Stihl MS 241 User Manual

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STIH)

STIHL MS 241 C

2010-11

1. Introduction and safety precautions 3

1.1 Introduction 3

1.2 Safety precautions 4

2. Specifications 5

2.1 Engine 5

2.2 Fuel system 5

2.3 Ignition system 5

2.4 Chain lubrication 5

2.5 Tightening torques 6

3. Troubleshooting 8

3.1 Clutch 8

3.2 Chain Drive, Chain Brake, Chain Tensioner 9

3.3 Chain lubrication 11

3.4 Starter 12

3.5 Ignition system 14

3.6 Carburetor 15

3.7 Engine 18

4. Clutch 19

4.1 Clutch drum 19

4.2 Clutch 19

5. Chain brake 20

5.1 Checking operation of chain brake 20

5.2 Brake band 20

5.3 Brake lever 21

5.4 QuickStop Super brake lever 23

5.4.1 Adjusting brake cable 25

5.4.2 Brake cable Removal and installation 27

5.5 Cam lever 28

5.6 Pins 29

5.7 Chain tensioner 31

5.7.1 Quick chain tensioner 31

5.7.2 Chain catcher 32

5.8 Bar mounting stud 32

5.9 Collar nut for chain sprocket cover 32

6. Engine 34

6.1 Muffler 34

6.2 Leak testing 35

6.2.1 Preparations 35

6.2.2 Vacuum test 36

6.2.3 Pressure test 36

6.3 Oil seals 37

6.3.1 Ignition side 37

6.3.2 Clutch side 37

6.4 Shroud 38

6.5 Cylinder 39

6.6 Crankshaft 41

6.6.1 Ball bearing / crankcase 46

6.7 Piston 47

6.8 Piston rings 49

6.9 Decompression valve 50

7. Ignition system 51

7.1 Ignition timing 51

7.2 Pre-separator 51

7.3 Control unit 51

7.4 Spark test check control unit 54

7.5 Spark plug boot 55

7.5.1 Ignition lead 56

7.6 Flywheel 56

7.7 Short circuit wire 57

7.7.1 Contact test 57

7.7.2 Removal and installation 57

7.7.3 Ground wire 64

7.7.4 Contact spring 64

7.8 Troubleshooting, ignition system 66

8. M-Tronic 69

8.1 Calibrating the control unit 69

8.2 Testing 70

8.2.1 Test preparations 70

8.2.2 Connect the test lead 70

8.2.3 Check screwed and plug connections as well as switch 70

8.2.4 Checking the solenoid valve 72

8.2.5 Checking the start detection function 73

8.2.6 Checking the wiring harness 74

8.3 Wiring harness 76

8.4 Switchgear 76

8.5 Troubleshooting, M-Tronic 80

8.5.1 Engine does not start 80

8.5.2 Engine does not start in position } 81

8.5.3 Engine speed drops under load – low power 82

8.5.4 Ignition – no ignition spark 83

8.5.5 Engine stops suddenly 84

8.5.6 Cut-off speed not reached 85

9. Rewind starter 86

9.1 General 86

9.2 Fan housing 86

9.3 Pawls 87

9.4 ErgoStart 88

9.5 Rope rotor 89

9.6 Starter rope / starter grip 89

9.7 Tensioning the rewind spring 90

9.8 Replacing the rewind Spring 91

RA_741_00_01_01

1MS 241 C

Contents

10. Maintaining the antivibration elements 94

10.1 Antivibration element on oil tank 94

10.2 Antivibration element on fuel tank 94

10.3 Antivibration element on front handle 96

10.3.1 Antivibration element on handlebar, version with heating 97

10.3.2 Stop buffer 98

10.3.3 Filter base buffers 98

10.4 Front handle 99

10.4.1 Handlebar with heating 100

11. Actuating levers 105

11.1 Master Control lever 105

11.1.1 Removal and installation 105

11.2 Throttle trigger / throttle trigger interlock 106

11.3 Throttle trigger / throttle trigger interlock / QuickStop Super 107

11.3.1 Trigger switch QuickStop Super 108

11.3.2 Trigger interlock QuickStop Super 109

11.4 Choke rod 110

11.5 Throttle rod 110

12. Chain lubrication 112

13. Fuel system 115

13.1 Air filter 115

13.2 Baffle 115

13.3 Filter base 115

13.4 Air guide shroud 117

13.4.1 Air guide shroud, versions with manual fuel pump 120

13.4.2 Air guide shroud version with heating 123

13.5 Carburetor 129

13.5.1 Leakage test 133

13.6 Repairing the carburetor 133

13.6.1 Metering diaphragm 134

13.6.2 Inlet needle 135

13.6.3 Pump diaphragm 135

13.6.4 Lead retainer 137

13.6.5 Lever of the throttle shaft 137

13.6.6 Lever of the choke shaft 138

13.7 Carburetor adjustment 138

13.8 Carburetor bracket 138

13.9 Intake elbow 140

13.10 Tank vent 141

13.10.1 Testing 141

13.10.2 Removal and installation 142

13.11 Fuel intake 143

13.11.1 Pickup body 143

13.11.2 Fuel hose 143

13.11.3 Fuel hoses manual fuel pump 146

13.11.4 Manual fuel pump 148

13.11.5 Tank housing 149

14. Heating 152

14.1 Carburetor heating 152

14.1.1 Check overall system 152

14.1.2 Check heating element 152

14.1.3 Thermostatic switch 153

14.2 Troubleshooting, carburetor heating 154

14.3 Handle heating systems 155

14.3.1 Troubleshooting 155

14.4 Heating switch 156

14.5 Heating element in handle 158

14.6 Heating element in front handle 159

14.7 Generator 160

14.7.1 Troubleshooting chart, handle heating systems and generator 162

14.7.2 Summary of test connections and test values 164

14.8 Wiring harness 166

14.9 Connecting leads heating elements 167

15. Special tools 170

16. Service accessories 172

12.1 Pickup body 112

12.2 Oil suction hose 112

12.3 Oil pump 112

12.4 Valve 114

2 MS 241 C

1. Introduction and safety precautions

1.1 Introduction

This Service Manual contains detailed descriptions of all the typical repair and servicing procedures for this machine.

Refer to the illustrated spare parts lists during all repair work. These lists show the installation position and order in which the individual parts and modules should be assembled.

Refer to the latest edition of the relevant spare parts list to check the part numbers of any spare parts required.

A fault on the machine may be due to several causes. To help locate the fault, consult the chapter on "Troubleshooting" and the "STIHL Service Training System" for all functional groups.

The special tools mentioned in the descriptions are listed in the chapter "Special Servicing Tools" of this manual. The tools can be identified according to part number in the "STIHL Special Tools" manual. The manual lists all tools supplied by STIHL.

Symbols are included in the text and pictures for greater clarity. The meanings are as follows:

In the text:

N Action to be taken as shown in

the illustration above the text

– Action to be taken that is not

shown in the illustration above the text

In the illustrations:

A Item pointer (short)

2710RA320 TG

Servicing and repairs are made considerably easier if the machine is mounted on assembly stand (3) 5910 890 3101. For this purpose, secure the clamp (2) 5910 850 1650 to the assembly stand with two screws (1).

The screws must not protrude, as they may damage the housings when clamping the machine, depending on the machine.

Refer to the "Technical Information" bulletins for engineering changes which have been introduced since publication of this Service Manual. Technical information bulletins also supplement the spare parts list and Service Manual until an updated edition is issued.

a Direction of

movement (long arrow)

@ 4.2 Reference to another

chapter, in this case to Chapter 4.2

Service Manuals and technical information bulletins are intended exclusively for the use of properly equipped repair shops. They must not be passed on to third parties.

2410RA000 TG

The machine is guided with the collar screw through the upper hole of the clamping rail and fastened using nut M 8 (arrow).

The machine is fastened to the mount on the clamping rail by the screw head on the crankcase.

3MS 241 C

Preparing to make repairs

Before repair tasks or clamping on the assembly stand, always remove the chain sprocket cover, saw chain and guide bar.

Always use original STIHL replacement parts. They can be identified by the STIHL part number the logo { and the STIHL parts symbol K The symbol may appear alone on small parts.

Storage or disposal of oil and fuel

Collect fuel or lubricating oil in a clean container and dispose of it in accordance with environmental regulations.

Plug connections on electrical leads

1.2 Safety precautions

Specific national safety regulations and the safety instructions in the instruction manual must be observed if the machine has to be started up during maintenance or repair work.

Gasoline is highly inflammable and can also be explosive under certain conditions.

Do not bring any fire, flame, spark or other source of heat near the fuel. All work with fuel must be performed outdoors only. Spilled fuel must be wiped away immediately.

Test for leakage after all work on the fuel system and engine.

Exercise extreme caution while carrying out maintenance and repair work on the ignition system. The high voltages which occur can cause serious or fatal accidents.

Suitable gloves must be worn without fail if parts are heated for assembly/disassembly purposes.

Improper handling may result in burns and other serious injuries.

The chapter "Tightening Torques" lists all components of this machine that must be tightened with the specified tightening torques or coated with thread-locking adhesive. These specifications must be observed throughout the Service Manual when tightening screws and nuts as well as other fasteners.

Fuel system – barbed connectors

Pull or push the fuel hoses, by hand whenever possible, in the direction of the connector in order to ensure leakproofness of the fuel system.

Avoid damaging the barbed connectors – sharp-edged pliers, screwdrivers, etc., may not be used. Also, do not cut open fuel hoses with a knife or similar aids.

Do not reuse fuel hoses after disassembly, but instead always replace them with new hoses – fuel hoses can be overstretched when being detached.

Mount new fuel hoses dry or using STIHL press fluid, b 16.

The insulating tube must be oriented so that it is centered over the plug connection and completely enclose the plug connection – danger of short-circuiting.

The plug connection is completely plugged together when it has a total length of a = max. 30 mm.

Always replace damaged parts. Check dismantled parts for wear and damage before installation, replace if necessary.

5902RA299 TG

Only use the machine with the shroud mounted – otherwise the rotating fan wheel poses a risk of injury and there is a risk of engine damage due to overheating.

Other press fluids are not permitted and may lead to fuel hose damage.

When using STIHL press fluid, apply press fluid to the ends of the hose and the connectors and press the new hoses onto the barbed connectors, b 16.

4 MS 241 C

2. Specifications

2.1 Engine

MS 241 C

Displacement: 42.6 cm

Bore: 42.5 mm Stroke: 30.0 mm Engine power to ISO 7293: 2.2 kW (3.0 HP)

at 10000 rpm

Max. permissible engine speed (with bar and chain): 14000 rpm

Idle speed: 2800 rpm Clutch: Centrifugal clutch without

linings Clutch engages at: 3500 rpm Crankcase leakage test at gauge pressure: p under vacuum p

= 0.5 bar

2.2 Fuel system

Carburetor leakage test at

gauge pressure: p

Operation of tank vent at

gauge pressure: p

Fuel: as specified in instruction

= 0.8 bar

= 0.5 bar

manual

2.3 Ignition system

2.4 Chain lubrication

Air gap between control unit

and fanwheel: 0.30 (+ 0.05/- 0.10) mm

Spark plug (suppressed): NGK CMR 6 H

Electrode gap: 0.5 mm

Speed-controlled oil pump with reciprocating piston and

manual oil flow control

Oil flow settings:

min:

4.0 (+/- 2.0) cm

/min

at 7000 rpm

max:

8.0 (+/- 3.0) cm

/min

at 7000 rpm

5MS 241 C

2.5 Tightening torques

DG and P screws are fitted in plastic and light alloy metal parts. These screws form a permanent thread when they are installed for the first time. The material is permanently deformed. Screws can be removed and installed as often as necessary without impairing the strength of the screwed assembly, provided that the specified tightening torque is observed. For this reason it is essential to use a torque wrench.

Fastener Thread size For component Tightening

torque Nm

Screw P 4x12 Cover plate / fan housing 2.0 Screw P 4x10 Cover / tank housing 1.0 Screw D 4x12 Cover / chain tensioner / crankcase 2.5 2), 4) Screw M 5x16 Antivibration element / crankcase 8.0 2), 4) Screw P 5x34 Antivibration element / tank housing 4.0 Screw D 4x12 Brake band / crankcase 3.0 2), 4) Screw P 4x10 Brake cable support / tank housing 1.0 Q Stud M 5x18 Stud 7.0 2), 3) Stud M 8 Bar mounting stud 23.0 1) Stud M 8 Bar mounting stud 23.0 1), B Stud D 8x18 Bar mounting stud (repair solution) 16.0 Screw D 4x12 Cover, chain brake / crankcase 3.0 2), 4)

M 10x1 Decompression valve 14.0 Nut M 5 Filter base / baffle / carburetor 3.5 Screw M 4x12 Generator / crankcase 3.0 3), VW Screw P 6x25 Handlebar / locking screw 8.0 VW Screw P 6x26.5 Handlebar / tank housing right 6.0 Screw P 6x30 Handlebar / tank housing right 6.0 2), 4), VW Screw M 5x16 Handlebar / tank housing bottom 5.0 2), 3) Screw M 5x12 Handlebar / tank housing bottom 8.0 3), VW Screw M 5x16 Handlebar / plugs antivibration springs 10.0 2), 3), VW Screw M 5x20 Hand guard / fan housing / crankcase 6.0 3) Screw P 6x30 Chain catcher / crankcase / bearing plugs 6.0 Nut M 5 Spiked bumper / crankcase / upper lock nut 8.0 Screw M 5x10 Spiked bumper / top of crankcase 8.0 2), 3) Screw M 5x16 Spiked bumper / bottom of crankcase 8.0 2), 3) Screw D 4x12 Manifold / cylinder 4.0 2), 4) Screw M 5x20 Crankcase drive side / fan side 10.0 2), 4) Screw M 5x16 Bearing plugs / cylinder 10.0 2), 3) Screw M 5x16 Fan housing / crankcase 6.0 2), 4) Screw D 4x12 Air guide shroud / crankcase 4.0 2), 4)

Comment

6 MS 241 C

Fastener Thread size For component Tightening

torque Nm

Carrier M 12x1 L Crankshaft carrier 50.0 Screw D 4x12 Oil pump / crankcase 4.0 2), 4) Screw M 5x16 Muffler / crankcase 10.0 2), 3) Screw M 5x16 Muffler / cylinder 10.0 2), 3) Nut M 8x1 Flywheel / crankshaft 28.0 5) Nut M 12x0.75 Switch 2.0 Screw P 4x10 Support 1.0 Screw D 4x12 Pre-separator / crankcase 4.0 2), 4)

M 10x1 Spark plug / cylinder 12.0 Screw D 4x20 Control unit / cylinder 4.5 2), 4) Screw M 5x20 Cylinder / crankcase 1st stage 4.0 2), 4) Screw M 5x20 Cylinder / crankcase 2nd stage 10.0 2), 4)

Remarks:

1) Loctite 242 or 243 medium strength

2) Screws with locking serration

3) Microencapsulated screws

4) Screws with easy-slide coating

5) Connection between crankshaft and flywheel must be degreased and oil-free Q) QuickStop Super B) Quick chain tensioner VW) Heating

Comment

When inserting DG and P screws into an existing screw thread:

Insert the DG or P screw in the hole and turn counterclockwise until it gently drops into the hole in axial direction. 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.

Coat micro-encapsulated screws with Loctite 242 or 243 medium strength before refitting them.

Screwdriver speed when used in plastic material: max. 500 rpm for DG and P-type screws. Do not use an impact wrench to release or tighten screw connections.

