Instruction Manual
Page 2
...Carburetor 20 Checking the Spark Plug 21 Engine Running Behavior 22 Lubricating the Gearbox 22 Replacing Starter Rope and Rewind Spring 23 Storing the Machine 25 Maintenance Chart 26 Main Parts and Controls 27 Specifications 28 Maintenance and Repairs 30 STIHL Incorporated Federal Emission Control Warranty Statement 31 STIHl BT 121... English / USA Allow only persons who understand this manual. !Warning! Contact your STIHL dealer or the STIHL distributor for your area if ...
...Carburetor 20 Checking the Spark Plug 21 Engine Running Behavior 22 Lubricating the Gearbox 22 Replacing Starter Rope and Rewind Spring 23 Storing the Machine 25 Maintenance Chart 26 Main Parts and Controls 27 Specifications 28 Maintenance and Repairs 30 STIHL Incorporated Federal Emission Control Warranty Statement 31 STIHl BT 121... English / USA Allow only persons who understand this manual. !Warning! Contact your STIHL dealer or the STIHL distributor for your area if ...
Instruction Manual
Page 11
...for a component which has not been serviced or maintained properly or if nonapproved replacement parts were used, STIHL may damage your owner's manual. Maintenance, Repair and Storing Maintenance, replacement, or repair of the hole...a short period after each use. However if you claim warranty for longer than a few days. 10 BT 121 Use of cracks in a hole. Use the specified spark plug and make sure it over a long distance.... Tighten all nuts, bolts and screws except the carburetor adjustment screws after the throttle lever is in the appropriate section of the muffler.
...for a component which has not been serviced or maintained properly or if nonapproved replacement parts were used, STIHL may damage your owner's manual. Maintenance, Repair and Storing Maintenance, replacement, or repair of the hole...a short period after each use. However if you claim warranty for longer than a few days. 10 BT 121 Use of cracks in a hole. Use the specified spark plug and make sure it over a long distance.... Tighten all nuts, bolts and screws except the carburetor adjustment screws after the throttle lever is in the appropriate section of the muffler.
Instruction Manual
Page 13
...-cycle engines. Use only STIHL two-stroke engine oil or equivalent high-quality two-stroke engine oils that you use in STlHL engines. Some fuel additives not only detrimentally affect elastomers (carburetor diaphragms, oil seals, fuel lines, etc.), but magnesium castings and catalytic converters as necessary. 12 BT 121 The canister should be kept...
...-cycle engines. Use only STIHL two-stroke engine oil or equivalent high-quality two-stroke engine oils that you use in STlHL engines. Some fuel additives not only detrimentally affect elastomers (carburetor diaphragms, oil seals, fuel lines, etc.), but magnesium castings and catalytic converters as necessary. 12 BT 121 The canister should be kept...
Instruction Manual
Page 14
... a long period, drain and clean the fuel tank. Close the canister and shake it to release slowly.. Before storing your machine. BT 121 13 After fueling, tighten down the filler cap by hand to ensure proper mixing of the oil with the fuel. Always thoroughly shake ...the mixture in approved fuel-canisters only. Gasoline Oil (STIHL 50:1 or equivalent high-quality oils) US gal. 1 2 1/2 5 US fl.oz 2.6 6.4 12.8 Dispose of storage. Run the engine until the carburetor is dry. Store in the can before fueling your machine for a few ...
... a long period, drain and clean the fuel tank. Close the canister and shake it to release slowly.. Before storing your machine. BT 121 13 After fueling, tighten down the filler cap by hand to ensure proper mixing of the oil with the fuel. Always thoroughly shake ...the mixture in approved fuel-canisters only. Gasoline Oil (STIHL 50:1 or equivalent high-quality oils) US gal. 1 2 1/2 5 US fl.oz 2.6 6.4 12.8 Dispose of storage. Run the engine until the carburetor is dry. Store in the can before fueling your machine for a few ...
Instruction Manual
Page 18
Make sure the carburetor is idling. press it down the engine: : Push the slide control in direction of c to $ At very low outside temperatures: Allow engine to warm up ... of the auger. : Disengage the auger brake by moving the activating lever to e even if the engine is cold. : Now start the engine. 427BA009 KN BT 121 17 To shut down firmly. : Move the slide control to START. : Move the choke knob to position B. If the engine does not start : : Push the...
Make sure the carburetor is idling. press it down the engine: : Push the slide control in direction of c to $ At very low outside temperatures: Allow engine to warm up ... of the auger. : Disengage the auger brake by moving the activating lever to e even if the engine is cold. : Now start the engine. 427BA009 KN BT 121 17 To shut down firmly. : Move the slide control to START. : Move the choke knob to position B. If the engine does not start : : Push the...
Instruction Manual
Page 19
... engine. Drain the fuel Kraftstofftank and store the machine in Period A factory new machine should not be dissipated by the flow of the hole. 18 BT 121 As all accessible screws and nuts (not adjusting screws) at idle speed so that the heat in the hole. During Break-in a dry place. This...
