Stihl BG86 Problems: Adjustment Tips For Optimal Wood Blowing (Pro Fixes)

Let’s talk about keeping your Stihl BG86 blower humming. One of the things I appreciate most about the BG86 is how relatively easy it is to maintain. A quick wipe down after each use, keeping the air filter clean, and using the right fuel mix goes a long way. But even with the best care, sometimes these tools develop issues. I’ve spent countless hours in my woodlot, clearing debris, and prepping for firewood season, and I’ve learned a thing or two about troubleshooting these blowers. The Stihl BG86 is a workhorse, but like any piece of machinery, it can occasionally throw a wrench (or a leaf) in your plans. This guide is designed to help you diagnose and fix common problems with your BG86, ensuring it’s always ready to tackle your wood-blowing needs.

Stihl BG86 Problems: Adjustment Tips for Optimal Wood Blowing (Pro Fixes)

This guide will cover everything from basic adjustments to more complex troubleshooting, helping you get the most out of your blower. Whether you’re clearing leaves, sawdust, or debris from your wood processing area, a properly functioning blower is essential for efficiency and safety.

Understanding the Importance of a Well-Adjusted Blower

A well-adjusted Stihl BG86 isn’t just about convenience; it’s about efficiency, safety, and prolonging the life of your tool. When your blower is running optimally, you’ll use less fuel, experience less wear and tear on the engine, and be able to clear debris more effectively. This is particularly important when you’re working in a wood processing environment, where efficiency can directly translate to increased productivity.

Key Terms and Concepts

Before diving into the specifics, let’s define some key terms that will be used throughout this guide:

Air-Fuel Mixture: The ratio of air to fuel in the engine. A lean mixture has more air, while a rich mixture has more fuel.
Carburetor: A device that mixes air and fuel for internal combustion engines.
Idle Speed: The engine’s speed when no throttle is applied.
Spark Arrestor: A device that prevents sparks from exiting the exhaust system, reducing the risk of fire.
Two-Stroke Engine: An engine that completes a power cycle with two strokes of the piston.
High-Speed Adjustment (H): The carburetor adjustment that controls the fuel mixture at high engine speeds.
Low-Speed Adjustment (L): The carburetor adjustment that controls the fuel mixture at low engine speeds.
Idle Speed Adjustment (LA): The screw that adjusts the engine’s idle speed.

Diagnosing Common Stihl BG86 Problems

The first step to fixing any problem is identifying it. Here are some common issues you might encounter with your Stihl BG86, along with potential causes:

1. Blower Won’t Start

This is perhaps the most frustrating issue. Here are the most common culprits:

Empty Fuel Tank: Obvious, but worth checking first!
Old or Stale Fuel: Two-stroke engines are particularly sensitive to fuel quality. Fuel older than 30 days can degrade and cause starting problems. I once spent an hour trying to start a BG86 only to realize the fuel I used was almost 6 months old. Now, I always mark the date on my fuel cans.
Spark Plug Issues: A fouled, wet, or damaged spark plug can prevent ignition.
Clogged Air Filter: A dirty air filter restricts airflow, leading to a lean fuel mixture.
Carburetor Problems: A clogged or improperly adjusted carburetor can prevent fuel from reaching the engine.
Ignition Coil Failure: The ignition coil provides the spark to ignite the fuel mixture.
Incorrect Starting Procedure: Make sure you’re following the correct starting procedure as outlined in the owner’s manual.

2. Blower Starts but Stalls Immediately

This often indicates a fuel delivery problem:

Incorrect Carburetor Adjustment: The carburetor may be set too lean or too rich.
Clogged Fuel Filter: A clogged fuel filter restricts fuel flow to the carburetor.
Ventilation Issues: The fuel tank vent may be blocked, creating a vacuum that prevents fuel from flowing.
Weak Fuel Pump: The fuel pump may not be supplying enough fuel to the carburetor.

