Stihl FC 75 User Manual Download Page 35

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Dirty and clogged air filters reduce
engine power, increase fuel con-
sumption and make starting more
difficult.

The air filter must be cleaned
whenever engine power begins to
drop.

- Close choke shutter.

•

Press tab on filter housing back-
wards.

•

Remove filter cover.

- Clean away all loose dirt around

air filter.

•

Remove foam filter (1) and felt
filter (2).

- Wash foam filter in dry, non-flam-

mable liquid (e.g. warm soapy
water) and dry it.

- The felt filter must be replaced!

It can also be cleaned by tapping
or blowing - it must not be
washed.

Note: Damaged parts must be
replaced immediately.

The parts are installed in reverse
order.

- Place foam filter in filter cover.

•

Place felt filter (with marking in-
side and tab outside) in filter
housing.

•

The nose on the filter housing
must engage in the opening in
the filter cover.

Refer to the manual "Trouble-
shooting, standard repairs" for
troubleshooting procedures.

Important! The tank vent must
also be checked and cleaned -

see 8.3

- if faults develop in the

carburetor or fuel supply.

The carburetor can be tested for
leaks with the carburetor and
crankcase tester 1106 850 2905.

- Remove shroud,

see 3.1.

•

Pull fuel hose off elbow
connector.

•

Connect fuel line (1)
1110 141 8600 onto socket (2)
0000 855 9200.

392RA104

392RA106

Innen

INSIDE

FACE INTERNE

392RA107

392RA108

143RA172

392RA105

Summary of Contents for FC 75

Page 1: ... carrier pawl 30 7 Throttle control 31 7 1 Throttle trigger interlock lever throttle cable with one short circuit wire 31 7 2 Throttle cable with one short circuit wire 32 7 3 Contact spring detent spring in control handle throttle cable with one short circuit wire 33 7 4 Throttle trigger interlock lever throttle cable with two short circuit wires 33 7 5 Throttle cable with two short circuit wires...

Page 2: ...Information sheets supp lement the parts list until a new edi tion is published The special tools mentioned in the text are listed in the last chapter of this manual The tools can also be identified in the manual of STIHL tools on the basis of their part number The manual lists all the tools supp lied by STIHL The following graphic symbols are used in the text and illustrations in order to make th...

Page 3: ...00 mm long Clutch Centrifugal clutch without linings Diameter 66 5 mm Clutch engages at 3700 rpm Crankcase leakage test at gauge pressure 0 5 bar under vacuum 0 5 bar 2 2 Fuel system Carburetor Diaphragm carburetor with one or two adjusting screws Standard setting for carburetors with two adjusting screws High speed adjusting screw H Back off approx 1 turn Low speed adjusting screw L Back off appr...

Page 4: ...fore TDC at n 8000 rpm Spark plug suppressed Bosch WSR 6F NGK BPMR 7 A or Champion RCJ 6Y Electrode gap 0 5 mm Spark plug thread M14 x 1 25 Length of thread 9 5 mm 2 4 Gearbox Type Helical toothed bevel gears Gear ratio 1 4 1 24 Bearing Deep groove ball bearing Lubrication STIHL gear lubricant FS 75 only has a bearing housing FS 80 85 FC 75 4 ...

Page 5: ...10 3 mowing head STIHL Polycut 20 3 STIHL Polycut 20 3 mowing head mowing head Grass cutting blade Grass cutting blade 230 4 230 4 Grass cutting blade Grass cutting blade 230 8 230 8 Brush knife 250 3 Circular saw blade 200 scratcher tooth Circular saw blade 200 chisel tooth Blade Some cutting attachments may not be available in some countries on account of the different conditions prevailing in e...

Page 6: ...al cutting tools STIHL multi purpose grease 80 g tube 0781 120 1109 STIHL gear lubricant 80 g tube 0781 120 1117 2 6 2 For service Carburetor parts kit for Walbro carburetor WT 447 4133 007 1060 Carburetor parts kit for Zama carburetor C1Q S28A 4227 007 1060 Gasket panel DIN A3 0457 281 4003 6 ...