Screws with and without locking serration must not be confused.

7MS 241 C

3. Troubleshooting

3.1 Clutch

Problem Cause Remedy

Saw chain becomes stuck under full load

Saw chain rotates at idle speed Idle speed too high Check M-Tronic

Loud noises Tension springs stretched Replace all tension springs

Clutch shoes badly worn Install new clutch

Clutch drum badly worn Install new clutch drum

Tension springs of the clutch shoes are stretched

Tension springs of the clutch shoes are broken

Needle cage damaged Replace needle cage

Clutch shoe retainer broken Examine retainer, replace if

Replace tension springs, replace clutch if necessary

Replace tension springs

necessary

Clutch shoes and carrier worn Install new clutch

8 MS 241 C

3.2 Chain Drive, Chain Brake, Chain Tensioner

Problem Cause Remedy

Chain sprocket wears rapidly Chain not properly tensioned Tension chain as specified

Wrong chain pitch Fit chain of correct pitch

Insufficient chain lubrication Check chain lubrication

Saw chain becomes stuck under full load

Saw chain rotates at idle speed Idle speed too high Check M-Tronic

Saw chain does not stop immediately when brake is activated

Clutch shoes badly worn Install new clutch

Clutch drum badly worn Install new clutch drum

Brake band stuck Check freedom of movement and

function of brake band

Tension springs of the clutch shoes are stretched

Tension springs of the clutch shoes are broken

Brake spring stretched or broken Fit new brake spring

Replace tension springs, replace clutch if necessary

Replace tension springs

Brake band stretched, worn or broken

Clutch drum worn Install new clutch drum

Fit new brake band

9MS 241 C

Problem Cause Remedy

QuickStop Super

Coasting brake is not released although trigger interlock is pressed

QuickStop Super

Brake band is not released although trigger interlock is pressed

QuickStop Super

Coasting brake does not brake properly – trigger interlock not pressed

Brake cable stretched Adjust brake cable

Brake cable unhooked or broken Reattach or replace brake cable

Excessive play on trigger interlock Adjust brake cable

Brake cable overstretched Adjust brake cable

Sleeve of the brake cable not seated completely in adjusting screw

Push the sleeve into the adjusting screw as far as it will go and adjust brake cable

10 MS 241 C

3.3 Chain lubrication

In the event of trouble with the chain lubrication system, check and rectify other sources of faults before disassembling the oil pump.

Problem Cause Remedy

Chain receives no oil Oil inlet hole in guide bar is blocked Clean oil inlet hole

Intake hose or pick-up body clogged or intake hose ruptured

Valve in oil tank blocked Clean or replace valve

Worm worn Replace worm

Oil pump damaged or worn Install new oil pump

Machine looses chain oil Oil pump damaged or worn Install new oil pump

Oil intake hose connection damaged

Crankcase cracked Check crankcase halves and

Oil pump delivers insufficient oil Oil pump damaged or worn Install new oil pump

Worm carrier is loose Replace worm

Fit new intake hose and pick-up body

Fit new oil intake hose

replace damaged crankcase halves

11MS 241 C

3.4 Starter

Problem Cause Remedy

Starter rope broken Rope pulled out too vigorously as

far as stop or over edge, i.e. not vertically

Normal wear Replace starter rope

Starter rope does not rewind Heavy fouling or rust on rewind

spring

Spring insufficiently tensioned Check rewind spring and increase

Rewind spring broken Replace rewind spring

Starter rope cannot be pulled out far enough

Starter rope can be pulled out almost without resistance (crankshaft does not turn)

Rewind spring overtensioned Check rewind spring and reduce

Guide peg on pawls or pawls themselves are worn

Replace starter rope

Clean or replace rewind spring

tension

Replace pawls

Spring clip fatigued Replace spring clip

Spring clip improperly installed Install spring clip properly

...Versions with ErgoStart Guide peg on pawls or pawls

themselves are worn

Torsion spring on flywheel are fatigued, pawls are worn or sticking

Lugs on carrier are worn Replace carrier

Anchor loop in spring housing not hooked onto carrier

Starter rope is difficult to pull – versions with ErgoStart

Spring in spring housing is fatigued Replace spring housing

Replace pawls

Clean mounts on the pawls, replace pawls and torsion springs if necessary

Hook anchor loop to carrier

12 MS 241 C

Problem Cause Remedy

Starter rope is difficult to pull or rewinds very slowly

Starter mechanism is very dirty Thoroughly clean complete starter

mechanism

At very low outside temperatures: Lubricant oil on the rewind spring becomes viscous (spring winding stick together) or moisture has penetrated the rewind spring (spring windings are frozen)

Coat rewind spring with a little standard solvent-based degreasant (containing no chlorinated or halogenated hydrocarbons), then pull rope carefully several times until normal action is restored

13MS 241 C

3.5 Ignition system

Problem Cause Remedy

Engine runs roughly, misfires, temporary loss of power

Spark plug boot is loose Press boot firmly onto spark plug

and fit new spring if necessary

Spark plug sooted, smeared with oil Clean the spark plug or replace if

necessary In the event of repeated sooting, check air filter

Fuel/oil mixture – contains too much oil

Wrong air gap between control unit and flywheel

Flywheel is cracked or has other damage or pole shoes have turned blue

Incorrect ignition timing, flywheel out of adjustment – Key in flywheel has sheared off

Weak magnetization in flywheel Install new flywheel

Use a fuel mixture with the correct mixing ratio

Set the correct air gap

Install new flywheel

Irregular spark Check operation of switch shaft/

contact spring and control unit Damaged insulation or interruption in ignition lead or short circuit wire. Check ignition lead/control unit, replace control unit if necessary. Check operation of spark plug, clean spark plug and replace if necessary. Check M-Tronic

14 MS 241 C

3.6 Carburetor

Problem Cause Remedy

Carburetor floods; engine stalls Inlet needle not sealing

– Foreign matter in valve seat or cone

Inlet needle worn Replace inlet needle

Inlet control lever sticking on spindle

Helical spring not located on nipple of inlet control lever

Perforated disc on diaphragm is deformed and presses constantly against the inlet control lever

Metering diaphragm is deformed Replace metering diaphragm

Poor acceleration Carburetor setting too lean Check M-Tronic

Carburetor setting too rich Check M-Tronic

Remove and clean inlet needle or clean carburetor

Examine control lever, replace if necessary

Remove the inlet control lever and refit it correctly

Replace metering diaphragm

Inlet needle sticking to valve seat Remove inlet needle, clean and

refit

Diaphragm gasket leaking Replace diaphragm gasket

Metering diaphragm damaged or shrunk

Tank vent faulty Replace tank vent

Leak in fuel line between tank and carburetor

Replace metering diaphragm

Seal connections or replace line

15MS 241 C

Problem Cause Remedy

Engine will not idle, idle speed too high

Engine stops when idling Idle jet bores

Throttle shutter is not closed properly when the throttle trigger is not pressed

Oil seals or crankcase leaking Seal oil seals or crankcase, replace

Throttle shutter does not close Replace carburetor

or ports blocked

Idle jet too rich or too lean

Tank vent faulty Replace tank vent

Leak in fuel line between tank and carburetor

Examine carburetor and throttle rod, replace if necessary

if necessary

Clean the carburetor

Check M-Tronic

Seal connections or replace line

Saw chain rotates at idle speed Idle speed too high Check M-Tronic

Clutch springs stretched or fatigued Replace tension springs, replace

clutch if necessary

Anchor loops of the clutch spring hooks are broken

Replace tension springs

16 MS 241 C

Problem Cause Remedy

Engine speed drops quickly under load – low power

Air filter dirty Clean air filter, replace if necessary

Throttle shutter not opened fully Check throttle rod

Tank vent faulty Replace tank vent

Fuel pick-up body dirty Replace pickup body

Fuel strainer dirty Clean fuel strainer in carburetor,

replace if necessary

Leak in fuel line between tank and carburetor

Carburetor setting too lean Check M-Tronic

Main jet bores or ports blocked Clean the carburetor

Pump diaphragm damaged or fatigued

Seal connections or replace line

Replace pump diaphragm

Engine runs extremely rich, lacks power and has very low final speed

Incorrect ignition timing, flywheel out of adjustment – Key in flywheel has sheared off

Choke shutter does not open Examine the carburetor and starter

Carburetor setting too rich Check M-Tronic

Install new flywheel

shaft and repair or replace if necessary

17MS 241 C

3.7 Engine

Always check and, if necessary, repair the following parts before looking for faults on the engine:

- Air filter,

- Fuel system,

- Carburetor,

- Ignition system

Problem Cause Remedy

Engine does not start easily, stalls at idle speed but operates normally at full throttle

Engine does not deliver full power or runs erratically

Oil seals in engine defective Replace oil seals

Crankcase leaking or damaged (cracks)

Intake manifold damaged/ hole is plugged

Piston rings worn or broken Replace piston rings

Muffler / spark arresting screen carbonized

Air filter dirty Clean or replace air filter

Fuel line kinked or cracked Replace fuel line and ensure that is

Replace damaged crankcase halves

Clean hole or replace intake manifold

Clean muffler (inlet and outlet openings), replace spark arresting screen, replace muffler if necessary

installed without kinking

Intake manifold damaged / hole is plugged

Engine is overheated Insufficient cylinder cooling. Air

inlets in fan housing blocked or cooling fins on cylinder very dirty

Air intake in fan housing is fouled Clean air intake on fan housing

18 MS 241 C

Clean hole or replace intake manifold

Thoroughly clean all cooling air openings and the cylinder fins

4. Clutch

4.1 Clutch drum

– Clutch drum removal and

installation, see Instruction Manual

– Remove needle cage

– Clean needle cage and

crankshaft stub, b 16

– Grease needle cage and

crankshaft stub, b 16

100%

: Remove the spark plug boot (1)

– Unscrew spark plug

2410RA001 TG

: Unscrew the clutch (1) with

hexagon (arrow) – left-hand thread

Installation

TOP

2410RA004 TG

80%

– Examine the clutch drum (1) for

signs of wear

The remaining thickness must be measured if there are distinct signs of wear on the inside diameter of the clutch drum (1). The clutch drum must be replaced if the remaining thickness is less than approx. 80 % of the original thickness.

– Install the clutch drum

4.2 Clutch

– Troubleshooting, b 3.1

– Removing the clutch drum,

b 4.1

– Remove shroud, b 6.4

5902RA018 TG

: Orient the locking strip (1)

0000 893 5904 so that the flat side of the metallic attachment faces the piston and insert it in the cylinder

: Locking strip (1) 0000 893 5904

must rest against the cylinder wall (arrow) and the flat side of the metal attachment must rest against the piston head – Position as shown

2410RA002 TG

2410RA005 TG

Slide washer (1) into place so that the word "TOP" is visible.

: Fit the clutch (2) on the

crankshaft stub so that the raised hexagon (arrow) can be seen

: Screw on and tighten the

clutch (2) – left-handed thread

– Pull the locking strip out of the

cylinder

– Reassemble remaining parts in

2410RA003 TG

reverse order

19MS 241 C

5. Chain brake

5.1 Checking operation of chain brake

The chain brake is one of the most important safety devices on the chain saw. Its efficiency is measured in terms of the chain braking time, i.e., the time that elapses between activating the brake and the saw chain coming to a complete standstill.

Fouling (particularly with chain oil, chips, fine particles of abrasion, etc.) and smoothing of the friction surfaces of the brake band and clutch drum impair the coefficient of friction. This in turn extends the braking time. A fatigued or stretched brake spring has the same negative effect.

– Starting the engine

– With the chain brake

activated (locked), open the throttle wide for a brief period (max. 3 seconds) – the chain must not rotate

– With the chain brake released,

open the throttle wide and activate the brake manually – the chain must come to an abrupt stop

Versions with QuickStop Super

When the trigger interlock is pressed, the clutch drum must rotate freely.

With the coasting brake released, open the throttle wide and release the trigger interlock in the rear handle – the saw chain must come to an abrupt stop

All versions

The braking time is in order if deceleration of the saw chain is imperceptible to the eye (less than 1 second).

If the chain brake does not operate properly, refer to the troubleshooting chart, b 3.2.

5.2 Brake band

– Remove the clutch drum, b 4.1

– Troubleshooting, b 3.2

: Remove screws (1)

: Remove the cover (2)

– Block chain brake

: Ease brake band (2) out of

guide (arrow)

– Remove brake band, taking care

not to overextend it

– Release the chain brake

: Turn brake band (1) slightly aside

and disconnect it from the brake lever (2)

2410RA006 TG

Install a new brake band if there are noticeable signs of wear on large areas on the inside diameter and/or parts of the outside (arrows) and its remaining thickness is less than < 0.6 mm.

5902RA024 TG

219RA049 TG

2410RA007 TG

: Unscrew screw (1) on the bottom

of the machine

20 MS 241 C

Installation

5.3 Brake lever

– Troubleshooting, b 3.2

– Remove shroud, b 6.4

– Remove fan housing, b 9.2

– Release the chain brake

: Attach brake band (1) to brake

lever (2) sideways and turn it towards its mount

: Insert brake cable (1) in

guide (arrow)

: Push brake band (1) fully home in

2410RA009 TG

the mount (arrow)

: Screw in and tighten screw (2) on

the bottom of the machine

: Insert cover (1)

2410RA010 TG

: Insert and tighten down the

screws (2)

– Remove brake band, b 5.2

2410RA012 TG

– Block chain brake

The brake spring is now relaxed.

: Use the assembly tool

2410RA013 TG

1117 890 0900 to unhook the brake spring (1) at the anchor pin (arrow)

– Unhook and remove the brake

spring at the brake lever

2410RA014 TG

– Block chain brake

: Guide brake band (1) over

studs (arrows) and press it into the mount

– Install the clutch drum, b 4.1

When the chain brake is released, the clutch drum must rotate freely.

– Carry out additional function

tests, b 5.1

– Reassemble remaining parts in

reverse order

2410RA011 TG

21MS 241 C

: Push out circlip (1)

– Examine pins and replace if

necessary, b 5.6

– Check cam on hand guard,

replace hand guard if necessary

Installation

– Clean pins and disassembled

2410RA015 TG

parts, b 16

2410RA020 TG

: Slightly lift up bearing eye of the

– Grease pins, b 16

hand guard (1) and brake lever (2) and guide the parts over the anchor pins (arrows)

: Draw hand guard (1) and brake

lever (2) off the anchor pins (arrows) simultaneously

– Take out hand guard and brake

lever

– Examine cam lever and replace if

necessary, b 5.5

: Pull brake lever (2) out of hand

guard (1)

2410RA016 TG

: Position brake lever (2) so that

mount for brake spring (arrow) is at the top

: Slide brake lever (2) into recess

in hand guard (1) until the holes are lined up

2410RA017 TG

: Slide hand guard (1) with brake

lever (2) across the machine until it rests against the anchor pins (arrows)

2410RA018 TG

: Turn cam lever (1) slightly aside

until cam of hand guard (arrow) slides past

– Press bearing eye of hand guard

and brake lever onto the anchor pins

2410RA019 TG

: Push circlip (1) into place

2410RA021 TG

2410RA022 TG

22 MS 241 C

5902RA040 TG2410RA023 TG

spring at the brake lever

2410RA024 TG

– Unhook and remove the brake

The turns of the brake spring must be tightly spaced when not installed; use a new brake spring if necessary.

