Stihl KA 120, KA 250 Instruction Manual

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STIHL KA 120, 250

Instruction Manual

Contents

English

KombiAttachmentSystem 2
Guide to Using this Manual 2
Safety Precautions and Working

Techniques 3
Approved Power Tool Attachments 7
Mounting the Bike Handle 7
Adjusting the Throttle Cable 9
Fitting the Carrying Ring 10

Original Instruction ManualPrinted on chlorine-free paper

Fuel 10
Fueling 11
Starting / Stopping the Engine 12
Operating Instructions 14
Cleaning the Air Filter 14
Adjusting the Carburetor 14
Spark Plug 16
Engine Running Behavior 17
Replacing the Starter Rope and

Rewind Spring 17
Storing the Machine 19
Inspections and Maintenance by

Dealer 19
Maintenance and Care 20

Printing inks contain vegetable oils, paper can be recycled.

Minimize Wear and Avoid Damage 21
Main Parts 22
Specifications 23
Maintenance and Repairs 23
Disposal 24

Dear Customer,

Thank you for choosing a quality
engineered STIHL product.

It has been built using modern
production techniques and
comprehensive quality assurance.
Every effort has been made to ensure
your satisfaction and trouble-free use of
the product.

Please contact your dealer or our sales
company if you have any queries
concerning this product.

Your

Dr. Nikolas Stihl

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© ANDREAS STIHL AG & Co. KG, 2018

0458-516-0121-A. VA2.K18.

0000006698_006_GB

KA 120, KA 250

This instruction manual is protected by copyright. All rights reserved, especially the rights to reproduce, translate and process
with electronic systems.

1

English

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002BA532 KN

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KombiAttachmentSystem

In the STIHL KombiAttachmentSystem
a number of different
KombiAttachmentEngines and
attachments can be combined to
produce a power tool. In this instruction
manual the functional unit formed by the
KombiAttachmentEngine and
attachment is referred to as the power
tool.

Therefore, the separate instruction
manuals for the
KombiAttachmentEngine and
attachment 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.

In this instruction manual the
KombiAttachmentEngine is also
referred to as the basic power tool.

The approved power tool models are
listed in the chapter on "Approved Basic
Power Tools".

The approved power tool models are
listed in the chapter on "Approved
Attachments".

Guide to Using this Manual

Pictograms

All the pictograms attached to the
machine are shown and explained in this
manual.

Symbols in text

WARNING

Warning where there is a risk of an
accident or personal injury or serious
damage to property.

NOTICE

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.

2

KA 120, KA 250

English

Safety Precautions and
Working Techniques

Special safety precau­tions must be observed
when working with a
power tool.

Always read and and
make sure you under­stand both instruction
manuals (KombiAttach­mentEngine and power
tool attachment) before
using your power tool for
the first time and keep
them in a safe place for
future reference. Non­observance of the safety
precautions may result in
serious or even fatal
injury.

Observe all applicable 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 machine or attend a
special course in its operation.

Minors should never be allowed to use
this product.

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.

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 instruction
manuals of the KombiAttachmentEngine
and power tool attachment.

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 power tool attachment you
are using.

It must not be used for any other
purpose because of the increased risk of
accidents and damage to the machine.
Never attempt to modify your power tool
in any way since this may result in
accidents or damage to the machine.

Do not operate the
KombiAttachmentEngine without a
properly mounted power tool attachment
since this may result in damage to the
machine.

Only mount attachments and
accessories that are explicitly approved
for this power tool by STIHL or are
technically identical. It is important that
you read the chapter on "Approved
Attachments". If you have any questions
in this respect, consult a servicing
dealer. Use only high quality tools and
accessories in order to avoid the risk of
accidents and damage to the machine.

STIHL recommends the use of genuine
STIHL tools and accessories. They are
specifically designed to match the
product and meet your performance
requirements.

Never attempt to modify your machine 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
the unit. The solid jet of water may
damage parts of the unit.

Clothing and Equipment

Wear proper protective clothing and
equipment.

See also notes on "Clothing and
Equipment" in the instruction manual of
the power tool attachment you are using.

KA 120, KA 250

3

English

Transporting the Power Tool

Always turn off the engine.

Transporting by 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
power tool attachment you are using.

Fueling

Gasoline is an extremely
flammable fuel. Keep
clear of naked flames. Do
not spill any fuel – do not
smoke.

