Stihl MS 261 User Manual
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Stihl MS 261 User Manual

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STIH)
STIHL MS 261
2010-05

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Summary of Contents for Stihl MS 261

  • Page 1 STIH) STIHL MS 261 2010-05...

  • Page 2: Table Of Contents

    Tensioning the 11.3 Oil Pump Chain Tensioner Rewind Spring 11.4 Valve 5.7.1 Quick chain tensioner 32 Replacing the Bar Mounting Studs Rewind Spring Collar Nuts for Sprocket Cover © ANDREAS STIHL AG & Co. KG, 2010 MS 261, MS 261 C...
  • Page 3 12.10.1 Testing 12.10.2 Removing and Installing Special Servicing 12.11 Fuel Intake Tools 12.11.1 Pickup Body 12.11.2 Fuel Hose 12.11.3 Fuel Hose – Models Servicing Aids with Manual Fuel Pump 12.11.4 Manual Fuel Pump 12.11.5 Tank Housing MS 261, MS 261 C...

  • Page 4: Introduction And Safety Precautions

    "Special Servicing Tools" in this This service manual contains manual. Use the part numbers to detailed descriptions of all the repair identify the tools in the "STIHL and servicing procedures specific to Special Tools" manual. The manual this power tool.

  • Page 5: Safety Precautions

    All work with fuel must be Install new fuel hoses either dry or performed outdoors only. Spilled Always use original STIHL with the aid of STIHL press fluid, fuel must be wiped away replacement parts. b 15. immediately.

  • Page 6: Specifications

    Speed-controlled oil pump with reciprocating piston and manual flow control Settings for oil delivery rate: min.: 4.5 (+/2.0) cm /min at 10,000 rpm Ematic 8.5 (+/3.0) cm /min at 10,000 rpm max.: 11.5 (+/3.0) cm /min at 10,000 rpm MS 261, MS 261 C...

  • Page 7: Tightening Torques

    Manifold/cylinder Screw M 5x25 Crankcase, sprocket side/fan side 10.0 Screw M 5x16 Bearing plug/cylinder 10.0 3), 4) Screw M 5x16 Fan housing/crankcase Screw M 4x12 Air baffle/crankcase Carrier M 12x1 L Carrier / crankshaft 50.0 MS 261, MS 261 C...
  • Page 8 Coat micro-encapsulated screws with medium strength Loctite 242 or 243 before reinstalling. Power screwdriver setting for polymer: DG and P screws max. 500 rpm Do not use an impact wrench for releasing or tightening screws. Do not mix up screws with and without binding heads. MS 261, MS 261 C...

  • Page 9: Troubleshooting

    Replace the clutch springs Loud noises Clutch springs stretched Replace all clutch springs Needle cage damaged Fit new needle cage Clutch shoe retainer broken Install new retainer or clutch Clutch shoes and carrier worn Install new clutch MS 261, MS 261 C...
  • Page 10 Saw chain does not stop Brake spring stretched or broken Fit new brake spring immediately when brake is activated Brake band stretched or worn Fit new brake band Clutch drum worn Install new clutch drum MS 261, MS 261 C...
  • Page 11 Adjust brake cable Coasting brake does not disengage lever properly even though interlock lever is depressed QuickStop Super Brake cable overtensioned Adjust brake cable Braking action of coasting brake inadequate – interlock lever not depressed MS 261, MS 261 C...

  • Page 12: Chain Lubrication

    Oil pump delivers insufficient oil Oil pump damaged or worn Install new oil pump Oil pump delivery rate set too low Adjust oil pump (only on version with adjustable oil pump) Worm driver is loose Install new worm MS 261, MS 261 C...
  • Page 13 Install new carrier Spring loop in spring housing not Attach spring loop to carrier attached to carrier Starter rope is difficult to pull – Spring in spring housing fatigued Install new spring housing models with ErgoStart MS 261, MS 261 C...
  • Page 14 (spring windings degreasant (containing no stick togteher) or moisture has got chlorinated or halogenated onto the rewind spring (spring hydrocarbons), then pull rope windings frozen together) carefully several times until normal action is restored MS 261, MS 261 C...

  • Page 15: Ignition System

    Faulty insulation or break in ignition lead or short circuit wire. Check ignition lead/ignition module and replace ignition module if necessary. Check operation of spark plug. Clean the spark plug or replace if necessary. MS 261, MS 261 C...

  • Page 16: Carburetor

    Replace tank vent Leak on fuel hose from tank to Seal connections or install new fuel carburetor hose Engine loses power during Sealing ring or spring in accelerator Install new carburetor acceleration pump worn or damaged MS 261, MS 261 C...
  • Page 17 Saw chain rotates at idle speed 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 MS 261, MS 261 C...
  • Page 18 – key in flywheel has sheared off Engine running extremely rich, has Choke shutter does not open Check carburetor and choke shaft, no power and a very low maximum service or replace if necessary speed MS 261, MS 261 C...

