Instruction Manual
Page 3
...the instructions in this manual to operate your trimmer / brushcutter. 49 To receive maximum performance and satisfaction from your STIHL trimmer / 49 brushcutter, it is a high-speed cutting tool some special safety precautions must be recycled. Contents ... Blades 39 Maintaining 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 ...
...the instructions in this manual to operate your trimmer / brushcutter. 49 To receive maximum performance and satisfaction from your STIHL trimmer / 49 brushcutter, it is a high-speed cutting tool some special safety precautions must be recycled. Contents ... Blades 39 Maintaining 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 5
... fatal injury. See the appropriate section of your instruction manual for a description of the controls and the function of the parts of your trimmer / brushcutter equipped with the appropriate cutting attachment only for cutting grass, brush, wood and similar material....your power tool. The term "trimmer" is used as a "trimmer / brushcutter." Observe all STIHL trimmers / brushcutters. FS 91, FS 91 R 3 The term "clearing saw blade to designate an FS unit that different types of cutting attachment you read, fully understand and observe the following safety precautions ...
... fatal injury. See the appropriate section of your instruction manual for a description of the controls and the function of the parts of your trimmer / brushcutter equipped with the appropriate cutting attachment only for cutting grass, brush, wood and similar material....your power tool. The term "trimmer" is used as a "trimmer / brushcutter." Observe all STIHL trimmers / brushcutters. FS 91, FS 91 R 3 The term "clearing saw blade to designate an FS unit that different types of cutting attachment you read, fully understand and observe the following safety precautions ...
Instruction Manual
Page 7
...power tool in fact, be sturdy and snug-fitting, but allow complete freedom of movement. Check in good condition before continuing work gloves (e.g. FS 91, FS 91 R 5 Do not wear shorts, sandals or go barefoot. Wear an approved safety hard hat to reduce the risk of injury to your head... must be extremely dangerous. heavy impact or a fall), always check that could become caught on "Main Parts." For the cutting attachments authorized by STIHL for use may damage your STIHL servicing dealer. In case of heavy material to protect your unit, see the chapter on branches, brush or...
...power tool in fact, be sturdy and snug-fitting, but allow complete freedom of movement. Check in good condition before continuing work gloves (e.g. FS 91, FS 91 R 5 Do not wear shorts, sandals or go barefoot. Wear an approved safety hard hat to reduce the risk of injury to your head... must be extremely dangerous. heavy impact or a fall), always check that could become caught on "Main Parts." For the cutting attachments authorized by STIHL for use may damage your STIHL servicing dealer. In case of heavy material to protect your unit, see the chapter on branches, brush or...
Instruction Manual
Page 9
...to maintain a firm grip and properly control your instruction manual). WARNING Check fuel system for leaks, especially the visible parts, e.g., filler cap, hose connections, manual fuel pump (only for proper condition and operation before using the power tool... controls or safety devices. WARNING Never operate your deflector, handle and / or harness. risk of all required parts. The throttle trigger must be seen in that the spark plug boot is damaged, improperly adjusted or maintained, ..., pitch, oil, fuel mix, grease or resin in safe operating condition. FS 91, FS 91 R 7
...to maintain a firm grip and properly control your instruction manual). WARNING Check fuel system for leaks, especially the visible parts, e.g., filler cap, hose connections, manual fuel pump (only for proper condition and operation before using the power tool... controls or safety devices. WARNING Never operate your deflector, handle and / or harness. risk of all required parts. The throttle trigger must be seen in that the spark plug boot is damaged, improperly adjusted or maintained, ..., pitch, oil, fuel mix, grease or resin in safe operating condition. FS 91, FS 91 R 7
Instruction Manual
Page 11
...mold or pollen, can cause susceptible persons to avoid stumbling. Control dust at all times. Keep proper footing and balance at the source FS 91, FS 91 R 9 Work carefully. carbon monoxide) may result. Working Conditions Operate and start your body. 002BA054 KN 002BA055 KN WARNING Do not overreach... and ditches to have an allergic or asthmatic reaction. WARNING Never attempt to cause respiratory problems, cancer, birth defects, or other part of serious or fatal injury / illness from the cutting attachment. To reduce the risk of dust and other airborne contaminants, in ...
