Instruction Manual
Page 3
...stihlusa.com. VA0.E16. 0000007402_001_GB WARNING Because a trimmer / brushcutter is equipped with electronic systems. 1 © ANDREAS STIHL AG & Co. For further information you read, understand and follow the safety precautions and the operating and maintenance instructions... the Mowing Head 40 Maintenance and Care 42 Main Parts 44 { FS 91, FS 91 R Specifications Maintenance and Repairs Disposal STIHL Incorporated Federal Emission Control Warranty Statement STIHL Incorporated California Exhaust and Evaporative Emissions Control Warranty Statement Trademarks 47 Allow ...
...stihlusa.com. VA0.E16. 0000007402_001_GB WARNING Because a trimmer / brushcutter is equipped with electronic systems. 1 © ANDREAS STIHL AG & Co. For further information you read, understand and follow the safety precautions and the operating and maintenance instructions... the Mowing Head 40 Maintenance and Care 42 Main Parts 44 { FS 91, FS 91 R Specifications Maintenance and Repairs Disposal STIHL Incorporated Federal Emission Control Warranty Statement STIHL Incorporated California Exhaust and Evaporative Emissions Control Warranty Statement Trademarks 47 Allow ...
Instruction Manual
Page 4
...the screw (1). As a result, engineering changes and improvements are made from those described in this manual, please contact your STIHL dealer or the STIHL distributor for your special attention. Therefore, some changes, modifications and improvements may not be covered in this manual may be ...on the machine are marked with the symbols and signal words described below: Engineering Improvements STIHL's philosophy is to continually improve all of its individual components. 2 FS 91, FS 91 R The individual steps or procedures described in the manual may contain item numbers that ...
...the screw (1). As a result, engineering changes and improvements are made from those described in this manual, please contact your STIHL dealer or the STIHL distributor for your special attention. Therefore, some changes, modifications and improvements may not be covered in this manual may be ...on the machine are marked with the symbols and signal words described below: Engineering Improvements STIHL's philosophy is to continually improve all of its individual components. 2 FS 91, FS 91 R The individual steps or procedures described in the manual may contain item numbers that ...
Instruction Manual
Page 5
..., harness and deflector for other purposes, since misuse may be used as a trimmer, i.e., they may fling them directly or by STIHL for use with a circular saw " indicates a high-powered trimmer / brushcutter that unauthorized persons do not use it . Read the...mounted on the nameplate were originally configured (at the time of your instruction manual for cutting grass, brush, wood and similar material. FS 91, FS 91 R 3 The terminology utilized in use of personal injury. Safety Precautions and Working Techniques Because a trimmer / brushcutter is a highspeed,...
..., harness and deflector for other purposes, since misuse may be used as a trimmer, i.e., they may fling them directly or by STIHL for use with a circular saw " indicates a high-powered trimmer / brushcutter that unauthorized persons do not use it . Read the...mounted on the nameplate were originally configured (at the time of your instruction manual for cutting grass, brush, wood and similar material. FS 91, FS 91 R 3 The terminology utilized in use of personal injury. Safety Precautions and Working Techniques Because a trimmer / brushcutter is a highspeed,...
Instruction Manual
Page 6
.... These conditions reduce the hand's ability to the operator's hands. Take frequent breaks. WARNING The ignition system of the STIHL unit produces an electromagnetic field of control. THE OPERATOR Physical Condition You must be strenuous. Working with your doctor before operating...Safe use of their physician and the pacemaker manufacturer before operating this machine. This field may also ricochet and strike the operator. 4 FS 91, FS 91 R the use of whitefinger disease and carpal tunnel syndrome, please note the following: - the operator 2. All factors which might ...
.... These conditions reduce the hand's ability to the operator's hands. Take frequent breaks. WARNING The ignition system of the STIHL unit produces an electromagnetic field of control. THE OPERATOR Physical Condition You must be strenuous. Working with your doctor before operating...Safe use of their physician and the pacemaker manufacturer before operating this machine. This field may also ricochet and strike the operator. 4 FS 91, FS 91 R the use of whitefinger disease and carpal tunnel syndrome, please note the following: - the operator 2. All factors which might ...