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 well­ventilated areas. If you spill fuel, wipe
the machine immediately – if fuel gets on
your clothing, change immediately.

Your power tool comes standard with
either a screw-type or bayonet-type fuel
cap.

After fueling, 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.

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.

– Check the fuel system for leaks,

paying special attention to visible
parts such as the tank cap, hose
connections and the manual fuel
pump (on machines so equipped). If

there are any leaks or damage, do
not start the engine – risk of fire.
Have your machine repaired by a
servicing dealer before using it
again.

– Use only an approved combination

of cutting attachment, deflector,
handle and harness. All parts must
be assembled properly and
securely.

– The power tool attachment must be

approved for use with this
KombiEngine.

– 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 the harness and handle(s) to

suit your height and reach.

To reduce the risk of accidents, 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.

4

KA 120, KA 250

English

002BA055 KN

002BA080 KN

See also notes on "Before Starting" in
the instruction manual of the power tool
attachment you are using.

Starting the Engine

Start the engine at least 3 meters from
the fueling spot, outdoors only.

Place the power tool on firm ground in
an open area. Make sure you have good
balance and secure footing. Hold the
power tool securely. The attachment
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 the Engine"
in the instruction manual of the power
tool attachment 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.

Models with bike handle

Right handle on control handle, left hand
on left handle.

Models with loop handle

Left hand on loop handle, right hand on
control handle, even if you are left­handed.

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 attachment
continues to run when the engine is
idling, have your dealer check your
machine and make proper adjustments
or repairs. STIHL recommends an
authorized STIHL servicing dealer.
Check and correct the idle speed setting
regularly.

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 machine only in the areas
specified in the instruction manual of the
power tool attachment.

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 loca­tions, even if your model
is equipped with a cata­lytic converter.

KA 120, KA 250

5

English

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. If the work area is very dusty or
smoky, wear a respirator.

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, consult 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 unintentional
engine start and injury, always shut off
the engine and remove the spark plug
boot before changing the attachment.

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

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 genuine
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.

6

KA 120, KA 250

English

FS

(B)

FS

(A)

BF

228BA071 KN

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.

Approved Power Tool
Attachments

The following STIHL attachments may
be mounted to the basic power tool:

Interchangeable
Attachment Application

1)

FS (A)

1) 2)

FS (B)

BF Cultivator with pick

1)

Use shoulder strap

2)

Barrier bar required on loop handle

Brushcutter with
mowing head

Brushcutter with
metal cutting
attachment

tines

Mounting the Bike Handle

Mounting Bike Handle with Swivelling
Handle Support

The machine is supplied with the
swiveling handle support already
mounted on the shaft. To mount the
handlebar it is necessary to remove the
clamp moldings.

Removing the clamp moldings

KA 120, KA 250

N Hold the lower clamp (1) and upper

clamp (2) firmly together.

N Release the wing screw (3) – the

clamps are loose once the wing
screw has been released. They are
pushed apart by the two
springs (4 and 5).

7

English

1

7

A

250BA046 KN

002BA234 KN

8

N Pull out the wing screw – the

washer (6) remains on the wing
screw.

N Separate the clamp moldings – the

springs (4 and 5) remain in the
lower clamp.

Securing the handlebar

N Place the handlebar (7) in the lower

clamp (1) so that distance A is no
more than 15 cm (6 in).

N Place the upper clamp in position

and hold both clamp moldings
together.

N Push the wing screw through the

two clamps as far as stop – hold all
parts together and secure them.

N Place the secured assembly on the

handle support (8) with the wing
screw at the side nearest the
engine.

N Push the wing screw into the handle

support as far as stop and then
screw it down – but do not finally
tighten yet.

N Line up the handlebar at a right

angle to the drive tube – check
distance A again.

N Tighten down the wing screw firmly.

Mounting the control handle

N Take out the s crew (9 ) – t he nut (1 0)

remains in the control handle (11).

N Push the control handle onto the

handlebar (7) until the holes (13)
line up – the throttle trigger (12)
must point towards the gearbox.

N Insert the screw (9) and tighten it

down firmly.

Fitting the throttle cable

NOTICE

Do not kink the throttle cable or lay it in
tight radii – make sure the throttle trigger
moves freely.

8

KA 120, KA 250

English

15

14

15

14

15

250BA002 KN

7

3

002BA650 KN

002BA163 KN

STOP

249BA017 KN

1

2

N Push the throttle cable (14) into the

retainers (15).