– Position the protective tube so

that it starts after the second turn (arrow)

– The pin for the brake spring must

be replaced if it shows signs of wear at the groove, b 5.6

: Hook brake spring (1) into brake

lever (arrow)

: Use the assembly tool (2)

1117 890 0900 to attach the brake spring (1) to the anchor pin (arrow)

– Grease brake lever, cam lever

and hand guard motion link, b 16

– Reassemble remaining parts in

reverse order

5.4 QuickStop Super brake lever

– Troubleshooting, b 3.2

– Remove shroud, b 6.4

– Remove fan housing, b 9.2

– Remove brake band, b 5.2

2410RA026 TG

: Unhook brake spring (1) from

anchor pin (arrow)

: Unhook and remove the brake

spring (1) at the brake lever

2410RA027 TG

: Draw hand guard (1) and brake

lever (2) off the anchor pins (arrows) simultaneously

– Block chain brake

The brake spring is now relaxed.

: Use the assembly tool

1117 890 0900 to unhook the brake spring (1) at the anchor pin (arrow)

– Take out hand guard and brake

lever

2410RA025 TG

23MS 241 C

Installation

– Clean pins and disassembled

parts, b 16

: Disconnect brake cable (1)

: Pull brake lever (2) out of hand

guard (1)

– Examine cam lever and replace if

necessary, b 5.5

– Examine pins and replace if

necessary, b 5.6

– Grease pins, b 16

2410RA028 TG

: Position brake lever (2) so that

mount for brake spring (arrow) is at the top

: Slide brake lever (2) into recess

2410RA029 TG

in hand guard (1) until the holes are lined up

2410RA032 TG

: Slide hand guard (1) with brake

lever (2) across the machine until it rests against the anchor pins (arrows)

2410RA030 TG

2410RA033 TG

: Slightly lift up bearing eye of the

hand guard (1) and brake lever (2)and guide the parts over the anchor pins (arrows)

– Check cam on hand guard,

replace hand guard if necessary

2410RA031 TG

: Attach brake cable (1) to

hole (arrow) in brake lever

24 MS 241 C

: Attach brake spring (1) to anchor

pin (2)

: Turn cam lever (1) aside until

cam of hand guard (arrow) slides past

– Press bearing eye of hand guard

and brake lever onto the anchor pins

: Check seat of the sleeve (1) at

the brake cable, push completely into the hole in the housing (arrow) if necessary

2410RA034 TG2410RA035 TG

The turns of the brake spring must be tightly spaced when not installed; use a new brake spring if necessary.

– Position the protective tube so

that it starts after the second turn (arrow)

– The pin for the brake spring must

be replaced if it shows signs of wear at the groove, b 5.6

: Use the assembly tool

1117 890 0900 to hook the brake

5902RA040 TG

spring (1) onto the anchor pin (arrow)

– Grease brake lever, cam lever

and hand guard motion link, b 16

– Adjust brake cable, b 5.4.1

– Reassemble remaining parts in

reverse order

5.4.1 Adjusting brake cable

If the coasting brake does not operate properly although the brake band is intact, it may be necessary to adjust the brake cable.

– Troubleshooting, b 3.2

– Check condition and play

2410RA025 TG

: Hook brake spring (1) into the

brake lever so that the opening of the anchor loop (arrow) is visible

: Hook brake spring (1) onto brake

lever (arrow)

2410RA036 TG

2410RA037 TG

– Remove chain brake cover,

b 5.2

When the trigger interlock is not pressed, the brake cable must be without tension.

25MS 241 C

Adjust brake cable

: Screw in adjusting screw (2)

– Play increases

– Press and hold the trigger

interlock down completely

Brake band (1) must rest against the crankcase (arrows) without play and the clutch drum must rotate freely.

– Release trigger interlock

2410RA038 TG

: Remove screw (1)

: Lower tank housing (2)

: Unscrew adjusting screw (2)

– Play decreases

: Once play is adjusted correctly,

tighten clamping screw (3)

2410RA039 TG

– Press and hold the trigger

interlock down completely

Brake band (1) must rest against the crankcase (arrows) without play and the clutch drum must rotate freely.

2310RA050 TG

2410RA038 TG

: Press trigger interlock (1) gently

to check the play

– The play must not exceed the

mark (a)

Play: is equal to the distance traveled by the trigger interlock (1) without causing the brake lever to move at the same time.

Play is necessary to ensure trouble free functioning of the coasting brake.

– Troubleshooting, b 3.2

: Loosen clamping screw (1) on

the support for the brake cable

0001RA456 TG

The sleeve (1) must be seated on the adjusting screw (2) as far as it will go.

: Position open-end wrench SW 6

on the adjusting screw (2) and adjust play

– Reassemble remaining parts in

reverse order

2410RA556 TG

26 MS 241 C

5.4.2 Brake cable Removal and installation

– Unhook brake spring, b 5.4

support (2) with a gentle twisting motion

: Push hook (1) through the

– Remove QuickStop Super

throttle trigger, b 11. 3

– Remove QuickStop Super trigger

switch, b 11.3.1

: Pull brake cable (1) out slightly

and disconnect it

– Loosen tank housing and lower it,

b 13.11.2

– Do not overextend fuel hose

: Examine brake cable (1) and

support (2), replace if necessary

Dismantle brake cable and support

2410RA040 TG

3 4

: Unscrew clamping screw (1) and

adjusting screw (2)

2310RA053 TG

2310RA056 TG

: Turn adjusting screw (1) until the

distance between the hexagon of the adjusting screw and the

holder is 2 mm

: Screw in the clamping screw (2)

and tighten

2310RA054 TG

: Remove screw (1)

: Remove support (2) with brake

cable

: Turn hook (3) so that the angled

part is at the opening (arrow) and twist it out of the support (4)

Installation

2410RA041 TG

: Turn hook (1) so that it runs along

the support (2) and push it into the hole (arrow)

2410RA042 TG

: Guide the brake cable (1) over

fuel hose (3) or, in versions with manual fuel pump, over the fuel hose (3) and fuel return line (2)

: Push brake cable (1) with short

hook (4) in front through the hole (arrow) in the crankcase

2310RA055 TG

27MS 241 C

reverse order

– Adjust brake cable and check

– Reassemble remaining parts in

operation, b 5.4.1

5.5 Cam lever

: Push brake cable (1) with sleeve

into the hole in the housing (arrow) as far as it will go

1 2

: Hook brake cable (1) into

hole (arrow) in brake lever (2)

2410RA043 TG

When raising the tank housing, make certain that the sleeve (1) is pushed completely into the adjusting screw (2) – incomplete insertion of the sleeve changes the setting of the brake cable.

– Check position of the fuel hose

and correct it if necessary, b 13.11.2

– Check position of the fuel return

line and correct it if necessary, b 13.11.3

2410RA044 TG

– Raise and fasten the

tank housing, b 13.11.2

2410RA046 TG

The cam lever defines the engaged position of the hand guard.

– Remove brake lever, b 5.3,

QuickStop Super, b 5.4

: Unhook the brake spring (1) from

the anchor pin (2)

– Unhook and remove the brake

spring (1) at the cam lever

2410RA048 TG

: Press brake cable holder with the

pin (1) through the opening and into the mount (arrow)

: Screw in the screw (2) and

tighten it

2410RA045 TG

: Insert brake cable (1) in

guide (arrow)

– Install QuickStop Super trigger

switch, b 11.3.1

– Install QuickStop Super throttle

trigger, b 11.3

: Push out circlip (3)

– Remove cam lever

2410RA047 TG

28 MS 241 C

5.6 Pins

The pins ensure that the springs are securely mounted. They must

therefore be replaced when worn, otherwise the springs may pop out.

: Examine cam lever (1) and brake

spring (2) and replace if necessary

: Check condition of cam

guide (arrow) and replace hand guard if necessary

– Examine all pins and replace if

necessary, b 5.6

Installation

– Clean pins and disassembled

parts, b 16

– Grease pins, b 16

2410RA049 TG

: Push circlip (1) into place

: Hook brake spring (1) into the

brake lever so that the opening of the anchor loop (arrow) is visible

: Hook brake spring (1) onto

pin (2)

The pins must be driven in square.

For reasons of simplicity, the parts

2410RA051 TG

connected to the pins have already been removed in the following illustrations.

132

2410RA052 TG

: Remove pins (1) through (6)

Item 6 is present only in the version with QuickStop Super.

2410RA053 TG

: Orient cam lever (1) so that the

cam (arrow) faces the pin (3)

: Slide cam lever (1) onto anchor

pin (2)

– Grease cam lever, b 16

The cam lever is not yet tensioned – the spring may become detached again.

– Reassemble remaining parts in

reverse order

2410RA050 TG

29MS 241 C

Installation

Machines with QuickStop Super

0001RA061 TG

– Coat the knurled area of the new

pin with Loctite before fitting the pin, b 16

: The pin must be inserted in the

hole (arrow) so that the knurling on the pin engages the knurled profile

Turn the pin back and forth slightly until it fits.

The pins must be driven in square.

: Pin (1) a = approx. 2.9...3.3 mm

2410RA054 TG2410RA055 TG

Pin (2) b = approx. 4.3...4.7 mm

4 5

: Drive in anchor pins (3), (4)

and (5) in accordance with the following information

: Drive in anchor pins (5) and (6) in

accordance with the following information

2410RA056 TG

: Pin (5) b = approx. 5.1...5.3 mm

Pin (6) a = approx. 2.9...3.3 mm

– Reassemble remaining parts in

reverse order

2410RA058 TG

2410RA059 TG

– Grease brake and cam levers,

: Drive in pins (1) and (2) in

accordance with the following information

30 MS 241 C

: Pin (3) a = approx. 8.9...9.1 mm

Pin (4) b = approx. 4.6...4.8 mm Pin (5) c = approx. 5.1...5.3 mm

2410RA057 TG

b 16

5.7 Chain tensioner

– Troubleshooting, b 3.2

: Turn the spur gear (2) clockwise

until the tensioner slide (1) makes contact on the right and the screw (3) is revealed

: Remove screw (3)

5.7.1 Quick chain tensioner

The quick chain tensioner is built into the chain sprocket cover.

2410RA060 TG

: Unscrew screw (1) and remove

side plate (2), remove Loctite residue if necessary

– Examine side plate, replace if

necessary

– Fold out wing nut (1)

: Push wing nut (1) into the

opening thin side (arrow) first,

2410RA544 TG

then press it in until it snaps into place

2410RA063 TG

: Remove spur gear (2) and

tensioner slide (1)

1 3

: Examine the cover (1), spur gear

kit (2), tensioner slide (3) and thrust pad (4) and replace if necessary

– Clean all disassembled parts,

b 16

– Coat the threads and gear

wheels with STIHL multi-purpose grease, b 16

– Coat screw with Loctite before

insertion, b 16

– Install parts in reverse order

2410RA061 TG

: Carefully pry out wing nut (1) at

the side (arrow)

– Check wing nut (1) and replace if

necessary

: Remove the screw (arrow)

: Remove cover plate (1) and

adjusting wheel (2)

When installing the adjusting wheel, make certain that the teeth face the cover plate

– Reassemble the parts in reverse

2410RA062 TG

order

2410RA064 TG

– Reassemble parts in reverse

order

31MS 241 C

5.7.2 Chain catcher

– Remove the chain sprocket cover

: Remove screw (1) and pull out

chain catcher (2) under the bumper strip

– Reassemble remaining parts in

reverse order

5.9 Collar nut for chain sprocket cover

This chain sprocket cover can only be used on the MS 241. It cannot be retrofitted to other models. The length and shape of the stud must be appropriate for the chain sprocket cover with captive nut.

2410RA300 TG

The special tool stud 5910 893 9600 is available for replacing the nut.

2410RA067 TG

– Flip over the chain sprocket cover

and clamp the assembly tool into a vise by the hexagon

: Drill out the collar nut with an

11 mm diameter drill bit – the base in the chain sprocket cover must not be drilled out

– Reassemble parts in reverse

order

5.8 Bar mounting stud

– Remove the chain sprocket cover

: Push stud driver (1)

5910 893 0501 onto the stud (2) as far as it will go and unscrew counterclockwise

– Remove the chain sprocket cover

: Screw the assembly tool (1)

5910 893 9600 with the short stud into the collar nut (2) as far as it will go

2410RA065 TG

– Pull out the collar nut

– Unscrew the assembly tool from

the collar nut

2410RA066 TG

– Coat stud with Loctite, screw in

and tighten, b 16

32 MS 241 C

Installation

: Push in new collar nut (1)

2410RA068 TG

– Hold the hexagon of the collar nut

in place

: Screw the assembly tool (1)

5910 893 9600 with the long stud into the opposite side of the collar nut as far as it will go

Now the new collar nut has been flanged and secured in the chain sprocket cover.

– Reassemble remaining parts in

reverse order

2410RA069 TG

33MS 241 C

6. Engine

6.1 Muffler

Check and if necessary repair the fuel supply, carburetor, air filter and ignition system before looking for faults on the engine.

– Troubleshooting, b 3.7

– Remove shroud, b 6.4

To keep dirt particles from entering the cylinder, move piston to top dead center before removing the muffler.

1 1

: Pry out the stoppers (1) around

the circumference at the markings – Do not reuse dismantled stoppers

– Remove and install spark

arresting screen, if present, see Instruction Manual

Installation

– Cover exhaust bore and remove

any fouling on the cylinder and exhaust bore

: Examine and clean the mating

surfaces (arrows), remove any

2410RA070 TG

gasket residues if necessary – there must not be any gasket residues or dirt particles in the exhaust bore

Parts with damaged mating surfaces must be replaced.

3 3

: Carefully fit the muffler (1)

: Fit screws (2) and check that

gasket is correctly positioned

: Insert screws (3) – do not tighten

: First tighten screws (2), then

tighten screws (3)

2410RA072 TG2410RA073 TG

– Press in new stoppers evenly and

straight around the circumference with a blunt tool – do not insert them on a slant or damage them

2410RA071 TG

2 2

: Remove screws (1) and (2)

: Take out and examine the

muffler (3), replace if necessary

– Remove exhaust gasket

2410RA071 TG

: Orient the exhaust gasket (1) so

that the tabs (arrows) face towards the cylinder

: Fit the exhaust gasket (1) and

orient it with the tabs (arrows) on the connector of the cylinder

– always use a new exhaust gasket

34 MS 241 C

6.2 Leak testing

Defective oil seals and gaskets or cracks in housing are the usual causes of leaks. Such faults allow supplementary air to enter the engine and upset the fuel-air mixture.

This makes adjustment of the prescribed idle speed difficult, if not impossible.

Moreover, the transition from idle speed to part or full throttle is not smooth.

Always start with the vacuum test and then continue with the pressure test.

The engine can be thoroughly checked for leaks under vacuum and at gauge pressure using the pump 0000 850 1300.

6.2.1 Preparations

– Remove shroud, b 6.4

– Take off the spark plug boot and

remove the spark plug

– Set the piston to the top

dead center (this can be checked through the spark plug hole)

– Remove the decompression

valve, b 6.9

: Fit the stopper (1) 1122 025 2200

and screw it tight

: Screw in spark plug (2) and

tighten it securely

– Remove muffler and gasket,

b 6.1

2 2

: Position flange (1)

5910 855 4201 on cylinder exhaust port

: Screw in screws (2)

– do not tighten

2410RA075 TG

The flange (1) 4224 893 2501 can be reworked as shown. a=13 mm b=39.25mm c=6mm

: Slide sealing plate (1)

0000 855 8106 between cylinder

2410RA076 TG

exhaust port and flange (2)

: Tighten screws (3) lightly

The sealing plate must fill the full width between the screws.

