Stihl KM 55 R User manual

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STIHL KM 55 R Instruction Manual
Notice d’emploi

GInstruction Manual
1 - 23
FNotice d’emploi
24 - 49

Original Instruction ManualPrinted on chlorine-free paper
Printing inks contain vegetable oils, paper can be recycled.
© ANDREAS STIHL AG & Co. KG, 2011 0458-461-8221-A. VA2.K11. 0000001981_004_GB
KM 55 R, KM 55 RC
English
1
{
Contents
Dear Customer,
Thank you for choosing a quality
engineered STIHL product.
This machine has been built using
modern production techniques and
comprehensive quality assurance.
Every effort has been made to ensure
your satisfaction and troublefree use of
the machine.
Please contact your dealer or our sales
company if you have any queries
concerning your machine.
Your
Hans Peter Stihl
KombiSystem 2
Guide to Using this Manual 2
Safety Precautions and Working
Techniques 2
Approved KombiTools 7
Mounting the Loop Handle 8
Fuel 9
Fueling 10
Starting / Stopping the Engine 10
Operating Instructions 12
Cleaning the Air Filter 13
Engine Management 13
Adjusting the Carburetor 14
Spark Plug 15
Engine Running Behavior 16
Rewind Starter 16
Storing the Machine 17
Inspections and Maintenance by
Dealer 17
Maintenance and Care 18
Main Parts 19
Specifications 20
Special Accessories 21
Maintenance and Repairs 21
STIHL Limited Emission Control
Warranty Statement 22

KM 55 R, KM 55 RC
English
2
In the STIHL KombiSystem a number of
different KombiEngines and KombiTools
can be combined to produce a power
tool. In this instruction manual the
functional unit formed by the
KombiEngine and KombiTools is
referred to as the power tool.
Therefore, the separate instruction
manuals for the KombiEngine and
KombiTool should be used together for
the power tool.
Always read and and make sure you
understand both instruction manuals
before using your power tool for the first
time and keep them in a safe place for
future reference.
Pictograms
All the pictograms attached to the
machine are shown and explained in this
manual.
Symbols in text
Warning where there is a risk of an
accident or personal injury or serious
damage to property.
Caution where there is a risk of
damaging the machine or its individual
components.
Engineering improvements
STIHL's philosophy is to continually
improve all of its products. For this
reason we may modify the design,
engineering and appearance of our
products periodically.
Therefore, some changes, modifications
and improvements may not be covered
in this manual.
Observe all application local safety
regulations, standards and ordinances.
If you have not used this type of power
tool before: Have your dealer or other
experienced user show you how to
operate your power tool or attend a
special course in its operation.
Minors should never be allowed to use a
power tool.
Keep bystanders, especially children,
and animals away from the work area.
When the power tool is not in use, shut it
off so that it does not endanger others.
Secure it against unauthorized use.
The user is responsible for avoiding
injury to third parties or damage to their
property.
KombiSystem
.
.
.
.
002BA442 KN
+
+
Guide to Using this Manual Safety Precautions and
Working Techniques
Special safety precau-
tions must be observed
when working with a
power tool.
Always read and and
make sure you under-
stand both instruction
manuals (KombiEngine
and KombiTool) before
using your power tool for
the first time and keep
them in a safe place for
future reference. Non-
observance of the safety
precautions may result in
serious or even fatal
injury.