Page 7: ... 5 Spline screw IS M5x16 Shroud starter cover 3 5 M8 Clutch 21 0 M8 Starter carrier 20 0 M14x1 25 Spark plug 20 0 Plastoform screw IS P5 5x12 Rope rotor in starter cover 3 5 Spline screw IS M5x16 AV sleeve clamping screw 5 5 Spline screw IS DG5x12 AV sleeve protective tube 2 5 Nut M5 Filter housing carburetor 4 0 Spline screw IS M5x18 Clamping collar bearing housing 6 5 2 Self tapping screw IS B3 ...

Page 8: ...uts bolts M5 All others 4 5 Spline screw IS M4x16 Gearbox cover gear housing 3 5 5 Spline screw IS M5x20 Blade guide gear housing 9 5 5 Spline screw IS M5x20 Gearbox gear housing 9 5 5 Nut M5 Blade 9 5 5 Screw plug M11x10 Gearbox cover 5 5 5 When inserting the DG and P type screws in an existing thread Insert the DG or P type screw in the hole and turn it anticlockwise until it gently drops into t...

Page 9: ...signs of ex cessive wear Important The remaining wall thickness must be measured if the inside diameter is distinctly worn A new clutch drum must be fitted see 11 4 if the wall thickness has declined to less than 80 of the original value Disconnect spark plug terminal 1 Remove spark plug 2 Insert the locking strip 1 0000 893 5903 in the cylinder 3 Clutch 3 1 Disassembly 1 1 2 2 392RA003 VA 392RA00...

Page 10: ...f necessary Position motor on fan housing ensuring that stubs 1 engage in inlays 2 Insert screws in fan housing and torque down to 5 5 Nm Remove locking strip from cylinder Screw in spark plug and torque down to 20 Nm Important Check that the separa te connecting nut is securely loca ted on the screw thread of spark plugs with separate nut and tighten the nut if necessary Reconnect spark plug term...

Page 11: ...l Tighten muffler screws to a torque of 9 5 Nm Refit shroud Defective oil seals and gaskets or cracks in castings cause leaks Such faults allow supplementary air to enter the engine and thus impair the fuel air mixture This makes adjustment of the specified idle speed difficult if not impossible It also prevents a smooth transi tion from idle speed to part or full throttle The crankcase can be tho...

Page 12: ...ust port and lightly retighten inner screws Note The sealing plate must fill the space between the mounting screws completely Carry out preparatory steps see 4 2 1 Slide pressure hose of tester 1106 850 2905 over nipple on test flange Close vent screw 1 on rubber bulb Pump air into crankcase with rubber bulb until pressure gauge indicates a pressure of 0 5 bar The crankcase is airtight if this pre...

Page 13: ...ernal coun terpressure Faults of this kind can be detected with the aid of a vacuum pump The preparations are the same as for the pressure test see 4 2 2 Connect suction hose of vacuum pump 0000 850 3501 to nipple of test flange Close vent screw 1 on pump cylinder Actuate lever 2 until pressure gauge 3 indicates a vacuum of 0 5 bar Note The oil seals are in good condition if the indicated vacuum i...

Page 14: ...he press sleeve 1 4112 893 2401 Fit flywheel see 5 3 Starter side Remove starter carrier see 6 6 Lightly tap the oil seal with a suitable tube or punch to knock it out of its seat Fit puller 1 5910 890 4400 jaws 0000 893 3706 with profile No 3 1 Tension legs Pull out oil seal Important The crankshaft stub must not be damaged Clean the sealing area with com mercially available solvent based degreas...

Page 15: ... cable from tensioner Remove screws Remove spacer flange and gasket Pull screws 1 out of spacer flange if necessary Loosen screw 2 and remove with bushing Draw tensioner 3 off spacer flange Remove adjusting screw from tensioner The parts are assembled in rever se order Insert screw 1 with bushing 2 Use a new self locking nut for the screw Use a new gasket Tighten down the screws of the spacer flan...

Page 16: ... assembly drift 2 1114 893 4700 Note If the piston pin is stuck it can be loosened by lightly tap ping the assembly drift with a ham mer The piston must be held steady during this process to en sure that no jolts are transmitted to the conrod Remove piston from conrod and draw needle cage out of small end Check piston rings and replace if necessary see 4 6 Thoroughly clean sealing area 1 Wet needl...

