Stihl 4141 Series Manual Download Page 43

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Series 4141 Powerhead

Summary of Contents for 4141 Series

Page 1: ......

Page 2: ...Replacing the Main Bearings 21 5 8 3 Installing the Crankshaft 23 6 Ignition System 24 6 1 Spark Plug Boot 24 6 2 Ignition Module 25 6 2 1 Ignition Timing 25 6 2 2 Removing and Installing 26 6 3 Flywheel 26 7 Rewind Starter 27 7 1 General 27 7 2 Removing and Installing the Rewind Starter 28 7 3 Starter Cup 28 7 4 Rewind Spring 28 7 4 1 Replacing 28 7 4 2 Tensioning 30 7 5 Starter Rope 30 8 Throttl...

Page 3: ...plement the parts list until a revised edition is issued The special servicing tools mentioned in the descriptions are listed in the last chapter of this manual Use the part numbers to identify the tools in the STIHL Special Tools manual The manual lists all special servicing tools currently available from STIHL Symbols are included in the text and pictures for greater clarity The meanings are as ...

Page 4: ...ions and warnings in the owner s manual Gasoline is an extremely flammable fuel and can be explosive in certain conditions Improper handling may result in burns or other serious injuries Warning Do not smoke or bring any fire flame or other source of heat near the fuel All work with fuel must be performed outdoors only Spilled fuel must be wiped away immediately 2 Safety Precautions ...

Page 5: ...s needle cages on small and big ends 8 mm 0 315 in Centrifugal clutch with linings 4 100 200 rpm 0 5 bar 7 25 psi 0 5 bar 7 25 psi 3 2 Ignition System Type Air gap Spark plug Electrode gap Transistorized magneto ignition breakerless with integral trigger unit 0 25 mm 0 010 in NGK CMR 7A 0 5 mm 0 020 in 3 3 Fuel System Carburetor Idle setting Carburetor leakage test at gauge pressure Fuel tank capa...

Page 6: ...r flange 2 6 3 5 Spline screw IS DG5x24 Gear housing drive tube 6 6 9 Spline screw IS M5x16 Shroud rewind starter crankcase 3 4 Spline screw IS M5x16 Shroud clutch housing crankcase 3 4 Spline screw IS M5x8 Sleeve setscrew 3 4 Spline screw IS M5x30 Sleeve tube clamp 4 4 6 Spline screw IS M6x35 Clamp molding clamp bike handle 3 3 4 5 Collar screw M6x22 Clutch flywheel 7 5 10 with washer Spline scre...

Page 7: ... rotate it counterclockwise until it drops down slightly Tighten the screw clockwise to the specified torque This procedure ensures that the screw engages properly in the existing thread and does not form a new thread and weaken the assembly Note Power screwdriver settings for polymer Plastoform screws max 600 rpm DG screws max 500 rpm ...

Page 8: ... the remaining wall thickness If it is less than about 80 of the original thickness fit a new clutch drum see 4 3 VA 145RA006 80 100 Remove the spark plug Fit the locking screw 1 4170 893 1200 in the spark plug hole Turn the crankshaft counterclockwise until the piston butts against the locking screw VA 380RA006 1 Take out the screws 1 and remove the clutch Remove the spacer washers from between t...

Page 9: ...ousing making sure the pegs 1 engage the holes 2 in the crankcase VA 380RA009 2 1 Insert screws in crankcase and tighten down to 6 Nm 4 4 lbf ft Install the shroud check that electrical wires are properly routed and fit the spark plug boot VA 380RA004 Fit throttle cable connect electrical wires in control handle Remove clutch drum with housing see 4 1 Release and remove screws VA 380RA066 Pull out...

Page 10: ...ch drum ball bearing from the outside inwards Note Take care not to damage guide pegs on clutch housing during VA 380RA071 1 removal process Use press arbor 1 4116 893 7205 to install the new bearing Secure bearing in position with circlip VA 380RA072 1 Press home the clutch drum 2 with assembly drift 1 1110 893 4700 Install the circlip Reassemble in the reverse sequence VA 380RA073 1 2 4 3 1 Repl...

Page 11: ...e clutch shoes together in the direction of the arrows VA 380RA075 Important Check installed position of spring The arrows on the clutch shoes face upwards Install the clutch shoes and clutch housing see 4 2 Remove screws 1 and 2 from rewind starter VA 380RA001 2 1 Pull off the spark plug boot VA 380RA002 Take out screw 1 on clutch housing Lift away the shroud and slip the spark plug boot through ...