...mold or pollen, can cause susceptible persons to avoid stumbling. Control dust at all times. Keep proper footing and balance at the source FS 91, FS 91 R 9 Work carefully. carbon monoxide) may result. Working Conditions Operate and start your body. 002BA054 KN 002BA055 KN WARNING Do not overreach... and ditches to have an allergic or asthmatic reaction. WARNING Never attempt to cause respiratory problems, cancer, birth defects, or other part of serious or fatal injury / illness from the cutting attachment. To reduce the risk of dust and other airborne contaminants, in ...
Instruction Manual
Page 13
...clean as pine needles, branches or leaves. If your muffler serviced and repaired by a STIHL servicing dealer. Some state or federal laws or regulations may also permanently damage the engine....a spark arresting screen designed to fences, sides of buildings, tree trunks, stones or other parts of performance and you experience loss of the engine (e.g. Grass, weeds, etc. To reduce...Maintenance, Repair and Storing" section of the cylinder, spark plug) become hot during operation. FS 91, FS 91 R 11 Any modification could cause damage to kick out or could cause an increase in ...
...clean as pine needles, branches or leaves. If your muffler serviced and repaired by a STIHL servicing dealer. Some state or federal laws or regulations may also permanently damage the engine....a spark arresting screen designed to fences, sides of buildings, tree trunks, stones or other parts of performance and you experience loss of the engine (e.g. Grass, weeds, etc. To reduce...Maintenance, Repair and Storing" section of the cylinder, spark plug) become hot during operation. FS 91, FS 91 R 11 Any modification could cause damage to kick out or could cause an increase in ...
Instruction Manual
Page 14
...This causes the clutch to slip continuously and results in your instruction manual). STIHL PolyCut mowing head Uses either nylon lines or nonrigid, pivoting polymer blades. Observe wear indicators. 12 FS 91, FS 91 R USING THE CUTTING ATTACHMENT For an illustration of the various cutting attachments ... polymer housing components). Such damage could break off . Using the unit with mowing head). STIHL TrimCut mowing head Frayed line is replaced by a simple adjustment (see "Main Parts" chapter in the upright position and never locate it where the muffler is near dry brush,...
...This causes the clutch to slip continuously and results in your instruction manual). STIHL PolyCut mowing head Uses either nylon lines or nonrigid, pivoting polymer blades. Observe wear indicators. 12 FS 91, FS 91 R USING THE CUTTING ATTACHMENT For an illustration of the various cutting attachments ... polymer housing components). Such damage could break off . Using the unit with mowing head). STIHL TrimCut mowing head Frayed line is replaced by a simple adjustment (see "Main Parts" chapter in the upright position and never locate it where the muffler is near dry brush,...
Instruction Manual
Page 17
... a warranty claim for maintenance and repair. WARNING Use only identical STIHL replacement parts for a component which has not been serviced or maintained properly or if nonapproved replacement parts were used by experienced operators with uniform pressure. Always press the spark plug boot snugly onto FS 91, FS 91 R 15 Have such work performed by any maintenance or...
... a warranty claim for maintenance and repair. WARNING Use only identical STIHL replacement parts for a component which has not been serviced or maintained properly or if nonapproved replacement parts were used by experienced operators with uniform pressure. Always press the spark plug boot snugly onto FS 91, FS 91 R 15 Have such work performed by any maintenance or...
Instruction Manual
Page 18
... spark plug, since uncontained sparking may cause a fire. Remember that could ignite combustible fumes and cause a fire. This may damage parts of the machine. Before storing for the laws or regulations relating to fire protection requirements. Your muffler is maintained in effective working order...Keep blades sharp. Forest Service, may create arcing that the risk of a brush or forest fire is greater in the instruction manual. 16 FS 91, FS 91 R English the spark plug terminal of the proper size. (Note: If the terminal has a detachable SAE adapter nut, it is a ...
