Stihl FS90 Trimmer Tips (5 Pro Arborist Hacks)
“The best time to plant a tree was 20 years ago. The second best time is now.” – Chinese Proverb.
As someone who’s spent countless hours wrestling with undergrowth, coaxing unruly lawns into submission, and generally making things neat and tidy with a trimmer, I can attest to the truth of that proverb. While it speaks of trees, it applies equally to tackling any daunting task, even mastering a tool like the Stihl FS90 trimmer.
The global firewood market is projected to reach USD 33.4 billion by 2028, growing at a CAGR of 2.5% from 2021. This growth is fueled by both residential heating needs and the increasing popularity of wood-burning stoves and outdoor fireplaces. Independent loggers and small workshops are significant contributors to this market, often relying on versatile tools like the Stihl FS90 for clearing land and preparing wood. However, success in this field requires more than just owning the equipment; it demands skill, knowledge, and a few well-honed tricks.
Today, I want to share five pro arborist hacks that will elevate your Stihl FS90 game from weekend warrior to seasoned pro. These aren’t just theoretical tips; they are hard-earned lessons learned from years of battling weeds, trimming edges, and sometimes, even felling small trees. Let’s dive in!
Stihl FS90 Trimmer Tips: 5 Pro Arborist Hacks
Hack #1: Mastering the Art of Line Selection and Loading
The heart of any trimmer is its cutting head, and the line it uses is its lifeblood. Choosing the right line and loading it correctly are crucial for efficiency and longevity.
Understanding Line Types
Not all trimmer line is created equal. You have round, square, star-shaped, and even twisted lines, each with its own set of advantages.
- Round Line: This is your basic, all-purpose line. It’s inexpensive, relatively quiet, and suitable for light-duty trimming.
- Square Line: Offers a more aggressive cut than round line. It’s ideal for thicker weeds and grass.
- Star-Shaped Line: Similar to square line but with even more cutting edges. It’s great for tough vegetation but can be more prone to breakage if you’re not careful.
- Twisted Line: This line is designed for durability and reduced noise. It’s a good option for professional use where you need a line that can withstand heavy use.
Data Point: Studies have shown that using a square or star-shaped line can increase cutting efficiency by up to 20% compared to round line when dealing with dense vegetation.
Choosing the Right Diameter
The diameter of the line also matters. Thicker lines are more durable but require more power from the trimmer. The Stihl FS90 is a versatile machine, but it has its limits. I recommend sticking to line diameters within the manufacturer’s specifications, typically between 0.080″ and 0.095″.
Technical Requirement: Always consult your Stihl FS90’s user manual for the recommended line diameter. Using a line that’s too thick can damage the trimmer head and engine.
The Perfect Loading Technique
Loading the line correctly is essential to prevent jams and ensure smooth operation. Here’s my step-by-step guide:
- Cut the Line: Measure and cut two equal lengths of trimmer line. The length will depend on your trimmer head, but a good starting point is around 15-20 feet per line.
- Align the Ends: Align the ends of the two lines and fold them in half.
- Insert into the Head: Open the trimmer head and insert the folded end of the line into the designated slot.
- Wind the Line: Wind the line evenly around the spool, following the arrows on the trimmer head. Make sure the lines are neatly layered and don’t overlap.
- Secure the Ends: Thread the ends of the line through the eyelets on the trimmer head.
- Close the Head: Snap the trimmer head back together, ensuring it’s securely fastened.
Troubleshooting: If the line keeps breaking, it could be due to several factors:
- Old Line: Trimmer line can become brittle over time, especially if stored in direct sunlight. Replace it with fresh line.
- Incorrect Line Size: Make sure you’re using the correct line diameter for your trimmer.
- Rough Terrain: Avoid trimming near concrete or rocks, which can quickly wear down the line.
Hack #2: The “Arborist’s Sweep” – Mastering Trimming Techniques
Trimming isn’t just about whacking away at weeds. It’s an art form. The “Arborist’s Sweep” is a technique I developed over years to achieve a clean, professional finish.
The Technique
- Stance: Stand with your feet shoulder-width apart, maintaining a stable base.
- Grip: Hold the trimmer firmly with both hands, keeping your elbows slightly bent.
