Stihl FS 240 User manual

STIH)
STIHL FS 240, 260, 360, 410, 460 2011-09

1FS 240 C, FS 260 C, FS 360 C, FS 410 C, FS 460 C-M
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© ANDREAS STIHL AG & Co. KG, 2011
RA_752_00_01_04
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 Gearbox 5
2.5 Tightening torques 6
3. Troubleshooting 8
3.1 Clutch 8
3.2 Gearbox 9
3.3 Drive tube assembly 10
3.4 Starter 11
3.5 Ignition system 13
3.6 Carburetor 14
3.7 Engine 18
4. Clutch 19
4.1 Clutch drum 19
4.1.1 Ball bearing 22
4.2 Clutch 23
5. Engine 25
5.1 Muffler 25
5.2 Leak testing 26
5.2.1 Preparations 26
5.2.2 Vacuum test 27
5.2.3 Pressure test 27
5.3 Oil seals 28
5.4 Shroud 29
5.5 Cylinder 30
5.6 Crankshaft 32
5.6.1 Ball bearing /
crankcase 35
5.7 Piston 36
5.8 Piston rings 38
6. Ignition system 39
6.1 Ignition timing 39
6.2 Ignition module 39
6.2.1 Control unit
(ignition module)
M-Tronic 41
6.3 Testing the
ignition module 42
6.4 Spark plug boot /
ignition lead 43
6.5 Flywheel 45
6.6 Short circuit wire 45
6.6.1 Testing 45
6.6.2 Short circuit wire
on engine,
removal and
installation 46
6.6.3 Short circuit wire
with M-Tronic on
engine, removal
and installation 48
6.6.4 Short circuit wire on
control handle for
loop handle,
removal and
installation 51
6.6.5 Short circuit wire
on control handle
for bike handle,
removal and
installation 52
6.6.6 Ground wire 54
6.6.7 Contact spring
versions with control
handle for bike handle 54
6.7 Troubleshooting,
Ignition System 55
7. M-Tronic 58
7.1 Calibrating
the control unit 58
7.2 Resetting the control
unit to factory defaults 58
7.3 Testing 58
7.3.1 Test preparations 58
7.3.2 Connect the test lead 58
7.3.3 Check screwed and
plug connections as
well as switch 59
7.3.4 Checking the solenoid
valve 59
7.3.5 Checking the start
detection function 60
7.3.6 Checking the wiring
harness 60
7.4 Removal and
installation 62
7.5 Troubleshooting,
M-Tronic 65
7.5.1 Engine does not start 65
7.5.2 Engine does not start
in position }66
7.5.3 Engine speed drops
under load
– low power 67
7.5.4 Ignition – no ignition
spark 68
7.5.5 Engine stops
suddenly 69
7.5.6 Cut-off speed
not reached 70
8. Rewind starter 71
8.1 General 71
8.2 Starter 71
8.3 Pawls 71
8.4 ErgoStart/rope rotor 72
8.5 Starter rope /
starter grip 73
8.6 Tensioning
the rewind spring 75
8.7 Replacing
the rewind spring 75
Contents