KM 55 R, KM 55 RC
English
3
Lend or rent your machine only to
persons who are familiar with this model
and its operation – do not lend of rent
your machine without the KombiEngine
and KombiTool instruction manuals.
The use of noise emitting power tools
may be restricted to certain times by
national or local regulations.
To operate the power tool you must be
rested, in good physical condition and
mental health.
If you have any condition that might be
aggravated by strenuous work, check
with your doctor before operating a
power tool.
Persons with pacemakers only: The
ignition system of your power tool
produces an electromagnetic field of a
very low intensity. This field may
interfere with some pacemakers. STIHL
recommends that persons with
pacemakers consult their physician and
the pacemaker manufacturer to reduce
any health risk.
Do not operate the power tool if you are
under the influence of any substance
(drugs, alcohol) which might impair
vision, dexterity or judgment.
Use your power tool only for the
applications described in the instruction
manual of the KombiTool you are using.
Do not use your power tool for any other
purpose because of the increased risk of
accidents.
Do not operate the KombiEngine without
a properly mounted KombiTool since
this may result in damage to the
machine.
Only use KombiTools and accessories
that are explicity approved for this power
tool by STIHL or are technically
identical. It is important that you read the
chapter on "Approved KombiTools". If
you have any questions in this respect,
consult a servicing dealer. Use only high
quality parts and accessories in order to
avoid the risk of accidents and damage
to the machine.
STIHL recommends the use of original
STIHL replacement parts. They are
specifically designed to match your
model and meet your performance
requirements.
Never attempt to modify your power tool
in any way since this may increase the
risk of personal injury. STIHL excludes
all liability for personal injury and
damage to property caused while using
unauthorized attachments.
Do not use a pressure washer to clean
your power tool. The solid jet of water
may damage parts of the power tool.
Clothing and Equipment
Wear proper protective clothing and
equipment.
See also notes on "Clothing and
Equipment" in the instruction manual of
the KombiTool you are using.
Transporting the Power Tool
Always turn off the engine.
Transporting in a vehicle: Properly
secure your power tool to prevent
turnover, fuel spillage and damage.
See also notes on "Transporting the
Machine" in the instruction manual of the
KombiTool you are using.
Fueling
Always shut off the engine before
refueling.
Do not fuel a hot engine – fuel may spill
and cause a fire.
Open the fuel cap carefully to allow any
pressure build-up in the tank to release
slowly and avoid fuel spillage.
Fuel your power tool only in well-
ventilated areas. If you spill fuel, wipe
the machine immediately – if fuel gets on
your clothing, change immediately.
Avoid clothing that could
get caught on branches
or brush or moving parts
of the machine. Do not
wear a scarf, necktie or
jewelry. Tie up and con-
fine long hair (e.g. with a
hair net, cap, hard hat,
etc.).
Gasoline is an extremely
flammable fuel. Keep
clear of naked flames. Do
not spill any fuel – do not
smoke.

KM 55 R, KM 55 RC
English
4
Your power tool comes standard with
either a screw-type or bayonet-type fuel
cap. After fueling,
This reduces the risk of unit vibrations
causing the fuel cap to loosen or come
off and spill quantities of fuel.
To reduce the risk of serious or fatal
burn injuries, check for fuel leakage. If
fuel leakage is found, do not start or run
the engine until leak is fixed.
Before Starting
Check that your power tool is properly
assembled and in good condition – refer
to appropriate chapters in the instruction
manuals.
–Use only an approved combination
of cutting attachment, deflector,
handle and harness. All parts must
be assembled properly and
securely.
–Slide control / stop switch must
move easily to STOP or 0
–Smooth action of throttle trigger
lockout and throttle trigger – the
throttle trigger must return
automatically to the idle position.
–Check that the spark plug boot is
secure – a loose boot may cause
arcing that could ignite combustible
fumes and cause a fire.
–Never attempt to modify the controls
or safety devices in any way.
–Keep the handles dry and clean –
free from oil and dirt – for safe
control of the power tool.
–Adjust harness and handle to suit
your height and reach.
To reduce the risk of personal injury, do
not operate your power tool if it is
damaged or not properly assembled.
If you use a shoulder strap or full
harness: Practice removing and putting
down the machine as you would in an
emergency. To avoid damage, do not
throw the machine to the ground when
practicing.
See also notes on "Before Starting" in
the instruction manual of the KombiTool
you are using.
Starting the Engine
Start the engine at least 3 meters from
the fueling spot, outdoors only.
Place the unit on firm ground in an open
area. Make sure you have good balance
and secure footing. Hold the unit
securely. The working tool must be clear
of the ground and all other obstructions
because it may begin to run when the
engine starts.
To reduce the risk of injury, avoid
contact with the attachment.
Do not drop start the power tool – start
the engine as described in the
instruction manual. Note that the
attachment continues to run for a short
period after you let go of the throttle
trigger – flywheel effect.
Check idle speed setting: The
attachment must be stationary when the
engine is idling with the throttle trigger
released.
To reduce the risk of fire, keep hot
exhaust gases and hot muffler away
from easily combustible materials (e.g.
wood chips, bark, dry grass, fuel).
See also notes on "Starting / Stopping
the Engine" in the instruction manual of
the KombiTool you are using.
Holding and Controlling the Power Tool
Always hold the power tool firmly with
both hands on the handles.
Make sure you always have good
balance and secure footing.
Left hand on loop handle, right hand on
control handle, even if you are left-
handed.
tighten down the screw-
type fuel cap as securely
as possible.
Insert the fuel cap with
hinged grip (bayonet-type
cap) correctly in the
opening, turn it clockwise
as far as stop and fold the
grip down.
002BA273 KN