Page 12: ... down first Spark arresting screen Remove shroud see 5 1 Use screwdriver to pry stub out of muffler outlet Remove the stub Clean the spark arresting screen VA 380RA010 or fit a new stub with screen if necessary Exhaust muffler Remove shroud see 5 1 Remove screws arrows from mufler 1 Remove exhaust gasket 2 and VA 380RA011 1 2 fit a new one Reassemble in the reverse sequence Tighten down muffler sc...

Page 13: ...ease muffler mounting screws 2 and back them off half way Slide the sealing plate 1 0000 855 8106 between the gasket and cylinder and retighten the mounting screws moderately VA 380RA015 2 1 Note The sealing plate must completely fill the space between the two screws Connect pressure hose 2 of tester 1106 850 2905 to nipple on test flange 1 VA 380RA014 2 1 Close the vent screw 1 on the rubber bulb...

Page 14: ...ed vacuum replace the oil seals impulse hoses 1 and or the diaphragm carriers 2 on the right and left of the cylinder VA 380RA103 1 2 1 In order to exclude the influence of the impulse hoses on the leakage test use hose 2 4203 708 9506 to connect the two diaphragm carriers 1 together Repeat the test with this setup VA 380RA013 1 2 If a leak is still indicated check for damage in the area of the cy...

Page 15: ...Installing oil seal at flywheel side Inspect crankshaft running face for scores Clean sealing face in the crankcase and lubricate lip of oil seal with grease see 11 VA 380RA020 1 2 3 Fit installing sleeve 2 1129 898 4600 over the crankshaft Slip the oil seal 3 over the crankshaft and against the crankcase Important Note installed position Closed side of oil seal faces the flywheel Use the press sl...

Page 16: ... crankshaft running face for scores Clean sealing face in the crankcase and lubricate lip of oil seal with grease see 11 Installing oil seal at starter side Fit installing sleeve 2 1129 898 4600 over the crankshaft Slip the oil seal 3 over the crankshaft and against the crankcase VA 380RA023 1 3 2 Important Note installed position Closed side of oil seal 3 faces the rewind starter Use press sleeve...

Page 17: ...e hoses 1 replace porous or torn hoses VA 380RA024 2 4 3 1 Replacing gaskets on intake stubs Note The cylinder has to be disassembled to remove the diaphragm carriers Take out the cylinder mounting screws 2 Raise the cylinder 1 slightly and slide the wooden assembly block 3 1108 893 4800 under the piston Lift away the cylinder VA 380RA025 1 2 3 Take out the screws 1 and remove the diaphragm carrie...

Page 18: ...see 5 2 Use combination wrench 4141 890 3400 to take out the spark plug Remove the ignition module see 6 2 2 Remove air filter carburetor and components of mixture supply system see 9 1 9 2 and 5 5 Take out the cylinder mounting screws 3 and raise the cylinder 2 slightly Slide the wooden assembly block 5 1108 893 4800 under the piston Lift away the cylinder 2 VA 380RA030 2 3 5 4 1 If a new cylinde...

Page 19: ...grooves see 5 7 Clean the gasket seating surface on the crankcase so that it looks bright Fit cylinder gasket 4 the word FAN faces up arrow points to flywheel VA 380RA035 3 2 1 4 Set connecting rod to top dead center Lubricate the needle bearing 3 with oil and fit it in the small end Fit cover washers 1 on either side of small end flat sides facing outwards to piston Place the wooden assembly bloc...

Page 20: ...fixing pin in the piston groove see 5 7 Lubricate piston and piston rings with oil and rest the piston on the wooden assembly block 2 VA 380RA028 2 1 1108 893 4800 Note Lubricate the inside of the cylinder with oil and line it up so that it is positioned as it will be in the installed condition It is important to observe this point as the piston rings might otherwise break Use clamping strap 1 000...

Page 21: ...nition module components of mixture supply system and the carburetor from the cylinder Disconnect the fuel hoses arrows from the carburetor and plug them Clean area around carburetor so that no dirt can fall into crankcase VA 380RA039 Take out cylinder mounting screws 1 and lift away cylinder 2 complete with attached components VA 380RA040 2 1 Place wooden assembly block 1108 893 4800 2 under the ...

