Instruction Manual
Page 2
... Buffers on Machines with Manual Fuel Pump 85 12.5 Carburetor 88 12.5.1 Leakage Test 89 RA_737_00_01_01 MS 231, MS 231 C, MS 251, MS 251 C q © ANDREAS STIHL AG & Co. QuickStop Super 75 10.3.3 Choke Rod 76 10.3.4 Throttle Rod 76 11. Chain Lubrication 78 11.1 Pickup Body 78 11.2 Oil Suction Hose 78 11.3 Oil Pump 78 11...
... Buffers on Machines with Manual Fuel Pump 85 12.5 Carburetor 88 12.5.1 Leakage Test 89 RA_737_00_01_01 MS 231, MS 231 C, MS 251, MS 251 C q © ANDREAS STIHL AG & Co. QuickStop Super 75 10.3.3 Choke Rod 76 10.3.4 Throttle Rod 76 11. Chain Lubrication 78 11.1 Pickup Body 78 11.2 Oil Suction Hose 78 11.3 Oil Pump 78 11...
Instruction Manual
Page 5
... disassembled parts for assembly or disassembly. do not use original STIHL replacement parts. Other press fluids are heated for wear or damage before carrying out repairs or mounting the machine to overheating. 4 MS 231, MS 231 C, MS 251, MS 251 C Gasoline is an extremely flammable fuel and can be explosive...open fuel hoses with the aid of it properly in damage to be wiped away immediately. Preparations for servicing Remove the chain sprocket cover, saw chain and guide bar before re-installing - Spilled fuel must be tightened to the hose barbs, b 14. hose barb ...
... disassembled parts for assembly or disassembly. do not use original STIHL replacement parts. Other press fluids are heated for wear or damage before carrying out repairs or mounting the machine to overheating. 4 MS 231, MS 231 C, MS 251, MS 251 C Gasoline is an extremely flammable fuel and can be explosive...open fuel hoses with the aid of it properly in damage to be wiped away immediately. Preparations for servicing Remove the chain sprocket cover, saw chain and guide bar before re-installing - Spilled fuel must be tightened to the hose barbs, b 14. hose barb ...
Instruction Manual
Page 6
...: Crankcase leakage test at gauge pressure: under vacuum: 2.2 Fuel System 2.3 Ignition System 2.4 Chain Lubrication MS 231 40.6 cm3 41.5 mm 30.0 mm 2.0 kW (2.7 bhp) at 9,500 rpm 13,000 rpm 2,800 rpm Centrifugal clutch without linings 3,500 rpm 0.5 bar 0.5 bar MS 251 45.6 cm3 44.0 mm 30.0 mm 2.2 kW (3.0 bhp) at 9,500 rpm 13... (resistor type): Electrode gap: 0.30 (+ 0.05/- 0.10) mm NGK CMR 6 H 0.5 mm Speed-controlled Ematic oil pump Oil delivery rate: 8.0 (+/3.0) cm3/min at 10,000 rpm MS 231, MS 231 C, MS 251, MS 251 C 5
...: Crankcase leakage test at gauge pressure: under vacuum: 2.2 Fuel System 2.3 Ignition System 2.4 Chain Lubrication MS 231 40.6 cm3 41.5 mm 30.0 mm 2.0 kW (2.7 bhp) at 9,500 rpm 13,000 rpm 2,800 rpm Centrifugal clutch without linings 3,500 rpm 0.5 bar 0.5 bar MS 251 45.6 cm3 44.0 mm 30.0 mm 2.2 kW (3.0 bhp) at 9,500 rpm 13... (resistor type): Electrode gap: 0.30 (+ 0.05/- 0.10) mm NGK CMR 6 H 0.5 mm Speed-controlled Ematic oil pump Oil delivery rate: 8.0 (+/3.0) cm3/min at 10,000 rpm MS 231, MS 231 C, MS 251, MS 251 C 5
Instruction Manual
Page 7
... M 5x16 Muffler / cylinder 10.0 M 8x1 Flywheel / crankshaft 28.0 P 4x10 Retainer 1.0 Q B 2), 3) 2) 1), 3) 1), 3) 1), 3) 2), 3) 4) 6 MS 231, MS 231 C, MS 251, MS 251 C Fastener Thread size For component Torque Nm Remarks Screw Screw Screw Screw Screw Collar screw Collar screw Collar screw Screw Nut Screw Screw Screw... Screw Screw Screw Screw Screw Screw Carrier Screw Screw Screw Nut Screw P 4x12 Chain...
