FS 91 R

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A professional trimmer packed with features for simplified and convenient trimming.

Product Description

Fulfilling the demanding landscaper’s trimming needs, the STIHL FS 91 R trimmer is the well-rounded choice for professionals. It features a low-emission engine and large fuel tank which provides 30% longer run times than the previous model. With its rubberized loop handle, this straight-shaft trimmer delivers a comfortable grip of product, the maneuverability needed to navigate obstacles and the power to cut them down. The FS 91 R trimmer also has a simplified three-step start procedure that saves users time, and a superior air filter benefitting you in the long run.

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.

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

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  • 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.
  • Protected Spark Arrestor Muffler
    Has large baffles which reduce noise level and contains a screen designed to reduce the emission of sparks.
  • 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.
  • 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.
  • Adjustable Front Handle
    Adjusts for comfort.


28.4 cc (1.73 cu. in.)
0.95 kW (1.27 bhp)
5.5 kg (12.1 lbs.)*
710 cc (24.0 oz.)
*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.


FS 91 R is rated 4.3 out of 5 by 196.
Rated 5 out of 5 by from Tons of power This trimmer has so much power! Great product cranks second pull every time. I would suggest to anyone to purchase
Date published: 2019-10-14
Rated 5 out of 5 by from Great trimmer Using this trimmer with a brush cutting blade. What a time saver. Lots of power and with the shoulder strap this is very comfortable and easy to maneuver.
Date published: 2019-10-03
Rated 2 out of 5 by from Bought 2 of these. Nothing but problems Have had both back in for warranty work constantly. Always bogging down after running for any decent time. Had to replace both carbs and still have issues.
Date published: 2019-09-28
Rated 5 out of 5 by from 2 pull starts Comfortable makes a chore to brush cut almost enjoyable...almost. 2 pull starts everytime. Big plus is my hands and arms aren't numb after using for 4 hours straight.
Date published: 2019-09-23
Rated 2 out of 5 by from Disappointingly Surprised I bought this weed eater to replace an FS70R that was lost in a fire. I had the 70 for approximately 3 years and used it about 20 hours a week. It was a solid machine, ran like it was on drugs and started with the 2nd pull every single time, even in winter. Its only drawback was that it was a little weaker than I needed as I have a lot of high grass and fibrous weeds. When it came replacement time, I did my homework and decided the best replacement would be the FS91R. The day I bought it, I mentioned to the tech it sounded rough and would not rev up. He mentioned the break-in period and as I read through the manual, I read about it and broke it in according to specs. Four months later, we are well past the break-in period and top end this thing runs like a 74 Pinto. I go to make the necessary adjustments to the carb and find some seriously deep and specialized screw heads for adjusting the high and low. Fine, call the dealer, he says, take the brass screen off the muffler and see if that helps. Holy cow, can I speak to a mgr. Mgr comes on, take the screen off. Jeez. Ok. I take the screen off, per the recorded phone instruction. Still runs terribly top end. Dropped it off at the shop and have yet to hear the news. I love Stihl. Almost everything I own in power tools is Stihls, have spent 10,s of thousands of dollars on pro equipment with Still and I have a high expectation for the high amount of money I pay, and I have never been let down until now. This weedeater is of a proven lineage and brand but it is just not up to the standard that I hold Stihl to for their pro line. I would not buy any more of this family of weedeater and I would no recommend it to anyone. As soon as mine returns, I will sell it and look for another.
Date published: 2019-09-20
Rated 5 out of 5 by from Great for helping me with 2.5 Acres Great size trimmer for me keeping up with my 2.5 acre property, fully fenced. I have a lot of trimming and this thing does a great job. I only have a few hours "behind the wheel" per se, but so far I'm happy with the purchase.
Date published: 2019-09-17
Rated 4 out of 5 by from User friendly My father and I use it on the farm from fence lines to normal edging. Makes fairly quick cutting of hedge bushes and small trees 2 to 3 inches thick with the bladed attachment that they offer. It’s light enough for my 70+ father to use almost all day but has plenty of power.
Date published: 2019-09-10
Rated 2 out of 5 by from very disappointed I have had a stihl fs 110 for many years and it was a great trimmer.decided to buy a new fs 91 and boy am I sorry.First off the single finger throttle is awful they need to go back to a three finger width throttle.The worst thing about this trimmer is is continues to bounce off the rev limiter which creates terrible vibration.I have taken it back to my dealer 4 times and they continue to tell me that is is running correctly,they give some epa guideline excuse for why it runs so rough at full throttle.Neither echo or Husqvarna run that way.i truly despise this trimmer.
Date published: 2019-09-02
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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.
  • 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.

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Cutting Heads & Blades Selection Chart (PDF)
FS 91 R Instruction Manual (PDF)
Download Instructions on How to Rewind Your Trimmer Head (PDF)
Product Safety Manual (PDF)
STIHL Limited Warranty
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