Adjusting the throttle cable
N Check adjustment of throttle cable –

see chapter on "Adjusting the
Throttle Cable".

Swivelling the handlebar

Transport position

N Loosen the wing screw (3) and

unscrew it until the handlebar (7)
can be turned clockwise.

N Turn the handlebar 90° and then

swing the handles down.

N Tighten down the wing screw (3)

firmly.

Working position
N Reverse the sequence described

above to swing the handles up and
turn the handlebar
counterclockwise.

Adjusting the Throttle Cable

A properly adjusted throttle cable is the
precondition for correct operation in the
full throttle, starting throttle and idle
positions.

Adjust the throttle cable only after the
unit is fully assembled – the control
handle must be in the normal operating
position.

N Use a suitable tool to push the slide

to the end of the slot (see
illustration).

N Press down the throttle trigger

lockout (1) and squeeze the throttle
trigger (2) (full throttle) – this sets
the throttle cable correctly.

KA 120, KA 250

9

English

002BA142 KN

1

2

1

Fitting the Carrying Ring

The carrying ring comes standard with
the machine or is available as a special
accessory.

For position of carrying ring see "Main
Parts".

N Place the clamp (1) against the

drive tube with the tapped hole on
the left (viewed from engine).

N Squeeze the two ends of the clamp

together and hold in that position.

N Insert the M6x14 screw (2).
N Line up the carrying ring.
N Tighten down the screw firmly.

Fuel

Your engine requires a mixture of
gasoline and engine oil.

WARNING

For health reasons, avoid direct skin
contact with gasoline and avoid inhaling
gasoline vapor.

STIHL MotoMix

STIHL recommends the use of STIHL
MotoMix. This ready-to-use fuel mix
contains no benzol or lead, has a high
octane rating and ensures that you
always use the right mix ratio.

STIHL MotoMix uses STIHL HP Ultra
two-stroke engine oil for an extra long
engine life.

MotoMix is not available in all markets.

Mixing Fuel

NOTICE

Unsuitable fuels or lubricants or mix
ratios other than those specified may
result in serious damage to the engine.
Poor quality gasoline or engine oil may
damage the engine, sealing rings, hoses
and the fuel tank.

Gasoline

Use only high-quality brand-name
gasoline with a minimum octane rating
of 90 – leaded or unleaded.

Gasoline with an ethanol content of
more than 10% can cause running
problems in engines with a manually
adjustable carburetor and should not be
used in such engines.

Engines equipped with M-Tronic deliver
full power when run on gasoline with an
ethanol content of up to 25% (E25).

Engine Oil

If you mix the fuel yourself, use only
STIHL two-stroke engine oil or another
high-performance engine oil in
accordance with JASO FB, JASO FC,
JASO FD, ISO-L-EGB, ISO-L-EGC or
ISO-L-EGD.

STIHL specifies STIHL HP Ultra two­stroke engine oil or an equivalent high­performance engine oil in order to
maintain emission limits over the
machine’s service life.

Mix Ratio

STIHL 50:1 two-stroke engine oil: 50
parts gasoline to 1 part oil

Examples

Gasoline STIHL engine oil 50:1
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)

N Use a canister approved for storing

fuel. Pour oil into canister first, then
add gasoline and mix thoroughly.

10

KA 120, KA 250

English

256BA060 KN

250BA051 KN

Storing Fuel

Store fuel only in approved safety-type
fuel canisters in a dry, cool and safe
location protected from light and the sun.

Fuel mix ages – only mix sufficient fuel
for a few weeks work. Do not store fuel
mix for longer than 30 days. Exposure to
light, the sun, low or high temperatures
can quickly make the fuel mix unusable.

STIHL MotoMix may be stored for up to
2 years without any problems.

N Thoroughly shake the mixture in the

canister before fueling your
machine.

WARNING

Pressure may build up in the canister –
open it carefully.

N Clean the fuel tank and canister

from time to time.

Dispose of remaining fuel and cleaning
fluid properly in accordance with local
regulations and environmental
requirements.

Fueling

Preparations

N Open the filler cap.
N Fill up with fuel.
N Close the filler cap.

WARNING

After fueling, tighten down the filler cap
as securely as possible by hand.

Changing the Fuel Pickup Body

KA 120, KA 250

N Before fueling, clean the filler cap

and the area around it to ensure that
no dirt falls into the tank.

