Instruction Manual
Page 2
...61 8.6 Starter Rope / Grip 61 8.7 Tensioning the Rewind Spring 62 8.8 Replacing the Rewind Spring 63 9. QuickStop Super 75 10.3.3 Choke Rod 76 10...MS 251, MS 251 C q © ANDREAS STIHL AG & Co. Ignition System 45 7.1 Ignition Timing 45 7.2 Preseparator 45 7.3 Install new ignition module 45 7.4 Testing the Ignition Module 47 7.5 Spark Plug Boot / Ignition Lead 48 7.6 Flywheel 49 7.7 Short Circuit Wire 50 7.7.1 Testing 50 7.7.2 Removing and Installing 50 7.7.3 Ground Wire 53 7.7.4 Contact Spring 53 7.8 Ignition System Troubleshooting 55 8. Chain...
...61 8.6 Starter Rope / Grip 61 8.7 Tensioning the Rewind Spring 62 8.8 Replacing the Rewind Spring 63 9. QuickStop Super 75 10.3.3 Choke Rod 76 10...MS 251, MS 251 C q © ANDREAS STIHL AG & Co. Ignition System 45 7.1 Ignition Timing 45 7.2 Preseparator 45 7.3 Install new ignition module 45 7.4 Testing the Ignition Module 47 7.5 Spark Plug Boot / Ignition Lead 48 7.6 Flywheel 49 7.7 Short Circuit Wire 50 7.7.1 Testing 50 7.7.2 Removing and Installing 50 7.7.3 Ground Wire 53 7.7.4 Contact Spring 53 7.8 Ignition System Troubleshooting 55 8. Chain...
Instruction Manual
Page 5
... Pull off or push on to the hose barbs, b 14. do not use original STIHL replacement parts. Coat the ends of engine damage due to overheating. 4 MS 231, MS 231 C, MS 251, MS 251 C there is otherwise a risk of injury from the fanwheel and a risk of the hoses...STIHL parts symbol K This symbol may result in damage to be performed outdoors only. Exercise extreme caution while carrying out maintenance and repair work , observe all local and countryspecific safety regulations as well as necessary. Check disassembled parts for servicing Remove the chain sprocket cover, saw chain...
... Pull off or push on to the hose barbs, b 14. do not use original STIHL replacement parts. Coat the ends of engine damage due to overheating. 4 MS 231, MS 231 C, MS 251, MS 251 C there is otherwise a risk of injury from the fanwheel and a risk of the hoses...STIHL parts symbol K This symbol may result in damage to be performed outdoors only. Exercise extreme caution while carrying out maintenance and repair work , observe all local and countryspecific safety regulations as well as necessary. Check disassembled parts for servicing Remove the chain sprocket cover, saw chain...
Instruction Manual
Page 9
...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 install new clutch Replace the clutch springs Loud noises Clutch ...springs stretched Needle cage damaged 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...
...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 install new clutch Replace the clutch springs Loud noises Clutch ...springs stretched Needle cage damaged 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...
Instruction Manual
Page 10
... 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
... 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
... intake hose and pickup or intake hose ruptured body Valve in oil tank blocked Clean or replace valve Teeth on worm worn Install new worm Oil pump damaged or worn Install new oil pump Machine losing chain oil Oil pump damaged or worn Oil suction hose connection damaged Engine housing cracked Install... 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 .
... intake hose and pickup or intake hose ruptured body Valve in oil tank blocked Clean or replace valve Teeth on worm worn Install new worm Oil pump damaged or worn Install new oil pump Machine losing chain oil Oil pump damaged or worn Oil suction hose connection damaged Engine housing cracked Install... 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 with idle speed 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 with idle speed 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 25
... (1) into its seat (arrow) as far as stop. 2310RA020 TG 24 MS 231, MS 231 C, MS 251, MS 251 C Check the cam on Machines with QuickStop Super 2 2 - The brake spring is worn, install a new engine housing. - 2310RA035 TG 5.4 Brake Lever on the hand guard and replace the hand 1 guard if necessary. Remove the brake spring (1) from the... the pivot pins, b 14 1 1 : Disconnect the spring (1) from the anchor pin (arrow). : Disconnect the brake cable (1). - Remove the shroud, b 6.4 - Remove the fan housing, b 8.2 - Engage the chain brake. Troubleshooting, b 3.2 -
... (1) into its seat (arrow) as far as stop. 2310RA020 TG 24 MS 231, MS 231 C, MS 251, MS 251 C Check the cam on Machines with QuickStop Super 2 2 - The brake spring is worn, install a new engine housing. - 2310RA035 TG 5.4 Brake Lever on the hand guard and replace the hand 1 guard if necessary. Remove the brake spring (1) from the... the pivot pins, b 14 1 1 : Disconnect the spring (1) from the anchor pin (arrow). : Disconnect the brake cable (1). - Remove the shroud, b 6.4 - Remove the fan housing, b 8.2 - Engage the chain brake. Troubleshooting, b 3.2 -
Instruction Manual
Page 27
...lever (1) can be the adjustment of the spring hook (arrow) is in that the open side of the brake cable. - Remove the chain brake cover, b 5.2 The brake cable must locate snugly against one another in the relaxed condition. 2 1 1 TOP 1 2310RA042 TG...turns of free travel - Troubleshooting, b 3.2 - Checking condition and free travel is not the case, replace the brake spring. - If this is necessary to the brake lever (arrow). 26 MS 231, MS 231 C, MS 251, MS 251 C A certain amount of the brake spring must rotate freely. - Troubleshooting, b 3.2 TOP 2310RA043 ...