  • Page 19: Engine

    Thoroughly clean all cooling air inlets in fan housing blocked or openings and the cylinder fins cooling fins on cylinder very dirty Air flow path into fan housing dirty Clean air flow path into fan housing MS 261, MS 261 C...

  • Page 20: Clutch

    0000 893 5903 into the spark plug hole, wide end first, so that "OBEN-TOP" faces up. : Clamp the clutch in a : Use hook (2) 5910 890 2800 to vise (arrow). remove the clutch springs (1). MS 261, MS 261 C...

  • Page 21: Clutch Drum

    80% of the original thickness, install – Reassemble all other parts in the a new clutch drum. reverse sequence. – Install the clutch drum. Clutch Drum – Remove and install the clutch drum, see instruction manual. MS 261, MS 261 C...

  • Page 22: Chain Brake

    The braking time is in order if deceleration of the saw chain (less than a second) is imperceptible to the eye. If the chain brake does not operate : Take out the screws (2). properly, refer to troubleshooting, b 3.2. MS 261, MS 261 C...
  • Page 23 (arrow) as far as stop. – Disengage the chain brake : Hold the brake band (1) sideways, attach it to the brake lever (2) and then swing it in the direction of its seat. MS 261, MS 261 C...

  • Page 24: Brake Lever

    (1) and line up the holes. : Take the brake lever (2) out of the : Take out the screws (arrows). hand guard (1). – Lift the hand guard a little and remove the fan housing. MS 261, MS 261 C...
  • Page 25 – If the groove in the spring's anchor pin is worn, install a new pin, b b 5.6 : Turn the cam lever (1) to one side until the cam of the hand guard (arrow) slips passed it. MS 261, MS 261 C...

  • Page 26: Brake Lever On Machines With

    (1) and : Take out the screws (arrows). line up the holes. : Lift the hand guard a little and : Disconnect the brake cable (1). remove the fan housing. MS 261, MS 261 C...
  • Page 27 : Attach the spring (1) to the anchor pin (2). : Lift the bearing boss of the hand guard (1) and the brake lever (2) a little and position them over the pivot pins (arrows). MS 261, MS 261 C...

  • Page 28: Adjusting The

    – Remove the chain brake cover, b 5.2 The brake band (1) must locate against the crankcase (arrows) without any play – the clutch drum must rotate freely. : Take out the screw (1). : Lower the tank housing (2). MS 261, MS 261 C...

  • Page 29: Brake Cable

    – Reassemble all other parts in the reverse sequence. : Remove the brake cable : Pull out the brake cable (2). retainer (2) with brake cable. – Pull the brake cable out of the crankcase. MS 261, MS 261 C...

  • Page 30: Cam Lever

    : Insert and tighten down the screw (2) firmly. : Remove the E-clip (3). : Push the brake cable (1), short hook (2) first, under the hose (3) – Pull off the cam lever. and through the housing bore (arrow). MS 261, MS 261 C...

  • Page 31: Pins

    – Lubricate the cam lever, b b 15 – Position the cam lever (1) so that its cam (arrow) faces the pin (3). : Push the cam lever (1) on to the pivot pin (2). MS 261, MS 261 C...
  • Page 32 : Drive home the pins (1 and 2) as specified below. : Pin (3) a = about 10.3 - 10.5 mm Pin (4) b = about 4.6 - 4.8 mm Pin (5) c = about 5.1 - 5.3 mm MS 261, MS 261 C...

  • Page 33: Chain Tensioner

    (see arrow), into the opening recess (arrow). and press it down until it snaps into position. – Clean all disassembled parts, b 15 – Lubricate the threads, gears and O-ring with STIHL multipurpose grease, b 15 MS 261, MS 261 C...

  • Page 34: Bar Mounting Studs

    : Push stud puller (1) unscrew the stud (2) 5910 893 0501 over the collar counterclockwise. studs (2) as far as it will go and unscrew the studs counterclockwise. MS 261, MS 261 C...

  • Page 35: Collar Nuts For Sprocket Cover

    Collar Nuts for Sprocket Cover This sprocket cover can only be used on the MS 261. Retrofitting other models is not possible. The length and shape of the collar studs must be matched to the sprocket cover with captive nuts.

  • Page 36: Engine

    : Position new insulating mat (1) use the tabs (arrows) to line it up and replace if necessary. as follows on the cylinder. a = flush b = 15 mm : Bond new insulating mat (1) in position. MS 261, MS 261 C...

