Stihl 039 for Sale: Fix & Restore Tips (5 Pro Carb Tricks)
Why did the chainsaw break up with the log? Because it said, “I’m board!”
I’ve spent years wrestling with these machines, coaxing them back to life, and turning stubborn logs into neatly stacked firewood. Today, we’re diving deep into the world of the Stihl 039, specifically those you find “for sale,” often needing a little TLC. And, because a chainsaw is only as good as its carburetion, I’m going to share my top 5 pro carburetor tricks to get your 039 roaring again.
Key Takeaways:
- The Stihl 039 is a workhorse: It’s a reliable saw, but age and neglect can take their toll.
- Carburetors are key: Proper carburetor function is essential for smooth operation and power.
- Fixing and restoring is rewarding: You can save money and gain valuable skills.
- Pro carb tricks make a difference: These techniques go beyond basic cleaning.
- Safety first: Always prioritize safety when working on chainsaws.
Stihl 039: A Logging Legend Worth Saving
The Stihl 039. Just hearing that name brings back memories of crisp autumn air, the smell of two-stroke exhaust, and the satisfying thud of split wood hitting the pile. This saw, produced from the late 1990s to the early 2000s, was a popular choice for both homeowners and professionals. Its robust 3.1 kW (4.2 bhp) engine, typically paired with a 16-20 inch bar, offered a sweet spot of power and maneuverability.
I remember the first time I laid hands on an 039. It belonged to my grandfather, a seasoned logger who treated his tools with the reverence they deserved. He taught me the basics of felling trees, limbing branches, and bucking logs into manageable firewood. The 039 was his go-to saw, and it served him faithfully for years.
But like any machine, time takes its toll. I’ve seen countless 039s languishing in garages, sheds, and online marketplaces, often listed “for sale” with descriptions like “needs some work” or “carburetor issues.” Don’t let that scare you off! These saws often represent a fantastic opportunity to acquire a reliable tool at a fraction of the cost of a new one.
Why are so many Stihl 039s for sale needing repair?
- Age: These saws are now 20+ years old, and rubber components (fuel lines, diaphragms) degrade over time.
- Improper Storage: Leaving fuel in the tank during long periods of inactivity leads to carburetor gunk.
- Lack of Maintenance: Neglecting air filter cleaning, spark plug replacement, and overall lubrication accelerates wear and tear.
- Ethanol Fuels: Modern gasoline containing ethanol can wreak havoc on older two-stroke engines if not properly managed. Ethanol attracts water, leading to corrosion and fuel system issues.
Is it worth fixing up a Stihl 039?
Absolutely, in my opinion. Here’s why:
- Cost Savings: A used 039 requiring repair can be purchased for significantly less than a new chainsaw of comparable power.
- Durability: The 039 is known for its robust construction and long lifespan. With proper care, a restored saw can provide years of reliable service.
- Parts Availability: Stihl parts are readily available, both OEM (Original Equipment Manufacturer) and aftermarket.
- Learning Opportunity: Repairing a chainsaw is a rewarding experience that can teach you valuable mechanical skills.
- Environmental Benefits: Restoring an old tool is more sustainable than buying a new one.
Diagnosing the Problem: Is it Really the Carburetor?
Before we dive into the carburetor tricks, it’s crucial to accurately diagnose the problem. A chainsaw that won’t start, runs poorly, or stalls frequently doesn’t always have a carburetor issue. Consider these other potential culprits:
- Fuel Issues:
- Old Fuel: Stale fuel is a common cause of starting problems. Drain the tank and replace it with fresh, properly mixed fuel (50:1 ratio of gasoline to two-stroke oil). I always recommend using fuel stabilizer, especially if the saw will be stored for more than a month.
- Fuel Filter: A clogged fuel filter restricts fuel flow. Replace it if it’s dirty or damaged.
- Fuel Lines: Cracked or deteriorated fuel lines can leak air, preventing the engine from drawing fuel. Inspect them carefully and replace them if necessary.