N Position the machine so that the

filler cap is facing up.

Filling Up with Fuel

Take care not to spill fuel while fueling
and do not overfill the tank. STIHL
recommends you use the STIHL filler
nozzle for fuel (special accessory).

Change the fuel pickup body every year:

N Drain the fuel tank.
N Use a hook to pull the fuel pickup

body out of the tank and take it off
the hose.

N Push the new pickup body into the

hose.

N Place the pickup body in the tank.

11

English

3

STOP

56

4

7

002BA182 KN

1

2

START

STOP-

250BA018 KN

9

8

002BA038 KN

002BA040 KN

Starting / Stopping the
Engine

Controls

1 Throttle trigger lockout
2 Throttle trigger
3 Slide control

Positions of slide control

4STOP-0 – engine off – ignition is

switched off

5 F – normal run position – the engine

is running or can start

6START – ignition is switched on –

the engine can start

Symbol on slide control
7 h – stop symbol and arrow. To stop

the engine, push the slide control in
the direction of the arrow on the stop
symbol (h) to STOP-0.

Starting

N Press down the trigger lockout lever

and squeeze the throttle trigger

N and hold them in that position.
N Move the slide control to START

and hold it there.

N Now release the throttle trigger,

slide control and trigger lockout in
that order. This is the starting
throttle position.

N Set the choke knob (8) to:

g if the engine is cold
e for warm start – also use this posi-

tion if the engine has been running
but is still cold.

N Press the manual fuel pump

bulb (9) at least five times – even if
the bulb is filled with fuel.

Cranking

N Place the power tool on the ground

so that it rests on the machine
support:

To reduce the risk of injury, check that
the attachment is not touching the
ground or any other obstacles – see also
"Starting / Stopping the Engine" in the
instruction manual of the attachment you
are using.

N Make sure you have a firm footing,

either standing, stooping or
kneeling.

N Hold the unit firmly on the ground

with your left hand and press down
– do not touch the throttle trigger,
lockout lever or slide control.

NOTICE

Do not stand or kneel on the drive tube.

12

KA 120, KA 250

English

002BA072 KN

N Hold the starter grip with your right

hand.

N Pull the starter grip slowly until you

feel it engage and then give it a brisk
strong pull.

NOTICE

Do not pull out the starter rope all the
way – it might otherwise break.

N Do not let the starter grip snap back.

Guide it slowly back into the housing
so that the starter rope can rewind
properly.

N Continue cranking.

When engine begins to fire

N Turn the choke knob to e.
N Continue cranking until the engine

runs.

As soon as the engine runs
N Blip the throttle trigger immediately.

The slide control moves to the
normal run position F – and the
engine settles down to idle speed.

Your machine is now ready for
operation.

Stopping the Engine

N Push the slide control in the

direction of the arrow on the stop
symbol (h) to STOP-0.

At very low outside temperatures

As soon as the engine runs:
N Blip the throttle trigger to disengage

the starting throttle position. The
slide control moves to the normal
run position F – and the engine
settles down to idle speed.

N Open the throttle slightly.
N Warm up the engine for a short

period.

If engine does not start

Choke knob
If you did not turn the choke knob to e

quickly enough after the engine began to
fire, the combustion chamber is flooded.

N Turn the choke knob to e.
N Select the starting throttle position.
N Start the engine by pulling the

starter rope briskly – 10 to 20 pulls
may be necessary.

If the engine still does not start
N Push the slide control in the

direction of the arrow on the stop
symbol (h) to STOP-0.

N Remove the spark plug – see

"Spark Plug".

N Dry the spark plug.
N Open the throttle wide.
N Crank the engine several times with

the starter to clear the combustion
chamber.

N Refit the spark plug – see "Spark

Plug".

N Move the slide control to START.
N Set the choke knob to e – even if

the engine is cold.

N Start the engine.

Throttle cable adjustment
N Check adjustment of throttle cable –

see chapter on "Adjusting the
Throttle Cable".

Fuel tank run until completely dry

Recommendation: Carry out the
following steps irrespective of the
engine's operating condition before the
tank was run dry.

N Turn the choke knob to g.
N Go to section on "Starting" and re-

start the engine as described for a
cold engine.

WARNING

Make sure the carburetor is correctly
adjusted. The working tool must not
rotate when the engine is idling.

KA 120, KA 250

13

English

250BA071 KN

Operating Instructions Cleaning the Air Filter

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 engine­mounted 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-of­service periods – see "Storing the
Machine".