  • Page 37: Leakage Test

    Defective oil seals and gaskets or cracks in castings are the usual causes of leaks. Such faults allow supplementary air to enter the engine and upset the fuel-air mixture. : Make sure the washer (1) is in place. MS 261, MS 261 C...

  • Page 38: Vacuum Test

    (3) indicates a pressure of 0.5 bar. If this pressure remains constant for at : Connect hose (1) of pump least 20 seconds, the crankcase 0000 850 1300 to the is airtight. nipple (arrow). MS 261, MS 261 C...

  • Page 39: Oil Seals

    1141 893 2400 to install the oil seal (1). – Pull out the oil seal. The seating face must be flat and free from burrs. – Wait about one minute, then rotate the crankshaft several times. MS 261, MS 261 C...

  • Page 40: Shroud

    : Fit the retaining ring (1). lock (arrow). – Wait about one minute, then rotate the crankshaft several times. – Reassemble all other parts in the reverse sequence. : Fit the installing sleeve (1) 1141 893 4600. MS 261, MS 261 C...

  • Page 41: Cylinder

    – Pull off the boot and unscrew the spark plug, b 4 – Remove the fan housing, b 8.2 – Remove the filter base, b 12.3 : Carefully lift the cylinder (1) away. – Remove the carburetor, b 12.5 MS 261, MS 261 C...
  • Page 42 : Slide the cylinder over the piston, the clamping strap moves : Slide the wooden assembly downwards at the same time. block (1) 1108 893 4800 between the piston and crankcase. Take care not to damage the cylinder gasket. MS 261, MS 261 C...

  • Page 43: Crankshaft

    – Reassemble all other parts in the Always install new bearings and oil reverse sequence. seals after removing the crankshaft, b 6.6.1 and b 6.3. : The tensioner slide (1) must butt against the thrust pad (arrow). MS 261, MS 261 C...
  • Page 44 6.6.1 : Insert three M5x72 screws (3) in the holes marked "23" and – Before installing, clean the tighten them down until they butt crankshaft, b 15 against the crankcase. : Remove the gasket (1). MS 261, MS 261 C...
  • Page 45 : Turn the spindle bolt (1) very quickly because heat is push it home. clockwise. absorbed by the crankshaft, and the inner bearing race shrinks. – Install the ignition side of the crankcase as far as stop. MS 261, MS 261 C...
  • Page 46 – Position the clutch side of the crankcase on the straight crankshaft stub and the two screws. Make sure the sleeves (arrows) engage the holes and the gasket is not pinched or twisted. MS 261, MS 261 C...
  • Page 47 : Turn the spindle (1) counterclockwise until the : Insert the screws (arrows) and crankcase locates against the tighten them down firmly in a guide sleeves. crosswise pattern. MS 261, MS 261 C...

  • Page 48: Bearings / Crankcase

    This operation must be carried out quickly because the bearing absorbs heat and begins to expand. – Check that ball bearing is properly seated. If necessary, use press arbor 1118 893 7200 to press the bearing fully home. MS 261, MS 261 C...

  • Page 49: Piston

    – Remove the oil pump, b 11.3 – Install the crankshaft, b 6.6 – Install the oil seals, b 6.3 – Reassemble all other parts in the reverse sequence. MS 261, MS 261 C...
  • Page 50 – Lubricate the piston pin (1) with oil. The inner pin (1) must point towards the flat face (2) of the tool's shank. : Fit the piston pin (1) on the assembly drift (2) and slide it into the piston. MS 261, MS 261 C...

  • Page 51: Piston Rings

    – Install the cylinder, b 6.5 upward (arrows). – Reassemble all other parts in the reverse sequence. Fit the snap ring (1) so that its gap (arrow) is on the piston's vertical axis (it must point up). MS 261, MS 261 C...

  • Page 52: Decompression Valve

    – Fit the decompression valve and screw it home by hand. – Tighten down the decompression valve firmly. – Reassemble all other parts in the reverse sequence. MS 261, MS 261 C...

  • Page 53: Ignition System

    : Pull the ignition lead (1) out of the two electrical connections on the guides (arrows). coil body: – the high voltage output (1) for the ignition lead – the connector tag (2) for the short circuit wire MS 261, MS 261 C...

  • Page 54: Spark Plug Boot

    (arrows) is properly positioned, b 13.7. : Pull the grommet (1) off the ignition module. : Unscrew the ignition lead (2) from the ignition module (3). MS 261, MS 261 C...

  • Page 55: Testing The Ignition Module

    : Lift the air guide shroud (1) a little and push the ignition lead (2) into position – take care not to distort the air guide shroud. MS 261, MS 261 C...

  • Page 56: Spark Plug Boot

    (3), check the ignition system with the aid of the – If no spark is visible in the troubleshooting chart, b b 7.8 window (2), check the ignition system with the aid of the troubleshooting chart, b 7.8 MS 261, MS 261 C...