KM 55 R, KM 55 RC
English
5
During Operation
In the event of impending danger or in
an emergency, switch off the engine
immediately by moving the slide control
/ stop switch to STOP or 0.
The correct engine idle speed is
important to ensure that the attachment
stops moving when you let go of the
throttle trigger. If the working tool
continues to move when the engine is
idling, have your dealer check the
machine and make proper adjustments
or repairs. Check and correct the idle
speed setting at regular intervals. STIHL
recommends you have this work done
by a STIHL servicing dealer.
Be particularly alert and cautious when
wearing hearing protection because
your ability to hear warnings (shouts,
alarms, etc.) is restricted.
To reduce the risk of accidents, take a
break in good time to avoid tiredness or
exhaustion.
Work calmly and carefully – in daylight
conditions and only when visibility is
good. Stay alert so as not to endanger
others.
Use your power tool only for those
applications described in the KombiTool
instruction manual.
To reduce the risk of serious or fatal
injury from breathing toxic fumes,
ensure proper ventilation when working
in trenches, hollows or other confined
locations.
To reduce the risk of accidents, stop
work immediately in the event of
nausea, headache, visual disturbances
(e.g. reduced field of vision), problems
with hearing, dizziness, deterioration in
ability to concentrate. Apart from other
possibilities, these symptoms may be
caused by an excessively high
concentration of exhaust gases in the
work area.
Operate your power tool so that it
produces a minimum of noise and
emissions – do not run the engine
unnecessarily, accelerate the engine
only when working.
To reduce the risk of fire, do not smoke
while operating or standing near your
power tool. Note that combustible fuel
vapor may escape from the fuel system.
The dusts, vapor and smoke produced
during operation may be dangerous to
health. Wear a suitable respirator in very
dusty or smoky conditions.
If your power tool is subjected to
unusually high loads for which it was not
designed (e.g. heavy impact or a fall),
always check that it is in good condition
before continuing work – see also
"Before Starting". Check the fuel system
in particular for leaks and make sure the
safety devices are working properly. Do
not continue operating your power tool if
it is damaged. In case of doubt, have the
unit checked by your servicing dealer.
Do not operate your power tool in the
starting throttle position – engine speed
cannot be controlled in this position.
Before leaving the power tool
unattended: Shut off the engine.
To reduce the risk of injury, always shut
off the engine before changing the
KombiTool or working tool.
Vibrations
Prolonged use of the power tool may
result in vibration-induced circulation
problems in the hands (whitefinger
disease).
No general recommendation can be
given for the length of usage because it
depends on several factors.
The period of usage is prolonged by:
–Hand protection (wearing warm
gloves)
–Work breaks
Your power tool produces
toxic exhaust fumes as
soon as the engine is
running. These fumes
may be colorless and
odorless and contain
unburned hydrocarbons
and benzol. Never run
the engine indoors or in
poorly ventilated loca-
tions, even if your model
is equipped with a cata-
lytic converter.

KM 55 R, KM 55 RC
English
6
The period of usage is shortened by:
–Any personal tendency to suffer
from poor circulation (symptoms:
frequently cold fingers, tingling
sensations).
–Low outside temperatures.
–The force with which the handles
are held (a tight grip restricts
circulation).
Continual and regular users should
monitor closely the condition of their
hands and fingers. If any of the above
symptoms appear (e.g. tingling
sensation in fingers), seek medical
advice.
Maintenance and Repairs
Service the machine regularly. Do not
attempt any maintenance or repair work
not described in the instruction manual.
Have all other work performed by a
servicing dealer.
STIHL recommends that you have
servicing and repair work carried out
exclusively by an authorized STIHL
servicing dealer. STIHL dealers are
regularly given the opportunity to attend
training courses and are supplied with
the necessary technical information.
Only use high-quality replacement parts
in order to avoid the risk of accidents
and damage to the machine. If you have
any questions in this respect, consult a
servicing dealer.
STIHL recommends the use of original
STIHL replacement parts. They are
specifically designed to match your
model and meet your performance
requirements.
To reduce the risk of injury, always shut
off the engine before carrying out any
maintenance or repairs or cleaning the
machine. – Exception: Carburetor and
idle speed adjustments.
Do not turn the engine over on the
starter with the spark plug boot or spark
plug removed unless the slide control /
stop switch is on STOP or 0 since there
is otherwise a risk of fire from
uncontained sparking.
To reduce the risk of fire, do not service
or store your machine near open flames.
Check the fuel filler cap for leaks at
regular intervals.
Use only a spark plug of the type
approved by STIHL and make sure it is
in good condition – see "Specifications".
Inspect the ignition lead (insulation in
good condition, secure connection).
Check the condition of the muffler.
To reduce the risk of fire and damage to
hearing, do not operate your machine if
the muffler is damaged or missing. –
Do not touch a hot muffler since burn
injury will result.
Vibration behavior is influenced by the
condition of the AV elements – check the
AV elements at regular intervals.
Maintenance, replacement, or repair of
the emission control devices and
systems may be performed by any
nonroad engine repair establishment or
individual. However, if you make a
warranty claim for a component which
has not been serviced or maintained
properly or if nonapproved replacement
parts were used, STIHL may deny
coverage.
For any maintenance please refer to the
maintenance chart and to the warranty
statement near the end of the instruction
manual.

