Stihl Wood Chipper BG86C Repairs (5 Pro Fixes You Must Know)

Stihl BG86C Repairs: 5 Pro Fixes You Must Know

The Stihl BG86C is a versatile tool, functioning as both a powerful blower and a capable leaf shredder/chipper. When it’s running smoothly, it’s a real time-saver. But like any piece of machinery, it can experience problems. I’ve found that many issues are easily resolved with a bit of knowledge and the right approach. This guide will walk you through five of the most common problems I’ve encountered with the BG86C, along with detailed, step-by-step solutions.

1. Starting Problems: Fuel and Ignition Issues

One of the most frustrating issues is a blower that refuses to start. This often boils down to fuel delivery or ignition problems. Let’s dive in.

Fuel System Troubleshooting

• Old Fuel: This is the most common culprit. Fuel degrades over time, especially when mixed with oil. I always recommend using fresh fuel, mixed according to Stihl’s specifications (typically 50:1 ratio with high-quality two-stroke oil).

  • Technical Requirement: Use a fuel stabilizer if storing fuel for more than 30 days. Stabilizers like STA-BIL can extend fuel life up to 12 months.
  • Practical Tip: I mark the date on my fuel cans when I mix them. If it’s older than a month, I discard it. Don’t risk it!
  • Data Point: Ethanol-blended fuel can absorb moisture, leading to phase separation. This can cause corrosion and poor engine performance. The maximum ethanol content recommended for small engines is typically 10% (E10).

  • Clogged Fuel Filter: The fuel filter prevents debris from entering the carburetor. A clogged filter restricts fuel flow, leading to starting problems or poor performance.

  • Procedure:

    1. Locate the fuel filter inside the fuel tank. It’s usually attached to the end of the fuel line.
    2. Use a small hook or wire to carefully pull the fuel line and filter out of the tank.
    3. Inspect the filter for dirt and debris.
    4. If the filter is clogged, replace it with a new one. Stihl part number: 0000-984-0802
    5. Reinstall the fuel line and filter.
  • Tool Requirement: Small hook or wire, replacement fuel filter.
  • Case Study: I once spent hours troubleshooting a BG86C that wouldn’t start. The problem? A completely clogged fuel filter. The owner had been using old, unfiltered fuel. Replacing the filter solved the issue instantly.

  • Blocked Fuel Lines: Fuel lines can crack or become blocked with debris over time.

  • Procedure:

    1. Inspect the fuel lines for cracks, kinks, or damage.
    2. Disconnect the fuel lines from the carburetor and fuel tank.
    3. Use compressed air or a small wire to clear any blockages in the lines.
    4. Replace any damaged fuel lines. Stihl part number: 4241-350-3200
  • Technical Requirement: Use fuel line specifically designed for small engines. Standard automotive fuel line may not be compatible with the fuel used in two-stroke engines.

  • Carburetor Issues: The carburetor mixes fuel and air to create a combustible mixture. A dirty or malfunctioning carburetor can cause starting problems, poor idling, or stalling.

  • Procedure:

    1. Carburetor Cleaning: The best approach is to disassemble the carburetor and clean it thoroughly with carburetor cleaner. Pay close attention to the jets and passages.
    2. Carburetor Adjustment: The BG86C has adjustable carburetor screws (high and low speed). Adjust these screws according to the Stihl BG86C service manual. I usually start by turning both screws all the way in and then backing them out 1.5 turns. Fine-tune from there.
    3. Carburetor Replacement: If cleaning and adjustment don’t solve the problem, consider replacing the carburetor. Stihl part number: 4241-120-0607
  • Tool Requirement: Carburetor cleaner, small screwdrivers, Stihl BG86C service manual.
  • Safety Code: Always disconnect the spark plug wire before working on the fuel system to prevent accidental starting.
  • Personalized Storytelling: I remember helping a friend who was struggling with a BG86C that wouldn’t idle. We tried everything, but the carburetor was just too far gone. Replacing it was the only solution. It’s sometimes the most efficient route.

Ignition System Troubleshooting

• Faulty Spark Plug: A worn or fouled spark plug can prevent the engine from starting.

