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 Beats anything on the market I’ve had other brands of trimmers and always had trouble starting them after they’ve sat for more than ten minutes. Today was the first time I’ve used my trimmer in almost two months and it started on the second pull, just like always. Excellent product, reliable, and far superior in quality to anything I’ve used before.
Date published: 2019-09-02
Rated 4 out of 5 by from Would purchase again It's perfect for what I do around the house and helping family out. But I did use a buddies 131 and was even more impressed. But like I said the fs91 is more then enough for what I do. Breezes through 5 acres of edging and clears reasonable vegetation really well. no need for the over priced Stihl string, Stihl pre-mix and whatever else they say is better, isn't necessary in my opinion. The less expensive products last just as long and won't shorten the life of anything.
Date published: 2019-08-17
Rated 4 out of 5 by from Great trimmer overall This trimmer starts well and does a great job. The engine sounds a little "rough" at full speed but I was told it was because it has a rev limiter. I broke the string on the first use in heavy weeds but the dealer was great about helping me out. The harness is a little short for a 6' 2" person, and its a little heavy for a 66 year old person. Overall it is a great trimmer.
Date published: 2019-08-15
Rated 1 out of 5 by from Poor quality! Just bought this trimmer today. Won't run worth a crap.Engine won't stay running along with the clutch rattling too. Could not get five minutes use out of it. Very disapointed. Sthil, you should have never discontinued the FS -90 - R which i owned for years . Flawless period. Taking it back to my good dealer and getting a refund I hope. I am a top contributer for you on several of your products do well. I am having doubts about the products the company is making. May never buy a product again.
Date published: 2019-08-14
Rated 5 out of 5 by from Great trimmer and easy to use! I bought this trimmer to keep blackberries, brush, and vegetation cut down on the back of my property. It is perfect for what I use it for. I change from string to a triangle blade when I get to the larger brush and it is a very simple change that takes very little time. Easy to start, easy to use, and very dependable. For cutting some of the heavier brush I strongly recommend the solid shaft of this trimmer for trouble free operation. Very pleased and would recommend this trimmer to everyone.
Date published: 2019-08-13
Rated 5 out of 5 by from Great product This trimmer works amazing, comfortable to use, plenty of power, starts right up every time 1-2 pulls. Bought the trimmer late last year so this has been my first full season with it and absolutely no complaints. I also got the brush blade attachment and that was a great investment also. I have always owned STIHL chainsaws and now I have another very satisfactory tool to add to my collection. In my opinion with my experience STIHL is the best product on the market hands down.
Date published: 2019-08-12
Rated 1 out of 5 by from This is by far the first weedeater I used This is by far the worst Weedeater I’ve used It doesn’t have the power and it lags a lot
Date published: 2019-08-06
Rated 5 out of 5 by from Great Trimmer Stihl Fs 91R ! I wanted another stihl trimmer though I’m a homeowner now I’ve always used stihl when I was a landscaper when I had stihl trimmers they always started on the first pull they were lightweight very powerful and their dealers are friendly do not sell you stuff in a box and are helpful and they even offer you extra years of a warranty if you buy their premixed fuel or oil for gas to be mixed definitely plus they gas up your machine to make sure it works right I was pleased with this trimmer I have a big property and this trimmer has the power to knock everything out in 15 minutes!
Date published: 2019-08-02
Rated 5 out of 5 by from Great product I’ve been using it and it’s been a good product I haven’t had any problems with it the only issue is it’s a little bit hard to start
Date published: 2019-07-31
Rated 5 out of 5 by from Great so far So far it's been a great trimmer. It's always started on the first or second pull, has more than enough power for what I need, and is great on gas. I don't understand all the problems everyone has with the bump head. There are some good videos on YouTube showing you how to properly spool the head. The only thing I wish I would have done was waited a little longer to get the KM91 instead, but that's not a big issue since you can change the gearbox out to run almost everything that the Kombi can run.
Date published: 2019-07-31
Rated 5 out of 5 by from I LIKE this trimmer. It is simple to start and operate. This is my 4th weed trimer. Of all, it is the simplest to start and run. It is balanced nicely. It needs to be simple as it is used by all who sign up to help maintain the grounds at our Church. Thanks!
Date published: 2019-07-24
Rated 5 out of 5 by from Best trimmer I’ve owned Starts easy, runs great. Plenty of power for all the tall nasty weeds I have around my house.
Date published: 2019-07-22
Rated 5 out of 5 by from Great trimmer Just purchased this FS 91 R trimmer and used it for the first time today. Works great, runs very smooth! it is well balanced with the shoulder strap that comes with it. When looking for another trimmer I was advised by family members to get a Stihl and glad I did! The neighbors on either side of me have Sthil trimmers and leaf blowers, so now I am the third member of the Sthil club! Highly recommend this product!
Date published: 2019-07-15
Rated 5 out of 5 by from Works well, cuts through the tough stuff I'm very happy with my trimmer, it even works its way through the viney weeds like a champ.
Date published: 2019-07-15
Rated 5 out of 5 by from Awesome trimmer! Just picked up the 91 R a few weeks ago. Used it for about 3 hours a day for about 4 days, and I have to say thoroughly impressed. Very strong for very thick heavy brush and thick weeds. But can also do good for thin weeds around houses or landscaping. Very smooth and easy running, quiet and awesome sounding (quiet) I was a little skeptical on how I would like the 4 mix engine, but after using it I’m amazed by it!! I was stuck between this and the 111 r, but with the 91 you could use a brush cutter, and also a solid steel shaft. It Cut down 6 foot hay weeds down with ease and will not bog down at all. Only problem is it’s a little short for me but for some others it might not be. Stihl is the only way to go!!!
