STIHL Chainsaw Shop Manual

The STIHL Chainsaw Shop Manual is a comprehensive guide for professional technicians and experienced users, detailing maintenance, repair, troubleshooting, and safety procedures for STIHL chainsaw models. It covers engine systems, fuel systems, ignition, cutting equipment, lubrication, electrical components, and detailed specifications. Below are key sections for safety, technical data, maintenance procedures, troubleshooting, and repair instructions.

1. Safety Precautions & Warnings 2. Technical Specifications 3. Maintenance Schedule 4. Engine Systems 5. Fuel System 6. Ignition System 7. Cutting & Bar/Chain Assembly 8. Lubrication System 9. Electrical Components 10. Disassembly & Assembly 11. Troubleshooting Guide

Safety Precautions & Warnings

Essential safety guidelines to prevent injury during maintenance and operation.

Hazard	Precaution
Fuel Handling	Use approved containers; no smoking; work in well-ventilated area
Sharp Components	Wear cut-resistant gloves when handling chain, bar, or sprocket
Hot Surfaces	Allow engine and muffler to cool before servicing
Electrical Shock	Disconnect spark plug wire before any repair
Chemical Exposure	Use safety glasses and gloves when handling oils, solvents, or cleaners
Flying Debris	Wear eye protection during testing or operation
Lifting Injury	Use proper lifting techniques; secure saw on bench
Fire Risk	Keep work area free of flammable materials
Noise Exposure	Wear hearing protection during operation
Vibration	Take regular breaks to reduce hand-arm vibration syndrome risk

Technical Specifications

Detailed specifications for common STIHL chainsaw models (examples).

Engine Type: 2-stroke, single cylinder, air-cooled.
Displacement: Ranges from 30.1 cc to 120+ cc across models.
Power Output: Varies by model (e.g., 1.8 kW to 6.5 kW).
Fuel/Oil Mix: 50:1 ratio (STIHL HP Ultra or equivalent ISO-L-EGD certified oil).
Idle Speed: Typically 2,500 - 3,000 rpm (adjustable).
Max Power Speed: 9,000 - 14,000 rpm depending on model.
Ignition System: Electronic, capacitor discharge (CDI).
Spark Plug: Bosch WSR6F or equivalent, gap 0.5 mm (0.020 in).
Bar Lengths: 12" to 36" (guide bar).
Chain Pitch/Gauge: Common: 3/8" LP, 0.325", 3/8", 0.404"; Gauge: 1.3 mm, 1.5 mm, 1.6 mm.
Oil Pump: Automatic, adjustable on professional models.
Weight (powerhead): 3.0 kg to 9.0 kg (without bar/chain).

Maintenance Schedule

Regular maintenance intervals to ensure optimal performance and longevity.

Before Each Use: Check chain tension, sharpness, and lubrication; inspect for loose fasteners; verify throttle trigger and chain brake function.
Daily/After Use: Clean air filter; check fuel filter; clean cooling fins and guide bar groove; wipe down exterior.
Weekly/25 Hours: Clean spark arrestor screen (if equipped); inspect spark plug; check anti-vibration elements; inspect clutch and sprocket.
Monthly/50 Hours: Replace fuel filter; clean carburetor air passage; check fuel lines for cracks; inspect ignition wiring.
Seasonal/100 Hours: Replace spark plug; clean/replace muffler (if serviceable); decarbonize combustion chamber; check piston/cylinder for scoring.
Annual/As Needed: Replace guide bar and chain; rebuild carburetor kit; replace clutch drum/bearing; check crankshaft seals.

WARNING! Always refer to specific model manual for exact intervals. Use only STIHL-approved parts and lubricants.

Engine Systems

Procedures for cylinder, piston, crankshaft, and cooling system service.

Cylinder & Piston Inspection: Remove muffler; inspect cylinder walls for scoring; check piston rings for free movement and end gap. Compression Test: Minimum 110 psi (warm engine). Decompression Valve: Test for leaks if equipped. Crankshaft Bearings: Check for play or roughness. Cooling System: Clean fins; ensure fan wheel is intact and clean.

Fuel System

Carburetor adjustment, fuel line replacement, tank vent service.

Carburetor Adjustment (H, L, LA screws): Initial settings: Turn H & L screws gently clockwise to stop, then back out 1 turn each. LA (idle speed): Adjust for smooth idle (chain not moving). Fine-tune at operating temperature.
Fuel Lines: Replace if cracked, hardened, or leaking. Use ethanol-resistant lines.
Fuel Filter: Replace periodically; ensure pickup is not restricted.
Tank Vent: Clean or replace if fuel flow is impeded or tank pressurizes.
Impulse Line: Check for cracks (connects crankcase to carburetor diaphragm).