– Carefully pull out the carburetor

over the studs and lay it aside – Do not overextend fuel hose, b 8.4

2710RA164 TG

2410RA077 TG

35MS 241 C

4 3

3 2

: Washer (1) must be fitted

: Orient flange (1) 1118 850 4200

and push it onto the studs

: Fit flange (1) 1118 850 4200

: Tightly screw on nuts (2)

6.2.2 Vacuum test

Oil seals tend to fail when subjected to a vacuum. In other words, the sealing lip lifts away from the crankshaft during the piston's induction stroke because there is no internal counterpressure.

This kind of fault can be detected by testing with pump 0000 850 1300.

2410RA078 TG

: Push the hose (1) of pump

0000 850 1300 onto the connector (arrow)

: Slide ring (2) to the left

– Vacuum test

: Operate lever (3) until the

pressure gauge (4) indicates a vacuum of 0.5 bar

If the vacuum reading remains constant, or does not decrease by

2410RA079 TG

more than 0.3 bar within 20 seconds, it may be assumed that the oil seals are in good condition. If the vacuum in the crankcase is reduced further, the oil seals must be replaced, b 6.3.

– After testing, slide the ring on the

pump back to the right to vent the pump.

– Continue with pressure test,

b 6.2.3

6.2.3 Pressure test

The same preparatory steps are required as for the vacuum test, b 6.2.2.

2310RA080 TG

: Slide ring (1) to the right

– Pressure test

: Operate the lever (2) until the

pressure gauge (3) indicates a pressure of 0.5 bar. If this pressure remains constant for at least 20 seconds, the engine crankcase is airtight

– If the pressure drops, the leak

must be located and the defective part replaced

To find the leak, coat the suspect area with soapy water and pressurize the crankcase. Bubbles will appear if a leak exists.

– After testing, slide the ring on the

pump to the left to vent the pump – disconnect the hose

– Remove flange 1118 850 4200

on intake elbow

– Refit carburetor, b 8.4

– Remove flange 5910 855 4201

and sealing plate 0000 855 8106

– Refit the muffler, b 6.1

– Press in new stoppers straight

with a blunt tool – Do not damage stoppers

2410RA081 TG

– Reassemble remaining parts in

reverse order

36 MS 241 C

6.3 Oil seals

It is not necessary to dismantle the complete engine if only the oil seals need to be replaced.

Pull out oil seals using puller 5910 890 4400 and jaws (profile no. 6) 0000 893 3711.

Installation

– Clean the mating surface, b 16

– Grease the sealing lips of the

new oil seal, b 16

– Clean the cone of the crankshaft

to ensure it is completely greasefree, b 16

– Reassemble remaining parts in

reverse order

6.3.2 Clutch side

6.3.1 Ignition side

– Remove fan housing, b 9.2

– Remove the flywheel, b 7.6

Versions with heating

– Unscrew screws, remove

generator and set it aside, b 14.7

: Fit the installing sleeve (1)

1141 893 4600

: Slide the oil seal (2) over the

installing sleeve with the sealing lip facing the crankcase

– Remove the installing sleeve (1)

2410RA082 TG

– Remove the clutch, b 4.2

– Remove oil pump, b 12.3

2410RA083 TG

2410RA085 TG

: Remove the circlip (1)

Avoid damage to the crankshaft stub.

– Free the oil seal in its seat by

tapping it with a suitable tube or a punch.

: Position puller (1) 5910 890 4400

– Clamp the puller arms

– Pull out the oil seal

2410RA084 TG

: Orient press sleeve (2)

1143 893 2400 with the collar (arrow) facing the engine

: Use the press sleeve (2)

1143 893 2400 to install the oil seal (1)

The seating face must be flat and free from burrs.

37MS 241 C

: Remove the installing sleeve (1)

6.4 Shroud

Avoid damage to the crankshaft stub.

– Free the oil seal in its seat by

tapping it with a suitable tube or a punch.

: Position puller (1) 5910 890 4400

– Clamp the puller arms

– Pull out the oil seal

Installation

2410RA086 TG

: Orient press sleeve (1)

1118 893 2401 with the collar (arrow) facing the engine

: Use the press sleeve (1)

1118 893 2401 to install the oil seal (2)

The seating face must be flat and free from burrs.

2410RA090 TG

2410RA088 TG

: Release quick release

locks (arrows) – Using the combination wrench, turn 1/4 turn counterclockwise

: Remove the shroud (1)

– Clean the mating surface, b 16

– Grease the sealing lips of the

new oil seal, b 16

: Fit the installing sleeve (1)

1141 893 4600

: Slide the oil seal (2) over the

installing sleeve with the sealing lip facing the crankcase

: Fit the circlip (1)

– Reassemble remaining parts in

reverse order

2410RA087 TG

2410RA089 TG

2410RA091 TG

: Push out cap (arrow) with drift (1)

38 MS 241 C

Installation

– Remove the carburetor, b 13.5

– Remove carburetor support,

b 13.8

: Push in cap (1) with drift (2)

– Reassemble remaining parts in

reverse order

6.5 Cylinder

Before removing the cylinder, decide whether or not the crankshaft is to be removed.

With cylinder installed

The crankshaft must be prevented from twisting by blocking the piston through the spark plug hole in order to remove the flywheel and clutch.

– Remove air guide shroud,

b 13.4, versions with manual fuel pump b 13.4.1, versions with heating b 13.4.2

– Remove the muffler, b 6.1

2410RA092 TG

– Remove the decompression

valve, b 6.9 – not for version with ErgoStart

– Remove the front handle,

b 10.4 – not for version with heating

– Remove antivibration spring on

front handle, b 10.3.1 – not for version with heating

2410RA094 TG

: Carefully pull off the cylinder (1)

2410RA095 TG

: Remove the cylinder gasket (1)

With cylinder removed

The crankshaft is blocked by placing the piston on the wooden assembly block in order to remove the flywheel and clutch.

– Remove shroud, b 6.4

– Take off the spark plug boot and

remove the spark plug, b 4

– Remove fan housing, b 9.2

– Remove short circuit wire,

b 7.7.2

– Remove the control unit, b 7.3

– Remove filter base, b 13.3

2410RA093 TG

: Take out the screws (arrows)

2410RA096 TG

: Examine and clean the mating

surface (arrow), b 16

The mating surface must be in perfect condition and without any damage whatsoever. Parts with damaged mating surfaces must be replaced, b 3.7.

39MS 241 C

Installation

: Examine the intake elbow (1),

replace if necessary. Engine operation may be impaired even by the slightest damage, b 3.7

: Remove screws (2)

: Remove intake elbow (1)

2410RA097 TG

: Position intake elbow (1)

: Insert and tighten down the

screws (2)

2410RA102 TG

– Coat piston, piston rings and

2410RA099 TG

inside of cylinder with oil, b 16

: Fit clamping strap (1)

0000 893 2600 around piston and piston rings

– Ensure that piston rings are

correctly positioned, b 6.8

The clamping strap (1) must be fitted in such a way that the piston rings do not protrude beyond the piston sides.

: Examine and clean the mating

surfaces (arrows), and remove any gasket residues, b 16

– Clean mating surface on intake

elbow, b 16

The mating surfaces must be in perfect condition and without any damage whatsoever. A new cylinder must be used if the mating surfaces are damaged.

Always use a new cylinder gasket after removing the cylinder.

: Guide new cylinder gasket (1)

2410RA098 TG

over the piston so that the tab (arrow) faces the spiked bumper

: Place wooden assembly

block (1) 1108 893 4800 between piston and crankcase

Avoid damage to the cylinder gasket.

2410RA100 TG

: Orient cylinder (1) so that the

intake elbow (2) faces the control handle

When fitting the cylinder over the piston, ensure that the clamping strap securely encloses the piston and that none of the piston rings

2410RA101 TG

protrudes – danger of breakage.

: Slide cylinder over piston; the

clamping strap is removed at the same time

2410RA103 TG

40 MS 241 C

6.6 Crankshaft

Clutch side half of crankcase

: Remove clamping strap (1) and

wooden assembly block (2)

Make certain that the cylinder gasket is oriented according to the holes.

– Push cylinder home as far as

possible

– Drain fuel tank and oil tank,

b 1.1

– Remove brake band, b 5.2

– Remove oil pump, b 12.3

2410RA104 TG

– Remove oil suction hose,

b 12.2

– Remove brake lever, b 5.3

QuickStop Super, b 5.4

– Remove the front handle,

b 10.4 Version with heating, b 10.4.1

– Remove the tank housing,

b 13.11.5

– Remove the flywheel, b 7.6

– Version with handle heating

Remove generator, b 14.7

– Remove the cylinder, b 6.5

2410RA093 TG

– Remove piston, b 6.7

2410RA106 TG

: Remove the circlip (1)

2410RA107 TG2410RA105 TG

The tools from the assembly tool kit 5910 007 2205 are used for removal and installation.

: Take out the screws (arrows)

: Fit screws (arrows) and secure

cylinder with gasket

: Tighten down the screws through

the holes (arrows) crosswise

– Reassemble remaining parts in

reverse order

– Remove spiked bumper

Always fit new ball bearings and oil seals when removing the crankshaft, b 6.6.1 and b 6.3.

: Remove screws (1) and pull out

chain tensioner (2)

41MS 241 C

Ignition side half of crankcase

: Align the assembly tool (1) with

the disk (2) 5910 893 2103 against the ignition-side half of

the crankcase so that the edge number "24" (arrow) is at the bottom

: Insert three M5 x 72 screws (3)

through the holes marked "24"

2410RA544 TG

and screw them as far as possible into the crankcase half

: Unscrew screw (1), remove

Loctite residue from the threaded hole if necessary

: On versions with quick chain

tensioner, remove side plate (2)

: Unscrew spindle (1) until it no

longer rests on the crankshaft stub

: Push assembly tool (2) from kit

5910 007 2205 onto the stud (arrow), twist on and tighten the nut

: Remove the gasket (1)

The tools from the assembly tool kit 5910 007 2201 are used for

2410RA108 TG

removal and installation. – Use disk 5910 893 2103

The assembly took kit 5910 007 2201 can be expanded with the disk 5910 893 2103.

The new assembly tool kit 5910 007 2201 contains all three disks.

2410RA109 TG

: Turn the spindle (1)

2410RA110 TG

counterclockwise until the crankshaft has been forced out of the ignition-side half of the crankcase

2410RA111 TG

: Turn spindle (1) clockwise until

the crankshaft stub has been forced out of the ball bearing

The clutch-side half of the crankcase is pulled off in this way and the two halves of the crankcase separated.

– Replace ball bearings and oil

seals, b 6.6.1 and b 6.3

: Adjust the spindle (1) of the

assembly tool so that the disk (2) rests against the half of the crankcase – Left-hand thread

The crankshaft (1), connecting rod (2) and the needle bearing between them make up a complete unit and must therefore always be replaced as a unit.

– Check the two halves of the

crankcase and the grooved ball bearing, replace if necessary, b 6.6.1

– Before installation, clean the

crankshaft, b 16

42 MS 241 C

2410RRA112 TG

Installation

Ignition side half of crankcase

Avoid damage to the crankshaft stub.

Examine and clean the mating surfaces of the ignition-side half of the crankcase (including the cylinder sealing surface) – the sealing face must not display any signs of damage, b 16.

: Orient the crankshaft with the

conical crankshaft stub (arrow) facing the ignition-side ball bearing

– Wear protective gloves

– risk of burns

If the inner race cannot be heated, the crankshaft can be drawn into the crankcase with the assembly tool 5910 007 2201. – Use disk 5910 893 2103.

: Screw the threaded sleeve (1)

5910 893 2420 onto the completely screwed in spindle as far as it will go

– Coat the tapered crankshaft stub

with oil.

2410RA113 TG

5902RA135 TG

: Fit the screw sleeve (2) over the

thread of the conical crankshaft stub (1) and screw it on

: By turning the spindle screw (1),

position disk 5910 893 2103 against the ignition-side half of the crankcase and orient it so that the edge number "24" is at the bottom

2410RA114 TG

2410RA115 TG

– Heat only the inner race of the

ball bearing to approx. 150 °C (300 °F)

: Press crankshaft stub fully home

The crankshaft must be fitted rapidly, as the heat is transmitted to the crankshaft stub and the inner bearing race contracts.

: Align the crankshaft with the

conical crankshaft stub (arrow) facing the ignition-side ball bearing and push it home

: Insert M5x72 screws (2) through

2410RA113 TG

the holes marked "24" – anti-twist device

: Turn the spindle screw (1)

clockwise

– Draw the ignition-side half of the

crankcase in as far as possible

43MS 241 C

The crankshaft also turns when it is drawn in with the installing tool. For this reason, ensure that the rod eye (1) always faces upwards towards the cylinder.

– Remove the installing tool

: Screw two screws (arrows)

M5x72 into the holes on the ignition side – for guidance and to prevent twisting

2410RA116 TG

: Fit a new gasket (1) and secure it

at the guide sleeves (arrows)

– Coat the cylindrical crankshaft

stub with oil

Clutch side half of crankcase

Avoid damage to the crankshaft stub.

Examine and clean the mating surfaces of the clutch-side half of the crankcase (including the cylinder sealing surface) – the sealing face must not display any signs of damage, b 16.

2410RA117 TG

2410RA118 TG

– Wear protective gloves

– risk of burns

– Heat only the inner race of the

ball bearing to approx. 150 °C (300 °F)

– Align the crankcase half with the

cylindrical crankshaft stub and the two screws and position it

: Push the crankcase home until it

makes contact

The crankcase must be fitted rapidly, as the heat is transmitted to the crankshaft stub and the inner bearing race contracts

If it is not possible to heat the inner race, the crankcase half is drawn in with the assembly tool from kit 5910 007 2205.

– Coat the cylindrical crankshaft

stub with oil

2410RA120 TG

– Align the crankcase half with the

cylindrical crankshaft stub and

2410RA119 TG

the two screws and position it

Ensure that the guide sleeves (arrows) line up with the holes and that the housing gasket is not jammed or buckled.

44 MS 241 C

165RA133 TG

2410RA121 TG2410RA122 TG

2410RA119 TG2410RA107 TG

– By turning it, screw the spindle

completely into the assembly tool

: Screw the threaded sleeve (1)

5910 893 2409 onto the spindle as far as it will go – Left-hand thread

: Fit threaded sleeve on crankshaft

stub (arrow) and push assembly tool over the studs

: Hold crankshaft steady and

screw threaded sleeve onto thread of crankshaft stub by turning the spindle counterclockwise

– Release crankshaft and hold

assembly tool steady and continue turning the spindle until the assembly tool rests against the crankcase half.

– Screw nut onto the stud and

tighten it by hand

0001RA494 TG

Ensure that the guide sleeves (arrows) line up with the holes and that the housing gasket is not jammed or buckled.

– Continue turning the spindle of

the assembly tool until the gap between the halves of the crankcase is closed

– Unscrew nuts

– Turn the spindle clockwise to

remove the assembly tool

– Remove the two M5x72 screws

which were fitted to prevent twisting

: Turn spindle (1)

counterclockwise until the crankcase half rests against the guide sleeves

: Insert the screws (arrows) and

tighten them down crosswise

45MS 241 C

6.6.1 Ball bearing / crankcase

Ignition-side half of the crankcase

The two halves of the crankcase can be replaced individually if they are defective.