Page 17: ...r gasket Lightly oil the piston and piston rings and rest the piston 1 on the wooden assembly block 2 1108 893 4800 Line up the piston rings so that the radii at the ring gap meet at the fixing pin in the piston groove Use clamping strap 1 0000 893 2600 to enclose piston and piston rings Ensure that piston rings are positioned correctly Coat inside of cylinder with oil and line it up in accordance...

Page 18: ...to enter the crankcase when fitting the piston rings and or cleaning the grooves Remove piston rings from piston Scrape the grooves clean with a piece of old piston ring Fit the new piston rings in the grooves so that the radii face upwards Install piston see 4 5 2 Remove cylinder see 4 5 1 Unscrew starter carrier from crankshaft stub Unscrew clutch from crankshaft stub Pull flywheel off crankshaf...

Page 19: ...5 can be modi fied as illustrated above The diagram shows the perforated disk as seen from below Turn spindle 1 anticlockwise until the crankshaft has been forced out of the deep groove ball bearing This also causes the two halves of the housing to come apart Place sleeve 1 5910 893 170 30 mm and sleeves 2 5910 893 1702 35 mm over the holes on the clutch side half of the housing Position assembly ...

Page 20: ...h press arbor 1 4119 893 7200 Examine both halves of the crankcase for cracks and replace them Both halves of the crankcase can be replaced if the crankcase is da maged Each half of the crankcase is supp lied with fitted deep groove ball bearing If the original crankcase is used again remove the gasket residues and clean the mating surfaces The mating surfaces must be ab solutely clean to ensure a...

Page 21: ...ng must be pres sed in very quickly as it imme diately absorbs heat and begins to expand If the clutch side of the crank case cannot be heated press the deep groove ball bearing in as far as possible with press arbor 1 4119 893 7200 Insert the shorter stub of the crankshaft into the deep groove ball bearing on the starter side of the crankcase Completely screw spindle 1 of assembly tool 5910 890 2...

Page 22: ...ns Slide the clutch side half of the housing over crankshaft stub Hold crankshaft and screw spind le 1 onto crankshaft stub 2 turning clockwise as far as possible Hold spindle and turn sleeve anticlockwise until it rests against the deep groove ball bearing Hold sleeve and turn spindle clockwise until the two halves of the housing have come together Remove the assembly tool Turn in screws and tigh...

Page 23: ...always start with the spark plug Refer to the ma nual Troubleshooting standard repairs Note The transistorized breaker less ignition system essentially comprises the ignition module 1 and flywheel 2 Remove shroud see 3 1 Pull terminal off spark plug Grip leg spring with pliers and pull it out of the spark plug termi nal Unhook leg spring from ignition lead Slip spark plug terminal off lead Coat en...

Page 24: ...ircuit wire 3 Ground lead 4 Accurate testing of the ignition module is only possible with test equipment Only a spark test should therefore be carried out in the workshop The complete igni tion module must be replaced if an ignition spark is not obtained although wiring and stop switch are intact The ignition timing is fixed and cannot be adjusted Since there is no mechanical wear in these systems...

Page 25: ... The ignition lead is em bedded in the ignition module Position ignition module and insert screws but do not tighten them yet Secure ground wire 1 and connector tab 2 for short circuit wire to upper screw Important One plastic washer 3 must be fitted on the upper and lower screw between cylinder and ignition module Slide setting gauge 1 4118 890 6401 between arms of ignition module and flywheel ma...

Page 26: ...ghtly tap the end of the puller with a hammer Unscrew the puller when the flywheel has loosened Flywheel 1 and magnet poles 2 must not be cracked or damaged otherwise a new flywheel must be fitted Installing the flywheel Important Degrease the crank shaft stub and bore of the flywheel hub with commercially available solvent based degreasing agent not containing CFCs or halocar bons see 13 2 Fit fl...