... engine. Drain the fuel Kraftstofftank and store the machine in Period A factory new machine should not be dissipated by the flow of the hole. 18 BT 121 As all accessible screws and nuts (not adjusting screws) at idle speed so that the heat in the hole. During Break-in a dry place. This...
Instruction Manual
Page 21
... the engine. : Remove the auger from that position. 20 BT 121 English / USA Adjusting the Carburetor General Information Your carburetor comes from the factory with the low speed screw (L). : Turn the idle speed screw (LA) clockwise until the drilling spindle stops rotating - With this carburetor it one full turn counterclockwise. : Start and warm up the...
... the engine. : Remove the auger from that position. 20 BT 121 English / USA Adjusting the Carburetor General Information Your carburetor comes from the factory with the low speed screw (L). : Turn the idle speed screw (LA) clockwise until the drilling spindle stops rotating - With this carburetor it one full turn counterclockwise. : Start and warm up the...
Instruction Manual
Page 22
... deposits to form on the insulator nose which have caused fouling of the approved range. BT 121 21 Idle setting too lean: : Turn the low speed screw (L) counterclockwise until the engine runs and accelerates smoothly. Fine tuning the carburetor for operation at idling speed, first check the spark plug. : Remove spark plug as...
... deposits to form on the insulator nose which have caused fouling of the approved range. BT 121 21 Idle setting too lean: : Turn the low speed screw (L) counterclockwise until the engine runs and accelerates smoothly. Fine tuning the carburetor for operation at idling speed, first check the spark plug. : Remove spark plug as...
Instruction Manual
Page 23
... tube (2) of STIHL gear lubricant 0781 120 1117 to the filler hole. : Squeeze 1/4 oz (5 - 10g) grease into the gearbox. English / USA Engine Running Behavior Lubricating the Gearbox 2 1 If engine running behavior is unsatisfactory even though the air filter is clean and the carburetor properly adjusted, the... authorized STIHL dealer. Always press spark plug boot (2) snugly onto terminal (1) of operation: : Unscrew the filler plug (1). Check grease level after about every 50 hours of the proper size. (Note: If terminal has detachable SAE adapter nut, it down firmly. 22 BT 121 Do ...
... tube (2) of STIHL gear lubricant 0781 120 1117 to the filler hole. : Squeeze 1/4 oz (5 - 10g) grease into the gearbox. English / USA Engine Running Behavior Lubricating the Gearbox 2 1 If engine running behavior is unsatisfactory even though the air filter is clean and the carburetor properly adjusted, the... authorized STIHL dealer. Always press spark plug boot (2) snugly onto terminal (1) of operation: : Unscrew the filler plug (1). Check grease level after about every 50 hours of the proper size. (Note: If terminal has detachable SAE adapter nut, it down firmly. 22 BT 121 Do ...
Instruction Manual
Page 26
BT 121 English / USA 25 out of the reach of fuel properly in a dry, high or locked location - this helps prevent carburetor diaphragms sticking together. : Thoroughly clean the machine - Storing the Machine For periods of about 3 months or longer: : Removing the auger. : Drain and clean the fuel tank in a well ventilated area. : Dispose of children and other unauthorized persons. pay special attention to the cylinder fins and air filter. : Store the machine in accordance with local environmental requirements. : Run engine until carburetor is dry -
BT 121 English / USA 25 out of the reach of fuel properly in a dry, high or locked location - this helps prevent carburetor diaphragms sticking together. : Thoroughly clean the machine - Storing the Machine For periods of about 3 months or longer: : Removing the auger. : Drain and clean the fuel tank in a well ventilated area. : Dispose of children and other unauthorized persons. pay special attention to the cylinder fins and air filter. : Store the machine in accordance with local environmental requirements. : Run engine until carburetor is dry -
Instruction Manual
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... or daily after 100 hours of operation Spark arresting screen in fuel tank Check Replace Fuel tank Clean Carburetor Check idle adjustment - drilling spindle must not rotate X Readjust idle Spark plug Readjust electrode gap Replace ... STIHL dealer All accessible screws and nuts (not adjusting screws) Retighten Antivibration elements Check X Have replaced by dealer 1) Gearbox Re-lubricate Drilling spindle Clean X Auger Inspect X Replace Safety labels Replace 1) STIHL recommends the STIHL servicing dealer X X X X X X X X X X X X X X X x 26 BT 121 before...
... or daily after 100 hours of operation Spark arresting screen in fuel tank Check Replace Fuel tank Clean Carburetor Check idle adjustment - drilling spindle must not rotate X Readjust idle Spark plug Readjust electrode gap Replace ... STIHL dealer All accessible screws and nuts (not adjusting screws) Retighten Antivibration elements Check X Have replaced by dealer 1) Gearbox Re-lubricate Drilling spindle Clean X Auger Inspect X Replace Safety labels Replace 1) STIHL recommends the STIHL servicing dealer X X X X X X X X X X X X X X X x 26 BT 121 before...