Page 22: ...crankcase VA 380RA042 The crankshaft 1 connecting rod 2 and needle bearing are an inseparable assembly It must always be replaced as complete unit When fitting a replacement crankshaft always install new VA 380RA043 1 2 ball bearings and oil seals see 5 4 Replacing main bearing at flywheel side Carefully pry the oil seal 1 out of the crankcase VA 380RA044 1 Use circlip pliers to remove circlip fro...

Page 23: ...g at starter side Carefully pry the oil seal 1 out of the crankcase VA 380RA049 1 Use press sleeve 1 4112 893 2401 1 to press the ball bearing out of the crankcase Note Ball bearing is pressed out from the starter side of the crankcase VA 380RA050 1 Heat bearing seat on starter side of crankcase to about 120 C 250 F Fit the ball bearing 2 by hand from inside the crankcase and push it home as far a...

Page 24: ...ust engage holes in flywheel VA 380RA054 side of crankcase Insert screws from flywheel side of crankcase and tighten down to 10 Nm 7 5 lbf ft Install oil seals see 5 4 VA 380RA042 Fit the fuel tank see 9 8 1 Install the piston see 5 6 2 Note Cylinder is installed later Slide wooden assembly block 2 1108 893 4800 under the piston and rest piston 1 on it Fit the Woodruff key Important Clean cranksha...

Page 25: ...ok Note The electronic breakerless ignition system basically consists of the ignition module 1 and flywheel 2 VA 380RA055 2 1 Remove the shroud see 5 1 Use suitable pliers to grip the spring and pull it out of the spark plug boot Unhook the leg spring from the ignition lead VA 380RA076 Slip the spark plug boot off the ignition lead Push back insulating tube and coat end of the ignition lead about ...

Page 26: ...nition module is only possible with special test equipment For this reason it is only necessary to carry out a spark test in the workshop A new ignition module must be installed if no ignition spark is obtained after checking that wiring and stop switch are in good condition Ignition timing is not adjustable Since there is no mechanical wear in these systems ignition timing cannot get out of adjus...

Page 27: ... Place the module 2 with spacer washers in position insert screws 1 but do not tighten them down yet VA 380RA058 2 1 3 Secure the ground wire to the left mounting screw Slide the setting gauge 3 1111 890 6400 under the arms of the ignition module rotate flywheel so that magnets face the module Press the ignition module against the setting gauge and tighten the screws to 5 Nm 3 7 lbf ft Remove the ...

Page 28: ...d the rope rewinds very slowly or not com pletely it can be assumed that the starter mechanism is in order but plugged with dirt At very low outside temperatures the lubri cating oil on the rewind spring may thicken and cause the spring windings to stick together This has a detrimental effect on the function of the starter mechanism In such a case it is sufficient to apply a few drops of paraffin ...

Page 29: ... Troubleshooting chart see Standard Repairs Trouble shooting handbook Remove the shroud see 5 1 Remove the rewind starter see 7 2 Note The rewind spring will not be under tension if the starter rope is broken To relieve tension pull out the starter rope a few centimeters Hold the rope rotor steady Use assembly hook 1 5910 890 2800 1 to make loop starter rope While still holding rope rotor 2 steady...

Page 30: ...ew drops of STIHL special lubricant before installation see 11 VA 392RA073 Fit rewind spring 1 in the rope rotor so that the anchor loop 2 engages the recess 3 The wire retainer slips off during installation Caution The rewind spring may pop out and 1 3 2 VA 380RA106 uncoil during installation If the rewind spring has popped out see Standard Repairs Trouble shooting handbook Fit rope rotor in star...

Page 31: ...le to rotate the rope rotor at least another half turn before maximum spring tension is reached If this is not the case pull the rope out hold the rope rotor steady and take off one turn of the rope Do not overtension the rewind spring as this will cause it to break Install the rewind starter see 7 2 It is not necessary to remove the rope rotor to replace the starter rope Remove the rewind starter...

Page 32: ...le 392RA084 VA 1 Lift the interlock lever 1 slightly and turn it to one side until the torsion spring 2 is relaxed Pull the interlock lever and torsion spring off the peg 392RA085 VA 1 2 Take the throttle trigger 1 with torsion spring 2 and throttle cable 3 off the peg 392RA087 VA 1 2 3 Disconnect throttle cable from trigger Reassemble in the reverse sequence Pay attention to the following points ...