Page 27: ... The entire starter mechanism in cluding rewind spring must be re moved and disassembled if clog ged with dirt or pitch Special care must be exercised when removing the spring All parts must be washed in paraf fin or white spirit The rewind spring and starter post must be lubricated with STIHL special lubricant see 13 2 before being installed Remove shroud see 3 1 Remove screws Remove starter cove...

Page 28: ... looking down onto the recesses The loop slips off when the spring is installed Important The rewind spring may pop out if not installed correctly Refer to the manual Trouble shooting standard repairs if the rewind spring pops out Install rope rotor see manual Troubleshooting standard repairs Tension rewind spring see 6 3 2 Install starter cover see 6 2 Form the starter rope into a loop Press star...

Page 29: ... If not pull the rope out hold the rope rotor stea dy and take off one turn of the rope The rewind spring may break if overtensioned Install starter cover see 6 2 Remove starter cover see 6 2 Remove starter rope from rope rotor see manual Troubleshoo ting standard repairs Prise cap out of starter grip Pull rope out of starter grip Guide end of new rope through starter grip from below Secure end of...

Page 30: ...r Press end of rope into locating slot Install rope rotor see manual Troubleshooting standard repairs Tension rewind spring see 6 3 2 Install starter cover see 6 2 Block piston with the aid of the locking strip see 3 1 Remove starter cover see 6 2 Unscrew starter carrier from crankshaft stub Remove pawl see manual Trou bleshooting standard repairs Screw on starter carrier and tighten to a torque o...

Page 31: ...rsion spring Pull throttle trigger 1 with tor sion spring 2 and fitted throttle cable 3 off its pivot pin Unhook throttle cable from throttle trigger The parts are assembled in rever se order After hooking in the throttle cable slip torsion spring over pi vot pin and slide the long leg of the spring into the slot The interlock lever must lie behind the throttle trigger Screw both halves of the han...

Page 32: ...ctive tube on throttle cable from throttle cable holder Remove throttle trigger see 7 1 Slightly pull up contact spring 1 and remove throttle cable 2 The parts are assembled in rever se order Ensure that throttle cable 1 contact spring 2 protective tube 3 and insulating element 4 are correctly seated Ensure that short circuit wire makes contact correctly 392RA091 2 1 VA 392RA057 VA 392RA092 2 VA 1...

Page 33: ...Pull slide control out of handle moulding The parts are assembled in rever se order The contact spring must be inser ted correctly in the outer groove around the stud bolt Throttle cable with two short circuit wires Refer to the manual Trouble shooting standard repairs with regard to changing the throttle trigger interlock lever contact spring and detent spring 7 3 Contact spring detent spring in ...

Page 34: ...tle trigger is in the full throttle position and against the idle speed adjusting screw when the trigger is in the idle position The throttle cable is adjusted by moving the tensioner Remove shroud see 3 1 Check correct setting of idle speed adjusting screw Important Note adjusting range of idle speed adjusting screw To make the adjustment press the throttle trigger to the full throttle position T...

Page 35: ... in reverse order Place foam filter in filter cover Place felt filter with marking in side and tab outside in filter housing The nose on the filter housing must engage in the opening in the filter cover Refer to the manual Trouble shooting standard repairs for troubleshooting procedures Important The tank vent must also be checked and cleaned see 8 3 if faults develop in the carburetor or fuel sup...

Page 36: ...r inlet control lever jammed 2 Metering diaphragm damaged The carburetor must be repaired in both cases refer to the Carbure tor manual After the test open venting screw and disconnect fuel line from elbow connector Connect fuel hose to elbow connector Refit shroud Remove shroud see 3 1 Disconnect throttle cable nipple 1 from slotted pin 2 on throttle lever Pull fuel hose 1 off connecting socket o...

Page 37: ...ack off low speed adjusting screw 2 one turn Minor corrections may be neces sary at great altitudes mountain regions at sea level or when changing the cutting attachment fitting a mowing head instead of the metal cutting tool and vice versa When correcting the setting of the H high speed adjusting screw Use a tachometer Note If a tachometer is not available the high speed and low speed adjusting s...