If there is a noticeable loss of engine
power

N Turn the choke knob to g.
N Press in the tab (1) and remove the

filter cover (2).

N Clean away loose dirt from around

the filter (3) and inside the filter
cover.

N Remove and check the filter

element – replace it if is dirty or
damaged.

N Install the filter element in the filter

cover.

N Refit the filter cover.

Adjusting the Carburetor

General Information

The carburetor comes from the factory
with a standard setting.

This setting provides an optimum fuel-air
mixture under most operating
conditions.

Preparations

N Shut off the engine.
N Mount the attachment.
N Check the air filter and replace if

necessary.

N Check that the throttle cable is

properly adjusted – readjust if
necessary – see chapter on
"Adjusting the Throttle Cable".

Carry out the standard setting.

– High speed screw (H) = 3/4

– Low speed screw (L) = 3/4

14

KA 120, KA 250

English

255BA006 KN

H

L

255BA007 KN

LA

N Turn high speed screw (H)

counterclockwise as far as stop (no
more than 3/4 turn).

N Turn the low speed screw (L)

carefully clockwise as far as stop,
then turn it back 3/4 turn.

Adjust idle speed

N Carry out the standard setting.
N Start and warm up the engine.

Engine stops while idling
N Turn the idle speed screw (LA)

clockwise until the engine runs
smoothly – the attachment must not
run.

Attachment runs when engine is idling
N Turn the idle speed screw (LA)

counterclockwise until the
attachment stops moving and then
turn the screw another 1/2 to 1 full
turn in the same direction.

WARNING

If the attachment continues to run when
the engine is idling, have your machine
checked and repaired by your servicing
dealer.

Erratic idling behavior, poor acceleration
(despite correction to setting of LA
screw).

Idle setting is too lean
N Turn the low speed screw (L)

counterclockwise, no further than
stop, until the engine runs and
accelerates smoothly.

Erratic idling behavior

Idle setting is too rich
N Turn the low speed screw (L)

clockwise, no further than stop, until
the engine runs and accelerates
smoothly.

It is usually necessary to change the
setting of the idle speed screw (LA) after
every correction to the low speed
screw (L).

Fine Tuning for Operation at High
Altitude

N Carry out the standard setting.
N Warm up the engine.
N Turn high speed screw (H) slightly

clockwise (leaner) – no further than
stop.

NOTICE

After returning from high altitude, reset
the carburetor to the standard setting.

If the setting is too lean there is a risk of
engine damage due to insufficient
lubrication and overheating.

KA 120, KA 250

A slight correction of the setting may be
necessary if engine does not run
satisfactorily:

15

English

250BA054 KN

000BA039 KN

A

1

000BA045 KN

2

002BA446 KN

1

Spark Plug

N If the engine is down on power,

difficult to start or runs poorly at idle
speed, first check the spark plug.

N Fit 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

N Turn off the engine.

N Pull off the spark plug boot (1).
N Unscrew the spark plug.

Checking the Spark Plug

N Clean dirty spark plug.
N Check electrode gap (A) and

readjust if necessary – see
"Specifications".

N Rectify 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.

N Use resistor type spark plugs with a

properly tightened adapter nut.

Installing the Spark Plug

N Screw the spark plug (2) into the

cylinder and fit the boot (1) (press it
down firmly).

16

WARNING

Arcing may occur if the adapter nut (1) is
loose or missing. Working in an easily
combustible or explosive atmosphere
may cause a fire or an explosion. This
can result result in serious injuries or
damage to property.

KA 120, KA 250

Engine Running Behavior Replacing the Starter Rope

1

1

1

1

256BA075 KN

3

2

4

256BA032 KN

6

5

256BA033 KN

and Rewind Spring

If engine running behavior is
unsatisfactory even though the air filter
is clean and the carburetor and throttle
cable are properly adjusted, the cause
may be the muffler.

Have the muffler checked by a servicing
dealer for contamination
(carbonization).

STIHL recommends that you have
servicing and repair work carried out
exclusively by an authorized STIHL
servicing dealer.

Removing the Fan Housing

N Take out the screws (1).
N Remove the fan housing.

English

KA 120, KA 250

Replacing the Starter Rope

N Remove the spring clip (2).
N Carefully remove the rope rotor with

washer (3) and pawl (4).

WARNING

The rewind spring may pop out and
uncoil during this operation – take care
to avoid the risk of injury.