Instruction Manual
Page 7
...the instruction manual or the STIHL "Cutting Attachments, Parts & Accessories" catalog. For the cutting attachments authorized by STIHL for your ability to your face STIHL recommends that it was not designed (e.g. Although certain unauthorized attachments are recommended. FS 91, FS 91 R 5 Heavyduty, nonslip gloves...machine and metal blades. Continual and regular users should have it is restricted. Only attachments supplied by STIHL and expressly approved by STIHL for use may damage your hands. Wear an approved safety hard hat to your goggles or protective...
...the instruction manual or the STIHL "Cutting Attachments, Parts & Accessories" catalog. For the cutting attachments authorized by STIHL for your ability to your face STIHL recommends that it was not designed (e.g. Although certain unauthorized attachments are recommended. FS 91, FS 91 R 5 Heavyduty, nonslip gloves...machine and metal blades. Continual and regular users should have it is restricted. Only attachments supplied by STIHL and expressly approved by STIHL for use may damage your hands. Wear an approved safety hard hat to your goggles or protective...
Instruction Manual
Page 8
...fuel mix. Select bare ground for fuel (see the chapter on the fuel used, the weather conditions and the tank venting system. STIHL recommends that you . Fueling Instructions WARNING To reduce the risk of fuel. WARNING Fuel your Instruction Manual for fuel leakage while refueling ... correctly position and tighten the fuel cap in the tank to reduce the risk of your clothing. WARNING Check for additional information. 6 FS 91, FS 91 R Take care not to reduce the risk of burns and other ignition source, it has been completely removed from the operator. Note that...
...fuel mix. Select bare ground for fuel (see the chapter on the fuel used, the weather conditions and the tank venting system. STIHL recommends that you . Fueling Instructions WARNING To reduce the risk of fuel. WARNING Fuel your Instruction Manual for fuel leakage while refueling ... correctly position and tighten the fuel cap in the tank to reduce the risk of your clothing. WARNING Check for additional information. 6 FS 91, FS 91 R Take care not to reduce the risk of burns and other ignition source, it has been completely removed from the operator. Note that...
Instruction Manual
Page 10
...At correct idle speed, the cutting attachment should not move the cutting attachment. Make sure you cannot set the correct idle speed, have your STIHL dealer check your instruction manual. Do not allow the engine to slow down to idle. WARNING When you pull the starter grip, do ...open area. Failure to follow this procedure may damage the starter mechanism. Keep your hands in injury to have good balance and secure footing. 8 FS 91, FS 91 R Starting Start the engine at idle, attach the power tool to engage and move . Once the engine has started, immediately blip the throttle ...
...At correct idle speed, the cutting attachment should not move the cutting attachment. Make sure you cannot set the correct idle speed, have your STIHL dealer check your instruction manual. Do not allow the engine to slow down to idle. WARNING When you pull the starter grip, do ...open area. Failure to follow this procedure may damage the starter mechanism. Keep your hands in injury to have good balance and secure footing. 8 FS 91, FS 91 R Starting Start the engine at idle, attach the power tool to engage and move . Once the engine has started, immediately blip the throttle ...
Instruction Manual
Page 12
... for the type of the cutting attachment at ground level with the cutting attachment parallel to obtain the proper torque. Never use your STIHL dealer. WARNING During cutting, check the tightness and the condition of dust encountered. The retaining nut may fling foreign objects directly or ...serious or fatal injury. Stop the engine immediately if you do not have control of injury, since the cutting attachment is normally to 10 FS 91, FS 91 R Make sure that the wind or operating process directs any bystanders should wear a respirator approved by the power tool away from such ...
... for the type of the cutting attachment at ground level with the cutting attachment parallel to obtain the proper torque. Never use your STIHL dealer. WARNING During cutting, check the tightness and the condition of dust encountered. The retaining nut may fling foreign objects directly or ...serious or fatal injury. Stop the engine immediately if you do not have control of injury, since the cutting attachment is normally to 10 FS 91, FS 91 R Make sure that the wind or operating process directs any bystanders should wear a respirator approved by the power tool away from such ...
