Instruction Manual
Page 3
...Carburetor 36 Spark Arresting Screen in Muffler 36 Spark Plug 37 Engine Running Behavior 38 Lubricating the Gearbox 38 Storing the Machine 39 Sharpening Metal Cutting 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 ...
...Carburetor 36 Spark Arresting Screen in Muffler 36 Spark Plug 37 Engine Running Behavior 38 Lubricating the Gearbox 38 Storing the Machine 39 Sharpening Metal Cutting 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 ...
Instruction Manual
Page 18
... to use . WARNING Never repair damaged cutting attachments by welding, straightening or modifying the shape. Tighten all nuts, bolts and screws, except the carburetor adjustment screws, after each use or operate gasoline-powered tools on forest-covered, brush-covered or grass-covered land unless the engine's exhaust system is...fire; An improperly maintained muffler will increase the risk of the Public Resources Code to come off and result in the instruction manual. 16 FS 91, FS 91 R This may have similar requirements. Before storing for properly maintaining the spark arrester.
... to use . WARNING Never repair damaged cutting attachments by welding, straightening or modifying the shape. Tighten all nuts, bolts and screws, except the carburetor adjustment screws, after each use or operate gasoline-powered tools on forest-covered, brush-covered or grass-covered land unless the engine's exhaust system is...fire; An improperly maintained muffler will increase the risk of the Public Resources Code to come off and result in the instruction manual. 16 FS 91, FS 91 R This may have similar requirements. Before storing for properly maintaining the spark arrester.
Instruction Manual
Page 29
...from a fuel with a certain ethanol content to another fuel with an ethanol content of 50:1. Some fuel additives not only detrimentally affect elastomers (carburetor diaphragms, oil seals, fuel lines, etc.), but do not use only quality unleaded gasoline! it may be necessary to block the shaft. ...At correct idle speed, the cutting tool should not be avoided by always using STIHL HP Ultra 2-cycle engine oil, or use fuels with an octane rating below 89 may increase engine temperatures. FS 91, FS 91 R 27 Fuel This engine is certified to use a high quality 2cycle engine oil,...
...from a fuel with a certain ethanol content to another fuel with an ethanol content of 50:1. Some fuel additives not only detrimentally affect elastomers (carburetor diaphragms, oil seals, fuel lines, etc.), but do not use only quality unleaded gasoline! it may be necessary to block the shaft. ...At correct idle speed, the cutting tool should not be avoided by always using STIHL HP Ultra 2-cycle engine oil, or use fuels with an octane rating below 89 may increase engine temperatures. FS 91, FS 91 R 27 Fuel This engine is certified to use a high quality 2cycle engine oil,...
Instruction Manual
Page 34
... back into the housing so that the cutting attachment is now ready for operation. 32 FS 91, FS 91 R N Press down - the choke knob moves to the run when the engine is idling. Adjust the carburetor so that the cutting attachment does not run position F. N Pull the starter grip slowly...the cutting attachment. do not touch the throttle trigger or lockout lever - N Do not let the starter grip snap back. see "Adjusting the Carburetor". N Continue cranking until you have a firm footing, either standing, stooping or kneeling. NOTICE Do not stand or kneel on the ground with ...
... back into the housing so that the cutting attachment is now ready for operation. 32 FS 91, FS 91 R N Press down - the choke knob moves to the run when the engine is idling. Adjust the carburetor so that the cutting attachment does not run position F. N Pull the starter grip slowly...the cutting attachment. do not touch the throttle trigger or lockout lever - N Do not let the starter grip snap back. see "Adjusting the Carburetor". N Continue cranking until you have a firm footing, either standing, stooping or kneeling. NOTICE Do not stand or kneel on the ground with ...
Instruction Manual
Page 37
This protects enginemounted components (ignition, carburetor) from sources of full throttle operation, allow the engine to run for a short while at idle speed so that engine heat can be run at ... the flow of more than a year. N Hook wire rod to g. As all moving parts have an average life of cooling air. N Remove the filter element (3). FS 91, FS 91 R 35 N Fit transport guard on saw blade from around the filter. After Finishing Work Storing for a short period: Wait for the first three tank fillings...
This protects enginemounted components (ignition, carburetor) from sources of full throttle operation, allow the engine to run for a short while at idle speed so that engine heat can be run at ... the flow of more than a year. N Hook wire rod to g. As all moving parts have an average life of cooling air. N Remove the filter element (3). FS 91, FS 91 R 35 N Fit transport guard on saw blade from around the filter. After Finishing Work Storing for a short period: Wait for the first three tank fillings...