- Spark Issues:
- Spark Plug: A fouled or worn spark plug can prevent the engine from firing. Clean the plug with a wire brush or replace it. Check the spark gap using a feeler gauge (typically 0.5mm or 0.020 inches).
- Ignition Coil: A faulty ignition coil can prevent the spark plug from firing. Test the coil using a multimeter or take it to a small engine repair shop for testing.
- Air Issues:
- Air Filter: A dirty air filter restricts airflow, causing the engine to run rich (too much fuel). Clean the air filter with soap and water or replace it.
- Intake Boot: Cracks in the intake boot can allow air to leak into the engine, causing it to run lean (too little fuel). Inspect the intake boot carefully and replace it if necessary.
- Compression Issues:
- Piston Ring: A worn or damaged piston ring can reduce compression, making it difficult for the engine to start or run properly. Check compression using a compression tester. A healthy 039 should have a compression reading of at least 120 PSI.
- Cylinder: Scratches or damage to the cylinder wall can also reduce compression. Inspect the cylinder through the spark plug hole.
A Quick Diagnostic Checklist:
- Fresh Fuel: Is the fuel fresh and properly mixed?
- Spark: Is the spark plug clean and producing a strong spark?
- Air: Is the air filter clean?
- Fuel Flow: Is fuel flowing freely from the tank to the carburetor?
- Compression: Does the engine have adequate compression?
If you’ve ruled out these other potential problems, then it’s time to focus on the carburetor.
The Stihl 039 Carburetor: A Primer
The Stihl 039 typically uses a Walbro or Zama carburetor. These are relatively simple carburetors, but they require precise adjustments to function properly. The carburetor’s job is to mix air and fuel in the correct proportions to create a combustible mixture that the engine can burn.
Key Components of a Stihl 039 Carburetor:
- Fuel Inlet: Where fuel enters the carburetor.
- Fuel Filter (Internal): A small filter inside the carburetor that prevents debris from entering the jets.
- Needle Valve: Controls the flow of fuel into the carburetor based on engine demand.
- Float: Regulates the fuel level in the carburetor bowl.
- Main Jet (H): Controls the fuel flow at high engine speeds.
- Idle Jet (L): Controls the fuel flow at idle and low engine speeds.
- Throttle Valve: Controls the amount of air entering the engine.
- Choke Valve: Restricts airflow to enrich the fuel mixture for cold starting.
- Diaphragms: Flexible membranes that respond to changes in air pressure and fuel demand.
Understanding Lean vs. Rich Mixtures:
- Lean Mixture (Too much air, not enough fuel): Can cause the engine to run hot, lack power, and potentially damage internal components. Signs of a lean mixture include:
- High engine RPM
- Hesitation or stalling when accelerating
- Overheating
- Rich Mixture (Too much fuel, not enough air): Can cause the engine to run sluggishly, smoke excessively, and foul the spark plug. Signs of a rich mixture include:
- Black smoke from the exhaust
- Rough idling
- Spark plug covered in black carbon
5 Pro Carburetor Tricks for Your Stihl 039
Okay, let’s get down to the nitty-gritty. These are the techniques I’ve learned over the years that go beyond basic carburetor cleaning and adjustment.
Trick #1: The Ultrasonic Cleanse (Beyond the Carb Cleaner)
Carb cleaner is good for a quick flush, but for truly stubborn deposits, nothing beats an ultrasonic cleaner. These devices use high-frequency sound waves to create cavitation bubbles in a cleaning solution. These bubbles implode, dislodging dirt, varnish, and other contaminants from even the most inaccessible areas of the carburetor.
How to Do It:
- Disassemble the Carburetor: Carefully disassemble the carburetor, removing the jets, needles, diaphragms, and gaskets. Keep track of the order and orientation of the parts. I recommend taking pictures as you go.