  • Procedure:
    1. Remove the spark plug.
    2. Inspect the spark plug for cracks, carbon buildup, or damage.
    3. Clean the spark plug with a wire brush or replace it with a new one. Stihl part number: 0000-400-7000 (Champion RCJ6Y).
    4. Check the spark plug gap. It should be 0.5 mm (0.020 inches). Use a spark plug gap tool to adjust the gap if necessary.
    5. Reinstall the spark plug.
  • Technical Requirement: Use the correct spark plug type and gap specified by Stihl. Using the wrong spark plug can damage the engine.
  • Practical Tip: I always keep a spare spark plug on hand. It’s a cheap and easy way to prevent downtime.

  • Defective Ignition Coil: The ignition coil generates the high-voltage spark needed to ignite the fuel mixture. A faulty ignition coil can prevent the engine from starting.

  • Procedure:

    1. Disconnect the spark plug wire from the spark plug.
    2. Use a spark tester to check for spark.
    3. If there is no spark, the ignition coil may be defective.
    4. Use a multimeter to test the resistance of the ignition coil. Refer to the Stihl BG86C service manual for the correct resistance values.
    5. If the ignition coil is defective, replace it. Stihl part number: 4241-400-1305.
  • Tool Requirement: Spark tester, multimeter, Stihl BG86C service manual.
  • Safety Code: Always disconnect the spark plug wire before testing the ignition system to prevent electric shock.

2. Loss of Power: Air Filter and Exhaust Issues

If your BG86C starts but lacks power, the problem often lies in air intake or exhaust.

Air Filter Issues

• Clogged Air Filter: A dirty air filter restricts airflow to the engine, leading to reduced power and poor performance.

  • Procedure:
    1. Remove the air filter cover.
    2. Remove the air filter.
    3. Inspect the air filter for dirt and debris.
    4. If the air filter is dirty, clean it with warm, soapy water. Rinse it thoroughly and allow it to dry completely before reinstalling. You can also use compressed air to blow out the dirt.
    5. If the air filter is damaged, replace it with a new one. Stihl part number: 4241-141-0300.
    6. Reinstall the air filter and air filter cover.
  • Technical Requirement: Clean the air filter regularly, especially in dusty conditions. I usually clean mine after every 5-10 hours of use.
  • Practical Tip: I keep a spare air filter on hand so I can quickly swap it out while the other one is drying.
  • Data Point: A clogged air filter can reduce engine power by up to 20%.

Exhaust System Issues

• Clogged Spark Arrestor: The spark arrestor prevents sparks from escaping the exhaust system, reducing the risk of fire. A clogged spark arrestor can restrict exhaust flow, leading to reduced power.

  • Procedure:
    1. Locate the spark arrestor on the muffler.
    2. Remove the spark arrestor screen.
    3. Clean the spark arrestor screen with a wire brush.
    4. Reinstall the spark arrestor screen.
  • Technical Requirement: Clean the spark arrestor regularly, especially if you use your BG86C frequently.
  • Safety Code: Allow the engine to cool completely before working on the exhaust system to prevent burns.

  • Blocked Exhaust Port: Carbon buildup in the exhaust port can restrict exhaust flow, leading to reduced power.

  • Procedure:

    1. Remove the muffler.
    2. Inspect the exhaust port for carbon buildup.
    3. Use a scraper or wire brush to remove the carbon buildup.
    4. Reinstall the muffler.
  • Tool Requirement: Scraper or wire brush.
  • Safety Code: Wear safety glasses when cleaning the exhaust port to protect your eyes from flying debris.

3. Overheating: Cooling System and Fuel Mixture Issues

Overheating can cause serious engine damage. Let’s look at the common causes.

Cooling System Issues

• Dirty Cooling Fins: The cooling fins on the cylinder head help dissipate heat. Dirty cooling fins can reduce cooling efficiency, leading to overheating.

  • Procedure:
    1. Remove the blower housing.
    2. Inspect the cooling fins for dirt and debris.
    3. Clean the cooling fins with a brush or compressed air.
    4. Reinstall the blower housing.
  • Technical Requirement: Clean the cooling fins regularly, especially in dusty conditions.

  • Blocked Air Intake: A blocked air intake can restrict airflow to the engine, leading to overheating.

  • Procedure:

    1. Inspect the air intake for obstructions.
    2. Remove any obstructions from the air intake.
  • Practical Tip: Make sure the air intake is not blocked by leaves or debris when using the BG86C.

