How To Start Stihl BG 86 Leaf Blower: Quick Start Guide

The Stihl BG 86 is a reliable, lightweight gas leaf blower, but like any two-stroke machine, its starting routine can feel finicky until you understand the sequence. Many users struggle not because the engine is faulty, but because they miss a crucial step—like properly seating the choke or using stale fuel. This guide walks you through the complete starting procedure, essential maintenance, and troubleshooting for both cold and warm starts. Whether you are a first-time owner or a seasoned user looking to master your equipment, you will find a clear, step-by-step plan that gets you blowing leaves in under a minute.

Gather essential safety gear and fuel before you begin.

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Why Preparation Matters More Than Pulling

Before you even touch the starter rope, a quick two-minute prep can prevent most starting headaches. The BG 86 is a simple machine, but it demands fresh fuel and a clean air supply. In practice, the most common reason a BG 86 refuses to start is not a mechanical failure—it is old, ethanol-blended gasoline that has gone stale, or a dirty air filter that starves the engine of oxygen. You can also read our guide on how to choose the right garden hose length.

Here is what you should have and check before pulling:

• Personal protection: Wear ANSI-rated safety glasses and hearing protection. The BG 86 is not the loudest blower, but sustained exposure is harmful. Gloves with a good grip are also a smart idea.
• Fresh 50:1 fuel mix: Use high-octane gasoline (89 or higher) mixed with a high-quality two-stroke engine oil. Avoid fuel that has been sitting for more than 30 days. Ethanol in modern gas attracts moisture and breaks down rapidly.
• A clean work area: Set the blower on flat, level ground, away from dry leaves or debris that could be sucked into the intake.
• A quick visual inspection: Check the blower tube is clear, the primer bulb is not cracked, and the air filter cover is secured tightly.

Following this short checklist puts you ahead of most problems. A common mistake is trying to start a blower that has been sitting all winter with last fall's fuel still in the tank. That fuel has likely turned to varnish, which clogs carburetor jets. If you understand proper fuel management, you will find starting much easier. For more on keeping your small engines healthy, you can explore the correct fluid level practices for other equipment.

Understanding the BG 86's Controls

Familiarize yourself with the controls before you start pulling. The BG 86 features a master control lever with clear positions, a primer bulb, and a throttle trigger with a lockout. For more on this, see our guide on how to start stihl leaf blower bg 86.

Locate the master control lever and primer bulb before starting.

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The key components you need to know are:

• Master control lever: This has distinct positions for stop, run, and cold start (choke). In cold start mode, the choke plate is fully closed, which enriches the fuel mixture for a cold engine.
• Primer bulb: This clear rubber bulb pushes fuel directly into the carburetor, filling the fuel line so the engine has fuel to draw on its first pull.
• Throttle trigger and lockout: The lockout prevents the trigger from being depressed accidentally, which could cause a surge when the engine fires.
• Starter grip: This is the handle you pull. Always pull it out in a smooth, brisk motion, and never let it snap back. Uncontrolled rewind can damage the starter mechanism.
• Air filter cover and muffler: The air filter must be clean for the correct fuel-to-air ratio. The muffler contains a spark arrestor screen that needs periodic cleaning.

Step-by-Step: Cold Start Procedure

The cold start sequence is the most critical to learn. Doing it wrong—usually by over-priming—is the primary cause of a flooded engine. Follow this exact order:

1. Place the blower on a firm, flat surface. Ensure the nozzle is pointed away from people, pets, and windows.
2. Verify the fuel tank has fresh 50:1 mix. Don't rely on memory; check the level.
3. Set the master control lever to the cold start position (choke). This is typically indicated by a snowflake icon or a partial circle symbol.
4. Press the primer bulb five to six times. You should see fuel moving through the clear bulb. Stop as soon as it is full of fuel. Pressing it more will flood the engine. This is a critical step: the bulb only fills the line; the piston still needs to draw the fuel in.
5. Hold the blower firmly with one hand on the handle. Your other hand should be on the starter grip.
6. Pull the starter rope briskly two to five times. You are listening for the engine to "fire" or cough—a brief sputter that indicates combustion is happening.
7. Move the master control lever to the run position immediately. This is the most common mistake: leaving it on choke after the engine fires. The closed choke starves the engine of air, so it will stall.
8. Pull the starter rope again one to three times. The engine should now start and run.
9. Let the blower idle for 30 to 60 seconds. This allows the carburetor and engine to reach a stable operating temperature.
10. Squeeze the throttle a few times. Confirm the engine revs up cleanly and settles back to idle without stalling.

In practice, a cold engine often needs the choke only until the first sign of life. Once you hear that initial pop, switching to run is the signal that tells the carburetor to lean out the mixture. If you pull more than five times on choke, you are likely flooding it.

Warm Restart: A Lighter Touch

A warm engine does not need the choke at all. The engine block is already hot, so the fuel atomizes more efficiently. Use a gentler approach:

1. Set the master control lever to the run position. Do not touch the choke.
2. Give the primer bulb one or two presses. If you just shut the blower off, the fuel line is likely still full, so you can often skip this step entirely.
3. Pull the starter rope one to three times. It should fire almost immediately.
4. If it doesn't start after five pulls, move the lever to half-choke (a position between choke and run, if available) for one pull only, then return to run and pull again.

This process prevents flooding. On a hot start, the engine needs very little additional fuel. For jobs where you are stopping and starting frequently—like clearing a driveway then stopping to pick up toys—this approach will save your arm and your spark plug. For more on this, see our guide on how to start stihl blower.

Leave the choke off for quick and reliable warm restarts.

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Troubleshooting: When the BG 86 Won't Start

If the blower resists all attempts to start, do not keep pulling. That will only flood the engine. Work through this triage checklist to identify the root cause.

Fuel and Priming Issues

• Flooded engine: The most common issue. If you smell raw fuel, the engine is flooded. Turn the master control to run, hold the throttle trigger fully open (if it will stay seated), and pull the starter rope 8 to 12 times. This clears excess fuel. Let it sit for 10 minutes, then retry without using the choke.
• Old or wrong fuel: If the fuel has been in the tank for more than a month, drain it. Ethanol-blended gas is the culprit here. Replace it with a fresh 50:1 mix. For ultimate reliability and a longer shelf life, consider using a pre-mixed, ethanol-free fuel, which you can learn more about in our guide to using TruFuel for small engines.

Mechanical and Airflow Checks

• Spark plug issues: A fouled or wet spark plug will prevent ignition. Use the correct plug for the BG 86 (usually NGK CMR6H) and set the gap to 0.5mm (0.020 inches). If the plug is black and sooty, clean it with a wire brush or replace it.
• Dirty air filter: A clogged foam air filter restricts air and makes the fuel mixture too rich, leading to hard starting and stalling. Remove the cover, wash the foam filter in soapy water, let it dry, and re-oil it with a light coat of air filter oil.
• Clogged spark arrestor screen: This screen is inside the muffler. If it is clogged with carbon, it creates back-pressure, kills power, and causes stalling. Remove the muffler cover and carefully clean the screen with a soft brush or replace it. This is a critical maintenance step that is frequently overlooked.
• Carburetor tuning: If the blower starts but surges or stalls at idle, the carburetor may be out of adjustment. The BG 86 has a low-speed adjustment screw (L) and an idle setting. Making small adjustments (1/4 turn at a time) can help, but be cautious. Consistent issues here are a sign to take it to a certified STIHL technician.

Pro Tips for Consistent Starts

Years of experience with small engines have taught me a few habits that make start-up effortless. The goal is to work with the engine, not against it. For more on this, see our guide on how to start a leaf blower backpack.