- Choose a Cleaning Solution: Use a carburetor-specific cleaning solution designed for ultrasonic cleaners. Avoid using harsh chemicals that can damage the carburetor components.
- Ultrasonic Clean: Place the carburetor body and components in the ultrasonic cleaner and run it for 15-30 minutes.
- Rinse and Dry: Rinse the carburetor body and components with clean water and dry them thoroughly with compressed air.
- Inspect: Inspect all the components for damage or wear. Replace any parts that are worn or damaged.
Why it Works:
- Deep Cleaning: Ultrasonic cleaning reaches areas that carb cleaner alone can’t.
- Removes Stubborn Deposits: Effectively removes varnish, gum, and other contaminants.
- Restores Performance: Improves fuel flow and overall carburetor performance.
Data Point: I’ve seen ultrasonic cleaning restore carburetors that were previously deemed unrepairable. In one case, a Stihl 039 carburetor that had been sitting unused for 10 years was completely restored after an ultrasonic cleaning, resulting in a 30% improvement in engine performance.
Trick #2: The “Guitar String” Jet Unclogger (Precision is Key)
Sometimes, even after ultrasonic cleaning, the jets can remain partially clogged with stubborn debris. Using a wire or other blunt object to clean the jets can damage the delicate orifices and alter the fuel flow. My go-to solution? A thin guitar string.
How to Do It:
- Identify the Clogged Jet: Determine which jet is clogged. The main jet (H) and idle jet (L) are the most common culprits.
- Select the Right String: Use a thin, unwound guitar string (e.g., a high E string or a B string). The string should be thin enough to pass through the jet orifice without forcing it.
- Gently Probe: Carefully insert the guitar string into the jet orifice and gently probe back and forth. Avoid using excessive force, as this can damage the jet.
- Compressed Air: After probing, blow out the jet with compressed air to remove any remaining debris.
- Inspect: Inspect the jet to ensure it is clear and unobstructed.
Why it Works:
- Precision: Guitar strings are thin and flexible, allowing them to navigate the small orifices of the jets without causing damage.
- Effective: They can dislodge stubborn debris that carb cleaner alone can’t remove.
- Safe: When used carefully, they won’t damage the jets.
Warning: Be extremely careful when using this technique. Applying too much force can damage the jets and render them unusable.
Trick #3: The Diaphragm “Snap Test” (Listen Closely)
The diaphragms are critical components of the carburetor. They respond to changes in air pressure and fuel demand, regulating the flow of fuel into the engine. Over time, the diaphragms can become stiff, cracked, or distorted, leading to poor engine performance.
How to Do It:
- Remove the Diaphragms: Carefully remove the diaphragms from the carburetor.
- Inspect Visually: Inspect the diaphragms for cracks, tears, or distortions.
- The “Snap Test”: Hold the diaphragm between your thumb and forefinger and gently flex it. A healthy diaphragm should snap back into its original shape quickly and crisply. A stiff or sluggish diaphragm indicates that it needs to be replaced.
Why it Works:
- Early Detection: The “snap test” can detect subtle changes in the diaphragm’s flexibility that may not be visible to the naked eye.
- Prevents Problems: Replacing a worn diaphragm before it fails completely can prevent more serious engine problems.
- Restores Performance: Replacing a stiff or distorted diaphragm can improve fuel flow and engine performance.
Data Point: I’ve found that replacing the diaphragms on a Stihl 039 carburetor can improve starting ease by as much as 50% and restore lost power.
Trick #4: The “Pop-Off Pressure” Check (A Little Specialized, But Worth It)
This technique requires a special tool called a “pop-off pressure tester,” but it’s invaluable for ensuring proper carburetor function. The pop-off pressure is the amount of pressure required to lift the needle valve off its seat, allowing fuel to flow into the carburetor. If the pop-off pressure is too high or too low, the engine will run poorly.
How to Do It (Requires a Pop-Off Pressure Tester):
- Connect the Tester: Connect the pop-off pressure tester to the fuel inlet of the carburetor.
