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FS 91

FS 91
A professional bike-handle trimmer with simplified starting, improved air filtration and 30% longer run time than the FS 90.

Product Description

If you’re a landscaping professional who uses their trimmer for mowing applications, grab the powerful STIHL FS 91 trimmer. Its bike-handle design adds greater comfort and leverage, thanks to its redesigned rubberized grips. The trimmer also features one touch stop and a simplified starting procedure enabled by the semi-automatic choke lever. Its low-emission engine is paired with a larger fuel tank, delivering 30% longer run times when compared to the FS 90. The engine also includes improved air filtration and STIHL exclusive IntelliCarb™ technology for maximum RPM. And when the terrain gets tough, this trimmer’s solid steel drive shaft accepts a wide range of heavy-duty cutting heads, including metal blades, for maximum versatility.

Model Features

  • Reduced-Emission Engine Technology - Caring for Nature
    The STIHL Inc. “Caring for Nature” seal identifies its powered products that are more environmentally conscious, producing zero or low exhaust emissions. STIHL Inc. defines “low exhaust emissions” as being cleaner than EPA and/or CARB exhaust emission standards.

    More information

  • Built in the USA
    Indicates products that are built in the United States from domestic and foreign parts and components.

    More information

  • Cutting Heads & Blades Selection Chart
    Need help selecting a cutting head or blade for your STIHL trimmer or brushcutter?

    Click here to view the Cutting Heads & Blades Selection Chart (PDF Format).
  • Bike Handle
    When used in conjunction with a harness, the bike handle allows the machine to be easily guided, enabling a smooth horizontal mowing action to cover large areas quickly and efficiently. With soft grips for increased comfort, the bike handle provides greater control and helps reduce operator fatigue.

    See it in action!
  • Shoulder Strap / Carrying System
    Using a shoulder strap or carrying system helps distribute the weight of the equipment for increased operator comfort and improved maneuverability.
  • Multi-Function Control Handle
    Having easy access to all of the controls on one comfortable handle makes it easy to complete tasks so the operator’s hand never has to leave the handle.
  • Tool-Free Handle Adjustment
    The central wing nut enables easy adjustment without the use of tools. For transportation and space-saving storage, the handle can be rotated 90°.
  • Purge Pump Primer
    By pressing the bulb, this small fuel pump delivers fuel to the carburetor, reducing the number of starting pulls needed after an extended break between uses.
  • Upright Translucent Fuel Tank
    Allows operator to easily check fuel level before starting work. Upright position makes it easier to refill.
  • Protected Spark Arrestor Muffler
    Has large baffles which reduce noise level and contains a screen designed to reduce the emission of sparks.
  • Protected Spark Plug
    Protected yet easy to change.
  • Heavy-Duty Steel-On-Steel Clutch
    Centrifugal clutch is designed to reduce slippage.
  • Protected or Enclosed Control Cables
    Eliminate dangling and loose wires.
  • Air Filter Cover
    Easily removed for fast and easy filter cleaning or replacement.
  • Throttle Trigger Interlock
    Must be depressed before the trigger can be activated.
  • Start/Run/Stop Controls on Handle
  • Protected Choke Lever/Knob
    Helps prevent damage.
  • High Tech Polymer Housing
    Housings are lightweight, withstand greater impact and are corrosion-resistant.
  • Fully Lined Drive Shaft
    Provides smooth operation and less vibration.

Specifications

DISPLACEMENT
28.4 cc (1.73 cu. in.)
ENGINE POWER
0.95 kW (1.27 bhp)
WEIGHT*
5.8 kg (12.8 lbs.)*
FUEL CAPACITY
710 cc (24.0 oz.)
POWER SOURCE
Gas
*Without deflector and cutting attachment.

Important Information

WARNING! Improper use of any trimmer/brushcutter can cause serious or fatal injury. Read, understand and follow all safety instructions in your instruction manual. To reduce the risk of injury from blade contact, circular saw blades may be used on FS brushcutters that have a limitstop, a bicycle handle and double shoulder harness and not on FS brushcutters with a "J" handle or loop handle. Other rigid blades may be used on FS brushcutters having a bicycle handle, a "J" handle or a loop handle equipped with a barrier bar. To reduce the risk of eye injury always wear proper eye protection. Always use the appropriate deflector for the type of cutting attachment, as explained in your instruction manual.

Note: STIHL engine products with the Caring for Nature logo are cleaner than EPA Standards for exhaust emissions.

Note: STIHL recommends use of fuel with no more than 10% Ethanol content. Using fuel with greater than 10% Ethanol content may cause damage to your equipment and may void your STIHL warranty. Learn More…

WARNING! Improper use of any power tool may cause serious or fatal injury. Read, understand and follow carefully the operating and safety instructions in your instruction manual before using such products.