KM 55 R, KM 55 RC
English
7
The following STIHL KombiTools may
be mounted on the KombiEngine:
The barrier bar supplied with the
machine must be mounted to the loop
handle – see also "Mounting the Loop
Handle".
Approved KombiTools
HT-KM
BF-KM
470BA018 KN
FCS-KM
FCB-KM
KW-KM
KB-KM
FH-KM
FS-KM FS-KM
FSB-KM BG-KM
KombiTool Purpose
FS-KM Brushcutter with
mowing head
FS-KM Brushcutter with
grass cutting blade
FSB-KM Brushcutter with
mowing head
HL-KM 135° Hedge trimmer,
adjustable
HL-KM 0° Hedge trimmer
FH-KM 135° Power scythe
BG-KM Blower
HT-KM Pole pruner
BF-KM Pick tines
FCB-KM Power edger
FCS-KM Power edger
KB-KM Bristle brush
KW-KM PowerSweep

KM 55 R, KM 55 RC
English
8
A barrier bar is supplied with the
machine. Attach the barrier bar to the
loop handle.
NInsert square nuts (1) in the barrier
bar (2) – the holes must line up
NInsert the clamp (3) in the loop
handle (4) and position them
together on the shaft (5)
NPosition clamp (6)
NPosition barrier bar (2) – note
position!
NLine up the holes
NInsert bolts (7) in the holes – and
screw them into the barrier bar as
far as possible
NFit the loop handle (4) at a distance
of (A) approx. 20 cm (8 in) forward
of the control handle (8)
NOrient the loop handle
NTighten the bolts – lock the nuts if
necessary
The sleeve (9) is present depending on
the country and must be located
between the loop handle and control
handle.
Always leave the barrier bar attached.
Mounting the Loop Handle
2
002BA098 KN
1
1
5
4
002BA099 KN
2
3
67
A
9
8
4
002BA353 KN

KM 55 R, KM 55 RC
English
9
This engine is certified to operate on
unleaded gasoline and with the mix ratio
50:1.
Your engine requires a mixture of high-
quality premium gasoline and high-
quality two-stroke air-cooled engine oil.
Use premium branded unleaded
gasoline with a minimum octane rating
of 89 RON.
Note: Models equipped with a catalytic
converter require unleaded gasoline. A
few tankfuls of leaded gasoline can
reduce the efficiency of the catalytic
converter by more than 50%.
Fuel with a lower octane rating may
result in preignition (causing "pinging")
which is accompanied by an increase in
engine temperature. This, in turn,
increases the risk of the piston seizure
and damage to the engine.
The chemical composition of the fuel is
also important. Some fuel additives not
only detrimentally affect elastomers
(carburetor diaphragms, oil seals, fuel
lines etc.), but magnesium castings as
well. This could cause running problems
or even damage the engine. For this
reason it is essential that you use only
high-quality fuels!
Fuels with different percentages of
ethanol are being offered. Ethanol can
affect the running behaviour of the
engine and increase the risk of lean
seizure.
Gasoline with an ethanol content of
more than 10% can cause running
problems and major damage in engines
with a manually adjustable carburetor
and should not be used in such engines.
Engines equipped with M-Tronic can be
run on gasoline with an ethanol content
of up to 25% (E25).
Use only STIHL two-stroke engine oil or
equivalent high-quality two-stroke air-
cooled engine oils for mixing.
We recommend STIHL 50:1 two-stroke
engine oil since it is specially formulated
for use in STIHL engines.
Do not use BIA or TCW (two-stroke
water cooled) mix oils!
Use only STIHL 50:1 heavy-duty engine
oil or an equivalent quality two-stroke
engine oil for the fuel mix in models
equipped with a catalytic converter.
Take care when handling gasoline.
Avoid direct contact with the skin and
avoid inhaling fuel vapour.
The canister should be kept tightly
closed in order to avoid any moisture
getting into the mixture.
The fuel tank and the canister in which
fuel mix is stored should be cleaned
from time to time.
Fuel mix ratio
Only mix sufficient fuel for a few days
work, not to exceed 3 months of storage.
Store in approved safety fuel-canisters
only. When mixing, pour oil into the
canister first, and then add gasoline.
Dispose of empty mixing-oil canisters
only at authorized disposal locations.
Fuel Examples
Gasoline Oil (STIHL 50:1 or equiva-
lent high-quality oils)
liters liters (ml)
1 0.02 (20)
5 0.10 (100)
10 0.20 (200)
15 0.30 (300)
20 0.40 (400)
25 0.50 (500)