  • Page 57: Spark Plug Boot / Ignition Lead

    Before installing the ignition lead, fill the high voltage output with STIHL – Coat the inside of the spark plug multipurpose grease b b 15. boot with STIHL press fluid,...

  • Page 58: Flywheel

    – Remove the shroud, b 6.4 released from the crankshaft. – Remove the fan housing, b 8.2 – Remove the puller (3) 5910 890 4504 from the flywheel. – Use locking strip to block the piston, b 4 MS 261, MS 261 C...

  • Page 59: Short Circuit Wire

    (1). – Remove the fan housing, b 8.2 : Take out the screw and remove : Pull the short circuit wire (1) out the ground wire (2). of the guide (arrow) and take it away. MS 261, MS 261 C...
  • Page 60 (arrow). : Push the rubber grommet (1) out of the crankcase (2). : Pull out the wiring harness (3). : Pull the short circuit wire (1) out from behind the tab (arrow). MS 261, MS 261 C...
  • Page 61 – take care not to distort the air guide shroud. Ground wire: Crimped side of – Use STIHL press fluid to simplify terminal (1) must face the screw assembly, b 15 head (2). : Push the rubber grommet (1) into...
  • Page 62 (arrow) as far as stop. : Pass the ring terminal (1) through – Reassemble all other parts in the the opening (arrow) in the filter reverse sequence. base. : Push the short circuit wire (1) into the guides (arrows). MS 261, MS 261 C...

  • Page 63: Ground Wire

    : Lift the contact spring (1) a little and ease it over the bead (arrow). : Push the contact spring (1) fully onto the ground wire's flag : Push the contact spring (1) into terminal (2). its seat as far as stop. MS 261, MS 261 C...
  • Page 64 – Fit the short circuit wire in the switch shaft, b 7.7.2 – Install the switch shaft, b 10.1 : When installing the switch shaft, lift the contact spring (1) a little – no more than 2 mm. MS 261, MS 261 C...

  • Page 65: Ignition System Troubleshooting

    – If necessary, install new spark plug boot and/ or leg spring, b 7.5 Test ignition system: with ZAT 3 or ZAT 4 (use ZAT 3 as main spark gap see TI 32.94), b 7.4 MS 261, MS 261 C...
  • Page 66 1.5 – 12 kΩ – Check resistance of ignition lead (spark plug boot and ignition module removed) Spec.: < 10 Ω, If necessary, install new spark plug boot and/or ignition lead with module, b 7.5 MS 261, MS 261 C...
  • Page 67 7.3 Engine runs Machine runs trouble-free, – Look for fault in fuel system or no further action necessary carburetor – Check engine for leaks – Check position of flywheel on crankshaft, b 6.2, b 7.6 MS 261, MS 261 C...

  • Page 68: Rewind Starter

    (2) as far as stop. – Examine the fan housing and Models with ErgoStart segment and replace if – Reassemble all other parts in the necessary. reverse sequence. – Relieve tension of rewind spring, b 8.4 MS 261, MS 261 C...

  • Page 69: Pawls

    – the pawls move outwards. – Reassemble all other parts in the reverse sequence. – Fit the new pawls in the bores (arrows) and lubricate the pegs (1), b 15 MS 261, MS 261 C...

  • Page 70: Ergostart

    – Remove the fan housing and, if springs at the same time and necessary, the segment, b 8.2 locate them against the ribs (arrow). : Remove the E-clips (arrows). : Pull off the pawls (1) and remove the torsion springs. MS 261, MS 261 C...

  • Page 71: Rope Rotor

    – Check the rope rotor and replace if necessary. – Remove the fan housing, b b 8.2 – Coat bore in rope rotor with STIHL special lubricant, b 15 MS 261, MS 261 C...

  • Page 72: Starter Rope / Grip

    – Pull the starter rope out of the rope rotor and fan housing. : Pull the rope into the starter grip until the knot is properly seated in the grip (small arrow). MS 261, MS 261 C...
  • Page 73 – Tension the rewind spring, b b 8.7 Do not shorten the starter rope. – Install the segment and fan housing, b 8.2 : Thread the starter rope (1) through the guide bushing (arrow). MS 261, MS 261 C...

  • Page 74: Tensioning The

    : Pull out the twisted rope (1) with Pull the rope out, hold the rope rotor the starter grip and straighten it steady and take off one turn of the out. rope. – Install the fan housing, b b 8.2 MS 261, MS 261 C...
  • Page 75 – Arrange the rewind spring (1) in rewind spring that has popped out and unwound. its original position. : Fit the anchor loop in its seat (arrow) in the fan housing. MS 261, MS 261 C...
  • Page 76 : Apply tool to openings (arrows) to push the rewind spring into its – Install the rope rotor, b b 8.5 seat in the fan housing. – Reassemble all other parts in the reverse sequence. MS 261, MS 261 C...