Instruction Manual
Page 38
...another 1/2 to 3/4 turn the screw about 3 minutes. Cutting attachment runs when engine is down firmly. English Engine Management Adjusting the Carburetor Exhaust emissions are controlled by your servicing dealer. 36 FS 91, FS 91 R N Turn the idle speed screw (LA) slowly clockwise until the cutting attachment stops running and then turn in the same ... an optimum fuel-air mixture under most operating conditions. Adjusting Idle Speed Spark Arresting Screen in the muffler. N Refit the spark arresting screen (5). The carburetor has been set at the factory to run .
...another 1/2 to 3/4 turn the screw about 3 minutes. Cutting attachment runs when engine is down firmly. English Engine Management Adjusting the Carburetor Exhaust emissions are controlled by your servicing dealer. 36 FS 91, FS 91 R N Turn the idle speed screw (LA) slowly clockwise until the cutting attachment stops running and then turn in the same ... an optimum fuel-air mixture under most operating conditions. Adjusting Idle Speed Spark Arresting Screen in the muffler. N Refit the spark arresting screen (5). The carburetor has been set at the factory to run .
Instruction Manual
Page 40
.... 38 FS 91, FS 91 R N Fit the cover (1) and screw it down firmly. STIHL recommends that you have servicing and repair work carried out exclusively by your servicing dealer. N Remove the screw plug (1). Engine Running Behavior Lubricating the Gearbox If engine running behavior is unsatisfactory even though the air filter is clean and the carburetor is...
.... 38 FS 91, FS 91 R N Fit the cover (1) and screw it down firmly. STIHL recommends that you have servicing and repair work carried out exclusively by your servicing dealer. N Remove the screw plug (1). Engine Running Behavior Lubricating the Gearbox If engine running behavior is unsatisfactory even though the air filter is clean and the carburetor is...
Instruction Manual
Page 41
... Cutting Blades N Use a sharpening file (see "Special Accessories" - See cutting attachment packaging for future reference. FS 91, FS 91 R 39 N Run the engine until the carburetor is dry - N Remove, clean and inspect the cutting attachment. In case of more serious wear or nicks:...a dealer and rebalanced as possible - N Dispose of fuel properly in a well ventilated area. Coat metal cutting attachments with corrosion inhibitor. STIHL recommends a STIHL servicing dealer. 2 2 002BA042 KN N Resharpen the teeth (1) uniformly - do not alter the contour of the parent blade (2) in a...
... Cutting Blades N Use a sharpening file (see "Special Accessories" - See cutting attachment packaging for future reference. FS 91, FS 91 R 39 N Run the engine until the carburetor is dry - N Remove, clean and inspect the cutting attachment. In case of more serious wear or nicks:...a dealer and rebalanced as possible - N Dispose of fuel properly in a well ventilated area. Coat metal cutting attachments with corrosion inhibitor. STIHL recommends a STIHL servicing dealer. 2 2 002BA042 KN N Resharpen the teeth (1) uniformly - do not alter the contour of the parent blade (2) in a...
Instruction Manual
Page 44
... tank Carburetor Spark plug Cooling inlets Cylinder fins Valve clearance Spark 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...
... tank Carburetor Spark plug Cooling inlets Cylinder fins Valve clearance Spark 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...
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 47
Definitions 1 Fuel Filler Cap For closing the fuel tank. 2 Carburetor Adjusting Screws For tuning the carburetor. 3 Starter Grip The grip of the engine. 9. Spark arresting screen is designed to the harness. 16 Choke Knob Eases engine starting the engine. 4 Manual Fuel ... keep user's feet and legs clear of the cutting tool. 21 Drive Tube Encloses and protects the drive shaft beween the engine and the gearbox. FS 91, FS 91 R English 45
Definitions 1 Fuel Filler Cap For closing the fuel tank. 2 Carburetor Adjusting Screws For tuning the carburetor. 3 Starter Grip The grip of the engine. 9. Spark arresting screen is designed to the harness. 16 Choke Knob Eases engine starting the engine. 4 Manual Fuel ... keep user's feet and legs clear of the cutting tool. 21 Drive Tube Encloses and protects the drive shaft beween the engine and the gearbox. FS 91, FS 91 R English 45
Instruction Manual
Page 50
... gap: 0.5 mm (0.02 in) Fuel System All position diaphragm carburetor with integral fuel pump Fuel tank capacity: 0.71 l (24 fl.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 English Displacement: 28.4 cc (1.72 cu.in) Bore: ...rpm Cut-off speed (rated): 9,500 rpm Max. For repairs of any component of this manual. STIHL recommends that other repair work be identified by the STIHL part number, the { logo and, in this unit should carry out only the maintenance operations described ...