... M 5x16 Muffler / cylinder 10.0 M 8x1 Flywheel / crankshaft 28.0 P 4x10 Retainer 1.0 Q B 2), 3) 2) 1), 3) 1), 3) 1), 3) 2), 3) 4) 6 MS 231, MS 231 C, MS 251, MS 251 C Fastener Thread size For component Torque Nm Remarks Screw Screw Screw Screw Screw Collar screw Collar screw Collar screw Screw Nut Screw Screw Screw... Screw Screw Screw Screw Screw Screw Carrier Screw Screw Screw Nut Screw P 4x12 Chain...
Instruction Manual
Page 8
... for polymer: DG and P screws max. 500 rpm Do not use an impact wrench for releasing or tightening screws. MS 231, MS 231 C, MS 251, MS 251 C 7 Coat micro-encapsulated screws with and without binding heads. Fastener Thread size For component Torque Nm Remarks Screw Screw ... Remarks: 1) Screws with binding head 2) Micro-encapsulated screws 3) Waxed screws 4) Degrease crankshaft/flywheel and mount oil-free Q) QuickStop Super B) Quick chain adjuster Use the following procedure when refitting a DG or P screw in an existing thread: Place the screw in the existing thread and does not...
... for polymer: DG and P screws max. 500 rpm Do not use an impact wrench for releasing or tightening screws. MS 231, MS 231 C, MS 251, MS 251 C 7 Coat micro-encapsulated screws with and without binding heads. Fastener Thread size For component Torque Nm Remarks Screw Screw ... Remarks: 1) Screws with binding head 2) Micro-encapsulated screws 3) Waxed screws 4) Degrease crankshaft/flywheel and mount oil-free Q) QuickStop Super B) Quick chain adjuster Use the following procedure when refitting a DG or P screw in an existing thread: Place the screw in the existing thread and does not...
Instruction Manual
Page 9
... under full load Cause Clutch shoes badly worn Clutch drum badly worn Remedy Install new clutch Install new clutch drum Saw chain rotates at idle speed Engine idle speed too high Clutch springs stretched Clutch springs broken Readjust idle speed screw LA Replace the clutch springs or ... Clutch shoe retainer broken Clutch shoes and carrier worn Replace all clutch springs Fit new needle cage Install new retainer or clutch Install new clutch 8 MS 231, MS 231 C, MS 251, MS 251 C 3.
... under full load Cause Clutch shoes badly worn Clutch drum badly worn Remedy Install new clutch Install new clutch drum Saw chain rotates at idle speed Engine idle speed too high Clutch springs stretched Clutch springs broken Readjust idle speed screw LA Replace the clutch springs or ... Clutch shoe retainer broken Clutch shoes and carrier worn Replace all clutch springs Fit new needle cage Install new retainer or clutch Install new clutch 8 MS 231, MS 231 C, MS 251, MS 251 C 3.
Instruction Manual
Page 10
...drum badly worn Brake band blocked Install new clutch Install new clutch drum Check freedom of movement and operation of brake band Saw chain rotates at idle speed Engine idle speed too high Clutch springs stretched Clutch springs broken Readjust idle speed screw LA Replace the clutch... springs or install new clutch Replace the clutch springs Saw chain does not stop immediately when brake is activated Brake spring stretched or broken Fit new brake spring Brake band stretched or worn Clutch drum worn Fit new brake band Install new clutch drum MS 231, MS 231 C, MS 251, MS 251 C 9
...drum badly worn Brake band blocked Install new clutch Install new clutch drum Check freedom of movement and operation of brake band Saw chain rotates at idle speed Engine idle speed too high Clutch springs stretched Clutch springs broken Readjust idle speed screw LA Replace the clutch... springs or install new clutch Replace the clutch springs Saw chain does not stop immediately when brake is activated Brake spring stretched or broken Fit new brake spring Brake band stretched or worn Clutch drum worn Fit new brake band Install new clutch drum MS 231, MS 231 C, MS 251, MS 251 C 9
Instruction Manual
Page 12
... Install new engine housing Oil pump delivers insufficient oil Oil pump damaged or worn Worm driver is loose Install new oil pump Install new worm MS 231, MS 231 C, MS 251, MS 251 C 11 rectify other sources of trouble with the chain lubrication system, check and .