  • Page 77: Servicing The Av System

    – Check the AV spring and plug, replace if necessary. : Take out the screws (1). – Use STIHL press fluid to simplify assembly, b 15 : Push the buffer (2) onto the peg (1) on the handlebar as far –...

  • Page 78: Av Spring On Fuel Tank

    : Push the AV spring (1), bearing plug (3) first, between the crankcase and tank housing. : Take out the screws (1). : Press the tank housing (2) down a little and hold it there. MS 261, MS 261 C...

  • Page 79: Av Spring On Handlebar

    – Remove the shroud, b 6.4 – Reassemble all other parts in the reverse sequence. – Remove the air filter, b 12.1 : Push the retainer (1), small nipple first, through the hole in the handlebar (2). MS 261, MS 261 C...

  • Page 80: Models With Heating

    (2) as far as stop. : Unscrew the spring (2) and pull out the retainer (arrow). : Position the AV spring (4) on the handlebar and cylinder. : Insert and tighten down the screw (2) firmly. MS 261, MS 261 C...

  • Page 81: Stop Buffer At Ignition Side

    (arrow) crankcase. facing the crankcase. : Take out the screw (1). – Use STIHL press fluid to simplify – Use STIHL press fluid to simplify assembly, b 15 assembly, b b 15 : Press the tank housing (2) down a little and hold it there.

  • Page 82: Handlebar

    : Insert and tighten down the bores. screw (1) firmly. – Use STIHL press fluid to simplify – Reassemble all other parts in the assembly, b 15 reverse sequence. : Push the tapered ends of the...

  • Page 83: Handlebar With Heating

    10.2 – Insert the screws and tighten – Remove the throttle rod, them down firmly. b 10.3.4 – Remove the air guide shrouds, b 12.4 : Push the handlebar, buffer (1) first, into the crankcase. MS 261, MS 261 C...
  • Page 84 (arrow). – Remove the handlebar. : Push the insulating tube (1) in the direction of the handlebar heating element. : Separate the pin and socket connector. MS 261, MS 261 C...
  • Page 85 – Check handlebar heating and replace handlebar if necessary, b 13.7.1 : Push home the handlebar : Fit the handlebar (1) over the stiffener (1) as far as stop. machine as far as the seat (arrow). MS 261, MS 261 C...
  • Page 86 (1) The peg (1) must engage the seat guide (arrows). into the guide (arrows). (arrow). Lay the wires without loops and snugly against the housing. : Fit the insulating hose (2). MS 261, MS 261 C...
  • Page 87 (arrow) and hold it there. upwards and hold it there. : Insert and tighten down the screw (1) firmly. – Reassemble all other parts in the reverse sequence. : Insert and tighten down the screws (1) firmly. MS 261, MS 261 C...

  • Page 88: Control Levers

    (arrow) and lift it slightly. : When installing the switch lever, lift the contact spring (1) a little : Push the tabs (1) apart and – no more than 2 mm. through the tank housing. MS 261, MS 261 C...
  • Page 89 (arrows). : Use a drift (2) to center the throttle trigger (1). : Drive home the pin (3) until it is recessed by same amount at both sides. MS 261, MS 261 C...

  • Page 90: Throttle Trigger/Lockout Lever - Quickstop Super

    : Push the tabs (1) apart and through the tank housing. : Use a drift (2) to drive out the pin (1). : Attach the throttle rod (1) to the trigger (2) and fit it in the guide (arrow). MS 261, MS 261 C...
  • Page 91 : Drive home the pin (3) until it is recessed by same amount at – Reassemble all other parts in the both sides. reverse sequence. : Attach the torsion spring (1) to the trigger (2) – note the installed position (arrow). MS 261, MS 261 C...

  • Page 92: Switch Lever - Quickstop Super

    – Check the switch lever (1) and sequence. replace it if necessary. – Check operation of switch lever by operating the lockout lever. – Check the lockout lever (1), torsion spring (2) and bushing (1) and replace if necessary MS 261, MS 261 C...

  • Page 93: Choke Rod

    – Check the choke rod and replace recessed by same amount at seated. it if necessary both sides. – Reassemble all other parts in the reverse sequence. – Reassemble all other parts in the reverse sequence. – Check operation. MS 261, MS 261 C...

  • Page 94: Throttle Rod

    (arrow). – Check the throttle rod and replace if necessary : Pry the filter base (1) out of the buffer (2). : Pry the throttle rod (1) out of the carburetor carrier (2). MS 261, MS 261 C...
  • Page 95 : Fit the wire (1) in the guide (arrows). – Reassemble all other parts in the reverse sequence. : Swing the filter base (1) in direction of clutch side so that it is against the carburetor (2) studs. MS 261, MS 261 C...