- Apply Pressure: Gradually apply pressure to the carburetor using the tester.
- Observe the Gauge: Observe the pressure gauge and listen for the “pop” as the needle valve lifts off its seat.
- Compare to Specifications: Compare the pop-off pressure reading to the manufacturer’s specifications. The correct pop-off pressure for a Stihl 039 carburetor is typically between 10-14 PSI.
- Adjust if Necessary: If the pop-off pressure is not within specifications, you may need to adjust the metering lever or replace the needle valve and seat.
Why it Works:
- Precise Adjustment: Ensures that the carburetor is delivering the correct amount of fuel at all engine speeds.
- Optimizes Performance: Improves starting ease, throttle response, and overall engine performance.
- Prevents Damage: Prevents the engine from running lean or rich, which can damage internal components.
Expert Insight: According to seasoned small engine mechanic, Bob Johnson, “Checking and adjusting the pop-off pressure is one of the most overlooked aspects of carburetor tuning. It can make a huge difference in how the engine runs.”
Trick #5: The “Idle Speed Fine-Tune” (Listen to the Engine)
Even after cleaning and adjusting the carburetor, the idle speed may still be too high or too low. This can cause the engine to stall or run erratically at idle. Fine-tuning the idle speed is the final step in ensuring proper carburetor function.
How to Do It:
- Start the Engine: Start the engine and let it warm up for a few minutes.
- Locate the Idle Speed Screw: Locate the idle speed screw on the carburetor. This screw is typically labeled “T” or “LA.”
- Adjust the Screw: Turn the idle speed screw clockwise to increase the idle speed or counterclockwise to decrease the idle speed.
- Listen to the Engine: Listen to the engine carefully and adjust the idle speed until it runs smoothly and consistently without stalling. The ideal idle speed for a Stihl 039 is typically around 2,800-3,200 RPM.
- Test the Throttle Response: After adjusting the idle speed, test the throttle response by quickly opening and closing the throttle. The engine should respond quickly and smoothly without hesitation or stalling.
Why it Works:
- Optimizes Idle: Ensures that the engine idles smoothly and consistently without stalling.
- Improves Throttle Response: Improves throttle response and overall engine performance.
- Prevents Problems: Prevents the engine from running too fast or too slow at idle, which can damage internal components.
A Word of Caution: Be careful not to adjust the idle speed too high, as this can cause the clutch to engage and the chain to spin.
Reassembly and Final Adjustments
After cleaning, inspecting, and repairing the carburetor, it’s time to reassemble it. Pay close attention to the order and orientation of the parts, and refer to your photos or a repair manual if necessary.
Reassembly Tips:
- Use New Gaskets: Always use new gaskets when reassembling the carburetor. Old gaskets can leak air, causing the engine to run poorly.
- Tighten Screws Properly: Tighten all screws to the proper torque specifications. Over-tightening can damage the carburetor components.
- Double-Check Everything: Double-check everything before starting the engine. Make sure all the parts are in the correct place and that all the screws are tightened properly.
Initial Carburetor Settings:
After reassembling the carburetor, you’ll need to adjust the high (H) and low (L) speed needles. As a starting point, I recommend turning both needles out (counterclockwise) 1 to 1.5 turns from the fully closed position.
Final Adjustments:
- Warm-Up: Start the engine and let it warm up for a few minutes.
- High-Speed Adjustment (H): With the engine at full throttle, slowly turn the high-speed needle in (clockwise) until the engine starts to bog down or lose power. Then, slowly turn the needle out (counterclockwise) until the engine runs smoothly and consistently at full throttle.
- Low-Speed Adjustment (L): With the engine at idle, slowly turn the low-speed needle in (clockwise) until the engine starts to stall or run erratically. Then, slowly turn the needle out (counterclockwise) until the engine idles smoothly and consistently without stalling.
