Stihl MS 201 TC-M User manual

STIH)
STIHL MS 201, MS 201 T 2012-01

1MS 201, MS 201 C, MS 201 T, MS 201 TC
q
© ANDREAS STIHL AG & Co. KG, 2012
RA_577_00_01_02
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 10
3.4 Rewind Starter 11
3.5 Ignition System 13
3.6 Carburetor 14
3.7 Engine 17
4. Clutch 18
4.1 Clutch 18
4.2 Clutch Drum 19
5. Chain Brake 20
5.1 Checking Operation 20
5.2 Brake Band 20
5.3 Brake Lever 21
5.4 Flat Spring 23
5.5 Pins 23
5.6 Chain Tensioner 24
5.6.1 Chain Catcher 25
5.7 Bar Mounting Stud 25
5.8 Collar Nut for
Sprocket Cover 25
6. Engine 27
6.1 Muffler 27
6.1.1 Insulating Plate 28
6.2 Leakage Test 29
6.2.1 Preparations 29
6.2.2 Vacuum Test 30
6.2.3 Pressure Test 31
6.3 Oil Seals 31
6.3.1 Ignition Side 31
6.3.2 Clutch Side 32
6.4 Cylinder 33
6.5 Crankshaft /
Crankcase 34
6.5.1 Roller Bearings /
Crankcase 37
6.6 Piston 38
6.7 Piston Rings 41
7. Ignition System 42
7.1 Ignition Timing 42
7.2 Ignition Module 42
7.3 Testing the
Ignition Module 45
7.4 Spark Plug Boot /
Ignition Lead 46
7.5 Flywheel 47
7.6 Short Circuit Wire 48
7.6.1 Testing 48
7.6.2 Removing and
Installing (MS 201) 48
7.6.3 Removing and
Installing (MS 201 T) 51
7.6.4 Ground Wire 52
7.6.5 Contact Spring
(MS 201) 53
7.6.6 Contact Springs
(MS 201 T) 54
7.7 Ignition System
Troubleshooting 56
8. Rewind Starter 59
8.1 General 59
8.2 Fan Housing 59
8.3 Pawls 60
8.4 Rope Rotor 61
8.4.1 Rope Rotor with
ErgoStart 61
8.5 Starter Rope / Grip 62
8.6 Tensioning the
Rewind Spring 64
8.7 Replacing the
Rewind Spring 65
9. AV Elements 67
9.1 Annular Buffer on Fuel
Tank (MS 201) 67
9.1.1 Annular Buffer on Fuel
Tank (MS 201 T) 67
9.2 AV Spring on Oil Tank
(MS 201) 68
9.2.1 AV Spring on Oil Tank
(MS 201 T) 69
9.3 Front Handle /
AV Spring (MS 201) 70
9.3.1 Front Handle /
AV Spring (MS 201 T) 71
9.4 Stop Buffer on Handle
Housing (MS 201) 72
9.5 Stop Buffer on Tank
Housing (MS 201) 73
10. Control Levers 74
10.1 Master Control Lever 74
10.1.1 Switch Shaft (MS 201) 74
10.1.2 Switch Shaft
(MS 201 T) 75
10.2 Throttle Trigger /
Lockout Lever
(MS 201) 76
10.3 Throttle Trigger /
Lockout Lever
(MS 201 T) 77
10.3.1 Choke and Throttle
Rods (MS 201) 78
10.3.2 Choke and Throttle
Rods (MS 201 T) 80
10.4 Handle Housing
(MS 201) 82
10.5 Handle Housing
(MS 201 T) 86
11. Chain Lubrication 89
11.1 Pickup Body 89
11.2 Oil Suction Hose 89
11.3 Connector /
Oil Pressure 89
11.4 Oil Pump 90
11.5 Valve 91
Contents

