STIHL Service Manual

The STIHL Service Manual provides comprehensive technical information for servicing and maintaining STIHL power equipment, including chainsaws, trimmers, blowers, and other outdoor power tools. This manual covers safety procedures, technical specifications, troubleshooting, maintenance schedules, repair instructions, and parts identification for qualified technicians. Below are key sections for safety, features, maintenance procedures, specifications, troubleshooting, and technical data.

Safety Information

Critical safety warnings and precautions for servicing STIHL equipment.

Safety Symbol	Meaning	Precaution
⚠️	Warning	Indicates a potentially hazardous situation which, if not avoided, could result in serious injury or death.
⚡	Electrical Hazard	Risk of electric shock. Disconnect spark plug before servicing.
🔥	Fire Hazard	Fuel is flammable. Work in well-ventilated area away from ignition sources.
🛡️	Personal Protective Equipment	Wear safety glasses, gloves, and hearing protection during service.

WARNING! Always use genuine STIHL parts. Improper service can cause equipment failure, injury, or death. Refer to specific model manual for exact procedures.

Product Overview

STIHL power equipment components and identification.

1. Engine: 2-stroke or 4-stroke air-cooled engines with specific displacement and power output.
2. Fuel System: Diaphragm carburetor, fuel filter, fuel lines, and tank.
3. Ignition System: Electronic ignition module, spark plug, and stop switch.
4. Cutting System: Guide bar, chain, sprocket, and clutch assembly (for chainsaws).
5. Electrical System: Starter, alternator (if equipped), and wiring harness.
6. Controls: Throttle trigger, choke, stop switch, and decompression valve.

Note: Component locations vary by model. Always verify with specific equipment manual.

Technical Specifications

• Engine Type: 2-stroke single cylinder (typical for handheld).
• Displacement: Ranges from 30.1cc to 120+cc depending on model.
• Power Output: Varies by model (e.g., 2.0 kW to 6.0 kW).
• Fuel Mix: 50:1 gasoline to 2-stroke oil (STIHL HP Ultra recommended).
• Idle Speed: Typically 2,800 - 3,200 RPM (adjust per manual).
• Max Speed: 12,500 - 14,000 RPM (varies by saw model).
• Ignition: Electronic, non-adjustable.
• Spark Plug: Bosch WSR6F or equivalent, gap 0.5mm (0.020").
• Bar Length: 12" to 36" for chainsaws.
• Chain Pitch/Gauge: .325", 3/8", or .404" pitch; .050" or .063" gauge.

Maintenance Procedures

Regular maintenance schedule and procedures.

Daily/Pre-Use: Check fuel level, chain tension (saws), air filter, and for loose fasteners.

Weekly/25 Hours: Clean air filter, check spark plug, clean cooling fins, inspect fuel filter.

Monthly/100 Hours: Clean carburetor (if needed), replace spark plug, check clutch and sprocket.

Annual/500 Hours: Replace fuel lines, inspect piston/cylinder through exhaust port, check all bearings.

Install: Use proper tools (torque wrench, feeler gauges). Follow specified torque values for all fasteners.

Engine Service

Cylinder, piston, crankshaft, and bearings service.

1. Compression Test: Use compression gauge. Minimum 110 psi for proper operation.
2. Cylinder Inspection: Remove muffler, inspect cylinder walls for scoring.
3. Piston Ring Replacement: Remove cylinder, replace rings if worn or broken.
4. Crankshaft Seals: Replace if leaking (causes air leak and lean condition).
5. Bearings: Check for play; replace if excessive.

WARNING! Engine disassembly requires special tools. Do not attempt without proper training.

Fuel System

Carburetor adjustment and fuel component service.

1. Turn off fuel valve (if equipped).
2. Drain fuel tank completely.
3. Remove carburetor cover and air filter.
4. Adjust idle (L), high speed (H), and idle speed (LA) screws per specifications.
5. Replace fuel filter and lines annually or if cracked.

Tip: Use pressure/vacuum tester to check carburetor diaphragms and inlet needle.

Ignition System

Spark testing and module replacement.

1. Remove spark plug, reconnect to wire, ground against cylinder.
2. Pull starter; look for strong blue spark.
3. No spark? Check stop switch wire for continuity to ground.
4. Test ignition module with multimeter per manual specifications.
5. Replace module if out of specification.
6. Set spark plug gap to 0.5mm (0.020").

WARNING! Never check for spark with plug removed and not grounded - risk of ignition module damage.

Cutting System

Chain, bar, and sprocket maintenance for chainsaws.

Supports various chain types: full chisel, semi-chisel, low-kickback.

1. Chain Tension: Adjust so chain snaps back when pulled from bar.
2. Bar Maintenance: Clean bar groove, flip bar regularly for even wear.
3. Sprocket Inspection: Replace if worn (teardrop shape on drive links).
4. Sharpening: Use correct file size (typically 5/32" for 3/8" pitch).
5. Depth Gauge: File rakers to proper height (0.025" below cutter).
6. Lubrication: Check oil pump output; adjust if needed.

WARNING! Always wear cut-resistant gloves when handling chain. Ensure chain brake is functional.

Electrical System

Starter, charging system (if equipped), and wiring.

Closed Circuit: Test with multimeter for continuity. Parental Controls: Not applicable for service manuals.

Troubleshooting Guide

Symptom	Possible Cause	Corrective Action
Engine won't start	No spark, no fuel, flooded	Check spark, fuel delivery, carburetor. Use choke properly.
Engine starts then dies	Fuel filter clogged, carb adjustment	Replace fuel filter, adjust L screw, check tank vent.
Loss of power	Clogged air filter, exhaust screen, carb issues	Clean/replace air filter, clean spark arrestor, adjust H screw.
Chain won't turn	Clutch worn, sprocket damaged, brake engaged	Inspect clutch springs/shoes, replace sprocket, disengage chain brake.
Excessive vibration	Unbalanced cutting attachment, engine mount loose	Balance trimmer head/chain, tighten all mounts.
Oil leakage	Seals damaged, lines cracked	Replace crankshaft seals, oil lines, check tank.

Reset: No electronic reset required for most models.

Parts Diagrams

Exploded views and part numbers for major assemblies.

• Cylinder Group: Piston, rings, cylinder, gaskets.
• Crankshaft Group: Crankshaft, bearings, seals.
• Carburetor Group: Complete carburetor, gaskets, adjustment screws.
• Clutch Group: Clutch drum, springs, shoes, bearing.
• Ignition Group: Module, coil, spark plug, wires.
• Fuel Tank Group: Tank, cap, lines, filter.

Note: Always use STIHL part numbers when ordering replacements.

Service Support: 1-800-467-2489; www.stihlusa.com