N Pry the cap (5) out of the grip.
N Remove the remaining rope from

the rotor and starter grip.

N Tie a simple overhand knot in the

new rope and then thread it through
the top of the grip and the rope
bushing (6).

N Refit the cap in the grip.

17

English

256BA034 KN

3

2

4

256BA032 KN

427BA016 KN

7

7

271BA053 KN

N Thread the rope through the rotor

and secure it with a simple
overhand knot.

N Coat the rope rotor bearing bore

with non-resinous oil.

N Slip the rotor over the starter post –

turn it back and forth to engage the
anchor loop of the rewind spring.

N Fit the pawl (4).
N Fit the washer (3).
N Push the spring clip (2) into position

– it must point counterclockwise as
shown and engage the pawl's peg.

18

Tension the rewind spring.

N Make a loop in the unwound starter

rope and use it to turn the rope rotor
six full revolutions
counterclockwise.

N Hold the rope rotor steady.
N Pull out and straighten the twisted

rope.

N Release the rope rotor.
N Slowly release the starter rope so

that it winds onto the rotor.

The starter grip must sit firmly in the rope
bushing. If the grip droops to one side:
Add one more turn on the rope rotor to
increase spring tension.

NOTICE

When the starter rope is fully extended it
must still be possible to rotate the rotor
another one and a half turns. If this is not
the case, the spring is overtensioned
and could break.

N Take one turn of the rope off the

rotor.

N Install the fan housing.

Replacing a Broken Rewind Spring

N Remove the rope rotor as described

in "Replacing the Starter Rope".

WARNING

The bits of the spring may still be under
tension and could fly apart when you
remove the rope rotor and spring
housing. To reduce the risk of injury,
Wear a face shield and work gloves.

N Take out the screws (7).
N Remove the spring housing and

pieces of spring.

N Lubricate the new, ready-to-fit

replacement spring in the new
spring housing with a few drops of
resin-free oil.

N Place the replacement spring with

spring housing in position – bottom
plate facing up.

If the spring pops out and uncoils, refit it
in the clockwise direction, starting
outside and working inwards.

N Fit the screws.
N Refit the rope rotor as described in

"Replacing the Starter Rope".

N Tension the rewind spring.
N Install the fan housing.

KA 120, KA 250

Storing the Machine Inspections and Maintenance

250BA066 KN

by Dealer

For periods of about 3 months or longer
N Drain and clean the fuel tank in a

well ventilated area.

N Dispose of fuel properly in

accordance with local
environmental requirements.

N Run the engine until the carburetor

is dry – this helps prevent the
carburetor diaphragms sticking
together.

N Thoroughly clean the machine.
N Check the air filter and replace the

element if necessary.

N Remove, clean and inspect the

attachment. Coat metal parts of
interchangeable attachment with
corrosion inhibiting oil.

N Store the machine in a dry and

secure 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.

Antivibration Element

A vibration-absorbing rubber element is
installed between the powerhead and
the drive tube. Have it checked if there
are signs of wear or a noticeable
increase in vibration levels.

English

KA 120, KA 250

19

English

Maintenance and Care

The following intervals apply to normal operating conditions only. If your daily work­ing 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

as required

Complete machine

Control handle Check operation XX

Air filter

Manual fuel pump

Pickup body in fuel tank

Fuel tank Clean XX

Carburetor

Spark plug

Cooling inlets

All accessible screws and nuts (not adjust­ing screws)

Anti-vibration elements

Safety labels Replace X

1)

STIHL recommends an authorized STIHL servicing dealer.

Visual inspection (condition, leaks) XX

Clean X

Clean XX

Replace X

Check X

Have repaired by servicing dealer

Check X

Replace XXX

Check idle adjustment – the attachment
must not move

Readjust idle speed X

Readjust electrode gap X

Replace after every 100 operating hours

Visual inspection X

Clean X

Retighten X

Check XXX

Have replaced by servicing dealer

1)

XX

1)

X

X

20

KA 120, KA 250

English

Minimize Wear and Avoid
Damage

Observing the instructions in this manual
helps reduce the risk of unnecessary
wear and damage to the power tool.

The power tool must be operated,
maintained and stored with the due care
and attention described in this owner's
manual.

The user is responsible for all damage
caused by non-observance of the safety
precautions, operating and maintenance
instructions in this manual. This includes
in particular:

– Alterations or modifications to the

product not approved by STIHL.