2MS 201, MS 201 C, MS 201 T, MS 201 TC
Contents
12. Repair fuel system 93
12.1 Air Filter 93
12.2 Baffle 93
12.3 Filter Base (MS 201) 93
12.3.1 Filter Base
(MS 201 T) 94
12.4 Carburetor (MS 201) 94
12.5 Carburetor (MS 201 T) 96
12.5.1 Leakage test 98
12.6 Servicing the
Carburetor 99
12.6.1 Metering Diaphragm 99
12.6.2 Inlet Needle 100
12.6.3 Pump Diaphragm 101
12.6.4 Lever on
Throttle Shaft 102
12.6.5 Levers on
Choke Shaft 102
12.6.6 Adjusting Screws 103
12.7 Adjusting the
Carburetor 105
12.7.1 Basic Setting 105
12.7.2 Standard Setting 107
12.8 Intake Manifold 108
12.8.1 Impulse Hose 109
12.9 Tank Vent 110
12.9.1 Testing 110
12.9.2 Tank Vent (MS 201) 111
12.9.3 Tank Vent
(MS 201 T) 112
12.10 Fuel Intake 112
12.10.1 Pickup Body 112
12.10.2 Fuel Suction Hose 112
12.10.3 Tank Vent Hose 114
12.10.4 Manual Fuel Pump
with Fuel Hoses 116
12.11 Tank Housing
Removing and
Installing 118
13. Special Servicing
Tools 120
14. Servicing Aids 122

3MS 201, MS 201 C, MS 201 T, MS 201 TC
1. Introduction and Safety Precautions
1.1 Introduction
This service manual contains
detailed descriptions of all the repair
and servicing procedures specific to
this power tool.
You should make use of the
illustrated parts lists while carrying
out repair work. They show the
installed positions of the individual
components and assemblies.
Refer to the latest edition of the
relevant parts list to check the part
numbers of any replacement parts.
A fault on the machine may have
several causes. To help locate the
fault, consult the chapter on
"Troubleshooting" and the
"STIHL Service Training System"
for all assemblies.
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 parts list until a
revised edition is issued.
The special tools mentioned in the
descriptions are listed in the chapter
on "Special Servicing Tools" in this
manual. Use the part numbers to
identify the tools in the
"STIHL Special Tools" manual. The
manual lists all special servicing
tools currently available from
STIHL.
Symbols are included in the text and
pictures for greater clarity.
The meanings are as follows:
In the descriptions:
: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:
APointer
aDirection of movement
@4.2 =Reference to another
chapter, i.e. chapter 4.2
in this example.
Service manuals and all technical
information bulletins are intended
exclusively for the use of properly
equipped repair shops. They must
not be passed to third parties.
Servicing and repairs are made
considerably easier if the machine
is mounted to assembly stand (3)
5910 890 3101. To do this, secure
the mounting plate (2)
5910 850 1650 to the assembly
stand with two screws (1) and
washers.
The screws must not project since
they, depending on the machine,
may damage housings when the
machine is clamped in position.
2710RA320 TG
2
3
1
Preparations for servicing
Remove the chain sprocket cover,
saw chain, guide bar and clutch
drum before carrying out repairs
– the chain brake must be
disengaged.
Mount the machine to the assembly
stand for servicing and repair work.
Engage the bar mounting stud in the
outer bore in the mounting plate and
secure the machine in position with
the M 8 nut (arrow).
The machine is held in position on
the mounting plate by the screw
head on the crankcase.
Always use original STIHL
replacement parts.
They can be identified by the STIHL
part number,
the {
logo and the
STIHL parts symbol K. This
symbol may appear alone on small
parts.
Storing and disposing of oils and
fuels
Collect fuel or lubricating oil in a
clean container and dispose of it
properly in accordance with local
environmental regulations.
7013RA000 TG

4MS 201, MS 201 C, MS 201 T, MS 201 TC
1.2 Safety Precautions
If the machine is started up in the
course of repairs or maintenance
work, observe all local and country-
specific safety regulations as well
as the safety precautions and
warnings in the instruction manual.
Fuel is extremely flammable and
can be explosive in certain
conditions.
Do not smoke or bring any fire,
flame or other source of heat near
the fuel. All work with fuel must be
performed outdoors only. Spilled
fuel must be wiped away
immediately.
Always perform leakage test after
working on the fuel system and the
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.
Always wear suitable protective
gloves for operations in which
components are heated for
assembly or disassembly.
Improper handling may result in
burns or other serious injuries.
Always replace damaged parts.
Check disassembled parts for wear
or damage before re-installing –
replace as necessary.
Run the machine only with the fan
housing mounted in position – there
is otherwise a risk of injury from the
flywheel and a risk of engine
damage due to overheating.
The chapter on tightening torques
lists all machine components that
have to be tightened to a specific
torque or coated with threadlocking
adhesive. The specifications must
be maintained when tightening
down screws, nuts and other
fasteners in all the procedures
described in this service manual.
Fuel system – hose barb
connectors
Pull off or push on fuel hoses in line
with the connector, preferably by
hand, to ensure the tightness of the
fuel system.
Avoid damaging the hose barb
– do not use sharp-edged pliers,
screwdrivers, etc.
Do not cut open fuel hoses with a
knife or similar tool.
Do not re-use fuel hoses after
removal. Always install new hoses
– fuel hoses can be overstretched
during removal.
Install new fuel hoses either dry or
with the aid of STIHL press fluid
– coat the ends of hoses and the
connectors, b14.
Other press fluids are not approved
and may result in damage to the fuel
hoses.

