Stihl Chainsaw MS290 Manual

The Stihl MS290 Farm Boss is a professional-grade chainsaw designed for demanding cutting tasks. It features a powerful engine, robust construction, advanced safety systems, and ergonomic design for user comfort and efficiency. Below are key sections covering safety, features, assembly, operation, maintenance, troubleshooting, and specifications.

1. Features at a Glance 2. Safety Information 3. Assembly & Preparation 4. Specifications 5. Controls and Components 6. Starting & Operation 7. Maintenance Schedule 8. Chain Sharpening & Tensioning 9. Storage Guidelines 10. Warranty Information 11. Troubleshooting

Features at a Glance

Key components: Powerful 2-stroke engine, Quickstop® inertia chain brake, Ematic™ lubrication system, anti-vibration system, side-access chain tensioner, and tool-free air filter cover.

Feature	Description
Engine Displacement	56.5 cc
Power Output	3.4 bhp
Guide Bar Lengths	16", 18", 20" (options)
Chain Pitch	3/8"
Fuel Tank Capacity	16.9 fl. oz. (500 ml)
Oil Tank Capacity	11.1 fl. oz. (330 ml)
Weight (powerhead)	12.8 lbs (5.8 kg)
Ignition System	Electronic, capacitor discharge
Safety Features	Quickstop® chain brake, front hand guard, throttle interlock
Vibration Damping	Advanced anti-vibration system

Safety Information

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

Personal Protective Equipment (PPE): Always wear chainsaw chaps, safety glasses, hearing protection, gloves, and sturdy boots.
Work Area Safety: Clear area of bystanders, especially children. Ensure secure footing.
Kickback Zone: Avoid contact with the upper quadrant of the guide bar tip.
Fuel Safety: Refuel in well-ventilated area, away from ignition sources. Use STIHL MotoMix® or equivalent 50:1 fuel/oil mix.

WARNING! Kickback can cause severe injury. Always hold saw firmly with both hands. Never operate when tired or under the influence.

Assembly & Preparation

Unpack and inspect contents. Assemble guide bar and chain.

Attach guide bar: Remove side cover, position bar over studs, ensure chain fits sprocket.
Install chain: Place chain over bar with cutters facing forward on top. Ensure drive links engage sprocket.
Tension chain: Use side tensioner to achieve proper tension (snug but pullable by hand).
Fill fluids: Add STIHL 50:1 fuel mix to fuel tank. Fill bar and chain oil reservoir with STIHL chain oil.
Check controls: Ensure throttle trigger, throttle lockout, and chain brake function properly.

CAUTION! Chain must be properly tensioned. Loose chain can derail; overtightened chain can damage bar or break.

Specifications

Model: MS 290 Farm Boss
Engine Type: Single cylinder, 2-stroke, air-cooled
Displacement: 56.5 cc (3.45 cu. in.)
Power Output: 3.4 bhp (2.5 kW)
Max Engine Speed: 13,000 RPM
Idle Speed: 2,800 RPM
Ignition: Electronic, capacitor discharge (CDI)
Carburetor: Diaphragm-type with manual choke
Fuel/Oil Ratio: 50:1 (STIHL MotoMix® or equivalent)
Recommended Bar Lengths: 16" (40 cm), 18" (45 cm), 20" (50 cm)
Chain Type: STIHL Oilomatic® .325" or 3/8" pitch
Sound Pressure Level: 106 dB(A)
Vibration Levels (front/rear): 4.5/2.5 m/s²

Controls and Components

Master Control Lever: Combines choke, throttle lock, and stop functions. Front Handle: Includes throttle trigger with interlock. Rear Handle: Main grip with vibration damping. Chain Brake Lever: Manual activation; inertia-activated by kickback. Decompression Valve: Eases starting. Side Tensioner: For chain adjustment without tools.

Main Components: Engine, carburetor, air filter, spark plug, fuel tank, oil tank, guide bar, chain, sprocket, muffler, anti-vibration system.

Starting & Operation

Cold Start Procedure (with decompression valve):

Engage chain brake by pushing lever forward.
Set Master Control lever to choke position (full down).
Press decompression valve (if equipped).
Place saw on ground, hold rear handle with right foot, grip front handle with left hand.
Pull starter rope sharply until engine fires (usually 3-5 pulls).
Move Master Control lever to half-throttle position.
Pull starter rope again until engine starts.
Blip throttle to disengage fast idle. Release chain brake before cutting.

Cutting Techniques: Use full throttle when cutting. Let chain do the work; don't force. Plan escape path. Beware of pinch points and spring poles.

Maintenance Schedule

Interval	Task
Before each use	Check chain tension, sharpness, fluid levels. Inspect for loose parts/damage.
Every 5 hours	Clean air filter. Check spark plug.
Every 10 hours	Clean spark arrestor screen (muffler).
Every 20 hours	Clean cooling fins. Check fuel filter.
Every 50 hours	Replace spark plug. Clean carburetor air intake.
Annually	Inspect/replace fuel lines, impulse line, and intake boot as needed.

Note: Maintenance intervals vary with operating conditions. More frequent maintenance required in dusty conditions.

Chain Sharpening & Tensioning

Sharpening: Use round file matching chain pitch (typically 5/32" for .325" chain). Maintain 30° filing angle. Ensure all cutters are same length. File depth gauges with flat file and gauge.

Tensioning: Chain should be snug against bar but pullable by hand. Re-tension when chain sags (common when new). Always tension with saw cold and chain brake engaged.

WARNING! Always wear gloves when handling chain. A sharp chain is safer and more efficient than a dull one.

Storage Guidelines

For storage over 30 days:

Drain fuel tank and run carburetor dry.
Remove chain, clean, and soak in oil.
Clean entire saw, especially cooling fins and air filter.
Store in dry, cool place, away from ignition sources.
Consider fogging engine through spark plug hole for long-term storage.

CAUTION! Old fuel can gum carburetor. Never store saw with fuel in tank for extended periods.

Warranty Information

STIHL Limited Warranty: 1-year commercial warranty, 1-year rental warranty, or 1-year private user warranty from date of retail sale. Warranty covers defects in materials/workmanship. Not covered: normal wear, misuse, improper maintenance, non-STIHL parts. Proof of purchase required. For warranty service, contact authorized STIHL servicing dealer.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine won't start	No spark, flooded, old fuel, clogged filter	Check spark plug; use fresh 50:1 fuel; clean air filter; follow cold start procedure.
Engine starts then dies	Clogged fuel filter, vent, or carburetor	Replace fuel filter; check tank vent; clean carburetor.
Loss of power	Dirty air filter, clogged spark arrestor, poor fuel	Clean/replace air filter; clean spark arrestor screen; use fresh fuel.
Chain doesn't turn	Chain brake engaged, clutch worn, sprocket damaged	Disengage chain brake; inspect clutch and sprocket; replace if worn.
Excessive vibration	Loose components, unbalanced chain, damaged AV mounts	Tighten all fasteners; balance chain; inspect anti-vibration mounts.
Chain throws oil	Overfilled oil tank, wrong oil viscosity	Use correct STIHL chain oil; fill to proper level.
Chain dulls quickly	Cutting dirty wood, hitting ground, improper filing	Avoid cutting into dirt; sharpen correctly; check depth gauges.

Service: For repairs beyond basic maintenance, contact an authorized STIHL servicing dealer. Use only STIHL-approved replacement parts.