– Using tools or accessories which

are neither approved or suitable for
the product or are of a poor quality.

– Using the product for purposes for

which it was not designed.

– Using the product for sports or

competitive events.

– Consequential damage caused by

continuing to use the product with
defective components.

Maintenance Work

All the operations described in the
"Maintenance Chart" must be performed
on a regular basis. If these maintenance
operations cannot be performed by the
owner, they should be 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.

If these maintenance operations are not
carried out as specified, the user
assumes responsibility for any damage
that may occur. Among other parts, this
includes:

– Damage to the engine due to

neglect or deficient maintenance
(e.g. air and fuel filters), incorrect
carburetor adjustment or
inadequate cleaning of cooling air
inlets (intake ports, cylinder fins).

– Corrosion and other consequential

damage resulting from improper
storage.

– Damage to the machine resulting

from the use of poor quality
replacement parts.

Parts Subject to Wear and Tear

Some parts of the power tool are subject
to normal wear and tear even during
regular operation in accordance with
instructions and, depending on the type
and duration of use, have to be replaced
in good time. Among other parts, this
includes:

– Clutch

– Filters (air, fuel)

– Rewind starter

– Spark plug

KA 120, KA 250

21

English

17

16

15

13

14

11

12

11

10

7

9

8

250BA070

1

2

3

4

5

#

6

Main Parts

1 Tank cap
2 Carburetor adjusting screws
3 Starter grip
4 Spark plug boot
5 Muffler
6 Bike handle (handlebar)
7 Throttle trigger
8 Slide control
9 Throttle trigger lockout
10 Handle support
11 Throttle cable retainer
12 Carrying ring
13 Manual fuel pump
14 Choke knob
15 Air filter cover
16 Fuel tank
17 Machine support
# Serial number

KA 120, KA 250

22

English

Specifications

Engine

Single cylinder two-stroke engine

KA 120

Displacement: 30.8 cc
Bore: 35 mm
Stroke: 32 mm
Engine power to

ISO 8893:
Idle speed: 2,800 rpm
Cut-off speed (rated): 12,300 rpm

KA 250

Displacement: 40.2 cc
Bore: 40 mm
Stroke: 32 mm
Engine power to

ISO 8893:
Idle speed: 2,800 rpm
Cut-off speed (rated): 12,300 rpm

Ignition System

Electronic magneto ignition

Spark plug (resistor
type):

Electrode gap: 0.5 mm

1.3 kW (1.8 bhp)
at 9,000 rpm

1.6 kW (2.2 bhp)
at 9,000 rpm

Bosch WSR 6 F,
NGK BPMR 7 A

Fuel tank capacity: 640 cc (0.64 l)

Weight

dry, without attachment
KA 120: 5.7 kg
KA 250: 5.7 kg

Overall length

without attachment
KA 120: 1700 mm
KA 250: 1700 mm

Exhaust Emissions

The CO2value measured in the EU type
approval procedure is specified at
www.stihl.com/co2.

The measured CO
determined on a representative engine
in accordance with a standardized test
procedure under laboratory conditions
and does not represent either an explicit
or implied guarantee of the performance
of a specific engine.

The applicable exhaust emission
requirements are fulfilled by the
intended usage and maintenance
described in this instruction manual. The
type approval expires if the engine is
modified in any way.

value was

2

Maintenance and Repairs

Users of this machine may only carry out
the maintenance and service work
described in this user manual. All other
repairs must be carried out 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.

When repairing the machine, only use
replacement parts which have been
approved by STIHL for this power tool or
are technically identical. Only use high­quality replacement parts in order to
avoid the risk of accidents and damage
to the machine.

STIHL recommends the use of original
STIHL replacement parts.

Original STIHL parts can be identified by
the STIHL part number, the {
logo and the STIHL parts symbol K
(the symbol may appear alone on small
parts).

Fuel System

All position diaphragm carburetor with
integral fuel pump

KA 120, KA 250

23

English

000BA073 KN

Disposal

Observe all country-specific waste
disposal rules and regulations.

STIHL products must not be thrown in
the garbage can. Take the product,
accessories and packaging to an
approved disposal site for environment­friendly recycling.

Contact your STIHL servicing dealer for
the latest information on waste disposal.

24

KA 120, KA 250

0458-516-0121-A

englisch

G

www.stihl.com

*04585160121A*

0458-516-0121-A