KM 55 R, KM 55 RC
English
10
Before fueling, clean the filler cap and
the area around it to ensure that no dirt
falls into the tank.
Always thoroughly shake the mixture in
the canister before fueling your
machine.
In order to reduce the risk of fire and
personal injury from escaping gas vapor
and fumes, remove the fuel filler cap
carefully so as to allow any pressure
build-up in the tank to release slowly.
After fueling, tighten fuel cap as securely
as possible by hand.
Controls
1Stop switch
2Throttle trigger lockout
3Throttle lever
4Tongue of throttle trigger
5Catch
Positions of stop switch
6I – normal run position – the engine
is running or can start
70 – engine off – the ignition is
switched off
Starting
NMove the stop switch to I.
NPress down the throttle trigger
lockout and hold it there.
NSqueeze the throttle trigger until the
catch on the tongue (4) can be
engaged on the housing.
NNow release the throttle trigger,
tongue and trigger lockout in that
order. This is the starting throttle
position.
Fueling
232BA046 KN
Starting / Stopping the
Engine
2
233BA048 KN
16 7
54
3
233BA049 KN
4

KM 55 R, KM 55 RC
English
11
NSet the choke lever (8) to
NPress the fuel pump bulb (9) at least
five times – even if the bulb is
already filled with fuel.
Starting
NPlace the unit on the ground: Check
that the working tool is not touching
the ground or any other obstacles –
see also "Starting / Stopping the
Engine" in the KombiTool
instruction manual.
NMake sure you have a safe and
secure footing.
NHold the unit with your left hand and
press it down firmly – your thumb
should be under the fan housing.
Do not stand or kneel on the drive tube.
NHold the starter grip with your right
hand.
Version without Easy2Start
NPull the starter grip slowly until you
feel it engage and then give it a brisk
strong pull.
Do not pull out the starter rope all the
way – it might otherwise break.
Version with Easy2Start
NPull the starter grip slowly until you
feel it engage and then pull it out
slowly and steadily.
Do not pull out the starter rope all the
way – it might otherwise break.
gif the engine is cold
efor warm start – also use this posi-
tion if the engine has been running
but is still cold.
9
8
232BA011 KN
232BA012 KN
233BA014 KN
232BA014 KN