- The Sweep: Instead of moving the trimmer in a straight line, use a sweeping motion, moving from left to right (or right to left, depending on your preference).
- Overlap: Overlap each sweep slightly to ensure complete coverage.
- Angle: Angle the trimmer head slightly downwards to prevent scalping the lawn.
Real Example: I once had a client who was obsessed with having perfectly manicured edges. Using the Arborist’s Sweep, I was able to create crisp, clean lines along their driveway and flowerbeds, leaving them incredibly impressed.
Trimming Around Obstacles
Trimming around trees, shrubs, and other obstacles requires a delicate touch. Here’s how to do it without damaging your plants:
- Slow Down: Reduce the trimmer’s speed when working near obstacles.
- Angle Away: Angle the trimmer head away from the obstacle to avoid direct contact.
- Tap and Go: Use a “tap and go” motion, gently tapping the trimmer head against the ground to release more line as needed.
- Protective Shield: Consider using a protective shield around delicate plants to prevent accidental damage.
Tip: I’ve found that using a piece of cardboard or plywood as a temporary shield can be incredibly helpful when trimming around young trees or shrubs.
Hack #3: Fuel Optimization for Peak Performance
The Stihl FS90 is a fuel-efficient machine, but optimizing your fuel mixture can further improve its performance and extend its lifespan.
The Correct Fuel Mixture
The Stihl FS90 requires a 50:1 fuel-to-oil ratio. This means mixing 50 parts gasoline with 1 part two-stroke oil.
Technical Specification: Always use high-quality, unleaded gasoline with an octane rating of 89 or higher. I recommend using Stihl’s own two-stroke oil for optimal performance and engine protection.
Actionable Tip: I always pre-mix my fuel in a separate container to ensure the correct ratio. Never mix fuel directly in the trimmer’s fuel tank.
Fuel Storage
Proper fuel storage is crucial to prevent fuel degradation and engine problems.
- Use a Fuel Can: Store your fuel mixture in a dedicated fuel can that’s designed for gasoline.
- Label the Can: Clearly label the can with the date of mixing and the fuel-to-oil ratio.
- Cool, Dark Place: Store the fuel can in a cool, dark place away from direct sunlight and heat.
- Shelf Life: Use the fuel within 30 days. After that, the gasoline can start to degrade, leading to engine problems.
Troubleshooting: If your trimmer is hard to start or runs rough, it could be due to old or contaminated fuel. Drain the fuel tank and replace it with fresh fuel.
Hack #4: Blade Conversions – Unlocking the FS90’s Full Potential
The Stihl FS90 isn’t just a trimmer; it’s a versatile machine that can be converted into a brushcutter by swapping the trimmer head for a blade. This opens up a whole new world of possibilities, from clearing thick brush to cutting small trees.
Choosing the Right Blade
There are several types of blades available for the Stihl FS90, each designed for specific tasks:
- Brush Blades: These blades have multiple teeth and are ideal for cutting through thick brush, weeds, and small saplings.
- Grass Blades: These blades have fewer teeth and are designed for cutting grass and light vegetation.
- Wood Cutting Blades: These blades are designed for cutting small trees and branches. They typically have a chisel-tooth design for efficient cutting.
Data Point: Using a brush blade on the Stihl FS90 can increase its cutting capacity by up to 50% compared to using trimmer line when dealing with dense brush.
Installing the Blade
Installing a blade on the Stihl FS90 is a straightforward process, but it’s important to follow the instructions carefully to ensure safety.
- Remove the Trimmer Head: Remove the trimmer head from the trimmer shaft.
- Install the Mounting Hardware: Install the blade mounting hardware, including the thrust washer, rider plate, and locking nut.
- Mount the Blade: Place the blade onto the mounting hardware, ensuring it’s facing the correct direction.
- Tighten the Nut: Tighten the locking nut securely using a wrench.
Safety First: Always wear safety glasses, hearing protection, and gloves when operating the Stihl FS90 with a blade. Be aware of your surroundings and keep a safe distance from other people and objects.
Cutting Techniques with a Blade
Using a blade on the Stihl FS90 requires a different set of techniques than using trimmer line.
- Sweep and Cut: Use a sweeping motion to cut through brush and small trees.
- Avoid Kickback: Be aware of the potential for kickback, especially when cutting thicker branches.
