Stihl BR 320 Manual

The Stihl BR 320 is a professional-grade backpack blower designed for demanding landscaping and cleanup tasks. It features a powerful 2-stroke engine, comfortable ergonomic harness, variable throttle control, and a robust air tube and nozzle for efficient debris movement. Below are key sections for safety, features, operation, maintenance, troubleshooting, and specifications.

Features at a Glance

Key components: 2-stroke engine, backpack frame with harness, throttle trigger, air tube, nozzle, and muffler.

Feature	Description
Engine Type	2-stroke, single-cylinder, air-cooled
Displacement	27.2 cc
Fuel Tank Capacity	Approx. 1.3 liters (0.34 US gal)
Airflow Velocity	Up to 75 m/s (242 ft/s)
Air Volume	Up to 750 m³/h (441 cfm)
Sound Power Level	Typically 112 dB(A)
Weight (dry)	Approx. 8.9 kg (19.6 lbs)
Harness System	Padded, adjustable backpack harness
Throttle Control	Variable-speed trigger with lock
Starter System	Rewind starter with decompression valve

Safety Instructions

Read all instructions before operation. Wear appropriate PPE.

1. Always wear eye protection, hearing protection, long pants, and sturdy shoes.
2. Operate in well-ventilated areas only; exhaust gases are hazardous.
3. Keep bystanders and pets at least 15 meters (50 feet) away.
4. Never point the air stream at people, animals, or fragile objects.
5. Inspect the blower before each use for loose parts or damage.

WARNING! Risk of fire and explosion. Use only approved fuel mix. Stop engine before refueling. Allow engine to cool.

Assembly & Preparation

Unpack and inspect all parts. Assemble according to instructions.

1. Attach harness: Connect shoulder straps and waist belt to backpack frame.
2. Install air tube: Push tube onto engine outlet until it clicks securely.
3. Attach nozzle: Screw or lock nozzle onto end of air tube.
4. Fuel mix: Prepare 50:1 gasoline to 2-stroke oil mix (use STIHL HP Ultra or equivalent).
5. Fill fuel tank: Use clean funnel; avoid spills. Securely close fuel cap.

CAUTION! Ensure all connections are tight. Do not operate with loose components.

Specifications

• Model: BR 320
• Engine Power: 0.9 kW (1.2 bhp)
• Idle Speed: 2,800 rpm
• Maximum Engine Speed: 12,500 rpm
• Fuel/Oil Ratio: 50:1 (gasoline to 2-stroke oil)
• Spark Plug: Bosch WSR 6 F or equivalent, gap 0.5 mm (0.020 in)
• Vibration Levels (left/right): Typically 4.5/5.5 m/s²
• Warranty: Limited commercial warranty (see manual for details)
• Compliance: Meets ANSI B175.2 and EPA Phase II emissions standards

Controls and Operation

Familiarize yourself with all controls before starting.

Controls: Master Control Lever (stop, run, start), Throttle Trigger, Throttle Lock, Choke Knob, Decompression Valve, Primer Bulb.

Starting Procedure:

1. Place blower on flat, clear ground. Put on harness.
2. Set Master Control to START (choke on).
3. Press decompression valve (if equipped).
4. Pump primer bulb 5-10 times until fuel is visible.
5. Hold blower securely, pull starter rope briskly until engine fires.
6. Move Master Control to RUN position.
7. Allow engine to warm up at idle for 30 seconds.

Stopping: Release throttle, set Master Control to STOP.

Fuel & Lubrication

Use only fresh, unleaded gasoline (min. 89 octane) mixed with a high-quality 2-stroke engine oil.

1. Mix fuel in a clean, approved container: 50 parts gasoline to 1 part oil.
2. Shake container gently before refueling.
3. Never use fuel older than 60 days; avoid ethanol blends above 10%.
4. Lubrication: Engine is lubricated by oil in fuel mix. Gearbox (if applicable) is factory filled.

Tip: Store fuel mix in a cool, dry place away from sunlight and ignition sources.

Maintenance Schedule

Regular maintenance ensures performance and longevity.

Interval	Task
Before each use	Check for loose fasteners, leaks, damage. Clean air intake.
Every 25 hours	Clean spark plug, check electrode gap. Clean/check air filter.
Every 50 hours	Replace spark plug. Check fuel filter, replace if dirty.
Every 100 hours	Clean combustion chamber, check muffler screen.
Annually	Inspect all hoses, cables, harness. Professional service recommended.

WARNING! Always disconnect spark plug wire before performing maintenance.

Storage Guidelines

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

1. Drain fuel tank and run engine until it stops to empty carburetor.
2. Remove spark plug, add a teaspoon of engine oil into cylinder, pull starter slowly 2-3 times, reinstall plug.
3. Clean entire unit, especially cooling fins and air filter.
4. Store in a dry, dust-free place, protected from moisture.

CAUTION! Never store with fuel in the tank for long periods. Fuel can degrade and damage components.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine will not start	No fuel, flooded, bad spark	Check fuel, set choke to RUN, dry plug, check spark.
Engine runs poorly, lacks power	Dirty air filter, clogged fuel filter, old fuel	Clean/replace air filter, replace fuel filter, use fresh mix.
Excessive vibration	Loose parts, damaged impeller	Tighten all fasteners, inspect impeller for damage.
Airflow is weak	Clogged tube/nozzle, worn impeller	Clear debris from tube, inspect/replace impeller.
Engine overheats	Dirty cooling fins, lean fuel mix	Clean cooling fins, ensure correct 50:1 fuel mix.

Reset: For electronic ignition issues, disconnect spark plug wire for 1 minute.

Warranty & Support

STIHL BR 320 is covered by a limited warranty for commercial use. Proof of purchase required. Warranty does not cover damage from misuse, improper fuel, neglect, or unauthorized modifications. For technical support, genuine parts, and authorized service, contact your local STIHL dealer or visit www.stihlusa.com.

Service Hotline: 1-800-467-8445