User manual STIHL MS 241 C-M

[. . . ] 5. 1 5. 2 5. 3 5. 4 5. 4. 1 5. 4. 2 5. 5 5. 6 5. 7 5. 7. 1 5. 7. 2 5. 8 5. 9 Introduction and safety precautions Introduction Safety precautions Specifications Engine Fuel system Ignition system Chain lubrication Tightening torques Troubleshooting Clutch Chain Drive, Chain Brake, Chain Tensioner Chain lubrication Starter Ignition system Carburetor Engine Clutch Clutch drum Clutch Chain brake Checking operation of chain brake Brake band Brake lever QuickStop Super brake lever Adjusting brake cable Brake cable Removal and installation Cam lever Pins Chain tensioner Quick chain tensioner Chain catcher Bar mounting stud Collar nut for chain sprocket cover 6. 9 11 12 14 15 18 19 19 19 20 20 20 21 23 25 27 28 29 31 31 32 32 32 7. 1 7. 2 7. 3 7. 4 7. 5 7. 5. 1 7. 6 7. 7 7. 7. 1 7. 7. 2 7. 7. 3 7. 7. 4 7. 8 6. 1 6. 2 6. 2. 1 6. 2. 2 6. 2. 3 6. 3 6. 3. 1 6. 3. 2 6. 4 6. 5 6. 6 6. 6. 1 6. 7 6. 8 6. 9 Engine Muffler Leak testing Preparations Vacuum test Pressure test Oil seals Ignition side Clutch side Shroud Cylinder Crankshaft Ball bearing / crankcase Piston Piston rings Decompression valve Ignition system Ignition timing Pre-separator Control unit Spark test check control unit Spark plug boot Ignition lead Flywheel Short circuit wire Contact test Removal and installation Ground wire Contact spring Troubleshooting, ignition system 34 34 35 35 36 36 37 37 37 38 39 41 46 47 49 50 51 51 51 51 54 55 56 56 57 57 57 64 64 66 8. 8. 1 8. 2 8. 2. 1 8. 2. 2 8. 2. 3 8. 2. 4 8. 2. 5 8. 2. 6 8. 3 8. 4 8. 5 8. 5. 1 8. 5. 2 8. 5. 3 8. 5. 4 8. 5. 5 8. 5. 6 M-Tronic Calibrating the control unit Testing Test preparations Connect the test lead Check screwed and plug connections as well as switch Checking the solenoid valve Checking the start detection function Checking the wiring harness Wiring harness Switchgear Troubleshooting, M-Tronic Engine does not start Engine does not start in position } Engine speed drops under load – low power Ignition – no ignition spark Engine stops suddenly Cut-off speed not reached Rewind starter General Fan housing Pawls ErgoStart Rope rotor Starter rope / starter grip Tensioning the rewind spring Replacing the rewind Spring 69 69 70 70 70 70 72 73 74 76 76 80 80 81 82 83 84 85 86 86 86 87 88 89 89 90 91 9. 9. 1 9. 2 9. 3 9. 4 9. 5 9. 6 9. 7 9. 8 RA_741_00_01_01 q © ANDREAS STIHL AG & Co. [. . . ] – Function between contact spring and contact of the switch shaft: – Position "F" = no connection – Position "0" = connection – Replace wiring harness if necessary, b 11. 1 Spark present? yes no Control unit needs to be replaced, b 7. 3 yes Machine runs? no Engine runs smoothly, troubleshooting procedure completed – Look for fault in fuel or carburetor system – Check engine for leaks – Check position of flywheel on crankshaft, b 3. 6, b 6. 2 68 MS 241 C 8. M-Tronic 8. 1 Calibrating the control unit If the control unit or carburetor is replaced during servicing. . . – Remove the saw chain and guide bar – Reinstall the chain sprocket cover – Set Master Control lever to Start } – Start machine – do not blip the throttle trigger After completion of the following procedure, the Master Control lever must be moved from Start } to STOP 0 without pressing the throttle trigger. – Let the machine warm up for at least 60 seconds in the Start } position and then move the Master Control lever to STOP 0 – Calibration is completed The control unit is adjusted to the carburetor while the engine runs in the position Start }. The machine must be switched off immediately for the information to be stored in the control unit. 2410RA546 TG If the outstanding running behavior and usual performance or maximum speed of the engine can no longer be attained, the usual engine performance can be attained again by calibrating the control unit. A regulating cycle only starts if the machine is operated for approximately 2 seconds under constant conditions. – Examine air filter, clean or replace if necessary, b 13. 1 – Examine the spark arresting screen (if installed); clean or replace it if necessary, b 6. 1 – Check chain tension, adjust if necessary – Check chain lubrication – Set Master Control lever to Start } – Start engine and let it warm up – Carry out five uniform cuts to length – speed between 8000 rpm and 11200 rpm, log diameter approx. 