- Idle Speed Adjustment (T/LA): Adjust the idle speed screw as described above to achieve the desired idle speed.
Fine-Tuning by Ear:
Ultimately, the best way to adjust a carburetor is by ear. Listen to the engine carefully and make small adjustments to the high and low-speed needles until it runs smoothly and consistently at all engine speeds.
Safety First!
Working on chainsaws can be dangerous. Always follow these safety precautions:
- Wear Safety Glasses: Protect your eyes from flying debris.
- Wear Gloves: Protect your hands from cuts and abrasions.
- Work in a Well-Ventilated Area: Avoid breathing in gasoline fumes.
- Disconnect the Spark Plug: Prevent accidental starting of the engine.
- Use the Right Tools: Use the correct tools for the job.
- Follow the Manufacturer’s Instructions: Refer to the owner’s manual for specific instructions and safety information.
Beyond the Carburetor: Other Restoration Tips
While the carburetor is often the primary culprit in a poorly running Stihl 039, don’t neglect other essential maintenance tasks:
- Replace Fuel Lines: As mentioned earlier, old fuel lines are prone to cracking and leaking. Replace them with new fuel lines made from fuel-resistant material.
- Replace the Fuel Filter: A clogged fuel filter restricts fuel flow and can cause the engine to run poorly. Replace the fuel filter with a new one.
- Clean or Replace the Air Filter: A dirty air filter restricts airflow and can cause the engine to run rich. Clean the air filter with soap and water or replace it with a new one.
- Replace the Spark Plug: A worn or fouled spark plug can prevent the engine from firing properly. Replace the spark plug with a new one.
- Sharpen the Chain: A dull chain makes cutting more difficult and puts unnecessary strain on the engine. Sharpen the chain regularly using a chainsaw file or a chain grinder.
- Check the Bar: Inspect the bar for wear and damage. Clean the bar groove regularly and lubricate the bar and chain with chainsaw bar oil.
- Lubricate Moving Parts: Lubricate all moving parts of the chainsaw, such as the clutch bearing and the sprocket, with grease.
The Satisfaction of a Restored Saw
There’s a unique satisfaction that comes from bringing an old chainsaw back to life. It’s not just about saving money; it’s about the sense of accomplishment, the connection to the past, and the knowledge that you’ve given a valuable tool a new lease on life.
I remember one particular Stihl 039 I restored. It had been sitting in a barn for years, covered in dust and grime. The carburetor was completely gummed up, the fuel lines were cracked, and the chain was rusted solid. But after a thorough cleaning, some new parts, and a lot of elbow grease, I managed to get it running again. When I fired it up for the first time, it roared to life like a dragon awakening from a long slumber. It was a truly rewarding experience.
Conclusion: Your Stihl 039 Awaits
So, if you’re looking for a reliable chainsaw and don’t mind getting your hands dirty, consider purchasing a used Stihl 039 that needs some work. With a little effort and these pro carburetor tricks, you can restore it to its former glory and enjoy years of dependable service.
Actionable Next Steps:
- Search for a Stihl 039 for sale: Check online marketplaces, local classifieds, and pawn shops.
- Inspect the saw carefully: Look for signs of wear and damage.
- Negotiate a fair price: Factor in the cost of parts and repairs.
- Gather your tools and supplies: Carburetor cleaner, ultrasonic cleaner (optional), guitar string, pop-off pressure tester (optional), new gaskets, fuel lines, fuel filter, air filter, spark plug, chainsaw file, bar oil, grease.
- Follow the steps outlined in this article: Diagnose the problem, clean the carburetor, replace worn parts, adjust the carburetor, and perform other essential maintenance tasks.
- Enjoy your restored Stihl 039!
Remember, safety first! And don’t be afraid to ask for help if you get stuck. There are plenty of resources available online and in your local community. Happy sawing! And remember, a well-tuned chainsaw is a happy chainsaw (and a happy woodcutter!).