3. Blower Lacks Power

A lack of power can be caused by several factors:

Clogged Air Filter: Again, restricted airflow can significantly reduce power.
Clogged Spark Arrestor: A clogged spark arrestor restricts exhaust flow, reducing engine performance.
Incorrect Carburetor Adjustment: An improperly adjusted carburetor can result in a lean or rich fuel mixture, both of which can reduce power.
Worn Piston Rings: Worn piston rings can reduce compression, leading to a loss of power. This is more common in older blowers with high usage.
Exhaust Port Blockage: Carbon buildup in the exhaust port can restrict exhaust flow.

4. Blower Runs Rough or Erratic

A rough-running engine can be caused by:

Incorrect Carburetor Adjustment: The carburetor may be set too lean or too rich.
Air Leaks: Air leaks in the intake manifold or carburetor can cause erratic engine performance.
Spark Plug Issues: A fouled or damaged spark plug can cause misfires and rough running.
Contaminated Fuel: Water or other contaminants in the fuel can cause the engine to run poorly.
Loose Components: Loose screws or bolts can cause vibrations and erratic engine performance.

5. Blower Smokes Excessively

Excessive smoke can indicate:

Incorrect Fuel Mixture: Using too much oil in the fuel mixture can cause excessive smoke. Stihl recommends a 50:1 fuel-to-oil ratio. I always use Stihl Ultra oil, which I find burns cleaner than some other brands.
Worn Piston Rings: Worn piston rings can allow oil to enter the combustion chamber, resulting in excessive smoke.
Oil Leak: An oil leak in the engine can cause excessive smoke.

Step-by-Step Adjustment and Repair Guide

Now that we’ve diagnosed the potential problems, let’s move on to the solutions. Remember to always consult your Stihl BG86 owner’s manual for specific instructions and safety precautions.

1. Fuel System Checks and Adjustments

The fuel system is the heart of your blower. Ensuring it’s clean and properly adjusted is crucial for optimal performance.

a. Fuel Tank and Fuel Lines

Inspection: Inspect the fuel tank for any cracks or leaks. Check the fuel lines for cracks, kinks, or signs of deterioration. Replace any damaged components.
Cleaning: Drain the fuel tank and clean it with fresh fuel. Use a clean cloth to wipe out any debris.
Fuel Lines Replacement: If the fuel lines are cracked or brittle, replace them. Use fuel lines specifically designed for two-stroke engines.
Fuel Filter Replacement: The fuel filter is located inside the fuel tank, attached to the fuel line. Replace it annually or more frequently if you use your blower heavily. To replace it, carefully pull the fuel line out of the tank. The fuel filter will be attached to the end. Use a small hook or pliers to gently remove the filter. Install the new filter by attaching it to the fuel line and carefully inserting it back into the tank.

b. Carburetor Adjustment

The carburetor is responsible for mixing air and fuel in the correct proportions. Adjusting the carburetor can be tricky, but it’s essential for optimal performance.