2FS 240 C, FS 260 C, FS 360 C, FS 410 C, FS 460 C-M
Contents
9. Antivibration
elements 77
9.1 Rubber insert
1-point antivibration
system 77
9.2 Rubber buffers/
springs 4-point
antivibration system 78
10. Actuating levers 82
10.1 Control handle for
loop handle 82
10.1.1 Throttle trigger /
throttle trigger
interlock 82
10.1.2 Slide control 84
10.2 Control handle
for bike handle 85
10.2.1 Removal and
installation 85
10.2.2 Throttle trigger /
throttle trigger
interlock 86
10.2.3 Lever for stop function 89
10.2.4 Adjusting
the throttle cable 89
10.2.5 Throttle rod 90
11. Fuel system 91
11.1 Air filter 91
11.2 Filter housing 91
11.3 Carburetor 93
11.3.1 Leakage test 95
11.4 Repairing
the carburetor 96
11.4.1 Metering diaphragm 96
11.4.2 Inlet needle 97
11.4.3 Pump diaphragm 98
11.4.4 Throttle shaft lever 99
11.4.5 Choke lever/choke
knob 100
11.4.6 Adjusting screws,
carburetor
without M-Tronic 102
11.5 Carburetor
adjustment
with M-Tronic 103
11.6 Carburetor
adjustment
without M-Tronic 103
11.6.1 Basic setting 103
11.6.2 User adjustment 104
11.7 Spacer flange 105
11.8 Tank vent 107
11.8.1 Testing 107
11.8.2 Removal
and installation 108
11.9 Fuel intake 108
11.9.1 Pickup body 108
11.9.2 Fuel hose 109
11.9.3 Fuel tank 110
12. Drive tube assembly 112
12.1 Drive tube assembly
with loop handle 112
12.2 Drive tube assembly
with control handle
for bike handle 113
12.2.1 Disassembling
the drive tube
assembly with a
diameter of 25.4 mm 114
12.2.2 Disassembling
the drive tube
assembly with a
diameter of 28 mm 116
12.2.3 Loop handle
with barrier bar 117
12.3 Deflector 118
12.3.1 Deflector for
gearbox with 25.4 mm
drive tube assembly
diameter 118
12.3.2 Deflector for gearbox
with 28 mm drive tube
assembly diameter 119
12.3.3 One-piece
carrying ring 120
12.3.4 Support 120
12.4 Gearbox for drive tube
assembly 25.4 mm
with square profile 120
12.4.1 Removal and
installation 120
12.4.2 Disassembly 121
12.5 Gearbox for drive tube
assembly 28 mm
with serration 124
12.5.1 Removal and
installation 124
12.5.2 Disassembly 124
13. Special tools 129
14. Service accessories 131

3FS 240 C, FS 260 C, FS 360 C, FS 410 C, FS 460 C-M
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.
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.
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:
NAction 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:
AItem pointer (short)
aDirection 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.
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.

4FS 240 C, FS 260 C, FS 360 C, FS 410 C, FS 460 C-M
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 protective gloves must be
worn without fail if parts are heated
for assembly/disassembly
purposes. Risk of burns from hot
grease. Lubricants in the parts
become hot due to heating.
Improper handling may result in
burns and other serious injuries.
Always replace damaged parts.
Check dismantled parts for wear
and damage before installation,
replace if necessary.
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.
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, b14.
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, b14.

5FS 240 C, FS 260 C, FS 360 C, FS 410 C, FS 460 C-M
2. Specifications
2.1 Engine
FS 240 C, FS 360 C FS 260 C, FS 410 C FS 460 C
Displacement: 37.7 cm341.6 cm345.6 cm3
Bore: 40.0 mm 42.0 mm 44.0 mm
Stroke: 30.0 mm 30.0 mm 30.0 mm
Engine power to ISO 8893: 1.7 kW (2.3 HP)
at 8500 rpm
2.0 kW (2.7 HP)
at 9000 rpm
2.2 kW (3.0 HP)
at 9500 rpm
Cut-off speed
(Nominal value): 12500 rpm, FS 240 RC
10500 rpm
12500 rpm, FS 260 RC
10500 rpm
12300 rpm
Idling speed
(Nominal value): 2800 rpm 2800 rpm 2700 rpm
Clutch: Centrifugal clutch
without linings
Centrifugal clutch
without linings
Centrifugal clutch
without linings
Clutch engages at: 3600 rpm 3600 rpm 3600 rpm
Crankcase leakage test
at gauge pressure: pü= 0.5 bar pü= 0.5 bar pü= 0.5 bar
under vacuum: pu= 0.5 bar pu= 0.5 bar pu= 0.5 bar
2.2 Fuel system
Carburetor leakage test at
gauge pressure: pü= 0.8 bar pü= 0.8 bar pü= 0.8 bar
Operation of tank vent at
gauge pressure: pü= 0.5 bar pü= 0.5 bar pü= 0.5 bar
Fuel: as specified in instruction
manual
as specified in instruction
manual
as specified in instruction
manual
2.3 Ignition system
Air gap between ignition
module and fanwheel: 0.30 (+ 0.15/- 0.20) mm 0.30 (+ 0.15/- 0.20) mm 0.30 (+ 0.05/- 0.10) mm
Spark plug (suppressed): NGK CMR 6 H NGK CMR 6 H NGK CMR 6 H
Electrode gap: 0.5 mm 0.5 mm 0.5 mm
2.4 Gearbox
Quantity of gear
lubricant:
Drive tube assembly
diameter
25.4 mm/28.0 mm
9.5 g,
STIHL gear lubricant for
brushcutters