Instruction Manual
Page 13
...stones or other parts of fire or wildfire, do not use metal blades around flammable materials or around the muffler clean. If your muffler. FS 91, FS 91 R 11 WARNING Never modify your gas/oil mix ratio is correct (i.e., not too rich), this screen will normally stay clean as pine ... plug boot before cleaning. WARNING To reduce the risk of unintentional rotation of hot particles. Have your muffler serviced and repaired by a STIHL servicing dealer. Never operate your muffler maintained by your local fire authorities or the U.S. To reduce the risk of fire, burn injury ...
...stones or other parts of fire or wildfire, do not use metal blades around flammable materials or around the muffler clean. If your muffler. FS 91, FS 91 R 11 WARNING Never modify your gas/oil mix ratio is correct (i.e., not too rich), this screen will normally stay clean as pine ... plug boot before cleaning. WARNING To reduce the risk of unintentional rotation of hot particles. Have your muffler serviced and repaired by a STIHL servicing dealer. Never operate your muffler maintained by your local fire authorities or the U.S. To reduce the risk of fire, burn injury ...
Instruction Manual
Page 14
... Nylon cutting line advances automatically when tapped against the ground (TapAction). STIHL PolyCut mowing head Uses either nylon lines or nonrigid, pivoting polymer blades. Mowing heads are no plants along the edge of the nylon cutting lines. Observe wear indicators. 12 FS 91, FS 91 R If the lawn edges are planted with trees or bordered...
... Nylon cutting line advances automatically when tapped against the ground (TapAction). STIHL PolyCut mowing head Uses either nylon lines or nonrigid, pivoting polymer blades. Mowing heads are no plants along the edge of the nylon cutting lines. Observe wear indicators. 12 FS 91, FS 91 R If the lawn edges are planted with trees or bordered...
Instruction Manual
Page 15
... the head. Observe wear indicators. The 4-tooth grass cutting blade is important to cut with cutting edges on the base are dull. STIHL FixCut mowing head Uses pre-cut grass and weeds. The mowing head may otherwise shatter and flying objects could result in an arc similar...with a solid rigid object like a tree, rock, bush or wall. It has 4 cutting knives with the grass cutting blade. front and rear. FS 91, FS 91 R 13 see right illustration above. The rapid counterclockwise rotation of the blade may be easily cut woody materials. This kickout (blade thrust) may cause loss...
... the head. Observe wear indicators. The 4-tooth grass cutting blade is important to cut with cutting edges on the base are dull. STIHL FixCut mowing head Uses pre-cut grass and weeds. The mowing head may otherwise shatter and flying objects could result in an arc similar...with a solid rigid object like a tree, rock, bush or wall. It has 4 cutting knives with the grass cutting blade. front and rear. FS 91, FS 91 R 13 see right illustration above. The rapid counterclockwise rotation of the blade may be easily cut woody materials. This kickout (blade thrust) may cause loss...
Instruction Manual
Page 16
... "kickout" (blade thrust) situations. Do not attempt to cut grass, i.e. English To cut wild growth and scrub, lower the rotating brush knife down small trees, STIHL recommends that the blade will crack and / or break, avoid all rigid cutting blades"). Use a chain saw blades are suitable for such work . WARNING To...
... "kickout" (blade thrust) situations. Do not attempt to cut grass, i.e. English To cut wild growth and scrub, lower the rotating brush knife down small trees, STIHL recommends that the blade will crack and / or break, avoid all rigid cutting blades"). Use a chain saw blades are suitable for such work . WARNING To...
Instruction Manual
Page 17
... will keep the trimmer / brushcutter against the tree trunk before doing any nonroad engine repair establishment or individual. Use of your STIHL servicing dealer only. Have such work performed by your instruction manual. replaced by the special limit stop deflector (see chapter on blades.... Special techniques using the non-shaded area of the stop helps to full throttle. Always press the spark plug boot snugly onto FS 91, FS 91 R 15 Wear gloves when handling or performing maintenance on "Mounting the Deflector"). However, if you make sure it and the ignition...