Page 33: ... the throttle cable see 8 3 Note Throttle lever 1 must butt against the stop 3 when throttle trigger is squeezed full throttle Throttle lever must butt against the low speed screw 2 stop screw when the trigger is in the idle position 4 VA 380RA080 3 1 2 The throttle cable is adjusted by moving the tensioning sleeve 4 Adjust idle speed correctly see 9 5 Throttle lever must butt against the low spee...

Page 34: ...e is a noticeable loss of engine power Close the choke shutter Clean away any loose dirt from around the air filter and filter cover Release the screw 1 and lift away the filter cover VA 380RA081 1 Take out the filter mat foam element 1 and prefilter wire mesh 2 VA 380RA082 2 1 Wash the filter mat and prefilter in a fresh non flammable cleaning solution e g warm soapy water and dry them Note Repla...

Page 35: ...380RA083 Close vent screw 1 on rubber bulb Use rubber bulb to pump air into the carburetor until gauge indicates a pressure of 0 8 bar 11 5 psi VA 143RA046 1 If this pressure remains constant the carburetor is airtight However if the pressure drops there are two possible causes 1 The inlet needle is not sealing foreign matter in valve seat or sealing cone of inlet needle is damaged or inlet contro...

Page 36: ...3 Servicing the carburetor includes the replacement of all gaskets and diaphragms The gasket kit contains all the parts required Clean exterior of carburetor VA 380RA085 Release and remove screws on the underside of the carburetor Disassemble parts of manual fuel pump 1 End cover with cap bulb 2 Flange with valve 3 Metering diaphragm 4 Gasket VA 380RA086 1 2 3 4 5 6 7 5 Spacer flange with inlet ne...

Page 37: ...sealing cone of the inlet needle it will be necessary to replace the inlet needle because it will no longer seal properly Fit the inlet needle Fit helical spring 1 in the hole Insert spindle 2 in the inlet control lever 3 Engage clevis of inlet control VA 380RA090 1 2 3 lever in annular groove on the head of the inlet needle Press down the inlet control lever and secure it with the screw Note Make...

Page 38: ...might break Installing the jet with a punch damages the jet body The carburetor is designed to provide an optimum fuel air mixture in all engine operating conditions Standard setting Mount the cutting attachment On nylon line heads Check that length of cutting line is correct Each cutting line must reach as far as line limiting blade on the deflector Check the air filter and clean if necessary Ins...

Page 39: ...ests on the fuel tank via the fuel hoses Disconnect both fuel hoses from the carburetor Seal one fuel hose with a suitable plug Perform pressure or vacuum test on tank via the other fuel hose VA 380RA094 1 Equalization of pressure from the outside inwards takes place via the valve 1 There must be no build up of pressure or vacuum in the tank In case of malfunction install a new valve The diaphragm...

Page 40: ...reverse sequence Drain the fuel tank Remove the filter cover and filter elements see 9 1 Pull fuel hoses off the carburetor elbow connectors VA 380RA039 Take out screws on fuel tank and lift away the tank Remove the fuel hoses if necessary Reassemble in the reverse sequence VA 380RA098 Unscrew the filler cap and remove together with retainer Pull fuel hoses with rubber grommet 1 out of tank Instal...

Page 41: ...Crankcase leakage test 12 Hose 4203 708 9506 Connecting diaphragm valves for leakage test 13 Puller 4112 890 4502 Removing flywheel 14 Puller 5910 890 4400 Universal puller Jaws No 6 Removing oil seals 15 Installing sleeve 1129 898 4600 Installing oil seal 16 Press sleeve 4112 893 2401 Installing oil seals and ball bearings 17 Wrench 4141 893 1300 Removing starter cup 18 Press sleeve 4119 893 2400...

Page 42: ...rinated or halogenated hydrocarbons Cleaning crankshaft stub 3 STIHL special lubricant 0781 417 1315 Bearing bore in rope rotor rewind spring 4 Electrical repair kit 5910 007 1050 Electrical system Part Name Part No Safety glasses STIHL gear lubricant for brushcutters 80 g 2 8 oz tube 225 g 8 oz tube 0781 120 1117 0781 120 1118 Stihl Getriebefett für Heckenscheren 80 g 2 8 oz tube 225 g 8 oz tube ...

Page 43: ...42 Series 4141 Powerhead ...

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