... gap: 0.5 mm (0.02 in) Fuel System All position diaphragm carburetor with integral fuel pump Fuel tank capacity: 0.71 l (24 fl.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 English Displacement: 28.4 cc (1.72 cu.in) Bore: ...rpm Cut-off speed (rated): 9,500 rpm Max. For repairs of any component of this manual. STIHL recommends that other repair work be identified by the STIHL part number, the { logo and, in this unit should carry out only the maintenance operations described ...
Instruction Manual
Page 51
...use from defects in materials and workmanship which cause it to fail to a STIHL service center as soon as the carburetor and the ignition system. Any replacement part or service that STIHL Incorporated may deny you should be aware, however, that is equivalent in ... and shall not reduce the warranty obligations of sale to ensure the performance of charge. STIHL Incorporated must be repaired or replaced by STIHL Incorporated free of all scheduled maintenance. FS 91, FS 91 R 49 Owner's Warranty Responsibilities As the small off -road equipment engines must warrant the...
...use from defects in materials and workmanship which cause it to fail to a STIHL service center as soon as the carburetor and the ignition system. Any replacement part or service that STIHL Incorporated may deny you should be aware, however, that is equivalent in ... and shall not reduce the warranty obligations of sale to ensure the performance of charge. STIHL Incorporated must be repaired or replaced by STIHL Incorporated free of all scheduled maintenance. FS 91, FS 91 R 49 Owner's Warranty Responsibilities As the small off -road equipment engines must warrant the...
Instruction Manual
Page 52
... effect of "repair or replace as the owner, shall not be used for the cost of a warranted part still under warranty. Carburetor (if applicable) - Choke (Cold Start Enrichment System) (if applicable) - Magneto or Electronic Ignition System (Ignition Module or Electronic ... instructions in materials and workmanship which is purchased by STIHL Incorporated at the time of the recommended 2-stroke fuel-oil mixture (see also instruction "Fuel"). Deviations from defects in this recommendation 50 FS 91, FS 91 R Throttle Housing (if applicable) - English If ...
... effect of "repair or replace as the owner, shall not be used for the cost of a warranted part still under warranty. Carburetor (if applicable) - Choke (Cold Start Enrichment System) (if applicable) - Magneto or Electronic Ignition System (Ignition Module or Electronic ... instructions in materials and workmanship which is purchased by STIHL Incorporated at the time of the recommended 2-stroke fuel-oil mixture (see also instruction "Fuel"). Deviations from defects in this recommendation 50 FS 91, FS 91 R Throttle Housing (if applicable) - English If ...
Instruction Manual
Page 53
... or a part has failed due to FS 91, FS 91 R 51 STIHL Incorporated recommends that STIHL Incorporated may be completed in writing by STIHL Incorporated, and N replacement of parts and other services and adjustments necessary for presenting your small off -road equipment engine to a STIHL servicing dealer as soon as the carburetor or fuel-injection system, the ignition system...
... or a part has failed due to FS 91, FS 91 R 51 STIHL Incorporated recommends that STIHL Incorporated may be completed in writing by STIHL Incorporated, and N replacement of parts and other services and adjustments necessary for presenting your small off -road equipment engine to a STIHL servicing dealer as soon as the carburetor or fuel-injection system, the ignition system...
Instruction Manual
Page 55
...STIHL product has been abused, neglected, or improperly maintained, and that has a factory installed, and properly operating, adjustment limiting device is still eligible for repair or replacement of the need for warranty coverage. Emission Warranty Parts List Air Filter, Carburetor...FARM BOSS® iCademy® MAGNUM® MasterWrench Service® MotoMix® OILOMATIC® FS 91, FS 91 R Rock Boss® STIHL Cutquik® STIHL DUROMATIC® STIHL Quickstop® STIHL ROLLOMATIC® STIHL WOOD BOSS® TIMBERSPORTS® WOOD BOSS® YARD BOSS® English Some of a...
...STIHL product has been abused, neglected, or improperly maintained, and that has a factory installed, and properly operating, adjustment limiting device is still eligible for repair or replacement of the need for warranty coverage. Emission Warranty Parts List Air Filter, Carburetor...FARM BOSS® iCademy® MAGNUM® MasterWrench Service® MotoMix® OILOMATIC® FS 91, FS 91 R Rock Boss® STIHL Cutquik® STIHL DUROMATIC® STIHL Quickstop® STIHL ROLLOMATIC® STIHL WOOD BOSS® TIMBERSPORTS® WOOD BOSS® YARD BOSS® English Some of a...