Locating Adjustment Screws: The Stihl BG86 carburetor typically has three adjustment screws:
- H (High-Speed Adjustment): Controls the fuel mixture at high engine speeds.
- L (Low-Speed Adjustment): Controls the fuel mixture at low engine speeds.
- LA (Idle Speed Adjustment): Adjusts the engine’s idle speed.
Basic Carburetor Adjustment Procedure:
1. Warm-Up: Start the engine and let it warm up for a few minutes.
2. Idle Speed Adjustment (LA): Turn the LA screw clockwise to increase the idle speed or counterclockwise to decrease it. The engine should idle smoothly without stalling. Aim for an idle speed where the blower nozzle is not producing significant airflow.
3. Low-Speed Adjustment (L): Turn the L screw slowly clockwise until the engine starts to stumble or stall. Note the position. Then, turn the L screw counterclockwise until the engine runs smoothly. Find the point where the engine runs the smoothest at low speeds and responds quickly to throttle input.
4. High-Speed Adjustment (H): Note: Adjusting the high-speed screw requires a tachometer to ensure the engine doesn’t exceed its maximum RPM. Over-revving can damage the engine. Turn the H screw clockwise to lean out the mixture (less fuel) or counterclockwise to richen the mixture (more fuel). The goal is to find the setting that provides the best power and acceleration without causing the engine to run lean (which can lead to overheating and damage). Generally, turning the H screw counterclockwise a small amount from the leanest setting will provide the best performance.
5. Fine-Tuning: After making adjustments, let the engine run for a few minutes and fine-tune the screws as needed. The engine should run smoothly at all speeds and respond quickly to throttle input.
Specialized Carburetor Adjustment Tools: In some regions, carburetors may have limiter caps on the adjustment screws to meet emissions regulations. These caps restrict the range of adjustment. Removing these caps may be necessary to achieve optimal performance, but it’s important to be aware of local regulations. Specialized tools are available for removing these caps without damaging the carburetor.
Using a Tachometer: A tachometer is essential for properly adjusting the high-speed screw. Refer to your Stihl BG86 owner’s manual for the recommended maximum RPM. Adjust the H screw until the engine reaches the specified RPM at full throttle.
Carburetor Cleaning: If adjusting the carburetor doesn’t solve the problem, the carburetor may be clogged. Disassemble the carburetor and clean it with carburetor cleaner. Pay close attention to the small jets and passages. Use compressed air to blow out any remaining debris. Reassemble the carburetor and reinstall it on the engine.
Carburetor Replacement: If the carburetor is severely damaged or cannot be cleaned effectively, it may need to be replaced. Purchase a new carburetor that is specifically designed for the Stihl BG86.

c. Fuel Pump

Testing: The fuel pump is responsible for drawing fuel from the tank to the carburetor. If the fuel pump is weak, it may not be supplying enough fuel to the engine. To test the fuel pump, disconnect the fuel line from the carburetor and crank the engine. Fuel should flow steadily from the fuel line. If the fuel flow is weak or nonexistent, the fuel pump may need to be replaced.
Replacement: Replacing the fuel pump involves removing the carburetor and accessing the fuel pump, which is typically located on the side of the engine. Follow the instructions in your Stihl BG86 owner’s manual for specific instructions on replacing the fuel pump.

2. Ignition System Checks and Adjustments

The ignition system is responsible for creating the spark that ignites the fuel mixture.

a. Spark Plug

Inspection: Remove the spark plug and inspect it for signs of fouling, damage, or wear. A healthy spark plug should have a clean, dry electrode with a light tan color. A fouled spark plug may be wet, black, or oily.
Cleaning: If the spark plug is fouled, clean it with a wire brush or spark plug cleaner.
Gap Adjustment: Use a spark plug gap tool to ensure the gap between the electrodes is correct. Refer to your Stihl BG86 owner’s manual for the correct gap specification. Typically, the gap should be around 0.020 inches.
Replacement: If the spark plug is damaged or worn, replace it with a new spark plug that is specifically designed for the Stihl BG86.
Spark Plug Type: Using the correct spark plug is crucial for optimal performance. Refer to your Stihl BG86 owner’s manual for the recommended spark plug type.

b. Ignition Coil

Testing: The ignition coil provides the high-voltage spark that ignites the fuel mixture. If the ignition coil is failing, it may not be providing enough spark to start the engine or keep it running. To test the ignition coil, use a spark tester. Connect the spark tester to the spark plug wire and ground it to the engine. Crank the engine and observe the spark. A healthy ignition coil should produce a strong, consistent spark. If the spark is weak or nonexistent, the ignition coil may need to be replaced.
Replacement: Replacing the ignition coil involves removing the engine cover and accessing the ignition coil, which is typically located near the flywheel. Follow the instructions in your Stihl BG86 owner’s manual for specific instructions on replacing the ignition coil.

c. Flywheel Key

Inspection: The flywheel key is a small metal key that aligns the flywheel with the crankshaft. If the flywheel key is sheared or damaged, it can cause the engine to run poorly or not start at all. To inspect the flywheel key, remove the flywheel and inspect the keyway on the crankshaft and flywheel. If the key is sheared, replace it with a new one.
Replacement: Replacing the flywheel key involves removing the flywheel and installing a new key. Follow the instructions in your Stihl BG86 owner’s manual for specific instructions on replacing the flywheel key.