Instruction Manual
Page 28
Main Parts and Controls BT 121 English / USA 1 Starter grip 2 Carburetor adjusting screws 3 Air filter cover 4 Fuel tank filler cap 5 Muffler (with spark arresting screen) 6 Slide control 7 Throttle trigger interlock 8 Throttle trigger 9 Spark plug boot 10 Screw plug 11 Drilling spindle 12 Fuel pump 13 Choke knob 14 Auger brake lever 15 Padding 27
Main Parts and Controls BT 121 English / USA 1 Starter grip 2 Carburetor adjusting screws 3 Air filter cover 4 Fuel tank filler cap 5 Muffler (with spark arresting screen) 6 Slide control 7 Throttle trigger interlock 8 Throttle trigger 9 Spark plug boot 10 Screw plug 11 Drilling spindle 12 Fuel pump 13 Choke knob 14 Auger brake lever 15 Padding 27
Instruction Manual
Page 29
... = 50 hours Engine STIHL single cylinder two-stroke engine Displacement: Bore: Stroke: Engine power to stop . engine speed without auger Idle speed 1.88 cu.in (30.8 cm3) 1.38 in (35 mm) 1.26 in (32 mm) 1.8 bhp (1.3 KW) 12,300 rpm 2,800 rpm 28 BT 121 Carburetor Adjusting Screws For tuning the carburetor. 3. Fuel Filler Cap...
... = 50 hours Engine STIHL single cylinder two-stroke engine Displacement: Bore: Stroke: Engine power to stop . engine speed without auger Idle speed 1.88 cu.in (30.8 cm3) 1.38 in (35 mm) 1.26 in (32 mm) 1.8 bhp (1.3 KW) 12,300 rpm 2,800 rpm 28 BT 121 Carburetor Adjusting Screws For tuning the carburetor. 3. Fuel Filler Cap...
Instruction Manual
Page 30
spindle speed 190 rpm Max. torque at drilling spindle 79 Nm Lubrication STIHL gear lubricant for brushcutters Weight without drilling tool (auger) 20.7 lb (9.4 kg) Dimensions Length of machine approx. 15.7 in (400 mm) Width of handle frame ... Fuel System Carburetor All position diaphragm carburetor with electronic speed governor Spark plug (resistor type) Bosch WSR 6 F, NGK BPMR 7 A or Champion RCJ 6 Y (not for all markets) Electrode gap 0.02 in (0.5 mm) Spark plug thread M 14 x 1.25; 0.37 in (450 mm) long Chuck For drill diameters from 5/64" to 1/2" (2 to 13 mm) BT 121 29...
spindle speed 190 rpm Max. torque at drilling spindle 79 Nm Lubrication STIHL gear lubricant for brushcutters Weight without drilling tool (auger) 20.7 lb (9.4 kg) Dimensions Length of machine approx. 15.7 in (400 mm) Width of handle frame ... Fuel System Carburetor All position diaphragm carburetor with electronic speed governor Spark plug (resistor type) Bosch WSR 6 F, NGK BPMR 7 A or Champion RCJ 6 Y (not for all markets) Electrode gap 0.02 in (0.5 mm) Spark plug thread M 14 x 1.25; 0.37 in (450 mm) long Chuck For drill diameters from 5/64" to 1/2" (2 to 13 mm) BT 121 29...
Instruction Manual
Page 32
...which cause the engine to fail to ensure the performance of time listed below provided there has been no cost to a STIHL service center as soon as the carburetor and the ignition system. The equipment engine must be designed, built and equipped, at an authorized dealer), parts, and ... the initial purchaser and you are warranted for small non road engines. The warranty repairs will be free from the date of charge. BT 121 31 In the U.S. EPA standards for presenting your small off -road equipment engine will be hoses, and connectors and other emission related assemblies...
...which cause the engine to fail to ensure the performance of time listed below provided there has been no cost to a STIHL service center as soon as the carburetor and the ignition system. The equipment engine must be designed, built and equipped, at an authorized dealer), parts, and ... the initial purchaser and you are warranted for small non road engines. The warranty repairs will be free from the date of charge. BT 121 31 In the U.S. EPA standards for presenting your small off -road equipment engine will be hoses, and connectors and other emission related assemblies...
Instruction Manual
Page 33
... at and after the first scheduled replacement point. 32 BT 121 Deviations from this manual are based on the application of the emission test. Warranty Work STIHL Incorporated shall remedy warranty defects at any authorized STIHL servicing dealer and present the signed warranty card. The...Limitations This Emission Control Systems Warranty shall not cover any of the following list specifically defines the emission-related warranted parts: Carburetor Choke (Cold start enrichment system) Intake manifold Air filter Spark plug Magneto or electronic ignition system (ignition module) Catalytic ...
... at and after the first scheduled replacement point. 32 BT 121 Deviations from this manual are based on the application of the emission test. Warranty Work STIHL Incorporated shall remedy warranty defects at any authorized STIHL servicing dealer and present the signed warranty card. The...Limitations This Emission Control Systems Warranty shall not cover any of the following list specifically defines the emission-related warranted parts: Carburetor Choke (Cold start enrichment system) Intake manifold Air filter Spark plug Magneto or electronic ignition system (ignition module) Catalytic ...