New crankcases are delivered with the relevant components preassembled

– see spare parts list

2410RA545 TG

– For versions with quick chain

tensioner, fit side plate

: Coat screw (1) with Loctite,

screw in and tighten, b 16

: Fit the circlip (1)

– Examine and install the piston,

b 6.7

– Examine and install the cylinder,

b 6.5

– Install chain tensioner, b 5.7

– Reassemble remaining parts in

reverse order

Those parts which are not supplied with the new crankcase must be removed from the old crankcase, examined and replaced if necessary.

When fitting a new crankcase, the machine's serial number must be stamped on the crankcase with

2.5 mm figure stamps.

If the original crankcase is reused, the oil seals and grooved ball bearings must be replaced, all gasket residues removed and the mating surfaces cleaned thoroughly. The mating surfaces must be absolutely flawless and

2410RA123 TG

clean to guarantee a perfect seal, b 16.

Examine both halves of the crankcase for cracks and check all mating surfaces for signs of damage.

– Refer also to troubleshooting,

b 3.7

– Remove crankshaft, b 6.6

– Wear protective gloves

– risk of burns

2410RA124 TG2410RA125 TG

: Carefully drive the oil seal out

with a punch

: Examine and clean the

crankcase, replace if necessary.

– Replace ball bearings if the

crankcase is in good condition

– Heat the bearing seat of the ball

bearing to approx. 150 °C (300 °F)

The bearing (1) drops out of its own accord when this temperature is reached.

46 MS 241 C

Installation

– Heat the bearing seat of the ball

bearing to approx. 150 °C (300 °F)

– Position ball bearing so that the

open side (balls visible) faces the inside of the crankcase

: Press the grooved ball bearing

home as far as possible

The ball bearing must be fitted rapidly, as it absorbs heat and expands.

– Check seat of ball bearing, if

necessary, use press arbor 1118 893 7200 to press the ball bearing fully home in the ball bearing seat

– Replace ball bearings if the

crankcase is in good condition

2410RA126 TG2410RA127 TG

– Heat the bearing seat of the ball

bearing to approx. 150 °C (300 °F)

The bearing (1) drops out of its own accord when this temperature is reached.

Installation

Because the clutch side half of the crankcase does not have a fixed bearing seat, the oil pump must be removed beforehand – The oil pump serves as a reference

– Install oil pump, b 12.3

The ball bearing must be fitted rapidly, as it absorbs heat and expands.

– Check seat of ball bearing, if

necessary, use press arbor 1118 893 7200 to carefully press the ball bearing fully home until it rests against the oil pump

– Remove oil pump, b 12.3

– Install crankshaft, b 6.6

2410RA128 TG

– Install the oil seals, b 6.3

– Reassemble remaining parts in

reverse order

6.7 Piston

Before removing the cylinder, decide whether the crankshaft is to be removed, b 6.6

– Remove the cylinder, b 6.5

The clutch side snap ring is not removed.

Clutch-side half of the crankcase

: Carefully drive the oil seal out

with a punch

– Examine and clean the

crankcase, replace if necessary.

– Heat the bearing seat of the ball

bearing to approx. 150 °C (300 °F)

– Position ball bearing so that the

centering ring (arrow) points towards the oil pump

: Press ball bearing fully home (oil

pump)

: Pry the hookless snap ring out of

2410RA129 TG

the recess (arrow) on the ignition side with a suitable tool

2410RA130 TG

47MS 241 C

Installation

: Push assembly drift (1)

1110 893 4700 through the installed snap ring

: Push the piston pin (2) out of the

piston with the assembly drift (1) 1110 893 4700

If the piston pin is stuck, tap the end of the drift gently with a hammer to loosen it. The piston must be held steady during this process to ensure that jolts are not transmitted to the connecting rod.

– Remove the piston

– Examine the piston rings and

replace if necessary, b 6.8

2410RA131 TG

– Coat needle bearing with oil and

slide it into the rod eye

Line up the piston so that the arrow (arrow) in the piston base points towards the spiked bumper (exhaust port)

The assembly drift can be inserted through the fitted snap ring.

– Position the piston on the rod eye

: Push assembly drift (1)

1110 893 4700 with the stub end first through piston hole and rod eye (needle cage) and secure the piston

: Remove the sleeve (1)

2410RA133 TG

5910 893 1707 from the installing tool (2) 5910 890 2210

: Attach the snap ring (1) to the

magnet (2) and align it so that the snap ring gap is on the flat side (arrow)

5904RA089 TG

165RA153 TG

: Take out the needle bearing (1),

examine and clean it, replace if necessary

2410RA132 TG

– Coat the piston pin (1) with oil

: Fit the piston pin (1) on the stub

of the assembly drift (2) and slide it into the piston

2410RA134 TG

: Push the slotted opening of the

sleeve over the magnet and snap ring

The inner pin (1) must point towards the flat face of the tool's shank (2).

5904RA090 TG

48 MS 241 C

6.8 Piston rings

– Remove piston, b 6.7

– Remove piston rings from piston

Press the assembly tool down in the sleeve until the magnet is at the end of the guide slits.

: Remove sleeve and fit it over the

opposite shaft end of the assembly tool, with the internal pin pointing towards the flat surface.

5904RA091 TG

: Position the installing tool

5910 890 2210 with the taper sleeve on the piston boss, hold the piston steady and press the tool shank home until the snap ring slips into the groove

The tool must be precisely aligned in axial direction of the piston pin.

216RA178 TG

– Examine the piston rings and

replace if necessary, b 6.8

– Install the cylinder, b 6.5

2410RA136 TG2410RA137 TG

2410RA138 TG2410RA139 TG

: Use a piece of old piston ring to

scrape the grooves (arrows) clean

: Align the new piston rings so that

the radiuses at the ends of the ring (arrows) face upwards

The snap ring (1) must be fitted so that the gap in the ring (arrow) points upwards in axial direction of the piston.

– Reassemble remaining parts in

reverse order

2410RA135 TG

49MS 241 C

– Carefully slide the piston rings

over the piston – danger of breakage

6.9 Decompression valve

– Remove shroud, b 6.4

2410RA140 TG

: Position the piston rings so that

the radiuses at the ring gaps encircle the fixing pins in the piston grooves (arrows)

: Check the correct installed

position of the piston rings again (arrows)

– Install the piston, b 6.7

– Reassemble remaining parts in

reverse order

2410RA141 TG

: Unscrew decompression

valve (1)

5902RA164 TG

: Examine the sealing

cone (arrow) on the decompression valve for signs of damage

– Use a new decompression valve

if the sealing cone on the decompression valve does not seal tightly or is damaged

– Fit the decompression valve by

hand and screw it in

– Screw the decompression valve

tight

– Reassemble remaining parts in

reverse order

50 MS 241 C

7. Ignition system

Exercise extreme caution while carrying out maintenance and repair work on the ignition system. The high voltages which occur can cause serious or fatal accidents.

Troubleshooting on the ignition system should always start with the spark plug, b 3.5

– Remove fan housing, b 9.2

The contactless electronic ignition system basically consists of a control unit (1), flywheel (2), switchgear (3) and solenoid valve (4).

The ignition module accommodates all the components required to control the ignition timing and fuel flow. There are only three electrical connections leaving the control unit:

Testing of the ignition module is not limited to only a spark test. If no ignition spark is obtained or other functions do not work, a diagnosis must be carried out according to the troubleshooting chart; replace control unit or M-Tronic wiring harness if necessary.

7.1 Ignition timing

Ignition timing is fixed and cannot be adjusted during repair work.

Since there is no mechanical wear in these systems, ignition timing cannot get out of adjustment during operation.

7.2 Pre-separator

2410RA142 TG

– Remove fan housing, b 9.2

7.3 Control unit

– Remove fan housing, b 9.2

– Unplug the spark plug boot

: Remove holders (1) and (2)

carefully from the slits (arrows) and open

: Pull the ignition lead (3) out of the

guide

2410RA144 TG

1. High voltage output for the ignition lead.

2. Connector tab for black lead – short circuit wire.

3. Connector tab for red lead – M-Tronic.

: Remove screw (1)

: Remove pre-separator (2), check

and replace if necessary

– Reassemble parts in reverse

order

2410RA143 TG

2410RA145 TG

: Lift retaining tab (arrow) and

remove angled plug (1)

– Examine insulating sleeve of the

angled plug, clean or replace if necessary, b 7.7.2

51MS 241 C

Installation

: Remove screws (1) with washers

– Remove control unit

: Remove wiring harness (1) and

ground wire (2) from the guides (arrows) and remove cable holder (3)

– Check ignition lead, replace if

necessary

– Examine the spark plug boot,

replace if necessary, b 7.5

– Troubleshooting, b 3.5

2410RA146 TG

: Position cable holder (1) on the

cylinder and secure it with the pins on the cylindrical raised parts

2410RA147 TG

: Hold cable holder (1) against

cylinder and position control unit (2)

: Insert screw (3) with washer – do

not tighten

On the cable lug of the ground wire, the crimped side must face the screw head.

: Position ground wire (1) so that

2410RA148 TG

the cable lug is pressed fully home (arrow) and the crimped side faces the screw head

: Insert screw (2) with washer – do

not tighten

2410RA149 TG

: Push back ignition module and

slide setting gauge (1) 1111 890 6400 between the legs of the ignition module and the magnetic poles of the flywheel

2410RA150 TG

2410RA151 TG

52 MS 241 C

Shown without setting gauge for a better view.

– Flywheel must turn freely

: Turn the flywheel until the

magnet poles "N/S" (arrows) are at the control unit (1)

: Press control unit (1) against the

setting gauge and tighten screws (2) – the cable lug of the ground wire must be fully seated

– Remove the setting gauge

– Checking correct functioning

– Turn the flywheel: it must not touch the control unit

2410RA152 TG

: Orient angled plug (1) so that the

retaining tab (2) faces the muffler

: Press the angled plug (1) straight

onto the connector tags until the retaining tab (2) snaps into place – Do not insert the angled plug on a slant or tilt it

Protective tube (2) must be positioned snug against the grommet in the air guide shroud.

2410RA154 TG

: Orient wiring harness (1) so that

the protective tube (2) lines up with the leading edge (arrow) and the red M-Tronic lead is underneath the short-circuit wire (black)

2410RA156 TG

2410RA157 TG

: Press wiring harness (1)

2410RA155 TG

completely into the guides (arrows)

: Press ground wire (1) completely

into the guide (arrow) – Ground wire is routed underneath the wiring harness

: Press the wiring harness (1) into

the guide so that the protective tube (2) a = ca. 8 mm is seated in the guide (arrow) – Ground wire is routed

2410RA153 TG

underneath the wiring harness

: Push the holder (3) into the slit of

the cable holder (4) until it clicks into place

2410RA158 TG

: Plug the spark plug boot (1) onto

the spark plug so that it runs parallel to the air guide shroud underneath the tab (2)

53MS 241 C

7.4 Spark test check control unit

The engine may start and accelerate during the test.

: Press ignition lead (1) completely

into the guide (arrow) – Note routing of the ignition lead, see illustration

Ignition lead and spark plug boot must not touch the air guide shroud.

: Press the holder (1) into the

slit (arrow) until it clicks into place

The ignition test refers only to a spark test, not the general functions of the control unit; these are described in the M-Tronic chapter, b 8.2, b 8.5.

To spark test the control unit, use

2410RA159 TG

either the ZAT 4 ignition system tester 5910 850 4503 or the ZAT 3 ignition system tester 5910 850 4520.

Using the ZAT 4 ignition system tester 5910 850 4503

2410RA160 TG

– Before starting the test, install a

new spark plug in the cylinder and tighten it down firmly.

If a spark is visible, the ignition system is in order.

– If no spark is visible in the

window (2), check the ignition system with the aid of the troubleshooting chart, b 7.8, b 8.5

Using the ZAT 3 ignition system tester 5910 850 4520

3 4

– Before starting the test, install a

165RA183 TG

new spark plug and tighten it down firmly

: Connect the spark plug boot to

the terminal (2)

165RA184 TG

– Reassemble remaining parts in

reverse order

: Connect the spark plug boot to

the input terminal (1). Push the tester's output terminal (3) onto the spark plug

Danger! High voltage – risk of electrocution.

– Crank the engine quickly with the

rewind starter and check sparkover in the window (2) of the ignition system tester

: Attach ground terminal (1) to the

spark plug

: Use adjusting knob (4) to set

spark gap to approx. 2 mm, see window (3)

54 MS 241 C

3 4

165RA185 TG

2310RA127 TG

2310RA128 TG2310RA129 TG

While using the ZAT 3, hold it only by the handle (4) or position it in a safe place. Keep fingers or other parts of your body at least 1 cm away from the spark window (3), high-voltage connection (2), ground connection (5) and the ground terminal (1).

Danger! High voltage – risk of electrocution.

– Crank the engine quickly with the

rewind starter and check sparkover in the window (3) of the ignition system tester

The engine may start and accelerate during the test.

If a spark is visible in the window (3), the ignition system is in order.

– If no spark is visible in the

window (3), check the ignition system with the aid of the troubleshooting chart, b 7.8

7.5 Spark plug boot

– Remove shroud, b 6.4

– Unplug spark plug boot and pull

ignition lead out of the guides,

b 7.3

: Use suitable pliers to pull the

torsion spring out of the spark plug boot

– Unhook the torsion spring from

the ignition lead

– Pull the boot off the ignition lead

– Check ignition lead, replace if

necessary, b 7.5.1

Installation

– With a new ignition module, use a

pointed tool to pierce the center of the new lead's insulation approx. 13 mm from the end of the ignition lead

: Pinch the hook of the torsion

spring into the center of the ignition lead (arrow) where it has been pierced

– Apply STIHL press fluid to the

inside of the spark plug boot,

b 16

: Push the ignition lead and torsion

spring into the spark plug boot

: Ensure that the torsion

spring (arrow) is located in the recess

– Plug spark plug boot onto spark

165RA188 TG

plug and press ignition lead completely into the guide, b 7.3

Ignition lead and spark plug boot must not touch the air guide shroud.

– Reassemble remaining parts in

reverse order

55MS 241 C

7.5.1 Ignition lead

The ignition lead is built into the high voltage output of the control unit. If the ignition lead is damaged, the control unit must be replaced.

– Remove spark plug boot, b 7.5

– Before twisting in the ignition

lead, fill the coil tower with STIHL multi-purpose grease, b 16

Do not use either graphite grease or silicone insulating paste.

– Block the piston with the locking

strip, b 4

– Remove the control unit, b 7.3

: Pull grommet (1) off of high-

voltage output (arrow)

: Twist ignition lead (2) out of

control unit

– Pull the grommet off the ignition

lead

– Push grommet onto ignition lead

: Twist ignition lead (2) into control

2410RA161 TG

unit

: Push on the grommet (1)

– Install control unit and adjust air

gap control unit/ flywheel, b 7.3

– Reassemble remaining parts in

reverse order

7.6 Flywheel

: Unscrew the flywheel nut (1)

2410RA162 TG

: Screw the screws (1) of the

puller (3) 5910 890 4504 into the flywheel as far as they will go – Ensure that the screws are screwed in uniformly

2410RA164 TG

2410RA163 TG

For versions with ErgoStart, the new puller 5910 890 4504 with extended clamping bridge must be used. The previous puller 1135 890 4500 is

– For versions with heating, only M

5 x 25 screws can be used to fasten the puller – Generator can be damaged

being replaced by the new puller,

– For versions with ErgoStart, do

not damage the pawls

: Turn screw (2) clockwise until the

flywheel comes off the crankshaft stub

: Unscrew puller (3)

: Use a pointed tool to pierce the

center of the end of the new ignition lead, which is to be twisted into the control unit.

but can still be used for the standard versions.

