The Husqvarna 125BT is a professional-grade backpack leaf blower designed for demanding commercial and residential use. This parts manual provides detailed diagrams, part numbers, and ordering information for all components of the 125BT blower, including the engine assembly, fan housing, throttle controls, harness system, fuel tank, and muffler. Use this guide for identification, maintenance, and replacement of genuine Husqvarna parts to ensure optimal performance and safety.
This manual is intended for authorized service technicians and users familiar with small engine equipment. Always prioritize safety when performing maintenance or replacing parts.
| Safety Symbol | Meaning |
|---|---|
| ⚠️ WARNING | Indicates a potentially hazardous situation which, if not avoided, could result in serious injury or death. |
| 🔥 HOT SURFACE | Engine and muffler parts become extremely hot during operation. Allow to cool before handling. |
| ⛽ FUEL VAPORS | Work in a well-ventilated area away from sparks or flames when servicing the fuel system. |
IMPORTANT: Use only genuine Husqvarna replacement parts. Non-genuine parts may void your warranty and compromise safety and performance.
Refer to the corresponding diagram number when ordering parts. Each exploded view is accompanied by a numbered list of components.
Note: Part numbers are subject to change. Always verify the latest part number with your Husqvarna dealer or the official parts website.
Core power unit components. Handle with care during disassembly.
| Ref # | Part Number | Description | Qty |
|---|---|---|---|
| 1 | 537 27 41-01 | Cylinder Complete | 1 |
| 2 | 537 27 42-01 | Piston Assembly | 1 |
| 3 | 501 84 29-01 | Crankshaft | 1 |
| 4 | 537 27 43-01 | Connecting Rod | 1 |
| 5 | 544 11 62-01 | Spark Plug (NGK BPMR7A) | 1 |
| 6 | 537 27 44-01 | Carburetor (Zama C1U) | 1 |
| 7 | 501 84 30-01 | Ignition Module | 1 |
| 8 | 537 27 45-01 | Rewind Starter Assembly | 1 |
Torque Specs: Cylinder head bolts: 10 Nm (7.4 ft-lb). Spark plug: 25 Nm (18.4 ft-lb).
Components responsible for generating airflow. Inspect for cracks or debris.
| Ref # | Part Number | Description | Qty |
|---|---|---|---|
| 9 | 537 27 46-01 | Fan Housing Upper | 1 |
| 10 | 537 27 47-01 | Fan Housing Lower | 1 |
| 11 | 501 84 31-01 | Impeller (Fan Blade) | 1 |
| 12 | 544 11 63-01 | Impeller Nut | 1 |
| 13 | 537 27 48-01 | Air Intake Cover | 1 |
| 14 | 544 11 64-01 | Air Filter Element | 1 |
| 15 | 537 27 49-01 | Blower Tube Adapter | 1 |
Warning: Always ensure the impeller is securely fastened and balanced. An unbalanced impeller can cause excessive vibration.
Support structure and carrying system. Check for wear on straps and padding.
| Ref # | Part Number | Description | Qty |
|---|---|---|---|
| 16 | 537 27 50-01 | Main Frame | 1 |
| 17 | 544 11 65-01 | Back Pad (Foam) | 1 |
| 18 | 537 27 51-01 | Shoulder Harness Strap Set | 1 |
| 19 | 544 11 66-01 | Waist Strap | 1 |
| 20 | 537 27 52-01 | Quick-Release Buckle | 2 |
| 21 | 501 84 32-01 | Vibration Dampening Mount Set | 4 |
Maintenance: Clean harness straps with mild soap and water. Do not use solvents.
Operator interface components. Ensure cables move freely without binding.
| Ref # | Part Number | Description | Qty |
|---|---|---|---|
| 22 | 537 27 53-01 | Throttle Lever Assembly | 1 |
| 23 | 544 11 67-01 | Throttle Cable | 1 |
| 24 | 537 27 54-01 | Stop Switch | 1 |
| 25 | 501 84 33-01 | Choke Lever | 1 |
| 26 | 544 11 68-01 | Front Handle Grip | 1 |
| 27 | 537 27 55-01 | Rear Handle | 1 |
Adjustment: Throttle cable free play should be 1-2 mm. Adjust at the carburetor end.
Components for fuel delivery and storage. Use ethanol-free fuel to prevent deterioration.
| Ref # | Part Number | Description | Qty |
|---|---|---|---|
| 28 | 537 27 56-01 | Fuel Tank | 1 |
| 29 | 544 11 69-01 | Fuel Cap with Gasket | 1 |
| 30 | 501 84 34-01 | Fuel Line (5x7mm) | 0.5 m |
| 31 | 537 27 57-01 | Fuel Filter (In-tank) | 1 |
| 32 | 544 11 70-01 | Primer Bulb | 1 |
CAUTION! Inspect fuel lines regularly for cracks or hardening. Replace every 2 years or as needed.
Exhaust system components. Critical for noise reduction and engine backpressure.
| Ref # | Part Number | Description | Qty |
|---|---|---|---|
| 33 | 537 27 58-01 | Muffler Assembly | 1 |
| 34 | 544 11 71-01 | Spark Arrestor Screen | 1 |
| 35 | 501 84 35-01 | Muffler Gasket | 1 |
| 36 | 537 27 59-01 | Heat Shield | 1 |
| 37 | 544 11 72-01 | Exhaust Deflector | 1 |
Service: Clean the spark arrestor screen regularly (every 25 hours) to prevent carbon buildup and fire hazard.
How to order parts and understand warranty coverage.
Note: Serial number is required for warranty claims and accurate part identification.
Common issues and part-related solutions.
| Symptom | Possible Faulty Part | Corrective Action |
|---|---|---|
| Engine won't start | Spark Plug, Fuel Filter, Ignition Module | Check/replace spark plug. Inspect fuel lines and filter. Test ignition with a spark tester. |
| Loss of power/airflow | Impeller, Air Filter, Muffler | Inspect impeller for damage or debris. Clean/replace air filter. Clean spark arrestor screen in muffler. |
| Excessive vibration | Impeller, Vibration Mounts, Fan Housing | Check impeller balance and tightness. Inspect and replace worn rubber vibration mounts. |
| Fuel leak | Fuel Lines, Fuel Tank, Fuel Cap Gasket | Inspect all fuel lines for cracks. Check tank for damage. Replace fuel cap gasket. |
| Throttle sticks or is unresponsive | Throttle Cable, Throttle Lever | Lubricate or replace throttle cable. Inspect lever assembly for wear or damage. |
Technical Support: Husqvarna USA: 1-800-487-5962. Website: www.husqvarna.com/us