KM 55 R, KM 55 RC
English
12
Both versions
NDo not let the starter grip snap back.
Guide it slowly back into the housing
so that the starter rope can rewind
properly.
NCrank the engine until it fires – after
no more than five pulls, move the
choke lever (8) to e.
NContinue cranking.
As soon as the engine runs
NSqueeze the throttle trigger to
disengage the tongue – the engine
will settle down to idle speed.
Your machine is now ready for
operation.
Make sure the carburetor is correctly
adjusted. The working tool must not
move when the engine is idling.
Stopping the engine
NMove the stop switch to 0.
If the engine does not start
If you did not move the choke lever to e
quickly enough after the engine began to
fire, the combustion chamber is flooded.
NSet the choke lever to e .
NSet the stop switch, lockout lever
and throttle trigger to the starting
throttle position.
NStart the engine by pulling the
starter rope briskly – 10 to 20 pulls
may be necessary.
If the engine still does not start
NMove the stop switch to 0.
NRemove the spark plug – see
"Spark Plug".
NDry the spark plug.
NCrank the engine several times with
the starter to clear the combustion
chamber.
NRefit the spark plug – see "Spark
Plug".
NMove the stop switch to I.
NSet the choke lever to e – even if
the engine is cold.
NNow start the engine.
Fuel tank run until completely dry
NAfter refueling, press the fuel pump
bulb at least five times – even if the
bulb is filled with fuel.
NStart the engine.
During break-in period
A factory-new machine should not be
run at high revs (full throttle off load) for
the first three tank fillings. This avoids
unnecessary high loads during the
break-in period. As all moving parts
have to bed in during the break-in
period, the frictional resistances in the
engine are greater during this period.
The engine develops its maximum
power after about 5 to 15 tank fillings.
During Operation
After a long period of full throttle
operation, allow the engine to run for a
short while at idle speed so that engine
heat can be dissipated by the flow of
cooling air. This protects engine-
mounted components (ignition,
carburetor) from thermal overload.
After Finishing Work
Storing for a short period: Wait for the
engine to cool down. Empty the fuel tank
and keep the machine in a dry place,
well away from sources of ignition, until
you need it again. For longer out-of-
service periods – see "Storing the
Machine".
8
232TI015 KN
Operating Instructions

KM 55 R, KM 55 RC
English
13
If there is a noticeable loss of engine
power
NSet the choke lever to g.
NPress in the tab (1) and swing the
filter cover (2) down.
NClean away loose dirt from around
the filter.
NRemove the felt element (3) from
the filter housing (4) and replace it –
knock out or blow out as a
temporary measure – do not wash.
NReplace damaged parts.
NFit the felt element (3) in the filter
housing (4).
NClose the filter cover so that it snaps
into position.
Exhaust emissions are controlled by the
design of the fundamental engine
parameters and components (e.g.
carburation, ignition, timing and valve or
port timing) without the addition of any
major hardware.
Cleaning the Air Filter
232BA017 KN
1
2
232BA018 KN
4
3
Engine Management

KM 55 R, KM 55 RC
English
14
The carburetor comes from the factory
with a standard setting.
This setting provides an optimum fuel-air
mixture under most operating
conditions.
With this carburetor it is only possible to
adjust the high speed screw within fine
limits.
Standard Setting
NStopping the Engine
NMount the KombiTool complete with
working tool or cutting attachment.
NCheck the air filter and replace it if
necessary.
NHave the spark arresting screen in
the muffler checked (not all
markets) – see “Inspection and
Maintenance by Dealer"
NTurn high speed screw (H)
counterclockwise as far as stop (no
more than 3/4 turn).
NTurn the low speed screw (L)
carefully clockwise as far as stop,
then turn it back 1.5 turns.
NStart and warm up the engine.
NAdjust idle speed with the idle speed
screw (LA) so that the cutting
attachment does not move.
Fine Tuning for Operation in Mountains
or at Sea Level
A slight correction of the setting of the
high speed screw (H) may be necessary
if engine power is not satisfactory when
operating at high altitude or at sea level.
NCarry out the standard setting.
NWarm up the engine for about
3 minutes at full throttle.
Rule of thumb:
Turn the high speed screw (H) about
one quarter of a turn for every 1000 m
(3300 ft) change in altitude.
At high altitude
NTurn high speed screw (H)
clockwise (leaner) – no further than
stop.
At sea level
NTurn high speed screw (H)
counterclockwise (richer) – no
further than stop.
It is possible that maximum engine
speed may be reached with the standard
setting in each case.
Aadjusting Idle Speed
It is usually necessary to change the
setting of the idle speed screw (LA) after
every correction to the low speed
screw (L).
NWarm up the engine for about 3
minutes.
Engine stops while idling
NTurn the idle speed screw (LA)
slowly clockwise until the engine
runs smoothly – the working tool or
cutting attachment must not move.
Cutting attachment runs when engine is
idling
NTurn the idle speed screw (LA)
counterclockwise until the working
tool or cutting attachment stops
Adjusting the Carburetor
L
H
LA
233BA050 KN

