STIHL 08S Chainsaw Manual

The STIHL 08S is a professional-grade gasoline-powered chainsaw designed for demanding cutting tasks. It features a robust engine, automatic chain oiling, anti-vibration system, quick-stop chain brake, and STIHL's renowned safety and durability features. Below are key sections for safety, features, assembly, operation, maintenance, and troubleshooting.

Features at a Glance

Key components: Engine, Guide Bar, Saw Chain, Chain Brake, Throttle Trigger, Master Control Lever, Chain Tensioner, Fuel and Oil Caps.

Feature	Description
Engine	STIHL 2-stroke gasoline engine with electronic ignition
Guide Bar	Available in various lengths; supports professional cutting
Saw Chain	STIHL Oilomatic chain with automatic lubrication
Chain Brake	Quick-stop inertia-activated brake for operator safety
Anti-Vibration System	Reduces operator fatigue during extended use
Master Control Lever	Combines choke, throttle lock, and stop functions
Automatic Oiling	Delivers bar and chain oil during operation
Decompression Valve	Eases starting by reducing cylinder pressure
Fuel Tank	Integrated tank for gasoline/oil mixture
Oil Tank	Separate reservoir for chain lubrication oil

Safety Information

Read and understand all instructions before operation. Always wear appropriate PPE.

1. Personal Protective Equipment: Wear safety glasses, hearing protection, gloves, chainsaw chaps, and sturdy boots.
2. Work Area Safety: Clear area of obstacles and bystanders; ensure secure footing.
3. Kickback Awareness: Understand kickback zone (upper quadrant of bar tip); use reduced-kickback chain.
4. Chain Brake: Test function before each use; engage when carrying or not cutting.
5. Fuel Safety: Refuel in well-ventilated area with engine off and cool; use proper fuel/oil mix.

WARNING! Failure to follow safety instructions can result in serious injury or death. Never operate a chainsaw while tired, under the influence, or in adverse conditions.

Assembly & Preparation

Unpack and inspect contents. Assemble guide bar and chain.

1. Attach Guide Bar: Place bar onto studs, align chain tensioning pin.
2. Install Saw Chain: Fit chain over bar sprocket and onto drive sprocket, ensuring cutting teeth face forward on top.
3. Tension Chain: Use side-mounted tensioning screw to achieve proper tension (snug but pullable by hand).
4. Fill Tanks: Add STIHL 2-stroke engine oil mixed with unleaded gasoline (50:1 ratio) to fuel tank. Fill oil tank with STIHL chain oil.
5. Check Controls: Ensure throttle trigger, master control lever, and chain brake function smoothly.

CAUTION! Always wear protective gloves when handling the saw chain. Ensure chain is properly tensioned before starting.

Specifications

• Engine Displacement: 45.4 cc (2.77 cu. in.)
• Power Output: 2.2 kW (3.0 hp)
• Fuel/Oil Ratio: 50:1 (STIHL 2-stroke oil)
• Fuel Tank Volume: 0.55 L (18.6 fl. oz.)
• Oil Tank Volume: 0.26 L (8.8 fl. oz.)
• Guide Bar Lengths: 40 cm (16"), 45 cm (18") recommended
• Chain Pitch/Gauge: 3/8" P / 1.5 mm (0.058")
• Weight (powerhead): 5.9 kg (13.0 lbs)
• Sound Pressure Level: 106 dB(A)
• Vibration Level: Front/Rear Handle: 4.5/2.5 m/s²

Controls and Components

Front Handle: Contains throttle trigger and throttle trigger lockout. Rear Handle: Contains master control lever and stop switch.

Master Control Lever Positions: STOP (0): Engine off. START (⏰): Choke engaged for cold start. RUN (I): Normal run position.

Chain Brake: Front hand guard; activates manually (push forward) or by inertia. Chain Tensioner: Side-mounted screw for adjusting chain tension. Decompression Valve: Button to press before cold starts. Fuel/Oil Caps: Screw-type caps with integrated dipsticks.

Starting & Stopping Procedure

Starting (Cold Engine):

1. Engage chain brake by pushing hand guard forward.
2. Press decompression valve (if equipped).
3. Set master control lever to START (⏰).
4. Place saw on ground, hold rear handle with right foot, pull starter rope briskly until engine fires.
5. Move master control lever to RUN (I) immediately.
6. Pull starter rope again to start engine. Allow brief warm-up.

Starting (Warm Engine): Omit steps 2 and 5; set lever directly to RUN (I).

Stopping: Release throttle, move master control lever to STOP (0). Engage chain brake for storage.

Tip: Always start the saw on the ground, never drop-starting.

Operation & Cutting Techniques

Supports felling, limbing, bucking, and pruning.

1. Grip: Firm two-handed grip, thumbs wrapped around handles.
2. Stance: Balanced, feet shoulder-width apart.
3. Basic Cut: Apply full throttle before contacting wood; let saw do the work.
4. Felling: Plan escape path; use notch and back cut techniques.
5. Limbing: Work from trunk outward; beware of spring-loaded branches.
6. Bucking: Support log; cut from top down, avoiding contact with ground.
7. Kickback Prevention: Keep nose of bar out of cut; do not overreach.

WARNING! Never cut above shoulder height. Be constantly aware of the bar tip to prevent kickback.

Maintenance Schedule

Daily/Before Use: Check chain tension, sharpness, and lubrication. Check fuel/oil levels. Inspect for loose fasteners and damage.

Weekly/Every 10 Hours: Clean air filter. Check spark plug. Clean cooling fins and external surfaces.

Monthly/Every 20 Hours: Clean fuel filter. Check clutch and sprocket wear. Inspect anti-vibration elements.

Annually/Professional Service: Have carburetor adjustment and internal components inspected by authorized STIHL dealer.

Chain & Bar Care

Sharpening: Use correct round file size (typically 4.0 mm / 5/32") and file guide. Maintain correct filing angle (30°). File all cutters evenly.

Depth Gauges: File down rakers (depth gauges) periodically with flat file to maintain proper height (0.65 mm / 0.025" below cutter).

Bar Maintenance: Clean bar groove weekly. Flip bar periodically for even wear. Dress bar rails with flat file if burred.

Lubrication: Always use STIHL chain oil or equivalent for proper adhesion and lubrication. Check oil flow by pointing bar tip at a light surface and running at full throttle; a fine line of oil should appear.

CAUTION! A dull or poorly maintained chain increases kickback risk and operator fatigue.

Storage Guidelines

Long-Term Storage (Over 30 Days):

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

CAUTION! Never store a chainsaw with fuel in the tank for extended periods. Old fuel can damage engine components.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine will not start	No spark, flooded, stale fuel	Check spark plug; set master control to RUN; use fresh fuel mix.
Engine starts then dies	Clogged air/fuel filter, carburetor	Clean or replace air filter; check fuel filter; see dealer for carb adjustment.
Chain does not turn	Chain brake engaged, clutch worn	Disengage chain brake; inspect clutch and sprocket.
Poor cutting performance	Dull chain, improper tension	Sharpen chain; adjust tension; check lubrication.
Excessive vibration	Loose components, unbalanced chain	Tighten all fasteners; check chain for damaged or uneven cutters.
Chain throws oil	Over-oiling, wrong oil type	Check oiler setting; use recommended chain oil.

Service: For repairs beyond basic maintenance, contact an authorized STIHL servicing dealer.

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