30 cm – If the outstanding running behavior and the usual performance are not attained, continue troubleshooting and test procedures as described under Testing, b 8. 2, Troubleshooting, b 8. 5 The fully electronic M-Tronic engine management system controls the ignition timing and fuel flow, taking all external conditions into account. The M-Tronic electronically adjusts the fuel-air mixture in the carburetor. The M-Tronic controls all operating states such as start, idle, part throttle and full throttle while accounting for the external conditions, e. g. , use at varying attitudes, as well as changing temperatures or fuel quality – the carburetor does not have any adjusting screws. Troubleshooting and test procedures are described in the following chapters, Testing, b 8. 2, Troubleshooting, b 8. 5. MS 241 C 69 8. 2 8. 2. 1 Testing Test preparations The following steps must be carried out before testing. 2410RA213 TG 1 1 2410RA216 TG – Carry out troubleshooting according to troubleshooting chart, b 8. 5 – Remove shroud, b 6. 4 – Remove the air filter, b 13. 1 – Remove coarse dirt from around the screwed connections, control unit, switchgear, solenoid valve and diagnostic jack : Remove diagnostic jack (1) from the guide (arrow) : Press the diagnostic jack (1) into the mount (arrow) until it is fully home – Reassemble remaining parts in reverse order 8. 2. 3 8. 2. 2 Connect the test lead 2410RA214 TG Check screwed and plug connections as well as switch – Remove shroud, b 6. 4 1 – Remove the air filter, b 13. 1 2 – Carry out test preparations, b 8. 2. 1 There must be a reliable connection for communication between control unit, switching device and solenoid valve. If communication between control unit and solenoid valve is interrupted or faulty, the control unit does not initiate an ignition spark. – In the event of a malfunction or if there is no ignition spark, first check the plug connections and wiring harness between control device and solenoid valve : Orient the plug (1) of the M-Tronic test lead 5910 840 0903 so that the angled shapes (arrows) match between diagnostic jack (2) and plug (1) 1 2410RA173 TG 2 1 2410RA215 TG : Remove the plug (1) : Push the plug (1) of the M-Tronic test lead 5910 840 0903 into the diagnostic jack (2) as far as it will go – After completion of the test procedure, unplug the test lead from the diagnostic jack 70 MS 241 C Versions with heating All versions 1 5 3 4 2410RA219 TG 1 1 Screw (1) must be tight. Leads (arrows) must be seated completely and firmly in the blade receptacles and the cable lug. 2410RA217 TG 2 : Remove blade receptacle (1) and contact sleeve (2) : Push out the holder (3) with ground wire (4) at the air guide shroud (5) and lay it aside Plug (1) must be seated completely and firmly in the recess of the solenoid. : If necessary, remove plug (1) and check contacts 2 1 Versions with manual fuel pump 1 2 3 Plug connection (1) must be pressed together completely – locking lug (3) must engage the recess. 2410RA218 TG 2 2410RA222 TG 1 2410RA220 TG 3 : If necessary. remove the plug connection (1) from the mount (arrow), remove the plug (2) and check the contacts, b 8. 2. 3 : Push out the holder (1) with the fuel pump at the air guide shroud (2), remove fuel hose (3) at the carburetor (arrow) and lay it on top of the air guide shroud : Set Master Control lever (1) to position }; the cam on the lever (2) must actuate the microswitch (arrow) – clicking sound – If the microswitch is not actuated by the lever at the carburetor, replace lever if necessary, b 13. 6. 6 – If the microswitch does not function although it was actuated, then the switchgear must be replaced, b 8. 4 MS 241 C 71 2410RA221 TG Versions with heating 1 3 2 2410RA225 TG 2410RA227 TG 1 2 2410RA223 TG 1 : Push the new fuel suction hose (1) completely onto the connectors (arrows) : Push the holder (1) with the ground wire (2) into the recess in the air guide shroud (3) as far as it will go : Push ground wire (2) into the guide (arrow) : Push blade receptacle (1) onto the connector tab – Push on blade receptacle all the way : Press lead (2) completely into the guide (arrow) of the filter base – Reassemble remaining parts in reverse order 8. 