Stihl Mini Boss Manual

The Stihl Mini Boss is a compact, professional-grade brushcutter/trimmer designed for demanding vegetation management. It features a powerful 2-stroke engine, lightweight construction, versatile cutting attachments (polycut head, metal blade), anti-vibration system, easy-start technology, ergonomic handles, and meets stringent emissions standards. Below are key sections for safety, features, assembly, operation, maintenance, and troubleshooting.

Features at a Glance

Key components: 2-stroke engine, drive shaft, anti-vibration system, harness attachment points, throttle trigger, stop switch, fuel tank, and cutting attachment interface.

Feature	Description
Engine Type	2-stroke, air-cooled, single cylinder
Starting System	Easy-start technology with decompression valve
Anti-Vibration	Integrated dampers in handle and shaft
Cutting Attachments	Quick-change system for polycut heads and metal blades
Fuel System	Diaphragm carburetor with purge bulb
Handle	Ergonomic loop handle with throttle lockout
Harness Points	D-rings for professional harness attachment
Exhaust	Spark-arresting muffler
Weight (without attachment)	Approximately 5.3 kg (11.7 lbs)
Emissions Compliance	Meets EPA Phase 3 and EU Stage V standards

Assembly & Preparation

Unpack and inspect all components. Assemble on a clean, flat surface.

1. Attach handle: Align handle with shaft and secure with provided bolts.
2. Install cutting attachment: Ensure engine is off. Fit chosen head/blade onto drive shaft and secure with retaining nut using appropriate wrench.
3. Attach harness: Connect harness D-rings to machine attachment points.
4. Fuel mixture: Prepare 50:1 fuel/oil mix using STIHL 2-stroke oil and unleaded gasoline (min. 89 octane). Fill tank.

WARNING! Always wear appropriate PPE: safety glasses, hearing protection, gloves, sturdy boots, and long pants. Never operate without proper guard installed.

First-Time Operation

Perform pre-operation check before starting.

1. Check fasteners: Ensure all bolts and nuts are tight.
2. Inspect cutting attachment: Verify guard is secure and attachment is properly installed.
3. Prime engine: Press fuel purge bulb 5-7 times until fuel is visible.
4. Set choke: Move lever to cold start position.
5. Start: Place unit on ground, hold securely. Pull starter rope briskly until engine fires. Move choke to run position and pull again to start.
6. Warm up: Allow engine to idle for 30 seconds before applying throttle.

CAUTION! Clear work area of bystanders, especially children and pets. Maintain firm footing and secure grip.

Specifications

• Engine Displacement: 27.2 cc
• Power Output: 0.9 kW (1.2 hp)
• Fuel Tank Capacity: 0.47 liters (16 oz)
• Idle Speed: 2800 rpm
• Maximum Power Speed: 10000 rpm
• Sound Power Level (LWA): 112 dB(A)
• Vibration Levels (ahv): Handle: 4.2 m/s²; Shaft: 6.1 m/s²
• Cutting Diameter (with polycut head): Up to 42 cm (16.5 in)
• Drive Shaft: Solid steel
• Warranty: Limited commercial warranty (see dealer for terms)

Controls and Functions

Main controls located on handle and engine housing.

Handle: Throttle trigger with lockout, stop switch (I/O), throttle latch for continuous operation.

Engine Housing: Choke lever (cold start/run), fuel purge bulb, air filter cover, spark plug access.

Operation Modes: Idle, full throttle. Use throttle latch for extended cutting sessions to reduce hand fatigue.

Stopping: Release throttle, allow engine to return to idle, press stop switch to "O".

Cutting Attachments

Supports various attachments for different vegetation.

1. Polycut Head (standard): For grass and light weeds. Load with STIHL Polycut line.
2. Circular Metal Blade: For thick weeds, brush, and saplings up to 10 cm diameter. Ensure correct blade guard is installed.
3. Changing Attachments: Stop engine and ensure it is cool. Use wrench to loosen retaining nut. Remove old attachment, install new one, and tighten nut securely.

Tip: Always match the attachment and guard to the task. Never use a damaged or dull blade.

Fuel & Lubrication

Use only fresh, unleaded gasoline (min. 89 octane) mixed with STIHL 2-stroke oil at 50:1 ratio.

1. Mixing: Pour oil into clean fuel can first, then add gasoline. Shake well.
2. Filling: Clean area around fuel cap. Use funnel to avoid spills. Do not overfill.
3. Gearbox Lubrication: Grease gearbox at attachment interface after every 25 hours of operation using STIHL grease cartridge.
4. Chain Lubrication (if equipped with brush knife): Apply bar and chain oil to lubrication points.

WARNING! Fuel is highly flammable. Mix and refuel outdoors, away from ignition sources. Allow engine to cool before refueling.

Maintenance Schedule

Regular maintenance ensures optimal performance and longevity.

Interval	Task
Daily (Before use)	Check fasteners, inspect cutting attachment and guard, check for fuel leaks
Every 25 hours	Clean air filter, check spark plug, grease gearbox
Every 50 hours	Replace fuel filter, inspect drive shaft
Every 100 hours	Clean cooling fins, check carburetor settings (dealer service recommended)
Annually or as needed	Replace spark plug, decarbonize exhaust system

CAUTION! Disconnect spark plug wire before performing any maintenance except refueling.

Storage Guidelines

Prepare unit for storage if not used for more than 30 days.

1. Empty fuel tank or add fuel stabilizer: Run engine dry or add STIHL fuel stabilizer to full tank and run for 2 minutes.
2. Clean unit: Remove debris from cooling fins, air intake, and exterior.
3. Remove cutting attachment: Clean and store separately.
4. Store: In a dry, locked place, out of reach of children.

CAUTION! Never store unit with fuel in tank in an enclosed space due to fire and fume hazards.

Safety & Compliance

Complies with ANSI B175.3 and applicable EPA regulations. Contains parts that may be hot during/after operation. The muffler contains a spark arrestor screen - inspect and clean regularly to prevent fire risk. For safety information, operation training, and service, contact your authorized STIHL dealer or visit www.stihlusa.com.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine will not start	No fuel, flooded, spark plug faulty	Check fuel level; move choke to run, pull starter 10x; check/replace spark plug.
Engine starts then dies	Clogged fuel filter, dirty air filter	Replace fuel filter; clean air filter.
Loss of power	Clogged muffler, dirty carburetor	Clean spark arrestor screen; have dealer service carburetor.
Excessive vibration	Loose fastener, bent shaft, unbalanced blade	Tighten all fasteners; inspect shaft and blade for damage.
Cutting attachment does not spin	Sheared drive pin, clutch issues	Replace shear pin; have dealer inspect clutch.

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

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