Stihl FC 91 Instruction Manual

Pages 84

Year 2020

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Stihl FC 91 Specification

The Stihl FC 91 is a robust, professional-grade edger designed for precision and durability, ideal for landscape professionals and demanding homeowners. It is powered by a reliable 28.4 cc, 4-Mix engine that combines the benefits of a two-stroke and four-stroke engine, providing a powerful yet fuel-efficient performance with reduced emissions. The engine's design ensures a smooth operation with a distinct sound and delivers high torque across a broad range of speeds. The edger features a large 710 cc fuel tank, allowing for extended use with fewer refueling stops, enhancing productivity on larger tasks.

The FC 91 is equipped with a sturdy, adjustable depth wheel, allowing users to customize the cutting depth for different edging tasks, ensuring clean and precise lines along driveways, walkways, and flower beds. Its open guard design helps minimize clogging, while the mud flap directs debris away from the user, enhancing safety and operational efficiency. The edger's handle is ergonomically designed with a rubberized grip, providing comfort and reducing fatigue during prolonged use. The simplified starting procedure is facilitated by a semi-automatic choke lever, making it easier to start in various conditions.

The shaft is made of lightweight, high-strength aluminum, contributing to the overall durability and ease of use of the tool. The unit's design allows for easy access to the spark plug and air filter, simplifying maintenance and ensuring the machine remains in peak condition. Overall, the Stihl FC 91 is engineered to deliver excellent cutting performance with user-friendly features, making it a reliable choice for those seeking precision and efficiency in lawn care tasks.

Stihl FC 91 F.A.Q.

How do I start the Stihl FC 91 edger?

To start the Stihl FC 91 edger, ensure the stop switch is in the "I" position. Press the primer bulb several times until fuel is visible. Set the choke lever to the closed position, pull the starter handle until you hear the engine attempting to start, then set the choke to the open position and pull the starter handle again until the engine starts.

What type of fuel mix should I use for the Stihl FC 91?

Use a 50:1 fuel mix ratio, which is 50 parts gasoline to 1 part two-stroke engine oil. Ensure you use high-quality, unleaded gasoline with a minimum octane rating of 89 and mix it with Stihl's two-stroke engine oil for optimal performance.

How do I replace the cutting blade on the FC 91?

To replace the cutting blade, first ensure the engine is off and the spark plug wire is disconnected to prevent accidental starts. Use the appropriate wrench to remove the blade nut, then remove the old blade. Install the new blade, ensuring it is seated correctly, and tighten the blade nut securely.

What regular maintenance is required for the Stihl FC 91?

Regular maintenance includes cleaning the air filter, checking and changing the spark plug annually, inspecting and replacing the fuel filter as needed, and sharpening or replacing the cutting blade when dull. Always ensure all screws and nuts are tightened and inspect for fuel leaks.

Why is my FC 91 not starting after storage?

If your FC 91 is not starting after storage, check the fuel for stale gas, which should be replaced with fresh fuel mix. Inspect the spark plug for fouling and replace if necessary. Ensure the air filter is clean, and check for any blockages in the fuel line or carburetor.

How can I improve the performance of my Stihl FC 91?

To improve performance, regularly clean or replace the air filter, use fresh, correctly mixed fuel, and ensure the blade is sharp. Additionally, follow the recommended maintenance schedule and store the edger in a dry, clean place.

What should I do if the FC 91 vibrates excessively during use?

Excessive vibration can be caused by an unbalanced or damaged blade. Check the blade for damage and ensure it is installed correctly. Inspect the engine mounts and handle screws for tightness, and replace any worn or damaged parts.

How do I adjust the carburetor on the Stihl FC 91?

Carburetor adjustments should be made by a qualified technician to ensure proper tuning. However, if you need to adjust it yourself, locate the "L", "H", and "LA" screws on the carburetor and consult the manual for proper settings. Adjust the screws slightly to achieve smooth idling and acceleration.

Can I use a different brand of oil in my Stihl FC 91?

While Stihl recommends using its own brand of two-stroke engine oil for optimal performance, you can use another high-quality two-stroke oil that meets the same specifications. Always maintain the 50:1 fuel-to-oil ratio.

What safety precautions should I follow when using the FC 91?

When using the FC 91, wear protective eyewear, gloves, and hearing protection. Ensure the work area is clear of debris and bystanders. Keep a firm grip on the tool with both hands, and do not operate in wet or slippery conditions. Always follow the safety guidelines outlined in the user manual.