Owner Manual STIHL 090

The STIHL 090 is a professional-grade chainsaw designed for heavy-duty forestry and logging applications. This manual provides essential information for safe operation, maintenance, and troubleshooting of the STIHL 090 chainsaw. Key sections include safety instructions, technical specifications, assembly, operation, maintenance procedures, and troubleshooting guidelines.

Features at a Glance

Key components: High-power engine, anti-vibration system, chain brake, decompression valve, adjustable oil pump, and professional-grade cutting equipment.

Feature	Description
Engine Type	2-stroke, single cylinder, air-cooled
Displacement	137 cc
Power Output	9.0 kW (12.2 hp)
Fuel Tank Capacity	1100 ml
Oil Tank Capacity	580 ml
Guide Bar Length	Up to 36 inches (91 cm)
Chain Pitch	0.404 inch
Weight (without cutting equipment)	10.5 kg
Ignition System	Electronic ignition (CDI)
Anti-Vibration System	Integrated dampeners in handles

Safety Instructions

Read and understand all safety warnings before operation. Always wear appropriate personal protective equipment (PPE).

1. Personal Protective Equipment: Wear safety helmet, hearing protection, eye protection, gloves, chainsaw chaps, and steel-toed boots.
2. Work Area Safety: Clear work area of obstacles and ensure secure footing. Keep bystanders at a safe distance.
3. Chain Brake: Test chain brake functionality before each use.
4. Kickback Prevention: Maintain proper grip and body position; avoid contact with bar nose.

WARNING! Chainsaws are dangerous tools. Failure to follow safety instructions can result in serious injury or death. Never operate when fatigued or under the influence of substances.

Assembly & Preparation

Unpack and inspect all components. Assemble according to instructions.

1. Attach Guide Bar and Chain: Place bar on studs, adjust tension, and secure with nuts. Ensure chain direction is correct.
2. Fill Fuel Tank: Use fresh fuel mixture (50:1 gasoline to 2-stroke oil). Do not use old or contaminated fuel.
3. Fill Chain Oil Tank: Use STIHL chain oil or equivalent. Adjust oil flow rate as needed.
4. Check Controls: Ensure throttle trigger, throttle lockout, and chain brake function properly.

CAUTION! Always assemble on a clean, flat surface. Ensure all fasteners are properly tightened.

Technical Specifications

• Engine: 2-stroke, 137 cc displacement.
• Power: 9.0 kW at 7000 rpm.
• Maximum Torque: 12.5 Nm at 5000 rpm.
• Fuel Consumption: Approx. 750 g/kWh.
• Sound Pressure Level: 112 dB(A).
• Vibration Level: Front handle: 4.5 m/s²; Rear handle: 5.5 m/s².
• Ignition: Electronic CDI with automatic timing advance.
• Starter: Rewind starter with decompression valve.
• Carburetor: Membrane-type with manual choke.
• Recommended Fuel: Unleaded gasoline min. 90 octane mixed with STIHL 2-stroke oil (50:1).

Controls & Operation

Familiarize yourself with all controls before starting the engine.

Main Controls: Master Control Lever (combines choke, stop, and run positions), Throttle Trigger, Throttle Lockout, Chain Brake Lever, Decompression Valve, Fuel Primer Bulb.

Starting Procedure: Engage chain brake. Set Master Control to choke. Press decompression valve. Pull starter rope until engine fires. Move Master Control to run position. Pull starter rope to start. Disengage chain brake before cutting.

Cutting Techniques: Use proper stance and grip. Let saw do the work; avoid forcing. Be aware of kickback zone. Use wedges for large cuts.

Maintenance Schedule

Regular maintenance ensures optimal performance and longevity.

1. Daily: Clean air filter, check chain tension and sharpness, inspect guide bar for wear.
2. Weekly: Clean cooling fins, check spark plug, inspect anti-vibration elements.
3. Monthly: Clean fuel filter, check fuel lines, inspect clutch and sprocket.
4. Annually: Replace spark plug, clean carburetor, check cylinder and piston condition.

Tip: Keep a maintenance log to track service intervals.

Chain & Bar Care

Proper chain and bar maintenance is critical for safe and efficient operation.

1. Chain Sharpening: Use correct round file size (typically 7.1 mm). Maintain proper filing angle (30°). File all cutters evenly.
2. Chain Tension: Adjust when chain sags from bar rails. Proper tension: chain should snap back when pulled from bar.
3. Bar Maintenance: Clean bar groove regularly. Flip bar periodically for even wear. Dress bar rails with flat file when needed.
4. Lubrication: Ensure oiler is working. Adjust flow rate for cutting conditions.

WARNING! Always wear cut-resistant gloves when handling chain. Ensure engine is off and cool before maintenance.

Fuel & Lubrication

Use only recommended fuels and lubricants.

Fuel Mixture: 50 parts unleaded gasoline (min. 90 octane) to 1 part STIHL 2-stroke oil. Mix thoroughly in clean container. Do not store mixed fuel longer than 30 days.

Chain Oil: Use STIHL chain oil or equivalent with good adhesive properties. In cold temperatures, use winter-grade oil.

CAUTION! Never use automotive oil or mixed fuel not intended for 2-stroke engines. Store fuel in approved containers away from heat sources.

Storage Guidelines

Proper storage prevents damage and ensures ready operation.

1. Short-term (up to 30 days): Drain fuel tank and run engine until it stops. Clean entire saw. Store in dry place.
2. Long-term (over 30 days): Drain all fuel from tank and carburetor. Remove spark plug and add 1-2 teaspoons of oil to cylinder. Pull starter slowly to distribute oil. Store in original box or protective cover.

CAUTION! Never store with fuel in tank. Keep away from children and unauthorized users.

Warranty Information

STIHL 090 comes with a 12-month commercial warranty from date of purchase. Warranty covers defects in materials and workmanship under normal use. Not covered: damage from misuse, improper maintenance, unauthorized modifications, or use of non-STIHL parts. For warranty claims, contact authorized STIHL dealer with proof of purchase. For support, visit www.stihl.com or contact STIHL customer service at 1-800-467-8445.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine won't start	Fuel issues, spark plug, flooding	Check fuel mixture and freshness; clean/replace spark plug; wait if flooded.
Engine runs poorly	Dirty air filter, carburetor adjustment	Clean air filter; adjust carburetor (H and L screws).
Chain doesn't turn	Chain brake engaged, clutch issues	Disengage chain brake; inspect clutch and sprocket.
Excessive vibration	Loose components, damaged AV mounts	Tighten all fasteners; inspect anti-vibration elements.
Chain oil not flowing	Clogged oiler, empty tank, wrong oil	Clean oil passages; refill with proper oil; check pump.
Overheating	Dirty cooling fins, lean mixture	Clean cooling fins; check carburetor adjustment.

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

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