... will keep the trimmer / brushcutter against the tree trunk before doing any nonroad engine repair establishment or individual. Use of your STIHL servicing dealer only. Have such work performed by your instruction manual. replaced by the special limit stop deflector (see chapter on blades.... Special techniques using the non-shaded area of the stop helps to full throttle. Always press the spark plug boot snugly onto FS 91, FS 91 R 15 Wear gloves when handling or performing maintenance on "Mounting the Deflector"). However, if you make sure it and the ignition...
Instruction Manual
Page 20
...strap may be used 24 Shoulder strap must be used 25 Full harness may be used WARNING Based on this unit. 18 FS 91, FS 91 R Use circular saw blades are permitted because of the risk of the table may be used 25 Full harness must be...to reduce the risk of control and contact with the cutting attachment. Cutting Attachments Mowing heads 1 STIHL SuperCut 20-2 2 STIHL AutoCut C 25-2 3 STIHL AutoCut C 26-2 4 STIHL AutoCut 25-2 5 STIHL AutoCut 36-2 6 STIHL TrimCut 31-2 7 STIHL DuroCut 20-2 8 STIHL PolyCut 20-3 Metal cutting attachments 9 Grass cutting blade 230-4 (230 mm dia.) 10 Grass...
...strap may be used 24 Shoulder strap must be used 25 Full harness may be used WARNING Based on this unit. 18 FS 91, FS 91 R Use circular saw blades are permitted because of the risk of the table may be used 25 Full harness must be...to reduce the risk of control and contact with the cutting attachment. Cutting Attachments Mowing heads 1 STIHL SuperCut 20-2 2 STIHL AutoCut C 25-2 3 STIHL AutoCut C 26-2 4 STIHL AutoCut 25-2 5 STIHL AutoCut 36-2 6 STIHL TrimCut 31-2 7 STIHL DuroCut 20-2 8 STIHL PolyCut 20-3 Metal cutting attachments 9 Grass cutting blade 230-4 (230 mm dia.) 10 Grass...
Instruction Manual
Page 21
... handlebar (7) in ). Removing the clamp moldings English N Pull out the wing screw - N Hold the lower clamp (1) and upper clamp (2) firmly together. FS 91, FS 91 R 19 To mount the handlebar it is no more than 15 cm (6 in the lower clamp (1) so that distance A is necessary to the basic power... swiveling handle support already mounted on the wing screw. the washer (6) remains on the shaft. Approved Power Tool Attachments The following STIHL attachments may be mounted to remove the clamp moldings. N Place the upper clamp in the lower clamp. the clamps are pushed...
... handlebar (7) in ). Removing the clamp moldings English N Pull out the wing screw - N Hold the lower clamp (1) and upper clamp (2) firmly together. FS 91, FS 91 R 19 To mount the handlebar it is no more than 15 cm (6 in the lower clamp (1) so that distance A is necessary to the basic power... swiveling handle support already mounted on the wing screw. the washer (6) remains on the shaft. Approved Power Tool Attachments The following STIHL attachments may be mounted to remove the clamp moldings. N Place the upper clamp in the lower clamp. the clamps are pushed...
Instruction Manual
Page 29
... maximum performance of control and / or contact with incorrect idle adjustment. To help your machine and make the proper adjustments and repairs. FS 91, FS 91 R 27 The chemical composition of EPA and CARB we recommend to the engine. At correct idle speed, the cutting tool should not ... Some fuel additives not only detrimentally affect elastomers (carburetor diaphragms, oil seals, fuel lines, etc.), but do not use your STIHL engine, use STIHL HP Ultra oil or equivalent. For further details, see www.STIHLusa.com/ethanol The ethanol content in turn, increases the risk of...
... maximum performance of control and / or contact with incorrect idle adjustment. To help your machine and make the proper adjustments and repairs. FS 91, FS 91 R 27 The chemical composition of EPA and CARB we recommend to the engine. At correct idle speed, the cutting tool should not ... Some fuel additives not only detrimentally affect elastomers (carburetor diaphragms, oil seals, fuel lines, etc.), but do not use your STIHL engine, use STIHL HP Ultra oil or equivalent. For further details, see www.STIHLusa.com/ethanol The ethanol content in turn, increases the risk of...