6FS 240 C, FS 260 C, FS 360 C, FS 410 C, FS 460 C-M
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
Comment
Screw M 5x17 Cover/ shroud 6.0
Screw D 5x24 Cover/ clutch housing 6.0 1), 5)
Screw P 4x14 Cover/ starter cover 2.0
Screw P 6x14 Line limiting blade/ deflector 2.5
Screw D 5x24 Starter 6.0 1)
Screw P 5x32 Plugs for antivibration springs/ antivibration
housing
3.0 6)
Screw M 5x48x22 Control handle/ handlebar/ locknut 2.5
Screw P 4x16 Control handle moldings outside/ inside 1.3
Screw M 5x12 Control handle clamp/ drive tube assembly 5.0
Screw P 4x10 Diagnostic jack/ bushing 1.5 7)
Screw M 5x21 Filter cover 6.0
Collar nut M 5 Filter housing 3.5
Screw M 6x35 Gearbox/ drive tube assembly 10.0 1)
Screw D 5x24
Gear housing/ drive tube assembly (1st stage) 4.0 1)
Screw D 5x24
Gear housing/ drive tube assembly (2nd stage) 9.0 1)
Screw M 5x10 Gear housing/ guard ring 8.0 2)
Screw M 5x48x22 Left handle/ handlebar/ locknut 2.5
Screw D 5x24 Shroud 6.0 1)
Screw P 4x14 Shroud/ slide 2.0
Screw P 4x10 Cable holder/ short circuit wire/ ignition
module
1.5
Screw M 6x30 Clamp/ drive tube assembly/ supports 8.0 1)
Screw M 5x16 Clamps handlebars 2.0 1)
Screw D 6x35 Clamping device clutch housing 8.0 1), 6)
Screw D 5x24 Fuel tank/ crankcase 6.0 1)
Screw M 6x25 Clutch/ flywheel 10.0
Screw D 5x24 Clutch housing/ crankcase 8.0 1)
Screw M 5x16 Crankcase fan side/ insert 6.0 2)
Screw D 5x24 Crankcase fan side/ starter side 8.0 1)
Screw P 3x6 Return spring/ fan housing 0.6
Screw M 5x16 Muffler / crankcase 9.0 2)
Screw M 5x16 Muffler/ cylinder/ first screw
(1st stage)
2.0 2)
Screw M 5x16 Muffler/ cylinder/ second screw
(2nd stage)
10.0 2)
Screw M 5x16 Muffler/ cylinder/ first screw
(3rd stage)
10.0 2)
Screw P 4x10 Switchgear/ bushing 1.5 7)

7FS 240 C, FS 260 C, FS 360 C, FS 410 C, FS 460 C-M
Fastener Thread size For component Tightening
torque
Nm
Comment
Screw M 5x20 Clamp/ control handle for loop handle/ nut 4.5 1)
Screw M 5x20 Cutting attachment deflector/ gear housing 4.3 1)
Screw M 5x23 Cutting attachment deflector/ gear housing 10.0
Screw IS 5x14 Deflector/ antivibration housing 4.0 6)
Screw D 5x32 Protective hip plate/ crankcase 8.0 1)
Nut M 8x1 Flywheel/ crankshaft 28.0
Screw M 6x14 Clamp/ drive tube assembly harness anchor 4.5 1)
Screw D 6x32 Clamp/ drive tube assembly with washer 12.0 1)
Screw M 5x18 Clamp/ supports/ drive tube assembly 4.0 1), 6)
Nut M 8x1 Starter cup / crankshaft 17.0
Screw P 6x19 Supports/ plugs antivibration springs 6.0 6)
Screw M 14x1.25x7 Supports/ muffler with spark arresting screen 8.0
Screw P 4x14 Bushing choke/ filter housing 2.0
Screw P 4x10 Shim/ deflector 1.0
Screw M 11x10 Screw plug/ gearbox 9.5
M 10x1 Spark plug/ cylinder 12.0
Screw D 4x18 Ignition module/ cylinder 4.0 1)
Screw M 5x20 Spacer flange/ cylinder 8.0 2)
Screw D 5x32 Cylinder / crankcase 9.0 1)
Remarks:
1) Easy-slide coating with locking serration
2) Microencapsulated with locking serration
3) Microencapsulated with washer
4) Connection between crankshaft and flywheel must be degreased and oil-free
5) 1-point antivibration system
6) 4-point antivibration system
7) M-Tronic
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.
As a rule, microencapsulated screws must be replaced after removal.
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.