Date published: 2019-07-13
Rated 4 out of 5 by from Great trimmer but it’s heavy so be ready! Cannot stop this machine it’s a great trimmer but it is heavy! Will run 3 or 4 hours according to how you run it on a tank of fuel! Highly recommend this product but if your looking to do steep banks or cutting for extended times it’s alittle on the heavy side.
Date published: 2019-07-11
Rated 5 out of 5 by from This trimmer is great I've owned different models of stihl trimmers in the past. I added this one to my collection. works great. has the power I am looking for and need
Date published: 2019-07-11
Rated 3 out of 5 by from Loses power Can't maintain a good fast speed starts to lose power even if the string is not that long but it gets the job done
Date published: 2019-07-08
Rated 5 out of 5 by from 2 acres i,ve been hitting my 3/4 acre and had no problem. My cousin has 3 acres across the street. I knocked out 2/3 of the 4 feet tall weeds with the power of the fs 91 r. Love it and recommend it to any home owner that wants to get the job done fast and complete.
Date published: 2019-07-05
Rated 5 out of 5 by from High quality product that performs well. This trimmer works exceptionally well. Easy to start and comfortable to use. It cuts very well. The one complaint that I have is the string that came loaded on it. It has a "memory" from being tightly wound and after a while would not feed automatically. If it was taken apart and rethreaded, the string was so coiled up it was almost unusable. I finally replaced it with other string. See pictures.
Date published: 2019-07-01
Rated 5 out of 5 by from You get the best bang for your buck Bought about two weeks ago and already very impressed. It has handled everything i have put in front of it and keeps coming back for more. Slightly heavy, but you get used to it eventually and it’s no problem. Cannot beat the amount of power it has and I will continue to buy from Stihl!
Date published: 2019-06-20
Rated 3 out of 5 by from easy start up easy start up, sounds like a beast, but doesn't seem to like too much string. if you go one bump past what the guard cuts off, it vibrates and slows the engine down considerably and wont recover until the string is short enough.
Date published: 2019-06-20
Rated 5 out of 5 by from Very powerful, easy to operate and maintain. I've owned my FS 91 R for almost a year now. The 28.4 cc 4-mix engine is powerful and economical with it's large fuel tank. I could do about 3 average size lawns on one tank of gas. It's comfortable and easy to operate, as well as easy to maintain. It starts up within 3 to 5 pulls and has excellent throttle response. There is minimal vibration thanks to it's solid steel shaft. The best grass trimmer I ever owned.
Date published: 2019-06-18
Rated 3 out of 5 by from Not for taller people! I stay bent over fighting the head angle and length of the shaft. I think it’s more of the angle, the outer portion of the line keeps scalping the yard, I have to stand in an awkward position to attemp to get the nose from digging in. I am 6’2, and asked for a long shaft, I was told they are all the same. As for engine power, line feed, and everything else great. But as for me using this for several years, I don’t see it. I am a Stihl fan and will continue buying other products.
Date published: 2019-06-15
Rated 5 out of 5 by from Exactly what I wanted in a trimmer! This trimmer has the perfect features and power for all my needs! The price was reasonable, I have no issue paying for the quality of Stihl. When the time comes to do maintenance I know I can go to my local dealer (True Value Hardware of Greenville) and they have all the knowledge and supplies needed to help me out!
Date published: 2019-06-11
Rated 5 out of 5 by from Excellent Trimmer I can not believe the difference between this trimmer and my old brand X trimmer. I knew this would be better but the difference is night and day. Starts super easy. Makes quick work of my most overgrown areas. Love how it has been cutting through smaller brush and very tall thick grass. I have also been extremely satisfied with the follow up I have gotten from Stihl. I messed around with cheaper stuff and finally got fed up, If I had just bought this trimmer years ago instead of the 4 I have gone through I'd be way better off.
Date published: 2019-06-10
Rated 1 out of 5 by from Good engine, terrible vibration. This was the first stihl product I have ever bought, and will be the last. Long story short, I have had it worked on several times for how bad it vibrates and has yet to be corrected. I really had high hopes for it, and was will to give them the benefit of the doubt. But now I’m just done. I’d rather use my 10 yr old echo.
Date published: 2019-06-10
Rated 5 out of 5 by from Easy to start I've had my FS91R for about a month. This trimmer starts easily, uses little fuel and doesn't vibrate very much. This is a well made trimmer and I'm sure it will last for years. My yard is 1.5 acres and boarded by woods. This trimmer will see about 1 hour of use per week.
Date published: 2019-06-04
Rated 4 out of 5 by from Good Power - Some Fits & Starts Quick, easy start within 2-3 pulls; excellent power acceleration to handle 5 acres of fence trimming and outbuilding perimeter cleanup. Frustration: head auto-line feed system is not consistent or reliable, i.e. frequent "fits and starts" to reset trim line so it will auto-feed properly when needed. All in all, this unit gets the job done and is fairly light on the shoulder.
Date published: 2019-06-03
Rated 4 out of 5 by from Great Stihl product The only reason I'm giving it 4 stars is because it's short! If your over 6 feet tall then your leaning over to do your weed eating. And thats no Bueno. Why are they all the same length? But if your under 6 ft your good to go.
Date published: 2019-06-03
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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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