5MS 201, MS 201 C, MS 201 T, MS 201 TC
2. Specifications
2.1 Engine
MS 201 MS 201 T
Displacement: 35.2 cm335.2 cm3
Bore: 40.0 mm 40.0 mm
Stroke: 28.0 mm 28.0 mm
Engine power to ISO 7293: 1.8 kW (2.4 bhp)
at 9,500 rpm
1.8 kW (2.4 bhp)
at 9,500 rpm
Cut-off speed
with bar and chain: 14000 rpm 14000 rpm
Idle speed: 3,000 rpm 3,000 rpm
Clutch: Centrifugal clutch without
linings
Centrifugal clutch without
linings
Clutch engages at: 3,700 rpm 3,700 rpm
Crankcase leakage test
at gauge pressure: 0.5 bar
under vacuum: 0.5 bar
2.2 Fuel System
Carburetor leakage test at gauge pressure: 0.8 bar 0.8 bar
Operation of tank vent at gauge pressure: 0.5 bar 0.5 bar
Fuel: as specified in instruction
manual
as specified in instruction
manual
2.3 Ignition System
Air gap between the ignition module and
flywheel: 0.30 (+ 0.05/- 0.10) mm 0.30 (+ 0.05/- 0.10) mm
Spark plug (resistor type): NGK CMR 6 H NGK CMR 6 H
Electrode gap: 0.5 mm 0.5 mm
2.4 Chain Lubrication
Speed-controlled oil pump with reciprocating piston and manual flow control or Ematic
Settings for oil delivery rate:
min.:
max.:
Ematic:
3.5 (+/1.0) cm3/min
at 7,000 rpm
9.5 (+/2.0) cm3/min
at 10,000 rpm
6.5 (+/1.5) cm3/min
at 10,000 rpm
3.5 (+/1.0) cm3/min
at 7,000 rpm
9.5 (+/2.0) cm3/min
at 10,000 rpm
6.5 (+/1.5) cm3/min
at 10,000 rpm

6MS 201, MS 201 C, MS 201 T, MS 201 TC
2.5 Tightening Torques
DG and P (Plastoform) screws are used in polymer and light metal components. These screws form a
permanent thread when they are installed for the first time. They can be removed and installed as often as
necessary without impairing the strength of the screwed assembly, providing the specified tightening torque is
observed.
For this reason it is essential to use a torque wrench.
Fastener Thread size For component Torque
Nm
Remarks
Screw M 4x12 Chain tensioner cover / crankcase 1.8 2) 4)
Screw M 4x16 Antivibration element on oil tank / crankcase 4.0 3)
Collar stud M 8 Collar stud for bar 22.0 1)
Screw P 4x14 Cover / chain sprocket cover 1.5
Screw M 4x12 Cover, oil pump / crankcase 2.0 2) 4)
Screw M 4x9.6 Spark arresting screen / muffler 2.0
Screw P 6x19 Handle housing / front handle (MS 201) 6.0
Screw P 6x19 Handle housing / front handle (MS 201 T) 3.5
Screw M 4x16 Handlebar / crankcase 4.0 3)
Screw P 4x14 Handle molding / handle housing 1.5
Screw P 6x19 Retainer, ring / tank housing 6.0
Screw P 4x10 Clamp, wiring harness / handle housing
(MS 201)
1.8
Screw P 4x10 Clamp, ignition lead 1.8
Screw M 5x16 Chain catcher / spiked bumper / crankcase 10.0 2) 4)
Screw M 5x16 Spiked bumper / crankcase 10.0 2) 4)
Screw M 4x12 Manifold / cylinder 3.0 2) 4)
Screw M 4x16 Crankcase, sprocket side/fan side 4.5 2) 4)
Screw P 5x16 Bearing plug / handle housing 3.0
Screw M 4x16 Fan housing / crankcase 4.0 2) 4)
Screw P 5x16 Fan housing / tank housing 4.0
Carrier M 8x1 L Carrier / crankshaft 25.0
Screw M 4x12 Oil pump / crankcase 3.5 2)
Screw P 5x29.5 Annular buffer / handle housing 3.0
Screw P 4x14 Annular buffer / tank housing 1.5
Screw P 4x10 Rewind spring retainer 1.5
Screw M 5x16 Muffler / cylinder, stage 1
(tightening first screw)
2.5 2) 3)
Screw M 5x16 Muffler / cylinder, stage 2
(tightening second screw)
10.0 2) 3)
Screw M 5x16 Muffler / cylinder, stage 3
(tightening first screw)
10.0 2) 3)
Collar stud M 5x18 Bar mounting / crankcase 7.0 2) 3)
Nut M 8x1 Flywheel / crankshaft 23.0 6)
Screw P 4x10 Insulating plate (MS 201) 1.5