...lever (1) can be the adjustment of the spring hook (arrow) is in that the open side of the brake cable. - Remove the chain brake cover, b 5.2 The brake cable must locate snugly against one another in the relaxed condition. 2 1 1 TOP 1 2310RA042 TG...turns of free travel - Troubleshooting, b 3.2 - Checking condition and free travel is not the case, replace the brake spring. - If this is necessary to the brake lever (arrow). 26 MS 231, MS 231 C, MS 251, MS 251 C A certain amount of the brake spring must rotate freely. - Troubleshooting, b 3.2 TOP 2310RA043 ...
Instruction Manual
Page 31
... chain catcher (arrow) is installed in the reverse sequence. 1 : Position the replacement chain catcher (1) so that it lines up with STIHL multipurpose grease, b 14 - Reassemble in the reverse sequence. - Check the wing nut (1) and replace if necessary 30 MS 231, MS 231 C, MS 251, MS 251...(arrow). : Remove the cover plate (1) and adjusting wheel (2). 22 4 1 5.5.2 Chain Catcher - If the chain catcher is damaged or worn, install a replacement chain catcher. 2310RA045 TG 5.5.1 Quick Chain Tensioner The quick chain tensioner is an integral part of the sprocket cover. -
... chain catcher (arrow) is installed in the reverse sequence. 1 : Position the replacement chain catcher (1) so that it lines up with STIHL multipurpose grease, b 14 - Reassemble in the reverse sequence. - Check the wing nut (1) and replace if necessary 30 MS 231, MS 231 C, MS 251, MS 251...(arrow). : Remove the cover plate (1) and adjusting wheel (2). 22 4 1 5.5.2 Chain Catcher - If the chain catcher is damaged or worn, install a replacement chain catcher. 2310RA045 TG 5.5.1 Quick Chain Tensioner The quick chain tensioner is an integral part of the sprocket cover. -
Instruction Manual
Page 79
.... - 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 Clean the oil tank if necessary, b1 : Line up the oil suction hose (1) - Install .... 1 - Check the oil suction hose and pickup body and replace if 2 necessary. - Fit the pickup body, b 11.1 219RA457 TG : Use hook (2) ...Reassemble all other parts in the reverse sequence. : Remove the shim (1). 1 2310RA300 TG - Installing - 11. Chain Lubrication 11.1 Pickup Body 11.2 Oil Suction Hose Impurities gradually clog the fine pores of the tab (arrow) ...
.... - 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 Clean the oil tank if necessary, b1 : Line up the oil suction hose (1) - Install .... 1 - Check the oil suction hose and pickup body and replace if 2 necessary. - Fit the pickup body, b 11.1 219RA457 TG : Use hook (2) ...Reassemble all other parts in the reverse sequence. : Remove the shim (1). 1 2310RA300 TG - Installing - 11. Chain Lubrication 11.1 Pickup Body 11.2 Oil Suction Hose Impurities gradually clog the fine pores of the tab (arrow) ...
Instruction Manual
Page 96
Check chain tension and adjust if necessary. - Warm up the engine. push the screwdriver through the pre-installed limiter cap on the ... opening (arrow) and then push home the limiter cap until it 1 1/2 turns counterclockwise - Inspect the spark arresting screen (if fitted) and clean or replace if necessary, b 3.7 or b 6.1 - Use the high speed screw (H) to set the engine speed again to make the mixture any leaner - this... cleaning and adjusting the carburetor from scratch. The carburetor and air filter are shown on the high speed screw H. MS 231, MS 231 C, MS 251, MS 251 C 95
Check chain tension and adjust if necessary. - Warm up the engine. push the screwdriver through the pre-installed limiter cap on the ... opening (arrow) and then push home the limiter cap until it 1 1/2 turns counterclockwise - Inspect the spark arresting screen (if fitted) and clean or replace if necessary, b 3.7 or b 6.1 - Use the high speed screw (H) to set the engine speed again to make the mixture any leaner - this... cleaning and adjusting the carburetor from scratch. The carburetor and air filter are shown on the high speed screw H. MS 231, MS 231 C, MS 251, MS 251 C 95
Instruction Manual
Page 97
Check chain tension and adjust if necessary. - Check the air filter and clean or replace if necessary, b 12.1 Standard setting - Carry out standard setting. - Engine stops while idling - It is usually necessary to the low... 3/4 turn . Troubleshooting, b 3.6 - Turn the high speed screw (H) slowly counterclockwise as far as a result of lack of lubrication and overheating. 96 MS 231, MS 231 C, MS 251, MS 251 C Adjusting engine idle speed - Erratic idling behavior, poor acceleration (although standard setting is idling - Turn the idle speed screw (LA) clockwise until the...
Check chain tension and adjust if necessary. - Check the air filter and clean or replace if necessary, b 12.1 Standard setting - Carry out standard setting. - Engine stops while idling - It is usually necessary to the low... 3/4 turn . Troubleshooting, b 3.6 - Turn the high speed screw (H) slowly counterclockwise as far as a result of lack of lubrication and overheating. 96 MS 231, MS 231 C, MS 251, MS 251 C Adjusting engine idle speed - Erratic idling behavior, poor acceleration (although standard setting is idling - Turn the idle speed screw (LA) clockwise until the...