STIHL products sold through U.S. STIHL Dealers are for distribution in the United States only.

Reviews

FS 91 is rated 4.5 out of 5 by 25.
Rated 5 out of 5 by from One serious weedwacker This is my first Stihl product and I'm very impressed. The smooth 4-cycle engine cuts through brush like butter. The first task I needed to do was to attach the cutting blade and cut down a bunch of oak brush saplings on our 5 acre property. This model was perfect for the job. Looking forward to years of reliable use from this product.
Date published: 2017-11-29
Rated 2 out of 5 by from Not enough torque/poor throttle response. I spent 13 hours with this machine and finally returned it to my dealer. (He was extremely polite when honoring my request.) I upgraded to the fs131 at almost the exact same weight. It's absolutely worth the extra money, and it comes with the harness.
Date published: 2017-11-18
Rated 5 out of 5 by from Excellent string trimmer. This is a replacement for the FS 90, that somebody would not return!!! The FS was still going strong, but since the other person would not return it I had to get another.
Date published: 2017-10-06
Rated 5 out of 5 by from Huge step up For this price, the step up in quality over the junky $70 weed eaters is awesome. Yes, 1 of these equates to 5 weed eaters but around my farm, trimming under a LOOOONNNNGGGG fence line to keep it from grounding on weeds and such is necessary, and the cheap ones just aren't up to the task.Power is there, the shoulder strap is amazing. It's very very good on fuel, and starts SO easily. It's best on fuel when you hold a steady amount of power continually instead of rev rev rev revving it constantly. The one thing I dislike is the clips to remove the head cap. They are so stiff when new, I had to use the handle of a screwdriver to press them in. Hurt my thumbs trying. I'd *strongly* recommend the lime green trimmer line, 2.4mm /.095", that stuff will cut the tiny trees down. You'll use a lot less of it too than the cheaper stuff.
Date published: 2017-10-04
Rated 5 out of 5 by from This product makes my job easier This product has plenty of power. It is easy to start and use. The bike style handlebars makes it easier to control and carry the trimmer, and reduces stress on the operator.The head is easy to change from the trimmer to the cutting blade.
Date published: 2017-09-21
Rated 5 out of 5 by from Perfect for any job around the farm! This machine is smooth and comfortable to operate! Between the handlebars and the shoulder strap, an amazing center of gravity is maintained with no strain on the back!
Date published: 2017-09-17
Rated 5 out of 5 by from Handier than pockets on a shirt. This is my second FS 91. My last one was "liberated " from my carport. After spending a day with a handsaw, I decided to pull the trigger on a new one. This newer model is really nice. Lots of improvements over my older one. I'm locking this one up this time. I will never do without one of these again. I only have 7 acres to care for, but this makes it so much easier. If I recall correctly, I paid more for my last one. These are a real bargain.
Date published: 2017-08-29
Rated 3 out of 5 by from Hoping for More! Purchased it, tried it, returned it!I bought this thinking that it would be more than enough for my 2 acres. However it lacked power and it bogged down and ran rough. Also head trimmer cord kept breaking off inside. When the dealer spooled the cord it did it and when I re-spooled the cord it did the same. Dealer said the cord looked old and brittle.For the professional landscaper these are probably small issues which are easily overcome, but for the price I thought it really wasn't worth the money. I ended up getting the FS130R (Loop handle) and the brush / saw cutter kit for a few dollars more. Lots of power doing the same job.
Date published: 2017-08-22
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Optional Accessories

  • Gearbox Attachments
    Gearbox attachments are available for this model. View the interchangeable gearbox chart to find out which attachments work with this model.
  • Straps and Harnesses
    They distribute the load from your hands to your shoulders. They also help reduce operator fatigue and make it easier to use trimmers, brushcutters and clearing saws for extended periods.
  • Deflectors
    Protect yourself from flying debris while trimming. Check out our selection of deflectors and find the one that will help protect you.
  • Trimmer Line
    There's high-performance STIHL trimmer line for every operating condition. 
  • Trimmer Heads & Blades
    Many trimmer heads and blades are available. Find out which ones to use with this model in this chart.  

Standard Features

  • Common Features for Trimmers
    View the features common to many STIHL trimmers.

You Will Also Need

For Your Safety

Support

Read what our customers say about STIHL Trimmers
STIHL Trimmers & Edgers, the Right Tools for the Job - Video
How to Wind a STIHL Trimmer Head - Video
Cutting Heads & Blades Selection Chart (PDF)
FS 91 Instruction Manual (PDF)
Download Instructions on How to Rewind Your Trimmer Head (PDF)
Product Safety Manual (PDF)
STIHL Limited Warranty
Contact Us

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