7MS 201, MS 201 C, MS 201 T, MS 201 TC
Fastener Thread size For component Torque
Nm
Remarks
Screw M 4x16 Tank housing / crankcase 4.5 2) 4)
Screw M 5x43 Carburetor / handle housing, stage 1 0.8 5)
Screw M 5x43 Carburetor / handle housing, stage 2 3.0 5)
M 10x1 Spark plug / cylinder 12.0
Screw M 4x20 Ignition module / crankcase 4.0 3)
Screw M 5x20 Cylinder / crankcase 10.0 2) 4)
Remarks:
1) Loctite 272, high strength up to 250 °C (482 °F)
2) Screws with binding head
3) Micro-encapsulated screws
4) Waxed screws
5) Bright and waxed screws
6) Degrease crankshaft/flywheel and mount oil-free
Use the following procedure when refitting a DG or P screw in an existing thread:
Place the screw in the hole and rotate it counterclockwise until it drops down slightly.
Tighten the screw clockwise to the specified torque.
This procedure ensures that the screw engages properly in the existing thread and does not form a new thread
and weaken the assembly.
Before reinstalling a micro-encapsulated screw, clean both threads (screw tap into female thread by hand and
then blow out with compressed air, clean male thread with brush), coat clean screw with medium strength
Loctite 242 or 243.
Power screwdriver setting for polymer: DG and P screws max. 500 rpm
Do not use an impact wrench for releasing or tightening screws.
Do not mix up screws with and without binding heads.

8MS 201, MS 201 C, MS 201 T, MS 201 TC
3. Troubleshooting
3.1 Clutch
Condition Cause Remedy
Saw chain stops under full load Clutch shoes badly worn Install new clutch
Clutch drum badly worn Install new clutch drum
Saw chain rotates at idle speed Engine idle speed too high Readjust idle speed screw LA
Clutch springs stretched Replace the clutch springs or install
new clutch
Clutch springs broken Replace the clutch springs
Loud noises Clutch springs stretched Replace all clutch springs
Clutch shoe retainer broken Install new retainer or clutch
Clutch shoes and carrier worn Install new clutch
Needle cage damaged Fit new needle cage

9MS 201, MS 201 C, MS 201 T, MS 201 TC
3.2 Chain Drive, Chain Brake, Chain Tensioner
Condition 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 stops under full load Clutch shoes badly worn Install new clutch
Clutch drum badly worn Install new clutch drum
Brake band blocked Check freedom of movement and
operation of brake band
Saw chain rotates at idle speed Engine idle speed too high Readjust idle speed screw LA
Clutch springs stretched Replace the clutch springs or install
new clutch
Clutch springs broken Replace the clutch springs
Saw chain does not stop
immediately when brake is
activated
Brake spring stretched or broken Fit new brake spring
Brake band stretched or worn Fit new brake band
Clutch drum worn Install new clutch drum

10 MS 201, MS 201 C, MS 201 T, MS 201 TC
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.
.
Condition Cause Remedy
Chain receives no oil Oil inlet hole in guide bar is blocked Clean oil inlet hole
Intake hose or pickup body clogged
or intake hose ruptured
Fit new intake hose and pickup
body
Connector blocked Clean the connector or replace if
necessary.
Valve in oil tank blocked Clean or replace valve
Worm flanks or driver worn Install new worm
Oil pump damaged or worn Install new oil pump
Machine losing chain oil Oil pump damaged or worn Install new oil pump
Oil suction hose connection
damaged
Install new oil suction hose
Crankcase cracked Install new crankcase
Oil pump delivers insufficient oil Oil pump damaged or worn Install new oil pump
Worm driver is loose Install new worm