  • Page 96: Chain Lubrication

    Do not overstretch the suction hose. – Pull off the pickup body (1), check it and replace if necessary. – Reassemble in the reverse sequence. : Push the oil suction hose (1), pickup body first, through the housing bore (arrow). MS 261, MS 261 C...

  • Page 97: Oil Pump

    : Push the oil suction hose (1) onto the nipple. : Fit a new sealing ring (1). Always use a new sealing ring. : Check the spring (1) and worm (2) and replace if necessary. MS 261, MS 261 C...

  • Page 98: Valve

    – Use a 6 mm drift to carefully drive in the new valve from outside – note installed depth. : Use a 6 mm drift to carefully drive the valve out of its seat in the housing and into the oil tank. MS 261, MS 261 C...

  • Page 99: Fuel System

    – Remove the switch shaft, b 10.1 : Swing the filter base (1) in direction of throttle trigger until it is clear of the studs. : Push the short circuit wire (1) out through the opening (arrow). MS 261, MS 261 C...
  • Page 100 : Engage the filter base (1) in the buffer (2) – make sure the peg (3) is properly seated in the buffer. : Turn the filter base (1) in direction – Use STIHL press fluid to simplify of ignition side. assembly, b b 15...

  • Page 101: Air Guide Shrouds

    (arrow) from the ignition side and lift the air guide underside of the air guide shroud. : Lift the air guide shroud (2) a little shroud (2). and pull it out of its seats. MS 261, MS 261 C...

  • Page 102: Air Guide Shrouds - Models With Manual Fuel Pump

    : Push the tab (1) towards the and place the ignition lead (2) in clutch side and under the edge of the guide the housing (arrow). – take care not to distort the air guide shroud. MS 261, MS 261 C...
  • Page 103 (arrow) at the same time. : Pull out the shutter (1), check it : To simplify disassembly, lift the and replace if necessary. bottom of the air guide shroud (2) slightly during the following steps. MS 261, MS 261 C...
  • Page 104 (2) slightly during the following steps. : Push the tab (1) towards the clutch side and under the edge of – Use STIHL press fluid to simplify the housing (arrow). assembly, b 15 MS 261, MS 261 C...

  • Page 105: Models With Heating

    – Reassemble all other parts in the reverse sequence. : Push the connector (1) with fuel return hose (2) into the fuel return hose (3) so that the contours (arrows) are in alignment. MS 261, MS 261 C...
  • Page 106 : Pull the wiring harness (1) out of the guides (arrows). : Pull out the shutter (1), check it and replace if necessary. : Pull the generator wire (2) out of the hole. MS 261, MS 261 C...
  • Page 107 (arrow) from the shroud and press it into its seat. underside of the air guide shroud. : Push the shutter (1) into the guide until it snaps into place. MS 261, MS 261 C...
  • Page 108 – Use STIHL press fluid to simplify : The wiring harness must be : Press the air guide shroud (1) assembly, b 15 properly seated in the guides on into its seat until the tab (2) snaps the tank housing, press it firmly into place.
  • Page 109 : Fit the wiring harness (1) into the guides so that the protective : Connect the pin (1) and tube (2) butts against the socket (2). guides (arrows). – Push the insulating tube (3) over the connector. MS 261, MS 261 C...

  • Page 110: Carburetor

    – the fuel hose is disconnected. : Push the insulating tube (1) in the direction of the thermostatic Generator wire (1) must be seated switch and separate the pin and at the bottom of the recess (arrow). socket connector. MS 261, MS 261 C...
  • Page 111 13.1.3 Models with manual fuel pump – Install a new fuel hose, b 11.2 : Fit the wire (1) behind the levers (2) and (3). : Fit the insulating tube (4). MS 261, MS 261 C...

  • Page 112: Leakage Test

    : Push the carburetor (2) fully home as far as stop. : Push the fuel hose (1) 1110 141 8600 onto the nipple (2) 0000 855 9200. : Push the new fuel hose (1) onto the nipples (arrows). MS 261, MS 261 C...

  • Page 113: Servicing The Carburetor

    (arrows) are in line with remove to clean, the recess (3). b 12.6.2 or b 12.6.2 2. Metering diaphragm or gasket damaged, replace if necessary, b 12.6.1 or b 12.10.1 MS 261, MS 261 C...

  • Page 114: Inlet Needle

    : Check the sealing ring (arrow) and replace it if necessary – Reassemble all other parts in the reverse sequence. : Remove the inlet needle (1). : Remove the spring (2). Inspect and replace if necessary. MS 261, MS 261 C...