... Install new engine housing Oil pump delivers insufficient oil Oil pump damaged or worn Worm driver is loose Install new oil pump Install new worm MS 231, MS 231 C, MS 251, MS 251 C 11 rectify other sources of trouble with the chain lubrication system, check and .
Instruction Manual
Page 17
... - throttle shutter completely closed Tank vent faulty Clean the carburetor Reset low speed screw (L) correctly Reset idle speed screw (LA) correctly Replace tank vent Saw chain rotates at idle speed Leak on fuel hose from tank to carburetor Seal connections or install new fuel hose Engine idle speed too high Readjust... screw LA (counterclockwise) Clutch springs stretched or fatigued Replace the clutch springs or install new clutch Clutch spring hooks broken Replace the clutch springs 16 MS 231, MS 231 C, MS 251, MS 251 C
... - throttle shutter completely closed Tank vent faulty Clean the carburetor Reset low speed screw (L) correctly Reset idle speed screw (LA) correctly Replace tank vent Saw chain rotates at idle speed Leak on fuel hose from tank to carburetor Seal connections or install new fuel hose Engine idle speed too high Readjust... screw LA (counterclockwise) Clutch springs stretched or fatigued Replace the clutch springs or install new clutch Clutch spring hooks broken Replace the clutch springs 16 MS 231, MS 231 C, MS 251, MS 251 C
Instruction Manual
Page 21
... the brake band (1) to troubleshooting, b 3.2. The clutch drum must come areas on inside diameter and/or parts of the machine. 20 MS 231, MS 231 C, MS 251, MS 251 C arrows) and its seat (arrow). - the chain must come to the eye. Install a new brake band if there are noticeable signs of wear (large With the coasting brake...
... the brake band (1) to troubleshooting, b 3.2. The clutch drum must come areas on inside diameter and/or parts of the machine. 20 MS 231, MS 231 C, MS 251, MS 251 C arrows) and its seat (arrow). - the chain must come to the eye. Install a new brake band if there are noticeable signs of wear (large With the coasting brake...
Instruction Manual
Page 22
... the direction of the machine and tighten it to disconnect the brake spring (1) from the brake lever. 2310RA015 TG MS 231, MS 231 C, MS 251, MS 251 C 21 Reassemble all other checks, b 5.1 - Troubleshooting, b 3.2 - Remove the shroud, b 6.4 - Engage the chain brake. 1 2 TOP 2 TOP 1 2310RA011 TG : Place the cover (1) in the reverse sequence. : Fit the screw (2) on the underside...
... the direction of the machine and tighten it to disconnect the brake spring (1) from the brake lever. 2310RA015 TG MS 231, MS 231 C, MS 251, MS 251 C 21 Reassemble all other checks, b 5.1 - Troubleshooting, b 3.2 - Remove the shroud, b 6.4 - Engage the chain brake. 1 2 TOP 2 TOP 1 2310RA011 TG : Place the cover (1) in the reverse sequence. : Fit the screw (2) on the underside...
Instruction Manual
Page 25
.... 2310RA033 TG 1 : Take the brake lever (2) out of the flat spring (1) into its seat (arrow) as far as stop. 2310RA020 TG 24 MS 231, MS 231 C, MS 251, MS 251 C TOP 2310RA031 TG - Lubricate the pivot pins, b 14 1 1 : Disconnect the spring (1) from the brake lever. 2 2310RA034 TG Installing -... Remove the brake band, b 5.2 1 1 TOP : Pull the hand guard (1) and brake lever (2) off the pivot pins (arrows) together. - Engage the chain brake. The brake spring is worn, install a new engine housing. - if it is now relaxed. : Use the assembly tool 1117 890 0900 to disconnect the...