11MS 201, MS 201 C, MS 201 T, MS 201 TC
3.4 Rewind Starter
Condition Cause Remedy
Starter rope broken Rope pulled out too vigorously as
far as stop or over edge, i.e. not
vertically
Install new starter rope
Normal wear Install new starter rope
Starter rope does not rewind Rewind spring very dirty or
corroded
Clean or replace rewind spring
Insufficient spring tension Check rewind spring and increase
tension
Rewind spring broken Install new rewind spring
Starter rope cannot be pulled out
far enough
Spring overtensioned Check rewind spring and reduce
tension
Starter rope can be pulled out
almost without resistance
(crankshaft does not turn)
Spring fatigued Install new spring
Spring not installed properly Install spring properly
Models without ErgoStart
Guide peg on pawl or pawl itself is
worn
Replace pawl
Models with ErgoStart
Guide pegs on pawls or pawls
themselves are worn
Replace pawls
Spring loop not attached to carrier Attach spring loop to carrier
Spring (ErgoStart) broken Replace spring, check carrier and
rope rotor, replace if necessary

12 MS 201, MS 201 C, MS 201 T, MS 201 TC
Condition 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:
Lubricating oil on rewind spring
becomes viscous (spring windings
stick together) or moisture has got
onto the rewind spring (spring
windings frozen together)
Coat rewind spring with a small
amount of standard solvent-based
degreasant (containing no
chlorinated or halogenated
hydrocarbons), then pull rope
carefully several times until normal
action is restored

13MS 201, MS 201 C, MS 201 T, MS 201 TC
3.5 Ignition System
Condition 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 spark plug, replace if
necessary. If sooting continues,
check air filter
Fuel/oil mixture
– too much oil
Use correct mixture of fuel and oil
Incorrect air gap between ignition
module and flywheel
Set air gap correctly
Flywheel cracked or
damaged or pole shoes have
turned blue
Install new flywheel
Ignition timing wrong, flywheel out
of adjustment
– key in flywheel has sheared off
Install new flywheel
Weak magnetization in flywheel Install new flywheel
Irregular spark Check operation of switch shaft /
contact spring(s) and ignition
module.
Check ignition lead and short circuit
wire for damaged insulation or
break.
Check ignition lead / module,
replace ignition module if
necessary. Check operation of
spark plug, clean or replace spark
plug if necessary.
Crankcase damaged (cracks) Install new crankcase

14 MS 201, MS 201 C, MS 201 T, MS 201 TC
3.6 Carburetor
Condition Cause Remedy
Carburetor floods; engine stalls Inlet needle not sealing
– foreign matter in valve seat or
cone
Remove and clean the inlet needle,
clean the carburetor
Inlet needle worn Fit new inlet needle
Inlet control lever sticking on
spindle
Check the inlet control lever and
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
Fit new metering diaphragm
Metering diaphragm warped,
hardened or swollen
Fit new metering diaphragm
Poor acceleration Setting of low speed screw (L) too
lean
Check basic setting, correct if
necessary
Setting of high speed screw (H) too
lean
Check basic setting, correct if
necessary
Inlet needle sticking to valve seat Remove and clean inlet needle
Diaphragm gasket leaking Fit new diaphragm gasket
Metering diaphragm damaged,
hardened or swollen
Fit new metering diaphragm
Tank vent faulty Fit new tank vent
Leak in fuel hose from tank to
carburetor
Seal connections or install new fuel
hose

15MS 201, MS 201 C, MS 201 T, MS 201 TC
Condition Cause Remedy
Engine will not idle, idle speed too
high
Throttle shutter opened too wide by
idle speed screw (LA)
Reset idle speed screw (LA)
correctly
Oil seals/crankcase leaking Seal oil seals / crankcase, replace if
necessary
Throttle shutter does not close Install new carburetor
Engine stops while idling Idle jet bores
or ports blocked
Clean the carburetor
Setting of low speed screw (L) too
rich or too lean
Reset low speed screw (L) correctly
Setting of idle speed screw LA
incorrect – throttle shutter
completely closed
Reset idle speed screw (LA)
correctly
Tank vent faulty Fit new tank vent
Leak in fuel hose from tank to
carburetor
Seal connections or install new fuel
hose
Saw chain rotates at idle speed Engine idle speed too high Readjust with idle speed screw
LA (counterclockwise)
Clutch springs stretched or fatigued Replace the clutch springs or install
new clutch
Clutch spring hooks broken Replace the clutch springs
Power tool smells of fuel or loses
fuel
Fuel hoses leaking or damaged Check fuel hoses, push fully onto
connectors or replace if necessary
Fuel tank damaged Install new fuel tank
Pump diaphragm, metering
diaphragm or diaphragm gasket
faulty
Replace pump diaphragm,
metering diaphragm or diaphragm
gasket