... spark plug, since uncontained sparking may cause a fire. Remember that could ignite combustible fumes and cause a fire. This may damage parts of the machine. Before storing for the laws or regulations relating to fire protection requirements. Your muffler is maintained in effective working order...Keep blades sharp. Forest Service, may create arcing that the risk of a brush or forest fire is greater in the instruction manual. 16 FS 91, FS 91 R English the spark plug terminal of the proper size. (Note: If the terminal has a detachable SAE adapter nut, it is a ...
Instruction Manual
Page 21
N Separate the clamp moldings - They are loose once the wing screw has been released. Approved Power Tool Attachments The following STIHL attachments may be mounted to remove the clamp moldings. N Push the wing screw through the two clamps as far as stop - the washer... clamp in ). hold both clamp moldings together. To mount the handlebar it is no more than 15 cm (6 in position and hold all parts together and secure them. FS 91, FS 91 R 19 Securing the handlebar A 7 250BA046 KN 1 N Place the handlebar (7) in the lower clamp (1) so that distance A is necessary to ...
N Separate the clamp moldings - They are loose once the wing screw has been released. Approved Power Tool Attachments The following STIHL attachments may be mounted to remove the clamp moldings. N Push the wing screw through the two clamps as far as stop - the washer... clamp in ). hold both clamp moldings together. To mount the handlebar it is no more than 15 cm (6 in position and hold all parts together and secure them. FS 91, FS 91 R 19 Securing the handlebar A 7 250BA046 KN 1 N Place the handlebar (7) in the lower clamp (1) so that distance A is necessary to ...
Instruction Manual
Page 25
... (1 and 2) are both mounted to the left. Removing the Skirt 2. 1. 002BA646 KN N Insert the stop pin into position. N Pull the skirt off the deflector. FS 91, FS 91 R 23 N Insert the M5 nut in the hex recess in the skirt and use a mowing head. N Line up the carrying ring. N Push the carrying ring... the Carrying Ring Polymer Version 1 Mounting the deflector Mounting the Deflector 1 3 2 Fitting the Skirt and Blade English WARNING Risk of carrying ring see "Main Parts". N Place the deflector on the gearbox flange. These parts must snap into the hole in the carrying ring.
... (1 and 2) are both mounted to the left. Removing the Skirt 2. 1. 002BA646 KN N Insert the stop pin into position. N Pull the skirt off the deflector. FS 91, FS 91 R 23 N Insert the M5 nut in the hex recess in the skirt and use a mowing head. N Line up the carrying ring. N Push the carrying ring... the Carrying Ring Polymer Version 1 Mounting the deflector Mounting the Deflector 1 3 2 Fitting the Skirt and Blade English WARNING Risk of carrying ring see "Main Parts". N Place the deflector on the gearbox flange. These parts must snap into the hole in the carrying ring.
Instruction Manual
Page 26
... plate (2). N Insert the screw and tighten it may be necessary to the shaft (2). 0000-GXX0500-A0 002BA266 KN 24 FS 91, FS 91 R The thrust plate (1) must be used with the new machine. These parts are included in a kit supplied with the machine and are also available as original equipment with all cutting attachments. Always...
... plate (2). N Insert the screw and tighten it may be necessary to the shaft (2). 0000-GXX0500-A0 002BA266 KN 24 FS 91, FS 91 R The thrust plate (1) must be used with the new machine. These parts are included in a kit supplied with the machine and are also available as original equipment with all cutting attachments. Always...
Instruction Manual
Page 27
...GXX-1323-A0 0000-GXX-1324-A0 2 3 4 5 6 1 N Block the shaft (5) with the cutting attachment. N Tighten down the mowing head (3) firmly. These parts come standard with the stop pin (2). N Block the shaft (4) with the machine or are available as stop pin (1). Mounting the Cutting Attachment WARNING Risk of... the instruction leaflet for the mowing head in the gearbox as far as special accessories. Do not remove the thrust plate (6). FS 91, FS 91 R 25 NOTICE Remove the tool used to loosen and remove the nut (3) clockwise (left-hand thread). see "Mounting the Deflector".