2. 4 Versions with manual fuel pump Checking the solenoid valve 2 2 1 2410RA224 TG 2410RA226 TG – Carry out test preparations, b 8. 2. 1 – Check screwed and plug connections, b 8. 2. 3 – Check contacts and operation, b 8. 2. 5 – Move the Master Control lever to position "F" – Connect the test lead, b 8. 2. 2 1 : Push contact sleeve (1) into heating switch – Push in contact sleeve completely 3 : Push the holder (1) with the fuel pump into the recess in the air guide shroud (2) as far as it will go : Press fuel return line (3) completely into the guide (arrow) : Press lead (2) completely into the guide (arrow) 72 MS 241 C Measuring resistance 1 2 1 2410RA222 TG 2410RA166 TG 1 2 2410RA228 TG : Measure resistance between plugs (1) and (2) of the M-Tronic test lead Target value: between 28 and 42 ohms – If the target value is not attained, check electrical leads for interruption, e. g. , due to cable breakage between solenoid valve and diagnostic jack, or contact due to damaged insulation : Set Master Control lever (1) to position }; the cam on the lever (2) must actuate the microswitch (arrow) – clicking sound : Lift retaining tab (arrow) and remove angled plug (1) – Check angled plug, dismantle and clean if necessary, b 7. 7. 2 – Set Master Control lever to position } – Connect the test lead, b 8. 2. 2 Versions with manual fuel pump – Push out the holder with the fuel pump and set it aside, b 8. 2. 3 Versions with heating – Disconnect leads, push out the holder with the heating switch and set it aside, b 8. 2. 3 8. 2. 5 Checking the start detection function All versions – Carry out test preparations, b 8. 2. 1 – Check screwed and plug connections, b 8. 2. 3 1 2410RA229 TG 2 : Disconnect the plug (1) from the solenoid valve (2) – the solenoid valve must not be twisted; if necessary, hold the solenoid valve in place when disconnecting the plug MS 241 C 73 2 Versions with manual fuel pump – Install holder with fuel pump, push new fuel hose onto connector and press fuel return line into the guide, b 8. 2. 3 2410RA230 TG Checking the ground connection 2 Versions with heating – Install holder with heating switch, press leads in and on and into the guides, b 8. 2. 3 – Reassemble remaining parts in reverse order – Connect M-Tronic test lead to multimeter : Insert black plug (1) in the "com" / "ground" jack and the red plug (2) in the "volt" / "ohm" jack – Set multimeter to "diode test" : Test diode on switchgear (3) (microswitch) in accordance with multimeter instruction manual If the switchgear (microswitch) is intact and the Master Control lever is set to the } position, the following target values will be attained: – Measurement in direction of flow, target value: 0. 3 volts to 0. 7 volts – Move the Master Control lever to position F – Measurement in direction of flow, required: 1. 2 volts to infinity – Observe display, e. g. , (O. L. ) or (1. ) – If the required values are not attained, replace switchgear and repeat test procedure, b 8. 4 – If the required values are not attained again, replace wiring harness; it may be possible to reuse the previous switchgear, b 7. 7. 2 : Measure the resistance between blade receptacle (1) with black lead and screw (2) at the control unit Target value: < 10 ohms. 8. 2. 6 Checking the wiring harness – Carry out test preparations, b 8. 2. 1 – Check contacts and operation, b 8. 2. 3 – Set Master Control lever to position STOP 0 2 1 : Measure the resistance between contact spring (1) and screw (2) at the control unit 1 2410RA166 TG Target value: < 10 ohms. If the target values are not attained – Check electrical leads for interruption, e. g. , cable breakage – if necessary, replace wiring harness, b 8. 2. 6 : Lift retaining tab (arrow) and remove angled plug (1) – Check angled plug, dismantle and clean if necessary, b 7. 7. 2 74 MS 241 C 2410RA232 TG 2410RA231 TG 1 3 1 Check leads between control unit and diagnostic jack – Connect the test lead, b 16 2 – Check continuity between leads and blade receptacles – Blade receptacles must be firmly connected to the leads; in the event of contact problems, the wiring harness must be replaced, b 8. 2. 3, b 8. 2. 6 Target value: < 10 ohms 1 1 2410RA233 TG – Connect the test lead, b 8. 2. 