3. Air Intake and Exhaust System Checks

Ensuring proper airflow is essential for engine performance.

a. Air Filter

Inspection: Remove the air filter and inspect it for dirt, debris, or damage.
Cleaning: If the air filter is dirty, clean it with warm water and mild soap. Rinse the filter thoroughly and allow it to dry completely before reinstalling it.
Oiling: Some air filters require oiling to improve their filtering efficiency. Refer to your Stihl BG86 owner’s manual for specific instructions on oiling the air filter. Use air filter oil specifically designed for foam air filters.
Replacement: If the air filter is damaged or cannot be cleaned effectively, replace it with a new air filter that is specifically designed for the Stihl BG86. I typically replace mine every year, regardless of how clean it looks. It’s cheap insurance.

b. Spark Arrestor

Inspection: The spark arrestor is a small screen located in the exhaust system that prevents sparks from exiting the exhaust. Over time, the spark arrestor can become clogged with carbon deposits, restricting exhaust flow and reducing engine performance. Remove the spark arrestor and inspect it for clogs.
Cleaning: Clean the spark arrestor with a wire brush or carburetor cleaner.
Replacement: If the spark arrestor is damaged or cannot be cleaned effectively, replace it with a new spark arrestor that is specifically designed for the Stihl BG86.

c. Exhaust Port

Inspection: Carbon buildup in the exhaust port can restrict exhaust flow, reducing engine performance. Remove the muffler and inspect the exhaust port for carbon deposits.
Cleaning: Clean the exhaust port with a scraper or wire brush. Be careful not to damage the cylinder walls.
Muffler Cleaning: Clean the muffler with a wire brush to remove any carbon buildup.

4. General Maintenance and Prevention

Preventive maintenance is key to prolonging the life of your Stihl BG86.

a. Fuel Storage

Use Fresh Fuel: Use fresh fuel that is no more than 30 days old.
Fuel Stabilizer: Add fuel stabilizer to the fuel to prevent it from degrading.
Proper Storage: Store fuel in a cool, dry place in a tightly sealed container.
Avoid Ethanol: If possible, use fuel that does not contain ethanol. Ethanol can damage the fuel system and cause starting problems.

b. Regular Cleaning

Clean After Each Use: Clean the blower after each use to remove dirt and debris.
Air Filter Cleaning: Clean the air filter regularly.
Spark Arrestor Cleaning: Clean the spark arrestor regularly.

c. Lubrication

Two-Stroke Oil: Use high-quality two-stroke oil specifically designed for air-cooled engines.
Proper Mixing Ratio: Use the correct fuel-to-oil ratio as specified in your Stihl BG86 owner’s manual. Stihl recommends a 50:1 ratio.
Moving Parts: Lubricate any moving parts on the blower as needed.

d. Storage

Drain Fuel: Before storing the blower for an extended period, drain the fuel tank and run the engine until it stalls to remove any remaining fuel from the carburetor.
Spark Plug: Remove the spark plug and pour a small amount of two-stroke oil into the cylinder. Pull the starter cord a few times to distribute the oil. Reinstall the spark plug.
Clean and Cover: Clean the blower and cover it with a protective cover.
Dry Location: Store the blower in a dry location.

Case Studies and Practical Examples

Let’s look at a few real-world scenarios where these adjustments and repairs can make a difference.

Case Study 1: The Sluggish Sawdust Blower

Problem: A Stihl BG86 used for clearing sawdust from a small woodworking shop was running sluggishly and lacking power.