• Count your primes: Five presses for cold, one or none for warm. This is your golden rule.
• Pull with a smooth, steady motion, not a sharp yank. A smooth pull gets the engine turning over faster and more consistently.
• Never pull the rope all the way to the end. This can snap the starter pawls and rewind spring. Pull until you feel resistance, then pull firmly.
• Keep a spare spark plug in your toolbox. It is a quick fix that solves many problems, especially in damp weather.
• On the first start of the season, be extra patient. The fuel system may be dry. You might need to prime a few extra times or pull a couple of extra times on choke. Just watch for the first sign of fire.

Maintenance Schedule for Reliable Starting

Regular maintenance is the secret to a blower that "just works" every time. The BG 86 is durable, but it relies on clean air and fuel. Here is a simple schedule:

• Before each use: Visually inspect the blower, check the fuel level, and clear any debris from the air intake.
• Every 10 hours of use: Check and clean the air filter.
• Every 25-50 hours of use: Clean the spark arrestor screen. This is a critical interval. Check the spark plug gap and condition.
• Seasonally: Drain the fuel system if you are not using the blower for more than a month. Tighten any loose fasteners and inspect fuel lines for cracking.

Proper storage in the off-season has a huge impact. Never let a two-stroke engine sit with untreated fuel in the carburetor. Run the carburetor dry by turning the blower off and then on again to burn the remaining fuel, or add a fuel stabilizer. This simple routine keeps varnish from forming in the tiny jets.

Regular air filter cleaning is key to preventing hard starts.

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Frequently Asked Questions

Do I need to use the choke every time I start the BG 86?

No. The choke is only for starting a cold engine. If the blower has been running recently (within 10-15 minutes), set the control to run and simply pull the starter rope. Using choke on a warm engine will flood it. For safe fuel mixing guidance, review our guide on mixing gas for your leaf blower. For more on this, see our guide on how to mix oil and gas for leaf.

What does the primer bulb actually do?

The primer bulb pushes a small amount of fuel from the tank into the carburetor's fuel line. This "primes" the system, so the engine doesn't have to pull fuel all the way from the tank on its first rotation. Think of it as filling the straw so you don't have to suck as hard.

Why does my BG 86 start, run briefly, and then stall?

This is a classic symptom of either not switching the choke off fast enough, a dirty spark arrestor screen, or a carburetor that is out of tune. First, ensure you are moving the master lever to run immediately after the first fire. If that is not the issue, check the spark arrestor.

How often should I clean the spark arrestor?

STIHL recommends cleaning it every 25 hours of operation, but in dusty or heavy-use conditions, you may need to do it more often. It is a 10-minute job and prevents poor performance and hard starting.

Is it better to use pre-mixed fuel or mix my own?

Using a pre-mixed, ethanol-free fuel is an excellent way to extend the life of your engine and eliminate guesswork. It has a much longer shelf life. If you mix your own, always use fresh gasoline and high-quality two-stroke oil at a 50:1 ratio, and remember to check the right gas quality for your equipment.

The pull cord feels tight and won't move.

This usually means the engine is hydrolocked, either from excess fuel (flooding) or, less commonly, debris jamming the fan/impeller. First, try the flooded engine procedure. If it still won't budge, check the blower intake for sticks or leaves. Never force the cord.

Conclusion

Mastering your Stihl BG 86 is about understanding the simple relationship between air, fuel, and ignition. By following a structured start-up routine—prepping your equipment, using the choke and primer bulb correctly, and starting on the run position—you can ensure a fast, reliable start every time. Remember the golden rules: fresh 50:1 fuel, a clean air filter, and avoiding the choke on warm restarts.

Regularly maintaining the spark arrestor and air filter will not only make starting easier but will also prolong the life of the machine. Blowing leaves is a chore; fighting with a reluctant engine makes it a frustration. Put these steps into practice, and you will spend less time pulling the cord and more time getting the job done. For deeper maintenance on your other yard equipment, make sure you are also following the correct servicing steps for everything from your garden hose to power equipment. Happy blowing.