2 – Versions with manual fuel pump, remove fuel pump and set it aside, b 8. 2. 3 2 : Measure the resistance between blade receptacle (1) with red lead and black plug (2) of the diagnostic cable Target value: < 10 ohms. : Measure the resistance between black lead (1) at the plug of the solenoid and red plug (2) of the diagnostic cable Target value: < 10 ohms If the target values are not attained 1 2410RA229 TG 2 2 1 2410RA234 TG – Check contact surfaces on plug of the plug connection, as well as checking electrical leads for interruption, e. g. , cable breakage – If the contact surfaces on the plug are damaged in the plug connection between wiring harness and switchgear, the wiring harness must be replaced, b 7. 7. 2, if the contacts in the jack are damaged, the switchgear must be replaced, b 8. 4 – Reassemble remaining parts in reverse order : Disconnect the plug (1) from the solenoid valve (2) – the solenoid valve must not be twisted; if necessary, hold the solenoid valve in place when disconnecting the plug : Measure the resistance between blade receptacle (1) with black lead and red plug (2) of the diagnostic cable Target value: < 10 ohms. If the target values are not attained – Check contact between blade receptacle of the switch shaft and contact spring 1 2 : Measure the resistance between red lead (1) at the plug of the solenoid and black plug (2) of the diagnostic cable MS 241 C 2410RA235 TG 75 2410RA236 TG Check leads between solenoid valve and diagnostic jack 8. 3 Wiring harness Versions with heating All versions – The M-Tronic leads and the ground wire are all combined into one wiring harness; removal and installation are described in the chapter "Short-circuit wire", b 7. 7. 2 1 1 2410RA240 TG 8. 4 Switchgear : Remove blade receptacle (1) : Remove heating element (2) from the studs – Remove shroud, b 6. 4 – Remove the air filter, b 13. 1 – Check switchgear, b 8. 2. 5 – Remove choke rod, b 11. 4 – Remove baffle, b 13. 2 – Remove filter base, b 13. 3 : Pull plug connector (1) out of the carburetor support mount (arrow) 2 Versions with manual fuel pump 1 1 1 : Disconnect the fuel hose (1) 2410RA239 TG 2 : Pull holder (1) of the switchgear over the studs (arrows) and lay it aside 1 : Push out the holder (1) with the fuel pump on the air guide shroud (2) and lay it on top of the air guide shroud 76 2410RA242 TG 2410RA241 TG : Hold the jack (1), press the tab (arrow) and pull out the plug (2) – do not tug on the leads MS 241 C 2410RA172 TG 2410RA243 TG 2 1 2 1 2 2410RA244 TG 2410RA247 TG 3 The fuel hose does not have to be removed from the carburetor support. : Carefully pull out the carburetor with the fuel hose over the studs and lay it aside – do not overextend the fuel hose : Pull the wiring harness (1) out of the guide (arrow) and pull it out between the special bolt (2) and the starter shaft (3) : Check lever on the starter shaft (3), replace if necessary, b 13. 6. 6 : Orient plug (1) so that the guide pin (arrow) faces the carburetor : Push the plug (1) into the jack of the solenoid (2) as far as it will go 1 2 Installation With a new switchgear, first the leads must be inserted in the guides of the switchgear. Leads and plug connections must not be damaged. 2410RA245 TG 3 2 : Turn the throttle shaft lever (1) slightly in the direction of fullthrottle, then turn the starter shaft (2) until the choke shutter is closed : Orient wiring harness (1) so that the red lead runs underneath the black lead 2 1 3 2410RA248 TG Choke shutter must be closed. [. . . ] : Press the leads of the handle heating and the wiring harness into the guide (arrows) – Reassemble remaining parts in reverse order : Clip one test lead to the terminal socket (1) of the thick connecting lead and the second to the contact sleeve of the heating switch If the heating element is intact, the ohmmeter will indicate a value of approx. 6. 4 Ω (reading 6. 0. . . 8. 0 Ω) in the measuring range "Ω". If the reading obtained is outside this tolerance, then the front handle (front handle heating element) must be checked directly at the connecting leads. – Disconnect plug connections at the front handle, b 10. 4. 1 14. 6 Heating element in front handle The heating element in the front handle cannot be replaced. [. . . ]