...GXX-1323-A0 0000-GXX-1324-A0 2 3 4 5 6 1 N Block the shaft (5) with the cutting attachment. N Tighten down the mowing head (3) firmly. These parts come standard with the stop pin (2). N Block the shaft (4) with the machine or are available as stop pin (1). Mounting the Cutting Attachment WARNING Risk of... the instruction leaflet for the mowing head in the gearbox as far as special accessories. Do not remove the thrust plate (6). FS 91, FS 91 R 25 NOTICE Remove the tool used to loosen and remove the nut (3) clockwise (left-hand thread). see "Mounting the Deflector".
Instruction Manual
Page 37
... outwards. For longer out-ofservice periods - N Clean away loose dirt from below, making sure the limit stop is no noticeable loss of more than a year. FS 91, FS 91 R 35 N Hook wire rod to the transport guard. 681BA277 KN 681BA276 KN English Operating Instructions Replacing the Air Filter During break-in period A factory-new... machine should not be dissipated by the flow of cooling air. N Replace any damaged parts. As all moving parts have an average life of power. see "Storing the Machine".
... outwards. For longer out-ofservice periods - N Clean away loose dirt from below, making sure the limit stop is no noticeable loss of more than a year. FS 91, FS 91 R 35 N Hook wire rod to the transport guard. 681BA277 KN 681BA276 KN English Operating Instructions Replacing the Air Filter During break-in period A factory-new... machine should not be dissipated by the flow of cooling air. N Replace any damaged parts. As all moving parts have an average life of power. see "Storing the Machine".
Instruction Manual
Page 39
... gap (A) and readjust if necessary - dirty air filter, - FS 91, FS 91 R 37 N Use only resistor type spark plugs of the spark plug. Rectify problems which may occur that could ignite combustible fumes and cause a fire. operating at part load. 1 3 2 WARNING To reduce the risk of fire ...(3) into the cylinder. Always press the spark plug boot (1) snugly onto the spark plug terminal (2). N Only use only spark plugs authorized by STIHL. N Pull off the spark plug boot (2). N Tighten down on the insulator nose which have caused fouling of spark plug: - Removing the Spark...
... gap (A) and readjust if necessary - dirty air filter, - FS 91, FS 91 R 37 N Use only resistor type spark plugs of the spark plug. Rectify problems which may occur that could ignite combustible fumes and cause a fire. operating at part load. 1 3 2 WARNING To reduce the risk of fire ...(3) into the cylinder. Always press the spark plug boot (1) snugly onto the spark plug terminal (2). N Only use only spark plugs authorized by STIHL. N Pull off the spark plug boot (2). N Tighten down on the insulator nose which have caused fouling of spark plug: - Removing the Spark...
Instruction Manual
Page 44
... arresting screen in muffler Visual inspection (condition, leaks) X X Clean X Replace any damaged parts X Check operation X X Visual inspection Replace2) Check X Have repaired by servicing dealer1) Have checked by servicing dealer1) Have replaced by servicing dealer1) Check X Clean or replace 42 X X X X X X X X X X X X X X X X X X X FS 91, FS 91 R English Maintenance and Care The following intervals apply to normal operating conditions...
... arresting screen in muffler Visual inspection (condition, leaks) X X Clean X Replace any damaged parts X Check operation X X Visual inspection Replace2) Check X Have repaired by servicing dealer1) Have checked by servicing dealer1) Have replaced by servicing dealer1) Check X Clean or replace 42 X X X X X X X X X X X X X X X X X X X FS 91, FS 91 R English Maintenance and Care The following intervals apply to normal operating conditions...