.... 2310RA033 TG 1 : Take the brake lever (2) out of the flat spring (1) into its seat (arrow) as far as stop. 2310RA020 TG 24 MS 231, MS 231 C, MS 251, MS 251 C TOP 2310RA031 TG - Lubricate the pivot pins, b 14 1 1 : Disconnect the spring (1) from the brake lever. 2 2310RA034 TG Installing -... Remove the brake band, b 5.2 1 1 TOP : Pull the hand guard (1) and brake lever (2) off the pivot pins (arrows) together. - Engage the chain brake. The brake spring is worn, install a new engine housing. - if it is now relaxed. : Use the assembly tool 1117 890 0900 to disconnect the...
Instruction Manual
Page 27
... the spring (1) to the anchor pin (2). : Use the assembly tool 1117 890 0900 to the brake lever (arrow). 26 MS 231, MS 231 C, MS 251, MS 251 C If this is in that the open side of the spring hook (arrow) is released. : Carefully press the lockout lever... (1) to guarantee correct operation of the brake spring must be tightly against engine housing (arrows) and the clutch drum must be depressed without the brake lever moving. Remove the chain...
... the spring (1) to the anchor pin (2). : Use the assembly tool 1117 890 0900 to the brake lever (arrow). 26 MS 231, MS 231 C, MS 251, MS 251 C If this is in that the open side of the spring hook (arrow) is released. : Carefully press the lockout lever... (1) to guarantee correct operation of the brake spring must be tightly against engine housing (arrows) and the clutch drum must be depressed without the brake lever moving. Remove the chain...
Instruction Manual
Page 30
1 2 1 2 - Check operation and adjust the brake cable, b 5.4.1 2310RA060 TG 2710RA079 TG 5.5 Chain Tensioner 2310RA066 TG : Attach the brake cable (1) to the bore (arrow) in the brake lever (2). 2 1 : Slide the brake cable retainer with lug (1) through...make sure the grommet (1) is not the case, the adjustment of fuel hose and correct if necessary, b 12.11.2 - Install the throttle trigger, b 10.3 MS 231, MS 231 C, MS 251, MS 251 C 29 Reassemble all other parts in the guide (arrow). - if this is pushed fully into the adjusting screw (2) - Install the switch lever, b 10.3.1 ...
1 2 1 2 - Check operation and adjust the brake cable, b 5.4.1 2310RA060 TG 2710RA079 TG 5.5 Chain Tensioner 2310RA066 TG : Attach the brake cable (1) to the bore (arrow) in the brake lever (2). 2 1 : Slide the brake cable retainer with lug (1) through...make sure the grommet (1) is not the case, the adjustment of fuel hose and correct if necessary, b 12.11.2 - Install the throttle trigger, b 10.3 MS 231, MS 231 C, MS 251, MS 251 C 29 Reassemble all other parts in the guide (arrow). - if this is pushed fully into the adjusting screw (2) - Install the switch lever, b 10.3.1 ...
Instruction Manual
Page 31
... installed in the reverse sequence. 1 : Position the replacement chain catcher (1) so that it lines up with STIHL multipurpose grease, b 14 - When installing the adjusting wheel, make sure its teeth face the cover plate. - Check the wing nut (1) and replace if necessary 30 MS 231, MS 231 C, MS 251, MS 251 C Lubricate thread and gears with the contour of...
... installed in the reverse sequence. 1 : Position the replacement chain catcher (1) so that it lines up with STIHL multipurpose grease, b 14 - When installing the adjusting wheel, make sure its teeth face the cover plate. - Check the wing nut (1) and replace if necessary 30 MS 231, MS 231 C, MS 251, MS 251 C Lubricate thread and gears with the contour of...
