stihl ms 660 manual

The STIHL MS 660 is a professional-grade chainsaw designed for heavy-duty felling, limbing, and bucking applications. It features a powerful engine, advanced anti-vibration system, Ematic lubrication, and STIHL Quickstop inertia chain brake for enhanced safety and performance. Below are key sections for safety, features, operation, maintenance, and troubleshooting.

Features at a Glance

Key components: High-performance engine, decompression valve, anti-vibration system, side-access chain tensioner, Ematic lubrication system, Quickstop inertia chain brake, and advanced air filtration.

Safety Information

Read and understand all safety warnings before operation. Always wear proper PPE: helmet, eye protection, hearing protection, gloves, chainsaw chaps, and steel-toe boots.

1. Maintain secure footing and balance at all times.
2. Never operate with one hand. Always use both hands on handles.
3. Keep bystanders and pets at least 15 meters away.
4. Do not operate in poor weather conditions (rain, strong wind).
5. Shut off engine before transporting or making adjustments.

WARNING! Chainsaw kickback can cause severe injury or death. Always hold saw firmly, avoid contact with bar tip, and use reduced-kickback chain.

Assembly & Preparation

Unpack and inspect contents. Assemble guide bar and chain before first use.

1. Attach guide bar: Remove bar nuts, position bar on studs, align chain tensioning pin.
2. Install chain: Place chain over sprocket and bar, ensure cutting teeth face forward on top.
3. Tension chain: Adjust with side-access tensioner until chain snaps back when pulled from bar.
4. Fill tanks: Use STIHL HP Ultra 2-stroke oil mixed 50:1 with 89+ octane gasoline. Fill chain oil with STIHL chain oil.
5. Check controls: Ensure throttle trigger, throttle lockout, and chain brake function properly.

CAUTION! Use only STIHL-approved fuel mix and lubricants. Improper fuel can cause engine damage.

Specifications

• Engine Type: 2-stroke, single cylinder, air-cooled.
• Displacement: 91.6 cc.
• Power Output: 7.4 bhp at 9,500 rpm.
• Idle Speed: 2,800 rpm.
• Max Engine Speed: 13,500 rpm.
• Fuel/Oil Ratio: 50:1 (STIHL HP Ultra).
• Ignition: Capacitor discharge, electronic.
• Spark Plug: Bosch WSR 6 F or equivalent.
• Sound Pressure Level: 112 dB(A).
• Vibration Levels: Left/Right 4.5 m/s², Front/Rear 2.5 m/s².

Controls and Components

Main components: Front handle with throttle trigger, rear handle, master control lever, chain brake handle, decompression valve, fuel and oil caps, spark plug cover, and muffler.

Master Control Lever: Combines choke, start, and run positions. Chain Brake: Manual activation via front hand guard; inertia-activated by kickback. Throttle Lockout: Must be depressed before throttle trigger can be engaged. Decompression Valve: Reduces cylinder pressure for easier starting.

Starting & Operation

Starting procedure (cold engine):

1. Place saw on clear, level ground. Engage chain brake.
2. Press decompression valve (if equipped).
3. Set master control lever to choke position (full down).
4. Press throttle lockout and pull starter cord 2-3 times until engine "pops".
5. Move master control to half-throttle position. Pull starter cord until engine starts.
6. Blip throttle to disengage fast idle. Release chain brake before cutting.

Operation Tips: Let engine warm up 30 seconds. Use full throttle when cutting. Never "ride" the chain brake. Allow chain to reach full speed before contacting wood.

Chain & Bar Maintenance

Regular maintenance ensures optimal performance and safety.

1. Chain sharpening: Use round file matching chain pitch (typically 3/8" or .404"). Maintain 30° cutting angle, 10° top plate angle.
2. Chain tension: Check frequently when hot and cold. Proper tension: chain snaps back when pulled from bar groove.
3. Bar maintenance: Clean bar groove weekly. Flip bar monthly for even wear. Dress bar rails with flat file if burred.
4. Sprocket inspection: Replace drive sprocket if worn (typically every 2-3 chains).
5. Lubrication: Ensure oiler is working; adjust flow rate as needed for cutting conditions.

WARNING! Always wear heavy gloves when handling chain. Shut off engine before maintenance.

Engine Maintenance

Air filter: Clean daily in dusty conditions. Replace when damaged. Spark plug: Clean and regap (0.020") every 20 hours. Replace annually. Fuel filter: Replace every 3 months or as needed. Muffler: Clean spark arrestor screen weekly. Cylinder fins: Keep clean for proper cooling. Carburetor adjustment: Only by qualified technician.

Storage

For storage over 30 days:

1. Drain fuel tank and run engine until it stops.
2. Remove spark plug, add 1 teaspoon of engine oil through spark plug hole, pull starter cord slowly 2-3 times, reinstall plug.
3. Clean entire saw, especially cooling fins and air filter.
4. Remove chain, clean and soak in oil. Store bar flat.
5. Store in dry, secure location away from children.

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

Regulatory Information

EPA and CARB compliant. Meets ANSI B175.1 safety standards. Contains parts from Global Manufacturing. Copyright © STIHL Incorporated. All rights reserved. STIHL is a registered trademark. For genuine parts and service, contact authorized STIHL dealers only. Customer service: 1-800-467-8445 or www.stihlusa.com.

Troubleshooting

Service: For major repairs, contact authorized STIHL service dealer. Use only STIHL genuine parts.

Support: 1-800-467-8445; www.stihlusa.com