  • Page 115: Pump Diaphragm

    : Use a needle to remove the fuel strainer (1) from the carburetor body. Clean or replace the fuel strainer. – Reassemble in the reverse sequence. : Take out the screw (1). : Remove the end cover (2). MS 261, MS 261 C...

  • Page 116: Levers On Throttle Shaft

    – Check that the pump diaphragm and gasket are properly seated. : Fit the screw (1) with washers and tighten it down firmly. : Take out the screw (1). : Pull off the lever (2). MS 261, MS 261 C...

  • Page 117: Adjusting Screws

    – left-hand thread. – Do not turn the puller (1) any further – the high speed screw (H) may otherwise be damaged. : Take out the low speed screw L (1). MS 261, MS 261 C...
  • Page 118 : If the high speed screw (H) is in as the first detent (arrow) order, remove the old polymer – do not push fully home. segment (1) – take care not to damage the high speed screw (H). MS 261, MS 261 C...

  • Page 119: Adjusting The Carburetor

    H (1) against its seat, If this speed is higher than open it 1 1/2 turns 3,700 rpm, abort the procedure and counterclockwise start again with step 1. – this is the basic setting. MS 261, MS 261 C...

  • Page 120: Standard Setting

    (L). stop, but not more than a 3/4 turn. – Turn the low speed screw (L) slowly clockwise as far as stop, then turn it back 1 full turn. MS 261, MS 261 C...

  • Page 121: Carburetor Carrier

    – take care not to stretch the hose. : Press the groove on the fuel hose (1) fully into its seat (arrow). : Remove the fuel hose (1) from the guides (arrows) – take care not to stretch the hose. MS 261, MS 261 C...

  • Page 122: Intake Manifold

    – Reassemble all other parts in the very minor damage can result in reverse sequence. engine running problems, b 3.7 : Position the carburetor carrier (1) so that the semi-circles (arrows) locate against the studs (2). MS 261, MS 261 C...

  • Page 123: Tank Vent

    Models with manual fuel pump, b 12.4.1 – Install the carburetor carrier, b 12.8 – Reassemble all other parts in the : Use a suitable plug (2) to seal the reverse sequence. fuel suction hose (1). MS 261, MS 261 C...

  • Page 124: Removing And Installing

    STIHL press fluid, b 15 – Push home the tank vent by hand until it snaps into position. – Reassemble all other parts in the reverse sequence. : Take out the screw (1). MS 261, MS 261 C...

  • Page 125: Fuel Hose

    : Pull off the pickup body (1), check it and replace if necessary. – Reassemble in the reverse sequence. 12.11.2 Fuel Hose – Use STIHL press fluid to simplify assembly, b b 15 : Pull the fuel suction hose (1) out – Open the tank cap.

  • Page 126: Fuel Hose - Models With Manual Fuel Pump

    : Install a new fuel return hose (2) : Pull the furl suction hose (1) off and new fuel suction hose (1), the nipples (arrows). inspect the connector (3) and replace if necessary. – Remove the carburetor, b 12.5 MS 261, MS 261 C...
  • Page 127 : Install a new fuel return hose (1), inspect the connector (2) and grommet (3) and replace as necessary. – Use STIHL press fluid to simplify assembly, b 15 : Fit the grommet (1) in the hole (arrow) in the fuel tank and make sure it is properly seated.

  • Page 128: Manual Fuel Pump

    : Disconnect the fuel suction wire's grommet (1). hose (1) and fuel return hose (2) from the nipples (arrows). : Push the connector (1) into the fuel return hose (2) as far as stop. MS 261, MS 261 C...

  • Page 129: Tank Housing

    – Check operation – Install new fuel suction hose and – fuel must flow when the fuel new fuel return hose, b 12.11.3 pump is operated. – Reassemble all other parts in the reverse sequence. MS 261, MS 261 C...
  • Page 130 : Push the tank housing (1) towards the ignition side and turn it until the peg (2) is inside the bore (arrow). : Slide the tank housing (1), narrow part (2) first, between the two halves of the crankcase. MS 261, MS 261 C...

  • Page 131: Heating System

    – Test the heating system as specified in the carburetor heating troubleshooting chart, b 13.2 – Remove the air filter, b 12.1 : Remove the heating element (1). – Set the ohmmeter to measuring range "Ω". MS 261, MS 261 C...

  • Page 132: Thermostatic Switch

    – Reassemble all other parts in the reverse sequence. – Check that the pump diaphragm and gasket are properly seated. – Hold the end cover (3) so that the pump diaphragm and gasket remain in position. MS 261, MS 261 C...