Page 38: ...must be ob tained first when adjusting the car buretor for the first time L Carefully turn the low speed adjusting screw 1 clockwise as far as possible then back off one turn counterclockwise L one turn open Fit an approved cutting tool The following must additio nally be noted when changing the mowing head Set correct line length every nylon line must extend as far as the blade on the deflector s...

Page 39: ...amaged diaphragm out of valve body and fit a new one Press new sintered filter 4 into fuel filler cap Fit O ring 6 over valve body Insert valve body in fuel filler cap and press until it is heard to engage Place cap on valve body and press until it is heard to engage Screw on fuel filler cap The diaphragm pump draws fuel out of the tank and into the carbu retor via the fuel hose Any impuri ties in...

Page 40: ...rs on carburetor see 8 2 2 Remove fuel tank Remove fuel hoses if necessary The parts are installed in reverse order Pegs 1 must engage in inserts 2 Fuel hoses Unscrew fuel filler plug and re move with chain Draw pickup body out of fuel tank with assembly hook 1 5910 893 8800 Pull pickup body off fuel hose Pull out venting hose 1 with grommet 2 Pull out fuel hose 3 with grom met 4 392RA121 1 VA 392...

Page 41: ...uring the clamping collars of the control handle on machines with looped handle Remove screw 1 securing the AV sleeve Undo clamping screw 1 Pull out protective tube Remove screws Remove fan housing Prise circlip out of fan housing Remove circlip above AV sleeve Slide assembly tool 1 4126 893 4900 into AV sleeve as far as possible Tighten clamping screw 2 Gently tighten locating screw 3 if necessar...

Page 42: ...ubber buffer Rub a little lubricant e g washing up liquid onto the rubber buffer Press rubber buffer into fan housing as far as possible so that the slit 1 is on the round side 2 of the housing Insert circlip with the opening facing the clamping screw so that it rests in the slots in the fan housing The remaining parts are installed in reverse order Slide protective tube on until the holes line up...

Page 43: ...to handlebar so that the longer ends point towards the gearbox and are at an angle of approx 10 15 de grees in relation to the protective tube Looped handle without U bar Unscrew nuts 1 Remove lower bracket 2 Pull out bolts 1 Remove looped handle 2 and upper bracket 3 The parts are fitted in reverse order Line looped handle up at a distance A 20 cm in front of control handle and secure it in posit...

Page 44: ...he side and pull off handle hose Position looped handle 1 on protective tube 2 Position clamping element 3 on protective tube and slide it into the looped handle Insert square nut Introduce bolt and tighten slightly Line looped handle up at a distance A 15 cm in front of control handle and secure it in position 392RA148 VA 2 3 1 392RA151 1 2 3 VA 392RA150 VA 392RA153 A VA 392RA149 VA 392RA152 VA 4...

Page 45: ...applied to the drive shaft uniform ly It must never be forced directly into the protective tube Push drive shaft into protective tube Push drive shaft into protective tube until it protrudes 20 mm FS 85 or 17 mm FS 75 80 FC 75 value A at the end of the protective tube If neces sary rotate the shaft slowly while applying gentle pressure until it can be pushed in to the extent necessary Install bear...

Page 46: ...chines with looped hand le pull protective tube 1 out of control handle 2 at the same time Remove throttle cable holder if fitted Remove bolts from carrying ring Pully carrying ring apart and remove it The parts are installed in reverse order Push protective tube in until the holes line up Torque locating screw down to 2 5 Nm and clamping screw to 5 5 Nm 392RA157 VA 392RA128 VA 392RA156 2 1 VA 392...

Page 47: ...ctive tube Refer to manual Trouble shooting standard repairs for further details on disassembly and assembly Slide gearbox onto protective tube turning the output shaft of the gear back and forth at the same time so that the square on the input shaft can engage the square socket in the drive pinion Push gearbox on as far as possi ble and align it Torque clamping screws down to 9 0 Nm Refit deflect...

Page 48: ...l deflector off gearbox Note The following three actions are required to replace the deflec tor Remove screws 1 on holder 2 Pull knurled screw 3 out and remove washer 4 Unscrew bearing bolt Remove wheel Remove screw 1 Remove rubber guard 2 Undo clamping screw Pull gearbox off protective tube 392RA171 VA 1 3 2 392RA168 VA 392RA169 VA 11 3 Gearbox FC 75 392RA172 1 2 VA 392RA165 1 2 VA 392RA164 VA 39...