Instruction Manual
Page 30
...static discharge and resulting fire and/or explosion, do not fill fuel containers that any excess pressure in summer. 0000-GXX-0476-A0 28 FS 91, FS 91 R STIHL recommends the use the right gasoline/oil mix ratio. Fueling Preparations N Before fueling, clean the filler cap and the area around it ..., i.e., winter blend in winter, summer blend in the tank can escape slowly. The machine's fuel tank should be cleaned as necessary. STIHL MotoMix uses STIHL HP Ultra two-stroke engine oil suited for a few days of oil and gasoline. When mixing, pour oil into the tank. WARNING ...
...static discharge and resulting fire and/or explosion, do not fill fuel containers that any excess pressure in summer. 0000-GXX-0476-A0 28 FS 91, FS 91 R STIHL recommends the use the right gasoline/oil mix ratio. Fueling Preparations N Before fueling, clean the filler cap and the area around it ..., i.e., winter blend in winter, summer blend in the tank can escape slowly. The machine's fuel tank should be cleaned as necessary. STIHL MotoMix uses STIHL HP Ultra two-stroke engine oil suited for a few days of oil and gasoline. When mixing, pour oil into the tank. WARNING ...
Instruction Manual
Page 39
...ignite combustible fumes and cause a fire. Always press the spark plug boot (1) snugly onto the spark plug terminal (2). Arcing may degrade performance. FS 91, FS 91 R 37 Do not use resistor type spark plugs with solid, non-threaded terminals Installing the Spark Plug N Screw the spark plug (3) into... of spark plug: - N Tighten down on the insulator nose which have caused fouling of fire and burn injury, use only spark plugs authorized by STIHL. see chapter "Specifications." N Unscrew the spark plug (3). 0000-GXX 0537-A0 000BA039 KN 0000-GXX-1831-A0 A N Clean dirty spark plug....
...ignite combustible fumes and cause a fire. Always press the spark plug boot (1) snugly onto the spark plug terminal (2). Arcing may degrade performance. FS 91, FS 91 R 37 Do not use resistor type spark plugs with solid, non-threaded terminals Installing the Spark Plug N Screw the spark plug (3) into... of spark plug: - N Tighten down on the insulator nose which have caused fouling of fire and burn injury, use only spark plugs authorized by STIHL. see chapter "Specifications." N Unscrew the spark plug (3). 0000-GXX 0537-A0 000BA039 KN 0000-GXX-1831-A0 A N Clean dirty spark plug....
Instruction Manual
Page 40
... grease can be the muffler. N Insert the screw plug (1) and tighten it down firmly. 38 FS 91, FS 91 R Have the muffler checked for contamination (carbonization) by an authorized STIHL servicing dealer. 1 Check grease level after every 25 hours of STIHL gear lubricant (special accessory) into the gearbox. NOTICE Do not completely fill the gearbox with...
... grease can be the muffler. N Insert the screw plug (1) and tighten it down firmly. 38 FS 91, FS 91 R Have the muffler checked for contamination (carbonization) by an authorized STIHL servicing dealer. 1 Check grease level after every 25 hours of STIHL gear lubricant (special accessory) into the gearbox. NOTICE Do not completely fill the gearbox with...
Instruction Manual
Page 41
... as possible - Storing the Machine For periods of about 5 times, check the cutting attachment for out-of-balance on a STIHL balancer - N Store the machine in any way. N Sharpen frequently, take away as little metal as necessary - N Remove...resharpening about 3 months or longer N Drain and clean the fuel tank in accordance with local environmental requirements. STIHL recommends a STIHL servicing dealer. 2 2 002BA042 KN N Resharpen the teeth (1) uniformly - FS 91, FS 91 R 39 In case of the parent blade (2) in a dry and secure location - see "Special Accessories...
... as possible - Storing the Machine For periods of about 5 times, check the cutting attachment for out-of-balance on a STIHL balancer - N Store the machine in any way. N Sharpen frequently, take away as little metal as necessary - N Remove...resharpening about 3 months or longer N Drain and clean the fuel tank in accordance with local environmental requirements. STIHL recommends a STIHL servicing dealer. 2 2 002BA042 KN N Resharpen the teeth (1) uniformly - FS 91, FS 91 R 39 In case of the parent blade (2) in a dry and secure location - see "Special Accessories...