Fuel Mixture Issues

• Lean Fuel Mixture: A lean fuel mixture (too much air, not enough fuel) can cause the engine to run hot.

  • Procedure:
    1. Adjust the carburetor. Refer to the Stihl BG86C service manual for the correct carburetor settings.
    2. Check the fuel lines for leaks or cracks.
    3. Check the fuel filter for clogs.
  • Technical Requirement: Use the correct fuel mixture specified by Stihl (typically 50:1).
  • Data Point: A lean fuel mixture can increase engine temperature by up to 50 degrees Celsius.

4. Excessive Vibration: Loose Components and Damaged Fan

Excessive vibration can be uncomfortable and can also damage the BG86C over time.

Loose Components

• Loose Screws and Bolts: Loose screws and bolts can cause vibration.

  • Procedure:
    1. Inspect the BG86C for loose screws and bolts.
    2. Tighten any loose screws and bolts.
  • Tool Requirement: Screwdrivers, wrenches.
  • Practical Tip: Use threadlocker (e.g., Loctite) on screws and bolts that tend to loosen over time.

Damaged Fan

• Cracked or Broken Fan: A cracked or broken fan can cause excessive vibration.

  • Procedure:
    1. Remove the blower housing.
    2. Inspect the fan for cracks or damage.
    3. If the fan is cracked or broken, replace it with a new one. Stihl part number: 4241-700-7100.
    4. Reinstall the blower housing.
  • Tool Requirement: Screwdrivers.
  • Safety Code: Always disconnect the spark plug wire before working on the fan to prevent accidental starting.

5. Chipper/Shredder Issues: Blockages and Blade Problems

If you’re using the BG86C as a chipper/shredder, you might encounter blockages or blade issues.

Blockages

• Clogged Chute: A clogged chute can prevent the BG86C from shredding leaves and debris effectively.

  • Procedure:
    1. Stop the engine and disconnect the spark plug wire.
    2. Remove any debris from the chute.
    3. Use a stick or tool to clear any blockages in the chute.
    4. Reinstall the spark plug wire.
  • Safety Code: Never use your hands to clear blockages in the chute.
  • Practical Tip: Only feed dry leaves and debris into the chipper/shredder. Wet leaves can clog the chute more easily.

Blade Problems

• Dull Blades: Dull blades can reduce the efficiency of the chipper/shredder.

  • Procedure:
    1. Stop the engine and disconnect the spark plug wire.
    2. Remove the blades.
    3. Sharpen the blades with a file or grinding wheel.
    4. Reinstall the blades.
  • Tool Requirement: File or grinding wheel.
  • Safety Code: Wear safety glasses and gloves when sharpening the blades.

  • Damaged Blades: Damaged blades can cause excessive vibration and reduce the efficiency of the chipper/shredder.

  • Procedure:

    1. Stop the engine and disconnect the spark plug wire.
    2. Remove the blades.
    3. Inspect the blades for damage.
    4. If the blades are damaged, replace them with new ones. Stihl part number: 4241-713-7300.
    5. Reinstall the blades.
  • Safety Code: Always wear gloves when handling the blades.

Maintenance Schedule

To keep your Stihl BG86C running smoothly, I recommend following this maintenance schedule:

• Every Use: Check fuel level, air filter, and spark arrestor.
• Every 25 Hours: Clean or replace air filter, clean spark arrestor, inspect spark plug.
• Every 100 Hours: Replace spark plug, inspect fuel lines, lubricate moving parts.
• Annually: Inspect and clean carburetor, check ignition system.

Technical Specifications (Example):

Wood Processing Insight:

I’ve noticed a direct correlation between the sharpness of chipper blades and the quality of the mulch produced. Dull blades tend to tear rather than cut, resulting in uneven mulch that decomposes slower. Sharpening blades regularly not only improves the mulch quality but also reduces the strain on the engine, prolonging its life. This is a critical point for anyone using the BG86C for composting or landscaping purposes.

By following these pro fixes and maintaining your Stihl BG86C regularly, you can keep it running smoothly for years to come. Remember, safety first! Always disconnect the spark plug wire before performing any maintenance or repairs. Good luck, and happy blowing (and chipping)!

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