KM 55 R, KM 55 RC
English
15
moving and then rotate the screw
another 1/2 to 1 turn in the same
direction.
If the working tool or cutting attachment
continues to run when the engine is
idling, have your machine checked and
repaired by your servicing dealer.
Erratic idling behavior, engine stops
even though setting of LA-screw has
been corrected, poor acceleration
Idle setting is too lean:
NIdle setting is too lean: Rotate the
low speed screw (L) about 1/4 turn
counterclockwise until the engine
runs and accelerates smoothly.
Erratic idling behavior
Idle setting is too rich
NRotate the low speed screw (L)
about 1/4 turn clockwise until the
engine runs and accelerates
smoothly.
NIf the engine is down on power,
difficult to start or runs poorly at idle
speed, first check the spark plug.
NFit a new spark plug after about 100
operating hours – or sooner if the
electrodes are badly eroded. Install
only suppressed spark plugs of the
type approved by STIHL – see
"Specifications".
Removing the Spark Plug
NMove the stop switch to 0.
NPull off the spark plug boot (1).
NUnscrew the spark plug.
Checking the spark plug
NClean dirty spark plug.
NCheck electrode gap (A) and
readjust if necessary – see
"Specifications".
NRectify the problems which have
caused fouling of the spark plug.
Possible causes are:
–Too much oil in fuel mix.
–Dirty air filter.
–Unfavorable running conditions.
If the spark plug comes with a
detachable adapter nut (1), screw the
adapter onto the thread and tighten it
down firmly to reduce the risk of arcing
and fire.
Spark Plug
1
232BA081 KN
000BA039 KN
A
1
000BA045 KN

KM 55 R, KM 55 RC
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Installing the spark plug
NScrew home the spark plug, fit the
boot and press it down firmly. If engine running behavior is
unsatisfactory even though the air filter
is clean and the carburetor is properly
adjusted, the cause may be the muffler.
Have the muffler checked for
contamination (carbonization) by your
servicing dealer.
STIHL recommends that you have
servicing and repair work carried out
exclusively by an authorized STIHL
servicing dealer.
To help prolong the wear life of the
starter rope, observe the following
points:
NPull the starter rope only in the
direction specified.
NDo not pull the rope over the edge of
the guide bushing.
NDo not pull out the rope more than
specified.
NDo not allow the starter grip to snap
back, guide it back into the housing
slowly – see chapter on "Starting /
Stopping the Engine."
Have a damaged starter rope replaced
by your dealer before it breaks
completely. STIHL recommends that
you have servicing and repair work
carried out exclusively by an authorized
STIHL servicing dealer.
Engine Running Behavior Rewind Starter

KM 55 R, KM 55 RC
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For periods of 3 months or longer
NDrain and clean the fuel tank in a
well ventilated area.
NDispose of fuel properly in
accordance with local
environmental requirements.
NRun the engine until the carburetor
is dry – this helps prevent the
carburetor diaphragms sticking
together.
NThoroughly clean the machine – pay
special attention to the cylinder fins
and air filter.
NRemove, clean and inspect the
working tool.
NStore the machine in a dry, high or
locked location, out of the reach of
children and other unauthorized
persons.
Maintenance Work
STIHL recommends that you have
servicing and repair work carried out
exclusively by an authorized STIHL
servicing dealer.
Fuel Pickup Body in Tank
NHave the pickup body in the fuel
tank replaced every year.
Spark Arrestor in Muffler
NIf the engine is low on power, have
your dealer check the spark arrestor
(country-specific option) in the
muffler.
Storing the Machine Inspections and Maintenance
by Dealer

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Maintenance and Care
The following intervals apply to normal operating conditions only. If your daily work-
ing time is longer or operating conditions are difficult (very dusty work area, etc.),
shorten the specified intervals accordingly.
before starting work after finishing work or daily after each refueling stop weekly monthly every 12 months if problem if damaged if required
Complete machine Visual inspection (condition, leaks) XX
Clean X
Control handle Check operation XX
Air filter Clean XX
Replace X
Pickup body in fuel tank Check X
Have replaced by dealer1) XXX
Fuel tank Clean XX
Carburetor
Check idle adjustment – the working tool
must not move XX
Readjust idle X
Spark plug Readjust electrode gap X
Replace after every 100 operating hours
Cooling inlets Visual Inspection X
Clean X
Spark arrestor2) in muffler
Have checked by dealer1) XX
Have cleaned or replaced by servicing
dealer1) XX
All accessible screws and nuts (not adjust-
ing screws) Retighten X
Safety labels Replace X
1) STIHL recommends a STIHL servicing dealer.
2) not in all versions, market-specific