FS 91
Solid drive shaft offers the end user more flexibility in trimming applications.
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.
| FS 91 Specifications - Professional Use | |
| POWER SOURCE | Gas |
| WEIGHT | 12.8 lbs. |
| CUTTING WIDTH | 16.5 in. |
| ENGINE POWER | 1.27 bhp |
| FUEL CAPACITY | 24.0 oz. |
| DISPLACEMENT | 28.4 cc |
| Note: Weight displayed does not include cutting attachment or deflector. | |
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.
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.
Model Features
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Made in America
A majority of STIHL products sold in America are made in America of U.S. and global materials. -
Loop Handle (R)
Loop handle grass trimmers and brushcutters are ideal for trimming between bushes and shrubs and other areas where space is limited. -
Anti-Vibration System
STIHL has a system for minimizing the vibration levels of handheld outdoor power equipment. The STIHL anti-vibration system helps reduce operator fatigue and provides a more comfortable working experience. -
IntelliCarb™ Compensating Carburetor
The IntelliCarb™ Compensating Carburetor measures the air pressure on the clean side of the air filter and adjusts the metering diaphragm in the carburetor. This keeps the RPM at a consistent level, even when the air filter begins to clog. -
Simplified Starting Procedure
To get started, simply pump the fuel primer, set the choke and pull the starter cord. The built-in stop switch allows the user to turn off the engine with a simple press of the button. When the engine is off, the throttle lock automatically returns to the “start” setting. Your power tool will be ready to be started when you’re ready to get back to work.
See it in action! -
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. -
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. -
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! -
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°. -
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). -
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. -
Fully Lined Drive Shaft
Provides smooth operation and less vibration. -
High Tech Polymer Housing
Housings are lightweight, withstand greater impact and are corrosion-resistant. -
Protected Choke Lever/Knob
Helps prevent damage. -
Throttle Trigger Interlock
Must be depressed before the trigger can be activated. -
Air Filter Cover
Easily removed for fast and easy filter cleaning or replacement. -
Protected or Enclosed Control Cables
Eliminate dangling and loose wires. -
Heavy-Duty Steel-On-Steel Clutch
Centrifugal clutch is designed to reduce slippage. -
Protected Spark Plug
Protected yet easy to change. -
Protected Spark Arrestor Muffler
Has large baffles which reduce noise level and contains a screen designed to reduce the emission of sparks. -
Upright Translucent Fuel Tank
Allows operator to easily check fuel level before starting work. Upright position makes it easier to refill.
Optional Accessories
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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.
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SPECIAL OFFER
HP Ultra 2-Cycle Engine Oil
No matter how you slice it (or trim it or shred it), there’s no better protection for your high performance 2-stroke engine than STIHL HP Ultra Oil. This 2-cycle engine oil has outstanding engine cleaning characteristics, plus “ultra” lubricating qualities that are superior to other 2-cycle engine oils. This fully synthetic oil is also highly biodegradable, degrading by 80% in 21 days. We’re so confident this oil will protect your engine, we’ll double your STIHL limited warranty* when you use it. It’s that good.
*Double your warranty when you purchase either STIHL HP Ultra Oil (six pack) or STIHL MotoMix® Patented Premixed Fuel (one gallon minimum) with your STIHL product purchase. Double limited warranty protection applies to select STIHL gasoline-powered products purchased for personal non-income producing, household purposes only. Other restrictions apply. See dealer for details or refer to STIHL’s Limited Warranty Policy.
Unopened container shelf life: 4 years from the date of filling, in originally sealed containers.
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SPECIAL OFFER
STIHL MotoMix®
STIHL MotoMix® is our patented premixed fuel, specially blended for ultimate performance. Like a sports drink for your engine, this 50:1 mixture is a combination of premium non-ethanol, high-octane motor fuel and our highest-quality STIHL HP Ultra Oil. Clean and convenient, MotoMix® eliminates the hassle of mixing your own 2-stroke engine fuel while providing superior performance and lubrication. Plus, we stand behind this formulation by doubling the limited warranty when you include MotoMix® with your power tool purchase. STIHL MotoMix® contains no ethanol, allowing it to maintain stability for up to two years after the seal is broken - so it stays fresh in your equipment during long storage periods. It’s no surprise that MotoMix® is the official fuel of the STIHL TIMBERSPORTS® Series.
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SPECIAL OFFER
CF3 Pro
Finally, a line your landscape won’t want to cross: The CF3 Pro Trimmer Line. This rugged line is formed using 3-component, tri-extrusion technology. Its high-quality polyamide components ensure strong durability with excellent cutting performance. Best of all, it is compatible with all STIHL nylon line trimmer heads, making the CF3 Pro at home on any landscape trailer or in any garage. Whether you’re a homeowner with challenging terrain or a professional landscaper requiring more wear and tear out of your line, the CF3 Pro is a line you can stand behind.
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SPECIAL OFFER
Trimmer Service Kit
All kits include an air filter, fuel filter and spark plug, and certain kits also include a spark arresting screen.
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For Your Safety
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SPECIAL OFFER
Brush Shield Protector
Cut through your day with the protection and comfort of the STIHL Brush Shield Protector. Developed for users of clearing saws, trimmers and brushcutters, the shield offers face and hearing protection in a lightweight package. The epoxy-coated steel full-face screen helps protect you from flying debris while comfortable, adjustable hearing protectors help reduce loud tool and engine noise.
Noise Reduction Rating (NRR) of 25 dB(A)
NOTE: Goggles or protective glasses meeting ANSI Standard Z87.1 must be worn under face screen and shield for primary eye protection.
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SPECIAL OFFER
STIHL Pro Mark™ Hearing Protectors
Heavy machinery doesn’t have anything interesting to say – block out that noise with our most noise-reducing hearing protection. These top-quality Hearing Protectors feature padded stainless steel spring-wire headbands maintain constant pressure. So no sliding around and letting in unwanted sound waves. They’re also easy to adjust. Set a comfortable fit and get to work in peace.
Meets ANSI S3.19-1974 standard. Noise Reduction Rating (NRR) of 29 dB(A).
Available color: Orange
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SPECIAL OFFER
Outdoor PRO Gloves
When you need professional-grade protection for your hands, STIHL Outdoor PRO Gloves deliver it all. High-quality synthetic leather offers comfort and durability. That durability is enhanced further by TPR (thermoplastic rubber) padded knuckle and finger areas. The gloves are lightweight and offer high dexterity. The material is also breathable for all-day comfort. They’re the PRO way to go.
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SPECIAL OFFER
Two-Tone Work Glasses
They’re comfortable. They’re functional. They’re from STIHL. Featuring a hollowed-out frame, our Two-Tone Work Glasses are as lightweight as they are stylish. Designed with flexible rubber tips and nose pads, these glasses help you get the job done with greater comfort and fewer slips. Meeting ANSI standard Z87.1+ and offering 99% UV protection, the STIHL Two-Tone Work Glasses will have you covered in more ways than one.
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