Tip: Always clean area around carburetor before removal to prevent debris ingress.

Ignition System

Testing and replacement of ignition module, spark plug, and stop switch.

Spark Test: Remove spark plug, reconnect boot, ground plug against cylinder, pull starter – look for strong blue spark. Ignition Module Air Gap: Set with feeler gauge (typically 0.3 mm / 0.012 in). Resistance Check: Primary coil resistance ~0.2-2.0 Ω; secondary ~8-20 kΩ (varies by model). Stop Switch Circuit: Test for continuity when off/open when on. Flywheel Key: Inspect for shearing if timing is off.

Cutting & Bar/Chain Assembly

Guide bar maintenance, chain sharpening, sprocket inspection, and tensioning.

Guide Bar: Clean groove; flip regularly for even wear; dress rails with file if burred; check for straightness and wear at sprocket nose.
Chain Sharpening: Use correct round file size and guide; maintain proper filing angle (typically 30°); equalize cutter length; maintain depth gauge height (0.025" / 0.65 mm below cutter).
Drive Sprocket: Inspect for wear (spur or rim type); replace if teeth are hooked or worn excessively.
Chain Tension: Adjust so chain snaps back when pulled from bar; should not sag from bottom rail.
Clutch: Inspect shoes for wear; springs for fatigue; clean drum interior.

WARNING! Always wear gloves. Ensure chain brake is disengaged when adjusting tension.

Lubrication System

Oil pump adjustment, flow test, and line service.

Oil Pump Output Test: Run saw at full throttle pointed at light surface; should throw an even line of oil. Adjustment Screw: Turn clockwise to increase flow (on adjustable models). Oil Lines: Check pickup in tank and delivery to bar pad. Oil Filter Screen: Clean if present in tank. Bar Pad Passage: Ensure it aligns with oil outlet and is clear.

Electrical Components

STIHL M-Tronic system basics (if equipped), wiring harness, and switch testing.

M-Tronic Diagnostics: LED on handle indicates status (green=OK, red=error). Reset by disconnecting spark plug wire, pulling starter 5-6 times, reconnecting. Wiring Harness: Inspect for chafing, especially near handle and tank. Throttle Interlock: Ensure safety switch functions correctly. Decompression Solenoid: Test resistance if engine hard to start.

Disassembly & Assembly

General sequence for major component access.

Remove top cover, air filter, and carburetor.
Remove clutch assembly (use clutch tool to hold piston).
Remove cylinder cover and muffler.
Separate crankcase halves (requires case splitter tool).
Reassembly: Use sealant on crankcase joints; torque fasteners to specification; pressure/vacuum test after reassembly.

CAUTION! Label all parts and fasteners. Use factory service tools (STIHL tool kit) where specified.

Troubleshooting Guide

Symptom	Possible Cause	Corrective Action
Engine will not start	No spark, flooded, fuel issue, compression low	Check spark, plug condition; dry plug; verify fuel mix and lines; test compression.
Engine starts then dies	Clogged fuel filter, tank vent blocked, carburetor adjustment	Replace filter; clean vent; adjust L screw slightly richer.
Lacks power under load	Clogged air filter, muffler screen blocked, carburetor H setting, fuel restriction	Clean/replace filter; clean spark arrestor; adjust H screw; check fuel line.
Chain does not oil	Empty oil tank, clogged oil passage, faulty pump, incorrect bar/chain	Fill tank; clean bar groove and oil ports; test pump output; verify compatibility.
Excessive vibration	Unbalanced chain, loose components, worn anti-vibration mounts, bent crankshaft	Sharpen chain evenly; tighten fasteners; replace mounts; inspect crankshaft.
Chain rotates at idle	Idle speed too high, clutch springs weak, drum grooved	Adjust LA screw; replace clutch springs; replace clutch drum.
Overheating	Lean fuel mix, clogged cooling fins, incorrect carb settings, low oil in fuel	Use correct 50:1 mix; clean fins; enrich L/H screws; verify oil quality.
Oil leaking from saw	Overtightened oil line, cracked tank, pump seal failure	Check line connections; inspect tank; replace pump seals.

Reset M-Tronic: As described in Electrical section. Pressure/Vacuum Test: Recommended after any crankcase seal or gasket replacement.

Service Support: For genuine parts and technical bulletins, contact STIHL authorized service or visit www.stihlusa.com.