165RA191 TG

– Remove shroud, b 6.4

– Remove fan housing, b 9.2

5910 890 4504 from flywheel

56 MS 241 C

– Reassemble remaining parts in

reverse order

7.7.2 Removal and installation

– Remove shroud, b 6.4

The flywheel and magnet poles (arrows) must not display any signs of damage or blue discoloration; replace flywheel if necessary.

– The magnet ring must also be

examined for signs of damage in versions with handle heating, b 7.6

– With versions with ErgoStart

pawls, check for damage and smoothness of motion, b 9.4.

Installation

7.7 Short circuit wire

Ground wire, short-circuit wire and M-Tronic lead are all combined into one wiring harness.

0001RA167 TG2310RA110 TG

Make a contact test of the short circuit wire if the spark plug and ignition lead with spark plug boot are in order.

7.7.1 Contact test

– Remove fan housing, b 9.2

– Move the Master Control lever to

– Unplug the spark plug boot

– Remove fan housing, b 9.2

– Remove choke rod, b 11.4

: Remove holders (1) and (2)

carefully from the slits (arrows) and open

2410RA165 TG

Flywheel and crankshaft stub must be free from grease for installation.

Ensure that the machined key (arrow) engages the slot in the crankshaft.

– Set the air gap between control

unit and flywheel, b 7.3

– Blade receptacle of the short-

circuit wire must touch the contact spring (arrow) in position "

Also carry out a contact and continuity test of the ground wire between cable lug and contact spring, replace wiring harness if necessary.

– If no fault can be found, test the

M-Tronic in accordance with flow chart, b 7.8

– Reassemble parts in reverse

order

2310RA155 TG

2410RA166 TG

: Lift retaining tab (arrow) and

remove angled plug (1)

57MS 241 C

: Remove screw (1) with washer

and remove ground wire cable lug (2)

: Remove wiring harness (1) and

ground wire (2) from the guides (arrows)

Versions with heating

2410RA167 TG

: Remove blade receptacle (1) of

the carburetor heating lead

Versions with manual fuel pump

2410RA168 TG

: 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

2410RA170 TG

: Pull plug connector (1) out of the

carburetor support mount (arrow)

2 1

: Hold the jack (1), press the

2410RA220 TG

tab (arrow) and pull out the plug (2) – do not tug on the leads

– Turn the carburetor a little in the

direction of the control handle – Do not overextend fuel hose

2410RA171 TG

2410RA172 TG

All versions

– Remove filter base, b 13.3

– Remove contact spring, b 7.7.4

– Remove switch shaft on filter

base, b 11.1

2410RA169 TG

: Pull out carburetor heating

lead (1) at the guide (arrow)

: Remove the plug (1)

58 MS 241 C

2410RA173 TG

: Remove diagnostic jack (1) with

connector housing (2) from the guides (arrows)

: Pry out and remove the cable

holder (1) at the pin (arrow)

: Remove wiring harness (1) from

the guides (arrows) of the air guide shroud

2410RA174 TG

: Pull out grommet (1) with wiring

harness

2410RA175 TG

: Remove ground wire (1) from the

guides (arrows)

2410RA176 TG

: Remove ground wire (1) from the

guide (arrow)

: Remove the switch shaft (2)

2410RA177 TG

: Pull the retaining tab (1) in the

direction of the leads and open the cover (2)

121

2410RA178 TG

: Pull blade receptacles (1) out of

the insulating sleeve (2)

– Check blade receptacles and

insulating sleeves, clean or replace insulating sleeves if necessary

With a new wiring harness, the grommets and the plugs as well as the insulating sleeve are preassembled.

2410RA179 TG

2410RA180 TG

2410RA181 TG

59MS 241 C

Installation

: Push the blade receptacle (1) of

the red lead (M-Tronic) into the rear receptacle (arrow) of the insulating sleeve (2) – Crimped side faces forward

The leads must not be reversed.

2410RA182 TG

: Close and lock the cover (1) so

that the tab (2) engages the slit (arrow) of the retaining tab (3) – the retaining tab must fit snugly against the insulating sleeve

The ground wire (4) must be routed behind the protective tube (2) – facing the cylinder.

2410RA184 TG

2410RA187 TG

: Push the grommet (1) into the

opening (arrow) in the air guide shroud (2) until it is flush with the edge of the air guide shroud

: Push the blade receptacle (1) of

the black lead (short-circuit wire) into the front receptacle (arrow) of the insulating sleeve (2) – Crimped side faces forward

The leads must not be reversed.

The protective tube (1) must rest

2410RA183 TG

against the grommet (2).

: If necessary, push the wiring

harness towards the grommet (2) until the protective tube (1) rests against the grommet (2)

: Orient the wiring harness (1) so

that the protective tube (2) and angled plug (3) face the control unit

2410RA185 TG

234

: Orient wiring harness so that the

red lead (1) is above and the black lead (2) is underneath the ground wire (3)

Starting at the protective tube (4), the ground wire branches out into a thin black lead (M-Tronic) and a thick blue lead (short-circuit wire).

When inserting the ground wire, the small guide rib (arrow) must be between these two leads

2410RA186 TG

2410RA189 TG

60 MS 241 C

3 2

: Press the red M-Tronic lead (1),

ground wire (2) and black lead (3) of the short-circuit wire all the way into the guides (arrows)

The protective tube (4) must start at the beginning of the rib and protective tube (5) must rest against the beginning of the rib.

: Slide cable holder (1) with the

hinge into the slot (arrow) of the air guide shroud

2410RA190 TG

: Check that the leads are properly

seated in the guides and press the cable holder (1) with the pin (arrow) into the mount until it snaps into place

: Orient diagnostic jack (1) so that

the black leads (2) face the control handle

2410RA191 TG

: Press diagnostic jack (1) and

connector housing (3) into the guides (arrows)

2410RA192 TG

: Press the diagnostic jack (1) into

the mount so that it is seated completely in the recess (arrows) and the tabs (2) snap into place

2410RA193 TG

: Press plug (1) into the mount as

far as it will go

2410RA194 TG

2410RA195 TG

: Turn the cable holder (1) towards

the cylinder and position it

: Using wiring tool 5910 890 4000,

press the blue ground wire (1) and black short-circuit wire (2) into the guide (arrow) so that the wires are snug against the air guide shroud

61MS 241 C

2410RA196 TG

1 2

: Orient plug (1) and jack (2) that

the tab (3) lines up with the mount (arrow) – do not twist the leads

: Plug connector (1) into jack (2)

until the tab (3) clicks into place in the mount (arrow)

: Press the plug connection (1)

into the mount (2) of the carburetor support so that the tab (arrow) engages in the recess of the plug connection

2410RA188 TG

: Slide the blade receptacle (1) of

the blue ground wire, with the crimped side facing the cam (2), into the guide (arrow) as far as it will go

: Hook ground wire (1) into the

2410RA197 TG

guides (arrows)

– Push switch shaft onto filter base,

b 11.1

– Install contact spring, b 7.7.4

2410RA199 TG

: Check the routing of the blue

ground wire (1) and black shortcircuit wire (2), if necessary, press them completely into the guide (arrow) using wiring tool 5910 890 4000 – wires must rest snug against the air guide shroud

2410RA200 TG

: Using wiring tool 5910 890 4000,

press the blue ground wire (1) and black short-circuit wire (2) into the guides so that the markings (arrows) are located at the guide ribs

2410RA201 TG

2410RA202 TG

– Push on the carburetor and

– Install filter base, b 13.3

observe cable routing as well as

– Conduct a function test of the

switch shaft, b 11.1

installation position of the M-Tronic and, if present, the heating system, b 8.4

62 MS 241 C

Versions with heating

: Press fuel return line (3)

completely into the guide (arrow)

2410RA204 TG

: Orient blade receptacle (1) so

that the crimped side faces the carburetor

: Press blade receptacle (1) onto

the connector tab (arrow) of the heating switch as far as it will go

: Press carburetor heating lead (1)

completely into the guide (arrow)

Versions with manual fuel pump

2410RA198 TG

Push the new fuel suction hose (1) completely onto the connectors (arrows)

All versions

2410RA169 TG

Ground wire: Crimped side of the cable lug (1) must be visible.

: Position cable lug (1) between

control unit (2) and stop (3)

42 3

: Press ground wire (1) completely

into the guide (arrow)

2410RA227 TG2410RA203 TG

– Ground wire is routed underneath the wiring harness

: Orient angled plug (1) so that the

retaining tab (2) faces the muffler

: Press the angled plug (1) straight

onto the connector tags until the retaining tab (2) snaps into place – Do not insert the angled plug on a slant or tilt it

2410RA205 TG

: Push the holder (1) with the fuel

pump into the recess in the air guide shroud (2) as far as it will go

: Insert screw (4) with washer and

tighten

2410RA226 TG

63MS 241 C

The short-circuit wire must be

7.7.4 Contact spring

seated firmly in the eye of the contact spring, if necessary, carry

out a contact and continuity test, b 7.7.1.

– Remove the filter base from the

2410RA155 TG

2410RA207 TG

studs, b 13.3

Protective tube (2) must be positioned snug against the grommet in the air guide shroud.

: Press the wiring harness (1) into

the guide so that the protective tube (2) a = approx. 8 mm is seated in the guide (arrow) – Ground wire is routed underneath the wiring harness

: Push the holder (3) into the slit of

the cable holder (4) until it clicks into place

: Orient wiring harness (1) so that

the protective tube (2) lines up with the leading edge (arrow) and the red M-Tronic lead is underneath the short-circuit wire (black)

: Press wiring harness (1)

completely into the guides (arrows)

– Check the air gap between

control unit and flywheel, adjust if necessary, b 7.3

Ignition lead (1) must be seated completely in the guide.

: Press the holder (2) carefully into

the slit (arrow) until it clicks into

2410RA206 TG

place

– Conduct a function test of the

switch shaft, b 11.1

– Reassemble remaining parts in

reverse order

: Turn filter base (1) to the side

2410RA209 TG

2410RA208 TG

2310RA151 TG

: Lift contact spring (1) slightly and

guide it over the tab (arrow)

: Press contact spring (1) out of

the guides in the filter base (2)

7.7.3 Ground wire

Testing and installation of ground wire is the same as for the shortcircuit wire

– Check contacts and operation,

b 7.7

64 MS 241 C

: Press contact sleeve (1) of the

short-circuit wire out of the contact spring (2)

– Examine contact spring, replace

if necessary

Installation

2410RA210 TG

: Position contact spring (1)

against the guide (arrows)

: Lift contact spring (1) slightly at

the connection of the short-circuit wire and guide it over the tab (2) – do not overextend the contact spring

2410RA212 TG

: Push the contact spring (1) into

the guide (arrows) as far it will go, until the tab surrounds the contact spring

– Install filter base, b 13.3

2310RA154 TG

2310RA155 TG

: Push the contact sleeve (1) of the

short-circuit wire into the eye (arrow) of the contact spring (2) as far as it will go

2410RA211 TG

Before pushing the contact spring (1) all the way in, lift it slightly and guide it over the switch shaft – 2 mm maximum.

: Checking correct functioning

2310RA153 TG

– Blade receptacle of the shortcircuit wire must touch the contact spring (arrow) in position "

– Reassemble remaining parts in

reverse order

65MS 241 C

7.8 Troubleshooting, ignition system

– Contacts shorted (threads)?

– Clean, adjust or replace spark plug,

Engine does not run

Stop switch:

– in position "

Check spark plug:

– Smeared with oil, black?

– Sooted?

– Electrode gap correct?

b 7.5

F"?

Check spark plug boot:

– Firmly seated on spark plug (torsion

spring)?

– Torsion spring hook in center of ignition

lead?

– Spark plug boot damaged?

– Replace spark plug boot and/or torsion

spring if necessary,

b 7.5

Check ignition:

with ZAT 3 or ZAT 4

(use ZAT 3 as main spark gap

see TI 32.94),

b 7.4

66 MS 241 C

Spark

present?

Air gap:

– Check control unit/ flywheel,

– adjust if necessary, b 7.3

Check flywheel:

– Have pole shoes turned blue? – Replace flywheel if necessary,

b 7.6

Check short circuit wire:

– Wire damaged?

– Plug connections firmly seated?

– Check continuity, replace wiring harness if

necessary, b 7.7.1

yes

Check ignition lead:

– Severe chafing?

– Spark plug boot: Holes / cracks?

– Resistance of spark plug boot to ground:

Required 1.5...12 kΩ

– Check resistance of spark plug lead to

ground, (spark plug boot and control unit have

been removed)

Value: Required < 10 Ω,

replace spark plug boot and/or ignition module

if necessary,

b 7.5.1

67MS 241 C

Switch shaft

Check correct operation:

– Short circuit wire chafed?

– Function between contact spring and

contact of the switch shaft:

– Position "

– Replace wiring harness if necessary,

F" = no connection

0" = connection

b 11.1

yes

Spark

present?

Control unit

needs to be replaced,

b 7.3

Machine

runs?

yes

Engine runs smoothly,

troubleshooting procedure

completed

68 MS 241 C

– Look for fault in fuel or carburetor

system

– Check engine for leaks

– Check position of flywheel on

crankshaft,

b 3.6, b 6.2

8. M-Tronic

The fully electronic M-Tronic engine management system controls the ignition timing and fuel flow, taking all external conditions into account.

A basic or standard setting of the carburetor is no longer required. 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.

8.1 Calibrating the control unit

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.

2410RA546 TG

A regulating cycle only starts if the machine is operated for approximately 2 seconds under constant conditions.

If the maximum speed is not reached...

– 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

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.

– 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

69MS 241 C

8.2 Testing

8.2.1 Test preparations

The following steps must be carried out before testing.

– Carry out troubleshooting

according to troubleshooting chart, b 8.5

– Remove shroud, b 6.4

– Remove the air filter, b 13.1

: Remove diagnostic jack (1) from

the guide (arrow)

2410RA213 TG

: Press the diagnostic jack (1) into

the mount (arrow) until it is fully home

2410RA216 TG

– Remove coarse dirt from around

the screwed connections, control unit, switchgear, solenoid valve and diagnostic jack

8.2.2 Connect the test lead

– Remove shroud, b 6.4

– Remove the air filter, b 13.1

: Remove the plug (1)

1 2

: 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)

2410RA173 TG

– Reassemble remaining parts in

reverse order

8.2.3 Check screwed and plug connections as well as switch

– Carry out test preparations,

2410RA214 TG

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

2410RA215 TG

: 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

2410RA222 TG

All versions

Screw (1) must be tight.

Leads (arrows) must be seated completely and firmly in the blade receptacles and the cable lug.

2410RA217 TG

: 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

Versions with manual fuel pump

3 4

2410RA219 TG

Plug (1) must be seated completely and firmly in the recess of the solenoid.

: If necessary, remove plug (1) and

check contacts

2410RA221 TG

Plug connection (1) must be pressed together completely – locking lug (3) must engage the recess.

