STIHL BR 500 Service Manual

The STIHL BR 500 is a professional-grade backpack blower designed for demanding commercial and residential applications. This manual provides comprehensive service, maintenance, and repair information for the BR 500 engine and blower unit. It covers safety procedures, technical specifications, troubleshooting, disassembly/assembly instructions, and parts identification. Below are key sections for safety, features, maintenance, troubleshooting, and technical data.

Features at a Glance

Key components: STIHL 2-MIX engine, backpack harness, throttle control, adjustable blower tube, air filter system, and anti-vibration mounts.

Safety Information

Always follow safety precautions to prevent injury or damage.

1. Personal Protective Equipment (PPE): Always wear safety glasses, hearing protection, gloves, long pants, and sturdy boots.
2. Work Area Safety: Keep bystanders and pets at least 15 meters away. Ensure good ventilation when operating.
3. Fuel Safety: Use only STIHL MotoMix or a 50:1 mixture of unleaded gasoline (min. 89 octane) and STIHL 2-stroke oil. Refuel in a well-ventilated area with engine off and cool.
4. Before Starting: Inspect for loose fasteners, damaged parts, and fuel leaks. Ensure blower tube is securely attached.
5. During Operation: Maintain secure footing. Never point the blower tube at people, animals, or debris that could become projectiles.

WARNING! The muffler and other engine parts become extremely hot during and after operation. Allow the engine to cool before performing any service or maintenance.

Maintenance Schedule

Regular maintenance ensures optimal performance and longevity. Refer to the table below.

CAUTION! Always disconnect the spark plug boot before performing any maintenance to prevent accidental starting.

Technical Specifications

• Engine: STIHL 2-MIX, single cylinder, air-cooled, 2-stroke.
• Bore x Stroke: 48 mm x 36 mm.
• Ignition System: Electronic, capacitor discharge (CDI).
• Spark Plug: Bosch WSR 6 F or equivalent, gap 0.5 mm (0.020 in).
• Carburetor: Zama C1Q-S series, adjustable (H, L, LA screws).
• Air Filtration: 2-stage (pre-filter and main foam element).
• Starting System: Recoil starter with decompression valve.
• Blower Tube: 2-piece, adjustable length, aluminum construction.
• Impeller: 6-blade plastic composite, balanced.
• Warranty: Commercial warranty terms apply (see dealer).

Controls and Components

Familiarize yourself with the main controls and components before operation or service.

Backpack Unit: Harness adjustment buckles, back pad, fuel tank cap, master control lever (stop switch, choke, throttle lock).

Handheld Controls: Throttle trigger, throttle lockout (safety lever), blower tube handle.

Engine Components: Recoil starter handle, air filter cover, muffler, spark plug, carburetor adjustment screws (H - High speed, L - Low speed, LA - Idle speed).

Service Points: Fuel filter (inside tank), fuel line, impulse line, crankcase seals.

Fuel System Service

Common service procedures for the fuel system.

1. Fuel Filter Replacement: Drain fuel. Remove tank cap and use a clean wire hook to extract the filter and fuel line. Replace filter, reconnect line, and reinstall.
2. Carburetor Adjustment (Basic): Engine must be at operating temperature. Turn H and L screws clockwise until lightly seated, then counter-clockwise 1 turn as a baseline. Fine-tune for smooth acceleration and idle.
3. Fuel Line Replacement: If cracked or brittle, remove tank and replace all fuel lines and impulse line. Ensure proper routing to avoid kinks.
4. Fuel Tank Vent: Check the tank vent (in cap) for blockage. Clean with compressed air if necessary.

Tip: Always use fresh fuel mix. Stale fuel is a primary cause of starting and running issues.

Ignition System Service

Diagnosis and service of the ignition system.

1. Spark Plug: Remove, inspect, clean, and regap or replace. Signs of fouling indicate incorrect fuel mix or carburetion.
2. Ignition Module (CDI) Test: Use a STIHL ignition tester or multimeter to check for spark. No spark may indicate a faulty module, broken wire, or faulty stop switch.
3. Stop Switch Circuit: The switch must close to ground to stop the engine. A short to ground in the wire can prevent starting. Disconnect wire from module to test.
4. Flywheel & Key: Check for sheared woodruff key if timing is incorrect (engine backfires or won't start).

WARNING! Never check for spark by holding the plug against the cylinder. Use a proper spark tester.

Air Filter & Cooling System

Maintaining clean intake and cooling paths is critical.

1. Air Filter Service: Remove cover. Separate pre-filter from main foam element. Wash both in warm, soapy water. Rinse, dry thoroughly, and re-oil the main element with STIHL filter oil (squeeze out excess).
2. Cooling Fins: Remove the recoil starter assembly and fan housing. Use a brush and compressed air to clean debris from cylinder cooling fins and flywheel fins.
3. Intake Manifold & Reed Valve: Inspect the rubber intake manifold for cracks. Check reed valve petals for breakage or improper sealing.

CAUTION! Never operate the engine without the air filter or with a wet filter, as this can cause severe engine damage.

Blower Tube & Impeller

Service procedures for the air delivery system.

1. Tube Removal: Loosen the clamp securing the tube to the blower housing. Twist and pull the tube straight off.
2. Impeller Inspection: Remove the blower housing (typically 4-6 screws). Visually inspect the plastic impeller for cracks, chips, or excessive wear. Check for balance by spinning manually; it should rotate freely without rubbing.
3. Impeller Replacement: Hold the crankshaft with a piston stop tool. Remove the impeller nut (standard thread). Replace impeller, ensuring the key is properly seated. Torque nut to specification (approx. 40 Nm).
4. Bearing Check: With impeller removed, check the crankshaft bearing in the housing for smooth rotation and no play.

Troubleshooting Guide

Reset: For electronic issues (if applicable), disconnect spark plug boot for 1 minute to reset module.

Parts Diagrams & Ordering

Use genuine STIHL parts for repair. Reference the specific Illustrated Parts List (IPL) for the BR 500 (Serial Number specific).

1. Finding Your Serial Number: Located on the engine housing or blower housing.
2. Ordering Parts: Contact an authorized STIHL servicing dealer with your model and serial number.
3. Common Replacement Parts: Air filter kit, fuel filter, spark plug, impeller, carburetor repair kit, starter rope, harness straps.
4. Special Tools: Piston stop tool, flywheel puller, carburetor adjustment tool may be required for some procedures.

Service Support: For technical assistance or to locate a dealer, visit www.stihlusa.com or contact STIHL customer service.