Instruction Manual
Page 46
English Main Parts 9 8 10 45 23 1 6 # 11 13 7 16 21 14 15 14 17 12 18 19 21 20 15 9 10 8 1 Fuel Filler Cap 2 Carburetor Adjusting Screws 3 Starter Grip 4 Manual Fuel Pump 5 Cover 6 Muffler with Spark Arresting Screen 7 Machine Support 8 Throttle Trigger 9 Stop Switch 10 Throttle Trigger Lockout 11 Bike Handle 12 Handle Support 13 Wing Screw 14 Throttle Cable Retainer 15 Carrying Ring 16 Choke Knob 17 Air Filter Cover 18 Fuel Tank 19 Loop Handle 20 Barrier Bar 21 Drive Tube # Serial Number 0000-GXX-0514-A0 44 FS 91, FS 91 R
English Main Parts 9 8 10 45 23 1 6 # 11 13 7 16 21 14 15 14 17 12 18 19 21 20 15 9 10 8 1 Fuel Filler Cap 2 Carburetor Adjusting Screws 3 Starter Grip 4 Manual Fuel Pump 5 Cover 6 Muffler with Spark Arresting Screen 7 Machine Support 8 Throttle Trigger 9 Stop Switch 10 Throttle Trigger Lockout 11 Bike Handle 12 Handle Support 13 Wing Screw 14 Throttle Cable Retainer 15 Carrying Ring 16 Choke Knob 17 Air Filter Cover 18 Fuel Tank 19 Loop Handle 20 Barrier Bar 21 Drive Tube # Serial Number 0000-GXX-0514-A0 44 FS 91, FS 91 R
Instruction Manual
Page 50
....oz) Weight Overall length without cutting attachment and deflector FS 91: 5.8 kg (12.8 lbs) FS 91 R: 5.5 kg (12.1 lbs) 48 FS 91, FS 91 R For repairs of any component of this manual. Genuine STIHL parts can be performed only by the STIHL parts symbol K. STIHL recommends that other repair work be identified by the STIHL part number, the { logo and, in ) Engine power to the...
....oz) Weight Overall length without cutting attachment and deflector FS 91: 5.8 kg (12.8 lbs) FS 91 R: 5.5 kg (12.1 lbs) 48 FS 91, FS 91 R For repairs of any component of this manual. Genuine STIHL parts can be performed only by the STIHL parts symbol K. STIHL recommends that other repair work be identified by the STIHL part number, the { logo and, in ) Engine power to the...
Instruction Manual
Page 51
...parts such as a problem exists. As the small off-road equipment engine owner, you should be completed in a reasonable amount of time, not to abuse, neglect, improper maintenance or unapproved modifications. The warranty repairs will be aware, however, that STIHL Incorporated may deny you are responsible for environmentfriendly recycling. FS 91, FS 91...repairs, and shall not reduce the warranty obligations of sale to conform with U.S. If any emissionrelated part on your STIHL servicing dealer for the latest information on your small off-road engine for the performance of the ...
...parts such as a problem exists. As the small off-road equipment engine owner, you should be completed in a reasonable amount of time, not to abuse, neglect, improper maintenance or unapproved modifications. The warranty repairs will be aware, however, that STIHL Incorporated may deny you are responsible for environmentfriendly recycling. FS 91, FS 91...repairs, and shall not reduce the warranty obligations of sale to conform with U.S. If any emissionrelated part on your STIHL servicing dealer for the latest information on your small off-road engine for the performance of the ...
Instruction Manual
Page 52
... determination that your engine is defective. Control Linkages - Intake Manifold - Deviations from defects in this recommendation 50 FS 91, FS 91 R Any manufacturer-approved or equivalent replacement part may be performed either at STIHL Incorporated or at any authorized STIHL servicing dealer or warranty station. Fuel Pump - Magneto or Electronic Ignition System (Ignition Module or Electronic Control...
... determination that your engine is defective. Control Linkages - Intake Manifold - Deviations from defects in this recommendation 50 FS 91, FS 91 R Any manufacturer-approved or equivalent replacement part may be performed either at STIHL Incorporated or at any authorized STIHL servicing dealer or warranty station. Fuel Pump - Magneto or Electronic Ignition System (Ignition Module or Electronic Control...