STIHL BT45 Manual

The STIHL BT45 is a professional backpack blower designed for demanding commercial and residential applications. It features a powerful 4-stroke engine, ergonomic harness system, variable speed throttle, cruise control, low vibration technology, and meets stringent emission standards. Below are key sections for safety, features, operation, maintenance, and troubleshooting.

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

Features at a Glance

Key components: 4-stroke engine, backpack frame with harness, blower tube, throttle trigger, cruise control lever, air filter, spark plug, fuel tank.

Feature	Description
Engine Type	4-stroke, single cylinder, air-cooled
Displacement	45.6 cc
Maximum Air Speed	Approx. 150 mph (241 km/h)
Maximum Air Volume	Approx. 765 cfm (21.7 m³/min)
Fuel Tank Capacity	1.9 US pt (0.9 liters)
Sound Power Level	112 dB(A)
Weight (dry)	24.7 lbs (11.2 kg)
Harness System	Padded, adjustable shoulder and waist straps
Throttle Control	Variable speed with cruise control lock
Vibration Damping	Low vibration handles and mounts

Safety Information

Read and understand all instructions before operation.

Wear appropriate PPE: Safety glasses, hearing protection, long pants, sturdy shoes.
Operate in well-ventilated areas only; never indoors.
Keep bystanders and pets at least 50 feet away.
Inspect unit before each use for loose parts or damage.
Use only STIHL-approved fuel and oil mixtures.

WARNING! Risk of fire, explosion, and injury. Do not operate near flammable materials or in wet conditions. Engine and muffler become extremely hot during and after use.

Assembly & Preparation

Unpack all components and inspect for damage.

Attach blower tube: Align tube with engine outlet and twist clockwise until secure.
Install harness: Thread shoulder straps through backpack frame loops; adjust for fit.
Fuel mixture: Use 89 octane minimum gasoline with STIHL 4-stroke engine oil. Fill tank to marked level.
Check air filter: Ensure clean and properly seated.
Priming: Press primer bulb 5-10 times until fuel is visible in bulb.

CAUTION! Assemble on a clean, flat surface. Keep fuel away from sparks, flames, and heat sources.

Specifications

Model: STIHL BT45
Engine Power: 2.1 kW (2.8 bhp)
Idle Speed: 2,800 rpm
Maximum Speed: 7,500 rpm
Fuel/Oil System: Separate fill (no mixing required)
Ignition System: Electronic, capacitor discharge
Starting System: Recoil starter
Carburetor: Diaphragm type with fixed jet
Emission Compliance: EPA Phase III, CARB Tier III
Warranty: Limited commercial warranty (see manual)

Controls and Operation

Main Controls: Throttle trigger, cruise control lever, choke knob, stop switch, primer bulb.

Operation: Wear harness, start engine on ground, allow warm-up, adjust throttle as needed. Use cruise control for extended operation at constant speed.

Blowing Techniques: Hold tube at low angle for ground debris; use sweeping motions. Avoid directing air at people, animals, or fragile objects.

Starting & Stopping Procedure

Cold Start:

Place unit on flat, clear ground.
Set stop switch to "I" (RUN).
Move choke lever to full choke position.
Press primer bulb 5-10 times.
Pull starter rope briskly until engine fires (1-3 pulls).
Move choke to half-choke position immediately.
Pull starter rope again until engine runs.
Allow 30-second warm-up at half-choke, then move choke to run position.

Warm Start: Choke in run position; prime 1-2 times if needed.

Stopping: Release throttle, let engine idle for 30 seconds, move stop switch to "0" (STOP).

Maintenance Schedule

Interval	Task
Before each use	Check for loose fasteners, leaks, damage; clean air filter
Every 25 hours	Clean spark arrestor screen; check spark plug gap
Every 50 hours	Replace air filter; clean cooling fins; check fuel filter
Every 100 hours	Replace spark plug; clean carburetor; check throttle cable
Annually	Change engine oil (0.63 qt/0.6L); inspect harness and tubes

Note: Use only STIHL genuine parts for replacement.

Storage Guidelines

For storage longer than 30 days:

Drain fuel tank completely or add fuel stabilizer.
Run engine for 2 minutes to circulate treated fuel.
Change engine oil if due.
Clean entire unit, especially cooling fins and air filter.
Store in dry, cool place away from ignition sources.
Remove spark plug and add 1 teaspoon of oil into cylinder; pull starter slowly to coat.

CAUTION! Never store with fuel in tank for extended periods without stabilizer.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine will not start	No fuel, flooded, bad spark	Check fuel level; wait if flooded; check spark plug.
Engine runs poorly	Dirty air filter, old fuel	Clean/replace air filter; use fresh fuel.
Loss of power	Clogged spark arrestor	Clean spark arrestor screen.
Excessive vibration	Loose parts, damaged tube	Tighten all fasteners; inspect tube.
Oil leakage	Overfilled, loose drain plug	Check oil level; tighten drain plug.

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

Warranty Information

STIHL BT45 includes a limited warranty for commercial use. Warranty period and coverage vary by region. Proof of purchase required. Warranty does not cover damage from misuse, neglect, improper fuel, or unauthorized modifications.

For warranty claims and service locations: Visit www.stihlusa.com or call 1-800-467-8445.