Instruction Manual
Page 32
... stud to the specified torque - Remove the chain sprocket cover. 2 1 Repair solution If the thread in the reverse sequence. the security of the collar stud (1) with threadlocking adhesive, fit and tighten down firmly. - Screw home the collar stud and tighten it will go and unscrew the stud counterclockwise. - MS 231, MS 231 C, MS 251, MS 251 C 31
... stud to the specified torque - Remove the chain sprocket cover. 2 1 Repair solution If the thread in the reverse sequence. the security of the collar stud (1) with threadlocking adhesive, fit and tighten down firmly. - Screw home the collar stud and tighten it will go and unscrew the stud counterclockwise. - MS 231, MS 231 C, MS 251, MS 251 C 31
Instruction Manual
Page 79
..., b 4 - Clean the oil tank if necessary, b1 : Line up the oil suction hose (1) - Remove the clutch, b 4 - Troubleshooting, b 3.3 - Pull off the pickup body (1), check it . - Chain Lubrication 11.1 Pickup Body 11.2 Oil Suction Hose Impurities gradually clog the fine pores of the filter with minute particles of problems with the pickup... system, first check the oil tank and the pickup body. - Push the oil suction hose (1), pickup body first, through the housing bore (arrow). 78 MS 231, MS 231 C, MS 251, MS 251 C Install the oil pump, b 11.3 - In the event of dirt.
..., b 4 - Clean the oil tank if necessary, b1 : Line up the oil suction hose (1) - Remove the clutch, b 4 - Troubleshooting, b 3.3 - Pull off the pickup body (1), check it . - Chain Lubrication 11.1 Pickup Body 11.2 Oil Suction Hose Impurities gradually clog the fine pores of the filter with minute particles of problems with the pickup... system, first check the oil tank and the pickup body. - Push the oil suction hose (1), pickup body first, through the housing bore (arrow). 78 MS 231, MS 231 C, MS 251, MS 251 C Install the oil pump, b 11.3 - In the event of dirt.
Instruction Manual
Page 96
... mixture any leaner - Use the low speed screw (L) to set the engine speed again to 2,800 rpm. 5. this is the basic setting. - MS 231, MS 231 C, MS 251, MS 251 C 95 As soon as a maximum engine speed of ± 200 rpm. 14 12 0 10 8 4 6 2310RA283 TG If this is the basic...high speed screw H (1) against its seat, open it 1 full turn counterclockwise - The carburetor and air filter are shown on the high speed screw H. Check chain tension and adjust if necessary. - Check the air filter and clean or replace if necessary, b 12.1 1 2 : Starting with a tachometer. Use the...
... mixture any leaner - Use the low speed screw (L) to set the engine speed again to 2,800 rpm. 5. this is the basic setting. - MS 231, MS 231 C, MS 251, MS 251 C 95 As soon as a maximum engine speed of ± 200 rpm. 14 12 0 10 8 4 6 2310RA283 TG If this is the basic...high speed screw H (1) against its seat, open it 1 full turn counterclockwise - The carburetor and air filter are shown on the high speed screw H. Check chain tension and adjust if necessary. - Check the air filter and clean or replace if necessary, b 12.1 1 2 : Starting with a tachometer. Use the...
Instruction Manual
Page 97
...idle speed screw (LA) clockwise until the engine runs and accelerates smoothly. Turn low speed screw (L) counterclockwise until the chain starts running behavior: The engine must not be removed for operation at high altitude A minor correction may be necessary if... the idle speed screw (LA) counterclockwise until the chain stops running behavior. Check standard setting. - Turn the adjusting screws only very slightly. 1 This completes the basic setting of lubrication and overheating. 96 MS 231, MS 231 C, MS 251, MS 251 C Adjustment for the standard setting. The setting of...
...idle speed screw (LA) clockwise until the engine runs and accelerates smoothly. Turn low speed screw (L) counterclockwise until the chain starts running behavior: The engine must not be removed for operation at high altitude A minor correction may be necessary if... the idle speed screw (LA) counterclockwise until the chain stops running behavior. Check standard setting. - Turn the adjusting screws only very slightly. 1 This completes the basic setting of lubrication and overheating. 96 MS 231, MS 231 C, MS 251, MS 251 C Adjustment for the standard setting. The setting of...