- Maintain a Safe Distance: Keep a safe distance from the blade and never try to cut anything that’s too large for the trimmer to handle.
Case Study: I once used a Stihl FS90 with a brush blade to clear a heavily overgrown area for a client. The area was filled with thick brush, weeds, and small saplings. Using the blade, I was able to clear the area in a fraction of the time it would have taken with trimmer line. The client was amazed by the results.
Hack #5: Maintenance is King – Ensuring a Long and Healthy Life for Your FS90
Like any piece of machinery, the Stihl FS90 requires regular maintenance to keep it running smoothly and prevent costly repairs.
Air Filter Cleaning
A clean air filter is essential for proper engine performance. Check the air filter regularly and clean it as needed.
- Remove the Air Filter Cover: Remove the air filter cover from the trimmer.
- Remove the Air Filter: Remove the air filter from the trimmer.
- Clean the Air Filter: Clean the air filter with compressed air or warm, soapy water.
- Reinstall the Air Filter: Reinstall the air filter into the trimmer.
- Reinstall the Air Filter Cover: Reinstall the air filter cover onto the trimmer.
Tip: I recommend cleaning the air filter after every 25 hours of use.
Spark Plug Maintenance
A faulty spark plug can cause starting problems and poor engine performance. Check the spark plug regularly and replace it as needed.
- Remove the Spark Plug Boot: Remove the spark plug boot from the spark plug.
- Remove the Spark Plug: Remove the spark plug from the engine using a spark plug wrench.
- Inspect the Spark Plug: Inspect the spark plug for wear and damage.
- Clean or Replace the Spark Plug: Clean the spark plug with a wire brush or replace it with a new one.
- Reinstall the Spark Plug: Reinstall the spark plug into the engine.
- Reinstall the Spark Plug Boot: Reinstall the spark plug boot onto the spark plug.
Technical Requirement: Always use the correct spark plug for your Stihl FS90. Consult your user manual for the recommended spark plug type.
Lubrication
Proper lubrication is essential for preventing wear and tear on the trimmer’s moving parts.
- Gearhead Lubrication: Lubricate the gearhead with grease every 25 hours of use.
- Cable Lubrication: Lubricate the throttle cable and other cables with a light oil.
Actionable Tip: I use a grease gun to lubricate the gearhead, ensuring that the grease reaches all the necessary parts.
Storage
Proper storage is crucial for preventing damage to the trimmer during periods of inactivity.
- Drain the Fuel Tank: Drain the fuel tank before storing the trimmer for an extended period.
- Clean the Trimmer: Clean the trimmer thoroughly to remove any dirt and debris.
- Store in a Dry Place: Store the trimmer in a dry place away from direct sunlight and extreme temperatures.
Pitfalls to Avoid:
- Neglecting Maintenance: Failing to perform regular maintenance is the biggest mistake you can make. It will lead to costly repairs and a shortened lifespan for your trimmer.
- Using Incorrect Fuel: Using the wrong fuel mixture can damage the engine.
- Overloading the Trimmer: Trying to cut material that’s too thick for the trimmer can damage the engine and trimmer head.
Next Steps and Additional Resources
Now that you’ve learned these five pro arborist hacks, it’s time to put them into practice. Grab your Stihl FS90, head out to your yard, and start trimming!
Here are some additional resources that you may find helpful:
- Stihl Dealer Locator: [Insert Link to Stihl Dealer Locator] – Find a local Stihl dealer for parts, service, and advice.
- Stihl FS90 User Manual: [Insert Link to Stihl FS90 User Manual] – Consult the user manual for detailed information about your trimmer.
- Online Forums: [Insert Link to Relevant Online Forums] – Connect with other Stihl FS90 users and share tips and advice.
Suppliers of Logging Tools and Drying Equipment:
- Bailey’s Online: [Insert Link to Bailey’s Online] – A leading supplier of logging tools and equipment.
- Northern Tool + Equipment: [Insert Link to Northern Tool + Equipment] – Offers a wide range of tools and equipment for various applications.
- Local Equipment Rental Services: Search online for equipment rental services in your area.
Mastering the Stihl FS90 is a journey, not a destination. Keep practicing, keep learning, and keep those edges sharp! And remember, the best time to start is always now. So, get out there and make some sawdust!