16 MS 201, MS 201 C, MS 201 T, MS 201 TC
Condition Cause Remedy
Engine speed drops quickly under
load – low power
Air filter dirty Clean air filter or replace if
necessary
Throttle shutter not opened fully Check throttle rod
Tank vent faulty Fit new tank vent
Fuel pickup body dirty Fit new pickup body
Fuel strainer dirty Clean fuel strainer in carburetor,
replace if necessary
Leak in fuel hose from tank to
carburetor
Seal connections or install new fuel
hose
Setting of high speed screw (H) too
rich
Check basic setting, correct if
necessary
Main jet bores or ports blocked Clean the carburetor
Pump diaphragm damaged or
fatigued
Fit new pump diaphragm
Ignition timing wrong, flywheel out
of adjustment
– key in flywheel has sheared off
Install new flywheel
Engine running extremely rich, has
no power and a very low maximum
speed
Choke shutter does not open Check carburetor and choke shaft,
service or replace if necessary

17MS 201, MS 201 C, MS 201 T, MS 201 TC
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
Condition Cause Remedy
Engine does not start easily, stalls
at idle speed, but operates normally
at full throttle
Oil seals in engine damaged Replace the oil seals
Crankcase leaking or damaged
(cracks)
Inspect crankcase, re-seal or
replace if necessary.
Intake manifold damaged / bore
blocked
Clean bore or install new manifold
Engine does not deliver full power
or runs erratically
Piston rings worn or broken Install new piston rings
Muffler / spark arresting screen
carbonized
Clean the muffler (inlet and
exhaust), replace spark arresting
screen, replace muffler if necessary
Air filter dirty Clean or replace air filter
Fuel hose kinked or cracked Fit new hose or position it free from
kinks
Intake manifold damaged / bore
blocked
Clean bore or install new manifold
Engine overheating Insufficient cylinder cooling. Air
inlets in fan housing blocked or
cooling fins on cylinder very dirty
Thoroughly clean all cooling air
openings and the cylinder fins
Air inlet in fan housing dirty Clean air inlet on fan housing

18 MS 201, MS 201 C, MS 201 T, MS 201 TC
4. Clutch
4.1 Clutch
– Troubleshooting, b3.1
– Disengage the chain brake and
remove the chain sprocket cover,
bar and chain.
:Pull boot (1) off the spark plug.
– Unscrew the spark plug.
:Push the locking strip (1)
1145 893 5900 into the cylinder
as far as stop.
7013RA001 TG
1
7013RA521 TG
1
:Secure the locking strip (1)
1145 893 5900 to cylinder fin
(arrow).
– Turn the clutch clockwise until the
piston butts against the locking
strip.
The locking strip (1) 1145 893 5900
must butt against the cylinder wall
(arrow) and the flat side of its metal
top must rest on the piston crown
– as shown in the illustration.
:Apply wrench to hexagon (arrow)
and unscrew the clutch (1) – left-
hand thread.
7013RA522 TG
1
7013RA003 TG
1
7013RA004 TG
1
Installing
:Position the clutch (1) on the
crankshaft stub so that the raised
hexagon (arrow) faces outwards.
:Fit the clutch (1) and tighten it
down firmly – left-hand thread.
– Remove the locking strip from the
cylinder.
– Reassemble all other parts in the
reverse sequence.
7013RA005 TG
1

19MS 201, MS 201 C, MS 201 T, MS 201 TC
4.2 Clutch Drum
– Disengage the chain brake and
remove the chain sprocket cover,
bar and chain.
– Remove the clutch, b4.1
:Pull off the clutch drum (1).
– Remove the needle cage.
– Clean the needle cage and
crankshaft stub, b14
– Lubricate needle cage and
crankshaft stub with STIHL
multipurpose grease, b14
7013RA006 TG
1
– Inspect the clutch drum (1) for
signs of wear.
If there are signs of serious wear on
the inside diameter of the clutch
drum (1), check the remaining wall
thickness. If it is less than about
80% of the original thickness, install
a new clutch drum.
Installing
– Push the needle cage on to the
crankshaft stub.
:Fit the clutch drum (1) so that it
engages the worm gear (arrow).
– Install the clutch, b4.1
– Reassemble all other parts in the
reverse sequence.
!
80%
100%
5902RA018 TG
1
7013RA007 TG
1