Diagnosis: The initial inspection revealed a clogged air filter and a spark arrestor coated in carbon.

Solution:

The air filter was removed, cleaned with warm soapy water, rinsed thoroughly, and allowed to dry completely.
The spark arrestor was removed and cleaned with a wire brush.
The carburetor was inspected, and the low-speed adjustment screw was slightly adjusted to improve throttle response.
Fresh fuel with the correct oil mixture was added.

Result: The blower regained its power and ran much more efficiently, significantly improving sawdust removal in the shop.

Case Study 2: The Fickle Firewood Prep Blower

Problem: A Stihl BG86 used for clearing leaves and debris during firewood preparation would start easily but stall after a few minutes of use.

Diagnosis: The fuel filter was clogged with debris, restricting fuel flow.

Solution:

The fuel filter was replaced with a new one.
The fuel tank was drained and cleaned to remove any remaining debris.
The fuel lines were inspected for cracks or kinks and replaced as needed.

Result: The blower ran smoothly and consistently, allowing for uninterrupted firewood preparation.

Case Study 3: The Smoky Woodlot Warrior

Problem: A Stihl BG86 used for clearing trails in a woodlot was smoking excessively.

Diagnosis: The fuel mixture was too rich, and the piston rings were showing signs of wear.

Solution:

The fuel mixture was adjusted to the correct 50:1 ratio.
The carburetor was adjusted to lean out the fuel mixture slightly.
While replacing the piston rings would have been the ideal solution, the owner opted for a temporary fix by using a slightly leaner fuel mixture and monitoring the engine closely. (Note: This is not a recommended long-term solution, and piston ring replacement should be considered in the future.)

Result: The excessive smoking was reduced, but the owner was advised to consider replacing the piston rings in the future for optimal performance.

Strategic Insights and Tactical Instructions

Beyond the specific adjustments and repairs, here are some strategic insights to keep in mind:

Invest in Quality Tools: A good set of screwdrivers, a spark plug wrench, a spark plug gap tool, and a tachometer are essential for maintaining your Stihl BG86.
Read the Manual: Your Stihl BG86 owner’s manual is your best resource for specific instructions and safety precautions.
Regular Maintenance is Key: Don’t wait until your blower breaks down to perform maintenance. Regular cleaning, lubrication, and inspections can prevent many problems.
Know Your Limits: If you’re not comfortable performing a particular repair, take your blower to a qualified service technician.
Safety First: Always wear appropriate safety gear when working on your blower, including eye protection, gloves, and hearing protection.
Keep Records: Maintain a log of maintenance and repairs to track the performance of your blower and identify potential problems early.

Global Considerations

The information provided in this guide is generally applicable to Stihl BG86 blowers worldwide. However, there may be some regional variations in fuel types, emissions regulations, and available parts. Be sure to consult your local Stihl dealer for specific recommendations and information.

Conclusion and Next Steps

Maintaining your Stihl BG86 blower doesn’t have to be a daunting task. By understanding the common problems, following the step-by-step adjustments and repairs outlined in this guide, and practicing regular preventive maintenance, you can keep your blower running smoothly and efficiently for years to come.

Next Steps:

Review Your Owner’s Manual: Familiarize yourself with the specific instructions and safety precautions for your Stihl BG86.
Gather Your Tools: Assemble the necessary tools for performing basic maintenance and repairs.
Inspect Your Blower: Perform a thorough inspection of your blower to identify any potential problems.
Start with the Basics: Begin with the simplest adjustments and repairs, such as cleaning the air filter and spark arrestor.
Don’t Be Afraid to Ask for Help: If you’re not comfortable performing a particular repair, take your blower to a qualified service technician.

By taking these steps, you can ensure that your Stihl BG86 is always ready to tackle your wood-blowing needs, whether you’re clearing leaves, sawdust, or debris.