: If necessary. remove the plug

connection (1) from the mount (arrow), remove the plug (2) and check the contacts, b 8.2.3

2410RA218 TG

: 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

2410RA220 TG

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

71MS 241 C

Versions with heating

1 2

2410RA225 TG

2410RA227 TG

: 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 contact sleeve (1) into

heating switch – Push in contact sleeve completely

: Push blade receptacle (1) onto

2410RA223 TG

the connector tab – Push on blade receptacle all the way

: Press lead (2) completely into the

guide (arrow) of the filter base

Versions with manual fuel pump

2410RA224 TG

: Push the holder (1) with the fuel

pump into the recess in the air guide shroud (2) as far as it will go

: Push the new fuel suction

hose (1) completely onto the connectors (arrows)

– Reassemble remaining parts in

reverse order

8.2.4 Checking the solenoid valve

– 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

2410RA226 TG

– Move the Master Control lever to

position "F"

– Connect the test lead, b 8.2.2

: Press lead (2) completely into the

guide (arrow)

: Press fuel return line (3)

completely into the guide (arrow)

72 MS 241 C

Measuring resistance

2410RA222 TG

2410RA166 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

8.2.5 Checking the start detection function

– Carry out test preparations,

b 8.2.1

: Set Master Control lever (1) to

2410RA228 TG

position }; the cam on the lever (2) must actuate the microswitch (arrow) – clicking sound

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

All versions

: 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

– Check screwed and plug

connections, b 8.2.3

: 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

2410RA229 TG

73MS 241 C

Versions with manual fuel pump

Checking the ground connection

– Install holder with fuel pump,

push new fuel hose onto connector and press fuel return line into the guide, b 8.2.3

– 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

Versions with heating

2410RA230 TG

– Install holder with heating switch,

press leads in and on and into the guides, b 8.2.3

– Reassemble remaining parts in

reverse order

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

: Lift retaining tab (arrow) and

remove angled plug (1)

– Check angled plug, dismantle

and clean if necessary, 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.

: Measure the resistance between

contact spring (1) and screw (2) at the control unit

Target value: < 10 ohms.

If the target values are not attained

2410RA166 TG

– Check electrical leads for

interruption, e. g., cable breakage – if necessary, replace wiring harness, b 8.2.6

2410RA231 TG

2410RA232 TG

74 MS 241 C

Check leads between control unit and diagnostic jack

– Connect the test lead, b 16

– 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

Check leads between solenoid valve and diagnostic jack

– Connect the test lead, b 8.2.2

Target value: < 10 ohms

2410RA236 TG

: 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

blade receptacle (1) with black lead and red plug (2) of the diagnostic cable

Target value: < 10 ohms.

– Versions with manual fuel pump,

2410RA233 TG

remove fuel pump and set it aside, b 8.2.3

: Disconnect the plug (1) from the

solenoid valve (2) – the solenoid valve must not be twisted; if necessary, hold the solenoid

2410RA234 TG

valve in place when disconnecting the plug

1 2

: 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

– Check contact surfaces on plug

of the plug connection, as well as checking electrical leads for interruption, e. g., cable

2410RA229 TG

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

If the target values are not attained

– Check contact between blade

receptacle of the switch shaft and contact spring

2410RA235 TG

: Measure the resistance between

red lead (1) at the plug of the solenoid and black plug (2) of the diagnostic cable

75MS 241 C

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

8.4 Switchgear

– 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

: Remove blade receptacle (1)

: Remove heating element (2)

from the studs

Versions with manual fuel pump

2410RA240 TG

: Pull plug connector (1) out of the

carburetor support mount (arrow)

2 1

2410RA243 TG

: Pull holder (1) of the switchgear

over the studs (arrows) and lay it aside

: Disconnect the fuel hose (1)

2410RA239 TG

: 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

: Hold the jack (1), press the

tab (arrow) and pull out the

2410RA241 TG

2410RA242 TG

plug (2) – do not tug on the leads

2410RA172 TG

76 MS 241 C

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

: Turn the throttle shaft lever (1)

slightly in the direction of fullthrottle, then turn the starter shaft (2) until the choke shutter is closed

2410RA244 TG2410RA245 TG

: 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

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.

2410RA247 TG

2410RA249 TG

: 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

2410RA250 TG

: Orient wiring harness (1) so that

the red lead runs underneath the black lead

Choke shutter must be closed.

: Guide wiring harness (1)

between the special bolt (2) and the starter shaft (3)

: 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

2410RA248 TG

: Press red lead (1) and black

lead (2) completely into the guides (arrows) of the switchgear (3) – see illustration

2410RA246 TG

77MS 241 C

Versions with manual fuel pump

1 2

: Position the wiring harness (1) so

that the protective tube (2) rests against the beginning of the guide

: Press the red and black leads

completely into the guides (arrows)

Versions with heating

2 3

: Check the lead (1) of the

thermostatic switch, if necessary, press it completely into the guides (arrows) on the base of the carburetor and route it behind the pin (5)

Plug connectors (2) and (3) and the generator lead (4) must be seated completely in the guides.

2410RA251 TG

: Check seat of the fuel return

line (1), if necessary. press it completely into the guides (arrows)

All versions

Washer (1) must be fitted.

2410RA252 TG

: Orient plug (1) and jack (2) that

2410RA253 TG

the tab (3) lines up with the opening (arrow) – do not twist the leads

: Plug connector (1) into jack (2)

until the tab (3) clicks into place

2410RA078 TG

: Press the plug connection (1)

into the mount (2) of the carburetor support so that the tab (arrow) engages and snaps into place in the recess of the plug connection – Plug connection (1) must be seated firmly in the mount (2)

– Push on the carburetor as far as

it will go – pay attention to cable routing and make sure not to pinch any leads

2410RA254 TG

2410RA188 TG

2410RA256 TG

Do not remove the fuel hose from the carburetor support.

: Carefully push the carburetor (1)

with the fuel hose (2) over the studs (arrows) – do not overextend the fuel hose

78 MS 241 C

Versions with heating

Versions with manual fuel pump

All versions

: Press thermostatic switch

lead (1) completely into the guide (arrow) of the air guide shroud – Lead (1) must form a loop at the plug connection

2410RA257 TG

: Push the holder (1) with the fuel

pump into the mount of the air guide shroud (2) as far as it will go; push new fuel hose (3) onto the connectors (arrows)

: Fuel return line (4) must be

seated completely in the guide (5); if necessary, press the fuel return line (4) into the guide (5) again

2410RA258 TG

2410RA259 TG

: Push the holder (1) of the

switchgear over the studs so that the tab rests against the pin (arrow)

– Install filter base, b 13.3

– Reassemble remaining parts in

reverse order

2410RA260 TG

: Slide the heating element (1)

over the studs so that the hole engages the pin (2)

: Orient the crimped side of the

blade receptacle (3) so that it faces the carburetor

: Push the blade receptacle (3)

completely onto the connector tab (arrow)

79MS 241 C

8.5 Troubleshooting, M-Tronic

8.5.1 Engine does not start

Engine does not start

– Set Master Control lever

to position }

– Check ignition (spark

plug, spark plug boot,

ignition spark), b 7.4

– Check start detection,

(microswitch, actuating

lever), b 8.2.5

Can engine be started?

Ignition spark

present?

Mechanically

OK?

yes

Troubleshooting completed

– Test ignition system

according to flow chart

"Ignition system

troubleshooting", b 7.8

yes

Is it possible to start

the engine?

– Examine switch gear,

clean or replace if

necessary, b 8.2.5

– Check start detection and

wiring harness electrically,

b 8.2.5, b 8.2.6

– Check solenoid valve,

b 8.2.4

80 MS 241 C

Are target values

attained?, b 8.2.5

yes

Are target values

attained? b 8.2.4

yes

– Look for a fault in the fuel

path, check engine for

leaks, b 13.11, b 6.2

– Examine switch gear and/

or wiring harness, clean or

replace if necessary,

b 8.2.5, b 8.2.6

– Replace carburetor,

b 13.5

8.5.2 Engine does not start in

position }

Engine does not start in

position } – engine floods.

Can the flooded engine be

started in position F?

Is it possible to start

the engine?

yes

Troubleshooting completed

– Check start detection (microswitch actuation)

clean if necessary

– Check start detection, wiring harness and plug

connections,

b 8.2.5,b 8.2.3

Mechanically

OK?

yes

Are target values

attained?, b 8.2.5

yes

– Look for a fault in the fuel

path (inlet needle, lever,

spring, membrane),

check engine for leaks,

b 13.11, b 6.2

– Examine switch gear,

clean or replace if

necessary, b 8.2.5, b 8.4

– Examine switch gear and/

or wiring harness, clean or

replace if necessary,

b 8.2.5, b 8.2.3

81MS 241 C

8.5.3 Engine speed drops under load – low power

Engine speed drops under load –

low power

– Examine air filter, clean or

replace if necessary, b 13.1

– Calibrate control unit,

b 8.1

yes

Troubleshooting completed

Machine OK?

– Look for a fault in the fuel

path, check engine for

leaks,

b 13.11, b 6.2

82 MS 241 C

8.5.4 Ignition – no ignition spark

No ignition spark

– Set Master Control lever

to position }

– Check the flywheel,

(two pairs of poles?) b 7.6

– Check air gap between

control unit and flywheel,

b 7.3

Can engine be started?

Combination

OK?

yes

Air gap

OK?

yes

– Test ignition system

according to flow chart

"Ignition system

troubleshooting", b 7.8

yes

Troubleshooting

completed

Establish correct control unit/

flywheel combination

– Set correct air gap, b 7.3

83MS 241 C

8.5.5 Engine stops suddenly

Engine stops suddenly

– Check fuel path (fuel pick-up

body, tank vent, fuel hoses),

b 13.11

– Check plug connection on

control unit or between wiring

harness and switchgear

– Check start

detection (microswitch,

actuating lever), clean if

necessary

Machine

OK?

Fuel path

OK?

yes

Connection

and firm seat of the

plugs OK?

yes

Mechanically

OK?

yes

Troubleshooting

completed

– Repair fuel

system

– Check plug connections,

replace wiring harness

and/or switching device, if

necessary b 8.2.3,

b 8.3, b 8.4

– Replace switchgear,

b 8.4

– Check start detection, wiring harness and plug connections,

b 8.2.5, b 8.2.6

– Check solenoid valve,

b 8.2.4

Are target values

attained?, b 8.2.5

yes

Are target values

attained?, b 8.2.4

yes

– Examine switch gear

and/or wiring harness,

clean or replace if

necessary, b 8.2.5,

b 8.2.6, b 8.3, b 8.4

– Replace carburetor,

b 13.5

– Check engine for leaks,

b 6.2

84 MS 241 C

8.5.6 Cut-off speed not reached

Maximum speed less than

13000 rpm

– Check air filter and spark arrestor screen

(if present) in muffler, clean or replace if

necessary, b 13.1, b 6.1

– Check saw chain tension and chain

lubrication

–Calibrate control unit,

b 8.1

– Check plug connection on

control unit, b 8.2.3

– Check start detection, wiring harness and plug

connections, b 8.2.5

b 8.2.3

Maximum speed

greater than 13000

rpm?

Connection

and firm seat of the

plug

OK?

yes

Are target values

attained?, b 8.2.5

yes

Troubleshooting

completed

– Check plug, replace

insulating housing or

wiring harness if

necessary, b 7.3

– Replace switchgear,

b 8.4

yes

– Look for a fault in the fuel

path, check engine for

leaks,

b 13.11, b 6.2

85MS 241 C

9. Rewind starter

9.1 General

If the action of the starter rope becomes very stiff and the rope rewinds very slowly or not completely, it may be assumed that the starter mechanism is in order but plugged with dirt. At very low outside temperatures, the lubricating 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.

To clean the rewind spring, it is sufficient to apply a few drops of a standard solvent-based degreasant not containing any chlorinated or halogenated hydrocarbons to the rewind spring.

Carefully pull out the starter rope several times and allow it to rewind until its normal smooth action is restored.

9.2 Fan housing

– Remove shroud, b 6.4

: Remove screw (1) with sleeve

and screws (arrows)

– Lift hand guard slightly and

remove fan housing

Installation

: First insert and position

segment (1) in the slit (arrow) on

2310RA201 TG

the fan housing

2310RA203 TG

Before installing, lubricate the rewind spring and starter post with STIHL special lubricant, b 16.

If clogged with dirt or pitch, the entire starter mechanism, including the rewind spring, must be removed and disassembled. Take particular care when removing the rewind spring.

– Clean all components

Versions with ErgoStart

– Relieve the tension of the rewind

spring, b 9.4

: Push out segment (1) on the

pegs (2) on the opposite side through the holes with drift

– Examine fan housing and

segment, replace if necessary.

: Press segment (1) as far as it will

go into the pegs (2)

2310RA202 TG

– Lift hand guard slightly and

position fan housing

: Insert and tighten screw (1) with

sleeve and screws (arrows)

2310RA202 TG

2310RA201 TG

– Reassemble remaining parts in

reverse order

86 MS 241 C

9.3 Pawls

Versions with ErgoStart

– Remove fan housing, b 9.2

– Relieve the tension of the rewind

spring, b 9.5

: Carefully ease the spring (1) off

the starter post

– Remove pawl

Installation

: Position the spring (1) so that the

loop of the spring encloses the peg of the pawl and the curved part of the spring (arrow) is located in the groove in the starter post

2310RA204 TG

: Then slide the straight part of the

spring over the starter post until it engages in the groove

– Remove ErgoStart, b 9.4

Two pawls are installed in the

version with ErgoStart. Removal is the same as with the standard version.

– Grease the mounts of the new

2310RA206 TG

pawls, b 16

– Insert the new pawls and oil the

pegs of the pawls with resin-free lubricating oil, b 16

Installation

– Press new pawl into hole (arrow)

and grease the peg (1), b 16

The guide loop of the spring must run along the pawl (arrow).

Checking correct functioning

2310RA205 TG

– Pull starter rope, the rope rotor

turns, and the peg at the pawl moves in the direction of the anchor loop – the pawl moves outward

– Reassemble remaining parts in

reverse order

Washer (1) must be fitted.

: Position spring (2) so that its

2310RA207 TG

anchor loops engage the pegs of the pawls and the curved part of the spring (arrow) is located in the groove of the rope rotor post

: Then slide the straight part (3) of

the spring over the starter post until it engages in the groove

– Reassemble remaining parts in

reverse order

2310RA208 TG

87MS 241 C

9.4 ErgoStart

Installation

Checking correct functioning

The spring may still have spring tension stored in it, thus release the spring tension before any assembly procedure:

– Pull out the starter until the

engine turns – the preloaded spring is relaxed

– Remove fan housing and, if

necessary, segment, b 9.2

3 2 1

: Remove the circlip (1)

: Remove washer (2) and

carrier (3)

: Remove spring housing (4)

: Install torsion springs in pawls (1)

– observe installation position (arrows)

2310RA209 TG

: Push pawls (1) onto the posts (2)

on the flywheel, in the process pretensioning the torsion springs and positioning them on the support ribs (arrow)

The pawls must move freely and rest against the stop due to the spring force.

533RA198 TG

: Push spring housing (1) over the

rope rotor post into the pawls of the rope rotor (2) – the pawls must engage in the spring housing

2 1 3 4

5902RA581 TG

2310RA210 TG

2310RA211 TG

: Insert the carrier (1) in the spring

housing so that the recess (arrow) engages the anchor loop (2) of the rewind spring

: Push out circlips (arrows)

: Pull out pawls (1) and remove

torsion springs

2710RA165 TG

: Push on the pawls (1) so that

they can move towards the middle of the flywheel as far as

: Fit washer (3)

: Fit the circlip (4)

2710RA274 TG

– Do not overextend circlip

– Reassemble remaining parts in

reverse order

they will go

– Clean the mounts of the

pawls (1), b 16

: Push circlips (2) into place

88 MS 241 C

9.5 Rope rotor

Relieve tension of rewind spring

The system will not be under tension if the starter rope or rewind spring is broken.