8FS 240 C, FS 260 C, FS 360 C, FS 410 C, FS 460 C-M
3. Troubleshooting
3.1 Clutch
Problem Cause Remedy
Cutting attachment stops under
load at full throttle
Clutch shoes badly worn Install new clutch
Clutch drum badly worn Install new clutch drum
Cutting attachment rotates at idle
speed
Idle speed too high Versions without M-Tronic:
Readjust idle speed screw LA
Versions with M-Tronic:
Carry out diagnosis
Tension springs of the clutch shoes
are stretched
Replace tension springs, replace
clutch if necessary
Tension springs of the clutch shoes
are broken
Replace tension springs
Loud noises Tension springs stretched Replace all tension springs
Ball bearing of the clutch drum is
damaged
Replace ball bearing
Screws of the clutch are loose Tighten screws, replace clutch if
necessary and check threaded
holes on the flywheel, replace
flywheel if necessary
Clutch shoes worn Install new clutch

9FS 240 C, FS 260 C, FS 360 C, FS 410 C, FS 460 C-M
3.2 Gearbox
Problem Cause Remedy
Loud noises Ball bearings damaged or worn Replace ball bearings on the drive
side and non-drive side
Pinion damaged or worn Replace set of pinions on the drive
side and non-drive side
Too little or no gear lubricant in
gearbox
Gearbox drive tube assembly
25.4 mm:
Add gear lubricant
Gearbox drive tube assembly
28 mm:
Remove drive pinion and add gear
lubricant
Gearbox becomes too hot Excessive friction due to damaged
or worn ball bearings
Replace ball bearings on the drive
side and non-drive side
Too little or no gear lubricant in
gearbox
Gearbox drive tube assembly
25.4 mm:
Add gear lubricant
Gearbox drive tube assembly
28 mm:
Remove drive pinion and add gear
lubricant
Gearbox runs rough and stops
running under load
Drive shaft does not fully engage
drive pinion
Push gearbox onto drive tube
assembly until the drive shaft fully
engages the drive pinion
Square profile or serration in the
drive train is damaged or worn
Check drive pinion, drive shaft and
clutch drum, replace if necessary
Clutch worn Check clutch and clutch drum,
replace if necessary
Gearbox frozen Locking pin for changing tools not
removed
Remove locking pin
Damaged or worn ball bearings
jammed
Replace ball bearings on the drive
and non-drive sides, also check
bearing seats in the gear housing,
replace gear housing if necessary
Serration damaged or broken –
fragments jammed
Replace set of pinions on the drive
side and non-drive side

10 FS 240 C, FS 260 C, FS 360 C, FS 410 C, FS 460 C-M
3.3 Drive tube assembly
Problem Cause Remedy
Drive tube assembly vibrates Flexible liner is worn
– Drive shaft is insufficiently
supported and can vibrate
Replace flexible liner
Cutting attachment out of true Resharpen cutting attachment
evenly, replace if necessary
Drive tube assembly becomes very
warm
Drive shaft not sufficiently
lubricated
Lubricate drive shaft along its entire
length – the entire length of the
flexible liner must be lubricated
Bike handle does not clamp Clamps are greasy or oily Clean clamps and bike handle
Bike handle can no longer be
adjusted
Clamps are dirty Clean clamps and bike handle

11FS 240 C, FS 260 C, FS 360 C, FS 410 C, FS 460 C-M
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
Replace starter rope
Normal wear Replace starter rope
Starter rope does not rewind Heavy fouling or rust on rewind
spring
Clean or replace rewind spring
Spring insufficiently tensioned Check rewind spring and increase
tension
Rewind spring broken Replace rewind spring
Starter rope cannot be pulled out
far enough
Rewind spring overtensioned Check rewind spring and reduce
tension
Starter rope can be pulled out
almost without resistance
(crankshaft does not turn)
Guide peg on pawls or pawls
themselves are worn
Replace pawls
Spring clip fatigued Replace spring clip
Spring clip improperly installed Install spring clip properly
Lugs on starter cup worn Replace starter cup, check pawls,
replace if necessary
Anchor loop in ErgoStart spring
housing not hooked onto carrier
Hook ErgoStart anchor loop to
carrier