  • Page 133: Carburetor Heating System Troubleshooting Chart

    12 Ω? element, b 13.1.2 Install new thermostatic switch, b 13.1.2 Carburetor heating element in order Circuit Diagram G Generator 1 Rear handle 2 Handlebar 3 Heater switch 4 Thermostatic switch 5 Heating element (carburetor) MS 261, MS 261 C...

  • Page 134: Handle Heating System

    If the system is in order, the ohmmeter will indicate a value of about 10 Ω in measuring range "Ω". If no reading is obtained, there is a break in the circuit. : Separate the pin and socket connector. MS 261, MS 261 C...
  • Page 135 (2). – Check operation. : Take out the screw (1). : Take the contact ring (2) out of its seat and pull the ground wire (3) out of the guides (arrows). MS 261, MS 261 C...

  • Page 136: Heating Element In Rear Handle

    The wire (1) must be seated in the guides so that the protective tube (2) butts against the guides (arrows). – Reassemble all other parts in the reverse sequence. MS 261, MS 261 C...

  • Page 137: Heating Element In Handlebar

    : Reconnect the pin and socket connectors. : Push the insulating tubes (1) over the connectors. – The insulating tubes (1) must completely cover the connectors to avoid the risk of a short circuit. MS 261, MS 261 C...

  • Page 138: Generator

    : Push back the insulating tube (1) in the direction of the wiring – Reassemble in the reverse harness and separate the pin and sequence. socket connector. : Take out the screws (1). : Remove the generator (2). MS 261, MS 261 C...
  • Page 139 : Press the generator wire and make sure the insulating tube wiring harness into the completely covers the connector. guides (arrows). : Push the pin and socket connector with insulating tube (1) into the guide (2). MS 261, MS 261 C...

  • Page 140: Handle Heating And Generator Troubleshooting Chart

    Install new rear handle heating element b 13.5 Resistance of rear handle heating element about 1.6 Ω? Checking the generator Resistance between engine ground Install new generator and generator connection b 13.7 about 0.5 – 1 Ω? MS 261, MS 261 C...
  • Page 141 9.6.1 Check the heater switch Install new heater (connector sleeve against switch housing) switch, Closed: about 0Ω? b 13.4 Open: Circuit interrupted, b 13.4 Reconnect connector to thermostatic switch, b 13.1.3 System in order MS 261, MS 261 C...

  • Page 142: Test Connections And Test Values

    Break in wire, Install new heating element handlebar damaged Short circuit – Repair insulation damaged insulation Pull out wire for this purpose MS 261, MS 261 C...
  • Page 143 Break in wire, Install new generator damaged generator Short circuit – Repair insulation damaged insulation Circuit Diagram G Generator 1 Rear handle 2 Handlebar 3 Heater switch 4 Thermostatic switch 5 Heating element (carburetor) MS 261, MS 261 C...

  • Page 144: Wiring Harness

    (arrows). in the direction of the wiring harness and separate the pin and socket connector. : Take out the screws (1). : Lift the handlebar (2) a little and ease it to the side. MS 261, MS 261 C...
  • Page 145 – total length of pin and socket connector a = max. 30 mm. : Push back the insulating tube (1) in the direction of the wiring harness and separate the pin and socket connector. – Remove the wiring harness. MS 261, MS 261 C...
  • Page 146 Make sure that the wires are not pinched. : Push the wire fully into the : Press the insulating tube into the guide (arrows). guide (arrows). The wires with protective tube (1) must be properly seated (arrow). MS 261, MS 261 C...
  • Page 147 – Install the air guide shroud, b 12.4 : Fit the terminal (1) through the bore (arrow). – Reassemble all other parts in the : Center the connector and reverse sequence. insulating tube (1) in the guide (arrow). MS 261, MS 261 C...

  • Page 148: Special Servicing Tools

    Installing oil seal (clutch side) Press arbor 1118 893 7200 Installing ball bearings Test flange 1119 850 4201 Leakage Test - Sleeve 5910 893 1701 Spacer sleeves for test flange Combination wrench 1129 890 3401 Spark plug MS 261, MS 261 C...
  • Page 149 Socket, 13 mm, long 5910 893 2804 Removing and installing decompression valve Setting disk 5910 893 6600 Add-on for screwdriver (adjusting carburetor) Hook 5910 893 8800 Removing pickup body Remarks: 1) Use for releasing only. MS 261, MS 261 C...

  • Page 150: Servicing Aids

    0786 111 2101 adhesive (Loctite 242) High-strength threadlocking 0786 111 2109 adhesive (Loctite 270) Standard commercial solvent- Cleaning sealing faces and carburetor, based degreasant containing no crankshaft stubs and flywheel taper chlorinated or halogenated hydrocarbons MS 261, MS 261 C...
  • Page 151 englisch / english 0455 573 0123. M0. E10. xxx. Printed in Germany...

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