engage when carrying the saw more than a few steps.
5. Fuel Safety: Refuel outdoors, away from ignition sources. Use fresh fuel mix.

WARNING! Failure to follow safety instructions can result in serious injury or death. This saw is for outdoor use only.

Assembly & Preparation

Unpack and inspect contents. Assembly requires attaching the guide bar and chain, and filling with fuel/oil.

1. Attach Guide Bar & Chain: Loosen bar nuts. Place chain over sprocket, ensuring cutting teeth face forward on top of bar. Fit bar onto studs. Adjust tension, then tighten nuts.
2. Fill Chain Oil: Use McCulloch chain and bar oil or equivalent. Fill to MAX line on translucent tank.
3. Prepare Fuel Mix: Use fresh unleaded gasoline (min. 89 octane) mixed with 2-stroke oil at a 40:1 ratio (3.2 oz oil per 1 US gallon gas). Shake well.
4. Fill Fuel Tank: Add fuel mix to tank. Wipe any spills immediately.

CAUTION! Never use straight gasoline or automotive motor oil. This will damage the engine.

Specifications

• Model: McCulloch MAC 120
• Engine Displacement: 38 cc
• Engine Type: 2-stroke, air-cooled
• Fuel/Oil Ratio: 40:1
• Guide Bar Length: 16 inches
• Chain Pitch/Gauge: 3/8" LP / 0.050"
• Chain Speed: Approx. 55 ft/s
• Sound Power Level: 112 dB(A)
• Vibration Level: Front Handle: 4.5 m/s², Rear Handle: 6.5 m/s²
• Weight (dry): 10.1 lbs (4.6 kg)

Controls and Components

Familiarize yourself with all controls before starting.

Main Components: Front handle with throttle trigger and lockout, rear handle, muffler, chain brake handle, combined choke/stop control, primer bulb, fuel cap, oil cap, decompression valve.

Controls: Throttle Trigger: Controls engine speed. Throttle Lockout: Must be depressed to engage throttle. Choke/Stop Control: Three positions: RUN (down), CHOKE (middle for cold start), STOP (up). Chain Brake Handle: Push forward to engage brake; pull back towards rear handle to disengage. Decompression Valve: Button to press before starting to reduce cylinder pressure.

Starting & Stopping

Always start on clear, level ground with chain brake engaged.

1. Cold Start: Engage chain brake. Set choke control to CHOKE. Press decompression valve. Press primer bulb 5-6 times. Pull starter cord sharply until engine 'pops'. Move choke to RUN. Pull starter cord again to start.
2. Warm Start: Set choke to RUN. Pull starter cord.
3. Stopping: Release throttle. Move choke/stop control to STOP position.

Tip: Never drop-start the saw. Always hold the rear handle firmly on the ground with your foot in the handle.

Operating Instructions

Use proper cutting techniques to maintain control and reduce fatigue.

1. Grip: Hold front handle with left hand, rear handle with right hand. Thumbs wrapped underneath.
2. Stance: Feet shoulder-width apart, firm footing.
3. Basic Cutting: Let the saw do the work. Use the bumper spike (if equipped) as a pivot point. Avoid cutting with the tip.
4. Bucking: Support log properly. Cut from top down. For pinched bars, stop and use a wedge.
5. Limbing: Stand on left side of trunk. Cut limbs from bottom to top on opposite side.

WARNING! Be alert for kickback. Never cut above shoulder height. Do not operate when fatigued.

Maintenance Schedule

Regular maintenance ensures performance and longevity.

Chain & Bar Care

Proper chain maintenance is critical for safe and efficient cutting.

1. Tensioning: Chain should be snug against bar but pull freely by hand. Adjust when cool using tool-free adjuster or scrench.
2. Sharpening: Use a round file and file guide matching chain pitch (5/32" for 3/8" LP). Maintain correct filing angle (typically 30°). File all cutters evenly.
3. Bar Maintenance: Clean bar groove weekly. Flip bar weekly to ensure even wear. Dress bar rails with a flat file if burred.
4. Oiler: Check oil flow by running saw at high speed near a light-colored surface (sawdust, cardboard). Adjust oiler screw if necessary.

CAUTION! Always wear heavy gloves when handling the chain.

Storage

Prepare the saw for storage to prevent fuel system issues.

1. Drain all fuel from the tank and run the engine until it stops to clear the carburetor.
2. Remove the chain and bar. Clean thoroughly and coat with oil.
3. Clean the entire saw of dirt and sawdust.
4. Store in a dry, secure place, out of reach of children.

Tip: For long-term storage (over 30 days), use a fuel stabilizer in the final tank mix before draining.

Troubleshooting

Service: For repairs beyond basic maintenance, contact an authorized McCulloch service center.

Support: For parts and manuals, visit www.mcculloch.com or contact customer service.