12 FS 240 C, FS 260 C, FS 360 C, FS 410 C, FS 460 C-M
Problem Cause Remedy
Starter rope is difficult to pull or
rewinds very slowly
Starter mechanism is very dirty Thoroughly clean complete starter
mechanism
Spring in ErgoStart spring housing
is fatigued
Replace ErgoStart
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

13FS 240 C, FS 260 C, FS 360 C, FS 410 C, FS 460 C-M
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
Use a fuel mixture with the correct
mixing ratio
Incorrect air gap between ignition
module/control unit and flywheel
Set the correct air gap
Flywheel cracked
or has other damage or pole shoes
have turned blue
Install new flywheel
Incorrect ignition timing, flywheel
out of adjustment
– Key in flywheel has sheared off
Install new flywheel
Weak magnetization in flywheel Install new flywheel
Irregular spark Check proper functioning of lever
for stop function/contact spring or
slide control/microswitch and
ignition module.
Damaged insulation or interruption
in ignition lead or short circuit wire.
Check ignition lead/ignition module,
replace ignition module if
necessary. Check operation of
spark plug, clean spark plug and
replace if necessary.
Versions with M-Tronic, carry out
diagnosis

14 FS 240 C, FS 260 C, FS 360 C, FS 410 C, FS 460 C-M
3.6 Carburetor
Problem Cause Remedy
Carburetor floods; engine stalls Inlet needle not sealing
– Foreign matter in valve seat or
cone
Remove and clean inlet needle or
clean carburetor
Inlet needle worn Replace inlet needle
Inlet control lever sticking on
spindle
Examine control lever, replace if
necessary
Helical spring not located on nipple
of inlet control lever
Remove the inlet control lever and
refit it correctly
Perforated disc on diaphragm is
deformed and presses constantly
against the inlet control lever
Replace metering diaphragm
Metering diaphragm is deformed Replace metering diaphragm
Poor acceleration, version without
M-Tronic
Low speed screw "too lean" Check basic carburetor setting,
correct if necessary
High speed screw "too lean" Check basic carburetor setting,
correct if necessary
... All versions Inlet needle sticking to valve seat Remove inlet needle, clean and
refit
Diaphragm gasket leaking Replace diaphragm gasket
Metering diaphragm damaged or
shrunk
Replace metering diaphragm
Tank vent faulty Replace tank vent
Leak in fuel line between tank and
carburetor
Seal connections or replace line
... Versions with M-Tronic Parts in carburetor or M-Tronic
wiring harness defective
Carry out M-Tronic diagnosis, if
necessary, replace carburetor or
M-Tronic wiring harness

15FS 240 C, FS 260 C, FS 360 C, FS 410 C, FS 460 C-M
Problem Cause Remedy
Power loss during acceleration, all
versions
Seal or spring of accelerator pump
worn or damaged
Replace carburetor
... Versions with M-Tronic Parts in carburetor or M-Tronic
wiring harness defective
Carry out M-Tronic diagnosis, if
necessary, replace carburetor or
M-Tronic wiring harness
Engine will not idle, idle speed too
high, versions without M-Tronic
Throttle shutter opened too wide by
idle speed screw LA
Set idle speed screw LA correctly
... All versions Oil seals / crankcase leaking Seal oil seals / crankcase, replace if
necessary
Throttle shutter does not close Replace carburetor
... Versions with M-Tronic Parts in carburetor or M-Tronic
wiring harness defective
Carry out M-Tronic diagnosis, if
necessary, replace carburetor or
M-Tronic wiring harness
Engine stops when idling, versions
without M-Tronic
Idle speed screw "too rich" or
"too lean"
Correct setting of low speed
screw L
Idle speed screw LA
setting incorrect – throttle shutter
completely closed
Set idle speed screw LA correctly
... All versions Idle jet bores
or ports blocked
Clean the carburetor
Tank vent faulty Replace tank vent
Leak in fuel line between tank and
carburetor
Seal connections or replace line
... Versions with M-Tronic Parts in carburetor or M-Tronic
wiring harness defective
Carry out M-Tronic diagnosis, if
necessary, replace carburetor or
M-Tronic wiring harness