– Remove fan housing and

segment, b 9.2

Versions with ErgoStart

: Remove the washer (1)

– Install pawl or pawls and spring,

b 9.3

– Install starter rope, b 9.6

– Tension the rewind spring, b 9.7

– Grease the pegs of the pawl or

pawls, b 16

2310RA213 TG

– Reassemble remaining parts in

reverse order

– Remove ErgoStart, b 9.4

All versions

: Pull out the starter rope (1)

about 5 cm, then hold the rope rotor (2) steady

– Still holding the rope rotor steady,

take three full turns off the rope rotor

The rewind spring must be relieved.

: Carefully pull off the rope rotor (2)

–The rewind spring may pop out

– Examine the rope rotor, replace if

necessary.

– Coat the hole in the rope rotor

with STIHL special lubricant, b 16

Installation

2310RA212 TG

9.6 Starter rope / starter grip

– Remove fan housing and

segment, b 9.2

Versions with ErgoStart

– Remove ErgoStart, b 9.4

All versions

– Relieve the tension of the rewind

spring, b 9.5

The rewind spring will not be under tension if the starter rope is broken.

– Remove any remaining rope from

the rope rotor if necessary

The starter rope must not be shortened.

– Pull out the rope with the starter

grip and carefully release the rope rotor

– Remove the starter rope; remove

any remaining scraps of rope, b 9.6

– Remove spring and pawl or

pawls, b 9.3

: Fit the rotor on the starter post so

that the inner loop of the spring (arrow) enters the recess (1)

The recess in the hub of the rope rotor acts as carrier for the anchor loop.

– Fit the washer.

2310RA214 TG

89MS 241 C

: Push starter rope (1) out a short

distance and undo the knot

– Pull starter rope out of rope rotor

and fan housing.

: Tie one of the two special knots

shown above at the end of the rope in the starter grip.

2310RA215 TG

Pull the rope through the grip until the knot at the end of the rope is in the recess (arrow)

: Then thread the rope (1) through

165RA227 TG

the opening (arrow)

4903RA132 TG2310RA216 TG

: Pull starter rope (1) into rotor until

the knot rests in the recess (arrow) of the rope rotor

– Tension the rewind spring, b 9.7

– Reassemble remaining parts in

reverse order

9.7 Tensioning the rewind spring

– Remove fan housing and

segment, b 9.2

2310RA218 TG

: Thread the new starter rope into

the starter grip from above

: Thread starter rope (1) into rope

4903RA131 TG

rotor

– Secure the rope (1) with a simple

overhand knot

: Pull out part of the starter rope (1)

2310RA217 TG

: Turn starter rope (1) with rope

rotor (2) six times clockwise

The rewind spring is now tensioned.

Hold the tensioned rope rotor firmly, as the rewind spring will be damaged if it jumps back suddenly.

2310RA219 TG

90 MS 241 C

: Hold the rope rotor (1) steady

: Pull out the twisted starter

rope (2) with the starter grip and straighten it out

When the starter rope is fully extended, it must still be possible to rotate the rope rotor at least another turn before the maximum spring tension is reached. If not, the spring tension must be reduced, otherwise it will break.

Reduce spring tension

Pull the rope out, hold the rope rotor

2310RA220 TG

steady and take off one turn of the rope.

– Reassemble remaining parts in

reverse order

9.8 Replacing the rewind Spring

– Troubleshooting, b 3.4

The replacement spring is supplied ready for installation and secured in a spring housing.

Install new rewind spring

2310RA224 TG

– Lubricate replacement spring

with frame with a few drops of STIHL special lubricant before installing it, b 16

: Position replacement spring with

frame in the fan housing so that the outer anchor loop (1) is positioned over the mount for the loop (2) and aligns with the mount (arrow)

: Hold the starter grip firmly to

keep the rope (1) tensioned

: Let go of the rope rotor (2) and let

the starter rope rewind slowly

The rewind spring is correctly tensioned when the starter grip (1) sits firmly in the rope guide bushing (arrow) without drooping to one side. If this is not the case, the rewind spring must be tensioned by one additional turn.

– Wear face shield and protective

gloves

2310RA221 TG

– risk of injury

– Remove fan housing and

segment, b 9.2

– Relieve the rewind spring if

necessary and remove the rope rotor, b 9.5

– Remove any fragments of the old

spring

If the rewind spring no longer produces sufficient tension, it must be replaced.

A worn rewind spring may still be under tension while installed.

2310RA222 TG

– Lay a blanket over the assembly

area and remove the rewind spring from the fan housing

2310RA226 TG

: Starting at the outer anchor loop,

push the new rewind spring through the openings (arrows) into the mount of the fan housing – in the process, the frame is removed

91MS 241 C

Reinstalling a rewind spring that has popped out

Versions with ErgoStart Install new rewind spring

: Press the frame (1) against the

rewind spring and turn it slightly clockwise until the rewind spring is completely seated

The rewind spring may pop out.

– Carefully remove the frame and

keep it – The frame is reused as an installation tool for installing rewind springs that have popped out

If the rewind spring pops out during installation, fit it in the fan housing as follows:

2310RA227 TG

– Arrange the rewind spring (1) as

shown in the illustration

: Insert outer anchor loop in the

recess (arrow) of the fan housing

2310RA223 TG

: Check washer (1) and replace if

necessary

2310RA230 TG

Make certain that the rewind spring (1) is inserted completely and the outer anchor loop is seated in the anchor loop mount (arrow), if necessary, press the rewind spring completely into the mount in the fan housing.

– Secure the rewind spring so that

it cannot pop out

– Install the rope rotor, b 9.5

– Reassemble remaining parts in

reverse order

2310RA228 TG

: Fit the rewind spring (1) in the

spring housing in a circular fashion, working in clockwise direction while holding the inserted turns of the spring in place

The further course of action is the same as for "Installing a new rewind spring".

– Lubricate replacement spring

with frame with a few drops of

STIHL special lubricant before installing it, b 16

Position replacement spring with frame in the fan housing so that the

2310RA231 TG

outer anchor loop (1) is positioned over the mount for the loop (2) and aligns with the mount (arrow)

The further course of action is the same as for "Installing a new rewind spring" in versions without ErgoStart.

2310RA225 TG

92 MS 241 C

– Secure the rewind spring so that

it cannot pop out

Reinserting a popped out rewind spring into the frame

In versions with ErgoStart, the rewind spring mount sits lower, thus the rewind spring can only be inserted directly into the fan housing premounted in a frame.

If the rewind spring pops out during

2310RA229 TG

installation, fit it in the frame as follows:

– Install the rope rotor, b 9.5

– Reassemble remaining parts in

reverse order

5902RA608 TG

: Insert anchor loop in the

recess (arrow) of the frame

: Fit the rewind spring (1) in the

frame in a circular fashion, working in counterclockwise direction while holding the inserted turns of the spring in place

The further course of action is the same as for "Installing a new rewind spring" in versions with ErgoStart.

93MS 241 C

10. Maintaining the antivibration elements

The front handle / tank housing and crankcase are connected by vibration-damping springs, rubber buffers and stop buffers.

Damaged springs rubber buffers and stop buffers must always be replaced.

10.1 Antivibration element on oil tank

The antivibration elements are located in the area of the oil tank and are fastened to the bottom of the machine.

– Remove the front handle,

b 10.4, versions with heating, b 10.4.1

: Twist out spring (1) with bearing

plug (2)

– Inspect spring with plug, replace

if necessary

Installation

2310RA233 TG

: Push the chain catcher (3) into

the mount so that it engages under the bumper strip (2)

: Screw in the screw (1) and

tighten it

– Reassemble remaining parts in

reverse order

10.2 Antivibration element on fuel tank

2 1

2410RA301 TG

: Remove screw (1)

: Remove the chain catcher (2)

– Remove the tank housing,

b 13.11.5

Bearing plug (1) must be twisted

2410RA300 TG

into the spring (2) as far as it will go.

: Twist spring (2) with bearing

plug (1) into the mount (arrow) as far as it will go

– Install the tank housing,

b 13.11.5

2310RA234 TG

2410RA302 TG

: Remove screw (1)

94 MS 241 C

Versions with heating

Installation

: Remove screw (1) on front

handle

All versions

: Remove screws (1)

: Push tank housing (2) down

slightly and hold it there

: Remove cover (1)

2410RA303 TG

: Push the antivibration

element (1) slightly upward and lift it out of the guide (arrow)

2310RA236 TG

: Remove antiivibration

element (1) between crankcase and tank housing

– Inspect spring and plug, replace if

necessary

2310RA237 TG

2310RA238 TG

– Push tank housing down slightly

and hold it there

: Orient antivibration element so

that the tab (1) faces the crankcase and push it bearing plug (2) first between crankcase and tank housing

: Push bearing plug (2) through

the opening

: Push the bearing plug (3) into the

mount (arrow)

2310RA239 TG

: Push front handle out of the

mount (arrow) on the peg (1) – Do not remove screws on front handle

2310RA240 TG

: Position cover (1) so that it

engages the peg (arrow)

2410RA304 TG

95MS 241 C

front handle

The antivibration element is between front handle and cylinder.

10.3 Antivibration element on

: Push tank housing upward until

the peg (1) of the front handle engages in the mount (arrow)

: Raise tank housing (1)

2410RA304 TG

: Position bearing stopper (1)

: Coat screw (2) with Loctite,

screw in and tighten, b 16

Versions with heating

2310RA241 TG

– Remove shroud, b 6.4

– Remove the air filter, b 13.1

2410RA306 TG

2410RA302 TG

: Remove screw (1)

– Remove the front handle,

b 10.4

2410RA307 TG

: Orient bearing plugs (2) and

cover (3) so that the holes align with the hole on the tank housing

: Screw in and tighten

screws (5) and (4)

: Position bearing plug (1) and

insert and tighten screw (2)

– Reassemble remaining parts in

reverse order

: Twist out bearing plug (1) and

unhook retainer (arrow)

: Twist out spring (2) and push

retainer (arrow) out of front handle

– Inspect spring and bearing plug

and retain, replace if necessary

2310RA243 TG

96 MS 241 C

Installation

5902RA246 TG

: Push retainer (1) with the small

nipple into the hole in the front handle (2)

: Twist spring (3) onto the

peg (arrow) as far as it will go

: Position bearing plug (1) against

2310RA244 TG

cylinder

: Coat screw (2) with Loctite,

screw in and tighten, b 16

– Reassemble remaining parts in

reverse order

10.3.1 Antivibration element on handlebar, version with heating

2410RA306 TG

: Twist out bearing plug (1) and

unhook retainer (arrow)

: Twist out spring (2) and pull out

retainer (arrow)

Installation

0001RA219 TG

: Hook retainer (arrow) onto

bearing plug (1)

: Push bearing plug (1) into the

spring as far as it will go

– Install the front handle, b 10.4

2310RA245 TG

: Remove screws (1) and (2)

: Remove the antivibration

element (3) completely

: Insert retainer (1) with the nipple

in the holder (2)

2410RA308 TG

: Twist spring (2) onto the peg

: Hook retainer (arrow) onto

bearing plug (1)

: Twist bearing plug (1) into the

spring (2) as far as it will go

0001RA219 TG

97MS 241 C

– Replace stop buffer

10.3.3 Filter base buffers

: Position antivibration element (1)

against front handle and cylinder

: Screw in the screw (2) and

tighten it

: Coat screw (3) with Loctite,

screw in and tighten, b 16

– Reassemble remaining parts in

reverse order

10.3.2 Stop buffer

The stop buffers are installed between crankcase and tank housing on the ignition and clutch side.

Installation

2410RA309 TG

– Orient the stop buffer (1) on both

sides – the conical pegs (arrow) facing the crankcase

– To simplify installation, coat the

conical pegs with STIHL press fluid, b 16

: Press the stop buffers (1) with the

pegs on the inside of the crankcase completely into holes – to simplify assembly, twist the stop buffers while pressing them in

– Remove filter base, b 13.3

2410RA311 TG

: Remove screw (1)

: Push tank housing (2) down

slightly and hold it there

1 1

2310RA249 TG

– Remove the tank housing,

b 13.11.5

: Pry out stop buffers (1) on the

ignition and clutch sides

2410RA313 TG

: Press out the buffers (1) on the

underside (arrows)

– Check buffers (1) and replace if

necessary

2410RA312 TG

The conical pegs must enclose the holes completely.

2410RA310 TG

– Reassemble remaining parts in

reverse order

98 MS 241 C

Installation

1 1

: Lift front handle (1) slightly at the

side and remove it from the guide (arrow).

: Orient buffers (1)

– conical pegs facing the holes (arrows)

– To simplify installation, coat the

conical pegs with STIHL press fluid, b 16

: Press the buffers (1) with the

conical pegs completely into the holes (arrows) –to simplify assembly, twist the buffers while pressing them in

: Push tank housing (1) upward

2410RA314 TG

and hold it there

: Screw in the screw (2) and

tighten it

– Reassemble remaining parts in

reverse order

10.4 Front handle

– Remove shroud, b 6.4

2310RA253 TG

1 1 2

: Remove screws (1) on the

underside of the machine and lift front handle (2) out of the mount (arrow)

2310RA157 TG

The conical pegs (arrows) must enclose the holes completely on the reverse.

2410RA315 TG

: Remove screw (1)

– Take out screws

: Remove front handle (1) from the

lower guide

2410RA302 TG

– Remove and examine front

handle (1), replace if necessary

– Examine the antivibration spring

and replace if necessary, b 10.3

2410RA315 TG

0001RA232 TG

99MS 241 C

Stihl MS 241 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Contents

1. Introduction and safety precautions

1.1 Introduction

1.2 Safety precautions

2. Specifications

2.1 Engine

2.2 Fuel system

2.3 Ignition system

2.4 Chain lubrication

2.5 Tightening torques

3. Troubleshooting

3.1 Clutch

3.2 Chain Drive, Chain Brake, Chain Tensioner

3.3 Chain lubrication

3.4 Starter

3.5 Ignition system

3.6 Carburetor

3.7 Engine

4. Clutch

4.1 Clutch drum

4.2 Clutch

5. Chain brake

5.1 Checking operation of chain brake

5.2 Brake band

5.3 Brake lever

5.4 QuickStop Super brake lever

5.4.1 Adjusting brake cable

5.4.2 Brake cable Removal and installation

5.5 Cam lever

5.6 Pins

5.7 Chain tensioner

5.7.1 Quick chain tensioner

5.7.2 Chain catcher

5.9 Collar nut for chain sprocket cover

5.8 Bar mounting stud

6. Engine

6.1 Muffler

6.2 Leak testing

6.2.1 Preparations

6.2.2 Vacuum test

6.2.3 Pressure test

6.3 Oil seals

6.3.2 Clutch side

6.3.1 Ignition side

6.4 Shroud

6.5 Cylinder

6.6 Crankshaft

6.6.1 Ball bearing / crankcase

6.7 Piston

6.8 Piston rings

6.9 Decompression valve

7. Ignition system

7.1 Ignition timing

7.2 Pre-separator

7.3 Control unit

7.4 Spark test check control unit

7.5 Spark plug boot

7.5.1 Ignition lead

7.6 Flywheel

7.7.2 Removal and installation

7.7 Short circuit wire

7.7.1 Contact test

7.7.4 Contact spring

7.7.3 Ground wire

7.8 Troubleshooting, ignition system

8. M-Tronic

8.1 Calibrating the control unit

8.2 Testing

8.2.1 Test preparations

8.2.2 Connect the test lead

8.2.3 Check screwed and plug connections as well as switch

8.2.4 Checking the solenoid valve

8.2.5 Checking the start detection function

8.2.6 Checking the wiring harness

8.3 Wiring harness

8.4 Switchgear