Stihl Km 55 R Manual

							KM 55 R, KM 55 RCEnglish
9 stay clean and need no service or 
maintenance. If you experience loss of 
performance and you suspect a clogged 
screen, have your muffler maintained by 
a STIHL servicing dealer.
MAINTENANCE, REPAIR AND 
STORING
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.
Strictly follow the maintenance and 
repair instructions in the appropriate 
section of your KombiEngine and 
KombiTool instruction manuals. Please 
refer to the maintenance charts 
respectively the maintenance notes in 
these manuals.Store the power tool in a dry and high or 
locked location out of reach of children.
Before storing for longer than a few 
days, always empty the fuel tank. See 
chapter Storing the machine in this 
manual.
Warning!
Use only identical STIHL replacement 
parts for maintenance and repair. Use of 
non-STIHL parts may cause serious or 
fatal injury.
Warning!
Always stop the engine and make sure 
that the working tool is stopped before 
doing any maintenance or repair work or 
cleaning the power tool. Do not attempt 
any maintenance or repair work not 
described in your KombiEngine and 
KombiTool instruction manuals. Have 
such work performed by your STIHL 
servicing dealer only.
Warning!
Use the specified spark plug and make 
sure it and the ignition lead are always 
clean and in good condition. Always 
press spark plug boot snugly onto spark 
plug terminal of the proper size. (Note: If 
terminal has detachable SAE adapter 
nut, it must be attached.) A loose con-
nection between spark plug boot and 
the ignition wire connector in the boot 
may create arcing that could ignite com-
bustible fumes and cause a fire.
Warning!
Never test the ignition system with the 
ignition wire boot removed from the 
spark plug or with a removed spark 
plug, since uncontained sparking may 
cause a fire.Warning!
Do not operate your power tool if the 
muffler is damaged, missing or modi-
fied. An improperly maintained muffler 
will increase the risk of fire and hearing 
loss. If your muffler was equipped with a 
spark-arresting screen to reduce the 
risk of fire, never operate your power 
tool if the screen is missing or damaged. 
Remember that the risk of forest fires is 
greater in hot or dry weather. 
						

							KM 55 R, KM 55 RC English
10The 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-KMFCB-KM
KW-KMKB-KM
FH-KM
FS-KMFS-KM
FSB-KMBG-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 RCEnglish
11 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 upNInsert 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 possibleNFit 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
11
5 4
002BA099 KN
2
3
6
7
A
9
8
4
002BA353 KN 
						

							KM 55 R, KM 55 RC English
12 This engine is certified to operate on 
unleaded gasoline and the STIHL two-
stroke engine oil at a mix ratio of 50:1.
Your engine requires a mixture of high-
quality gasoline and quality two-stroke 
air cooled engine oil.
Use mid-grade unleaded gasoline with a 
minimum octane rating of 89 (R+M/2). If 
the octane rating of the mid-grade 
gasoline in your area is lower, use 
premium unleaded fuel.
Fuel with a lower octane rating may 
increase engine temperatures. This, in 
turn, increases the risk of 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 and 
catalytic converters as well. This could 
cause running problems or even 
damage the engine. For this reason 
STIHL recommends that you use only 
high-quality unleaded gasoline!
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 
engine oils that are designed for use 
only in air cooled two-cycle engines.We recommend STIHL HP Ultra 2-Cycle 
Engine Oil since it is specially 
formulated for use in STIHL engines.
Do not use BIA or TCW rated (two-
stroke water cooled) mix oils or other 
mix oils that state they are for use in both 
water cooled and air cooled engines 
(e.g., outboard motors, snowmobiles, 
chain saws, mopeds, etc.).
Take care when handling gasoline. 
Avoid direct contact with the skin and 
avoid inhaling fuel vapor. When filling at 
the pump, first remove the canister from 
your vehicle and place the canister on 
the ground before filling. Do not fill fuel 
canisters that are sitting in or on a 
vehicle.
The canister should be kept tightly 
closed in order to avoid any moisture 
getting into the mixture.
The machine‘s fuel tank and the canister 
in which fuel mix is stored should be 
cleaned as necessary.
Fuel mix ages
Only mix sufficient fuel for a few days 
work, not to exceed 3 months of storage. 
Store in approved fuel-canisters only. 
When mixing, pour oil into the canister 
first, and then add gasoline. Close the 
canister and shake it vigorously by hand 
to ensure proper mixing of the oil with 
the fuel.Dispose of empty mixing-oil canisters 
only at authorized disposal locations.
FuelGaso-
lineOil (STIHL 50:1 or equiva-
lent high-quality oils)
US gal. US fl.oz
12.6
2 1/2 6.4
5 12.8 
						

							KM 55 R, KM 55 RCEnglish
13 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.
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 toI.
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
In order to reduce the risk of burns 
or other 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.
232BA046 KN
Starting / Stopping the 
Engine
2
233BA048 KN
167
54
3233BA049 KN
4 
						

							KM 55 R, KM 55 RC English
14 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.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.
Version with Easy2Start
NPull the starter grip slowly until you 
feel it engage and then pull it out 
slowly and steadily. 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
Do not stand or kneel on the drive 
tube.
232BA012 KN
233BA014 KN
Do not pull out the starter rope all 
the way – it might otherwise 
break.
Do not pull out the starter rope all 
the way – it might otherwise 
break.
232BA014 KN 
						

							KM 55 R, KM 55 RCEnglish
15 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.
Stopping the engine
NMove the stop switch to0.
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 to0.
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 toI.
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 perionds – see Storing the 
Machine.Make sure the carburetor is 
correctly adjusted. The working 
tool must not move when the 
engine is idling.
8
232TI015 KN
Operating Instructions 
						

							KM 55 R, KM 55 RC English
16 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
12
232BA018 KN
4
3
Engine Management 
						

							KM 55 R, KM 55 RCEnglish
17 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 DealerNTurn 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
LH
LA
233BA050 KN 
						

							KM 55 R, KM 55 RC English
18moving and then rotate the screw 
another 1/2 to 1 turn in the same 
direction.
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.If engine is down on power, difficult to 
start or runs poorly at idling speed, first 
check the spark plug.
Fit a new spark plug after approx. 100 
operating hours or earlier if the 
electrodes are badly eroded.
Wrong fuel mix (too much engine oil in 
the gasoline), a dirty air filter and 
unfavorable running conditions (mostly 
at part throttle etc.) affect the condition 
of the spark plug. These factors cause 
deposits to form on the insulator nose 
which may result in trouble in operation.
Removing the Spark Plug
NMove the stop switch to0.
NPull off the spark plug boot (1).
NUnscrew the spark plug.Wrong fuel mix (too much engine oil in 
the gasoline), a dirty air filter and 
unfavorable running conditions (mostly 
at part throttle etc.) affect the condition 
of the spark plug. These factors cause 
deposits to form on the insulator nose 
which may result in trouble in operation.
If engine is down on power, difficult to 
start or runs poorly at idling speed, first 
check the spark plug.
NRemove spark plug – see Starting / 
Stopping the Engine.
NClean dirty spark plug.
NCheck electrode gap (A) and 
readjust if necessary – see 
Specifications.
NUse only resistor type spark plugs of 
the approved range.
Rectify problems which have caused 
fouling of spark plug:
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.
Spark Plug
1
232BA081 KN
000BA002 KN