16 FS 240 C, FS 260 C, FS 360 C, FS 410 C, FS 460 C-M
Problem Cause Remedy
Cutting attachment stops when
idling, versions without M-Tronic
Idle speed too high Readjust with idle speed screw
LA (counterclockwise)
... All versions Clutch springs stretched or fatigued Replace tension springs, replace
clutch if necessary
Clutch spring hooks broken Replace tension springs
... Versions with M-Tronic Parts in carburetor or M-Tronic
wiring harness defective
Carry out M-Tronic diagnosis, if
necessary, replace carburetor or
M-Tronic wiring harness
Engine speed drops quickly under
load – low power,
all versions
Air filter dirty Clean air filter, replace if necessary
Throttle shutter not opened fully Check throttle cable and 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
Seal connections or replace line
Main jet bores or ports blocked Clean the carburetor
Pump diaphragm damaged or
fatigued
Replace pump diaphragm
Incorrect ignition timing, flywheel
out of adjustment
– Key in flywheel has sheared off
Install new flywheel
... Versions without M-Tronic High speed screw H"too rich" Check basic carburetor setting,
correct if necessary

17FS 240 C, FS 260 C, FS 360 C, FS 410 C, FS 460 C-M
Problem Cause Remedy
Engine speed drops quickly under
load – low power, versions with M-
Tronic
Parts in carburetor or M-Tronic
wiring harness defective
Carry out M-Tronic diagnosis, if
necessary, replace carburetor or
M-Tronic wiring harness
Engine runs extremely richly, lacks
power and has very low final speed
Choke shutter does not open Check carburetor and choke shaft,
if necessary, repair lever at the
choke shaft (choke lever) or
replace carburetor
Engine does not start No spark Replace spark plug, check ignition
module/control unit, replace if
necessary
Starter grip not pulled forcefully
enough
– Fuel/air mixture too rich (flooded)
Remove and dry the spark plug,
crank the engine several times with
the starter to clear the combustion
chamber, reinsert and tighten spark
plug, repeat starting procedure

18 FS 240 C, FS 260 C, FS 360 C, FS 410 C, FS 460 C-M
3.7 Engine
Always check and, if necessary,
repair the following parts before
looking for faults on the engine:
- Air filter
- Fuel supply
- Carburetor
- Ignition system/ M-Tronic
Problem Cause Remedy
Engine does not start easily, stalls
at idle speed but operates normally
at full throttle
Oil seals in engine defective Replace oil seals
Crankcase leaking or
damaged (cracks)
Reseal crankcase, replace if
necessary
Engine does not deliver full power
or runs erratically
Piston rings worn or broken Replace piston rings
Muffler / spark arresting screen
carbonized
Clean muffler (inlet and outlet
openings), replace spark arresting
screen, replace muffler if necessary
Air filter dirty Clean or replace air filter
Fuel line kinked or cracked Fit new lines and ensure they are
installed without kinking
Engine is overheated Insufficient cylinder cooling.
Air inlet openings in clutch housing
or air slits in shroud, cover or
antivibration housing are clogged.
Cooling fins on cylinder are
severely fouled.
Thoroughly clean all cooling air
openings and the cylinder fins
Starter air intake fouled Clean starter air intake

19FS 240 C, FS 260 C, FS 360 C, FS 410 C, FS 460 C-M
4. Clutch
4.1 Clutch drum
– Troubleshooting, b3.1
– Remove drive tube assembly,
1-point antivibration system,
b12.1, 4-point antivibration
system, b12.2
:Pry out cable holder (1) on one
side
– Remove cable holder (1)
– Lay aside protective tube with
control handle
– Do not kink protective tube
:Remove screws (1)
:Remove cover (2)
– Remove starter, b8.2
– Remove shroud, b5.4
– Remove protective hip plate,
b11.9.3
5904RA000 TG
1
5904RA001 TG
1
2
1
:Remove screws (1)
:Remove filter cover (2) with
screws
:Remove screws (1)
:Remove bushing (2)
– Detach short circuit wire and
cable holder from engine,
b6.6.2
Versions with M-Tronic
:Remove the plug (1)
5904RA002 TG
1
2
1
5904RA003 TG
1
1
2
1
2
5904RA290 TG
2
3
:Remove screws (2) and tilt
bushing (3) to the side
– Detach short circuit wire and
cable holder from engine,
b6.6.3
:Remove screws (1)
:Remove clutch housing (2)
Versions with 4-point
antivibration system
Removal and installation of the
clutch housing are the same as for
1-point antivibration systems.
– Examine the rubber buffers,
replace if necessary, b9.2
All versions
:Remove the circlip (1)
5904RA004 TG
1
1
1
1
2
5904RA005 TG
1