Page 49: ... 7 5 Nm Refit rubber guard on deflector if removed Slide washer 1 onto bearing bolt 2 Insert bearing bolt in wheel Fit washer 3 Position wheel on deflector Screw in bearing bolt and tighten to a torque of 19 0 Nm Refit knurled screw on deflector if removed Position deflector on gearbox Slide a washer 1 over clamping screw Position clamping element 2 Screw on new self locking nuts and torque down t...

Page 50: ... drum out of deep groove ball bearing with assem bly drift 1 1108 893 4700 Examine ball bearing and re place fan housing if found to be defective Press clutch drum in as far as possible with assembly drift 1 1108 893 4700 The remaining parts are installed in reverse order 392RA177 1 VA 392RA180 1 VA 11 4 Clutch drum 392RA178 1 VA 392RA179 VA 50 ...

Page 51: ...bly Slide gearbox onto protective tube turning the gearbox back and forth at the same time so that the square on the input shaft can engage the inner square of the drive pinion Slide gearbox on as far as possi ble and line it up Torque screws on gearbox down to 9 5 Nm Torque clamping screws down to 9 0 Nm Remove gearbox see 12 1 Remove screws Remove gearbox cover Remove gasket Remove thrust plate ...

Page 52: ...acing downwards Slip band spring 3 onto the screws with the pockets facing upwards Secure both blades 4 on the pockets with cutting edges wor king against one another Place sliders 5 in the pockets of the band spring Then add the second guide 6 Screw on new locking nuts 7 and torque down to 9 5 Nm Pin 1 must engage hole 2 in conrod Stub 3 must engage hole 4 392RA193 1 2 VA 392RA190 VA 392RA189 VA ...

Page 53: ... it up to the next gradation on the tube scale This forces approx 20 g of grease into the gearbox Note Use STIHL multi purpose grease see 13 2 to lubricate the gearbox Remove cutting blades see 12 2 Remove gear wheel from gear housing Remove conrod from gear housing Remove thrust plate from gear housing The parts are fitted in reverse order 392RA196 VA 392RA199 VA 392RA200 VA 12 3 Gear wheel 392RA...

Page 54: ... Fit thrust plate with bent corners pointing towards gear housing Fit conrod with marking upwards Fit gear wheel with bevelled side of teeth pointing towards conrod 392RA203 VA 392RA196 VA 54 ...

Page 55: ...55 9200 15 Fuel line 1110 141 8600 16 Sealing plate 0000 855 8106 Sealing exhaust port for leakage test 17 Test flange 1128 850 4200 For leakage test 18 Setting gauge 4118 890 6401 Setting air gap between ignition module and flywheel 19 Socket 13 mm 5910 893 5608 Unscrewing clutch and starter carrier 20 Torque wrench 5910 890 0301 Screw connections 2 0 5 to 18 Nm 5910 890 0302 3 21 Torque wrench 5...

Page 56: ...h drum 35 Assembly stand 5910 890 3100 Mounting power unit for repairs 36 Clamping plate 5910 890 2100 37 Screwdriver T20 5910 890 2301 Separating the handle mouldings 38 Assembly hook 5910 890 2800 Pulling plug out of protective tube Remarks 1 Corresponds to puller 0000 890 4400 but with longer spindle 5910 890 8400 2 DG P screws may only be tightened down with a torque wrench 3 The machine versi...

Page 57: ...bricant 0781 417 1315 Bearing bore in rope rotor rewind spring in rope rotor 4 Ignition lead HTR 10 m 0000 930 2251 5 Dirko sealant 0783 830 2120 Crankcase sealing faces 100 g tube 6 STIHL multi purpose grease Lubricating drive shaft in protective tube 80 g tube 0781 120 1109 225 g tube 0781 120 1110 7 STIHL gear lubricant Gear lubrication 80 g tube 0781 120 1117 225 g tube 0781 120 1119 13 2 Serv...

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Stihl FC 75, User Manual

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