Stihl MS 261 C-M User manual

{
STIHL MS 261 C-M Instruction Manual
Notice d’emploi

GInstruction Manual
1 - 49
FNotice d’emploi
50 - 102

Original Instruction ManualPrinted on chlorine-free paper
Printing inks contain vegetable oils, paper can be recycled.
© ANDREAS STIHL AG & Co. KG, 2013 0458-153-8221-A. VA0.D13. 0000006429_001_GB
MS 261 C-M
English
1
{This instruction manual is protected by copyright. All rights reserved, especially the rights to reproduce, translate and process
with electronic systems.
Contents
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 troublefree use of
the product.
Please contact your dealer or our sales
company if you have any queries
concerning this product.
Your
Dr. Nikolas Stihl
Guide to Using this Manual 2
Safety Precautions and Working
Techniques 2
Cutting Attachment 14
Mounting the Bar and Chain 15
Tensioning the Chain 16
Checking Chain Tension 16
Fuel 17
Fueling 18
Chain Lubricant 19
Filling Chain Oil Tank 20
Checking Chain Lubrication 20
Chain Brake 21
Winter Operation 22
Electric Handle Heating 23
Starting / Stopping the Engine 23
Operating Instructions 26
Oil Quantity Control 27
Taking Care of the Guide Bar 28
Shroud 28
Cleaning the Air Filter 29
Engine Management 29
M-Tronic 30
Spark Arresting Screen in Muffler 30
Spark Plug 30
Rewind Starter 31
Storing the Machine 32
Checking and Replacing the Chain
Sprocket 32
Maintaining and Sharpening the
Saw Chain 33
Maintenance and Care 37
Main Parts 39
Specifications 41
Special Accessories 42
Ordering Spare Parts 42
Maintenance and Repairs 42
Disposal 43
Important Safety Instructions 43
Key to Symbols 45
STIHL Limited Emission Control
Warranty Statement 46
CSA Standard 48

MS 261 C-M
English
2
Pictograms
Pictograms that appear on the machine
are explained in this Instruction Manual.
Depending on the machine and
equipment version, the following
pictograms may appear on the machine.
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.
Observe the national safety regulations
issued, e. g. by the employers' liability
insurance association, social security
institutions, occupational safety and
health authorities or other organizations.
If you have never used a power tool
before: Ask the salesperson or another
expert to explain how to use it safely – or
attend a training course.
Minors should never be allowed to use
the machine – except for young trainees
over the age of 16 when working under
supervision.
Children, animals and bystanders must
remain at a distance.
Guide to Using this Manual
Fuel tank; fuel mixture of
gasoline and engine oil
Tank for chain oil; chain
oil
Engage and release
chain brake
Coasting brake
Direction of chain travel
Ematic; chain oil flow
adjustment
Tension saw chain
Intake air baffle: winter
operation
Intake air baffle: summer
operation
Handle heating
Actuate decompression
valve
Actuate manual fuel
pump
Safety Precautions and
Working Techniques
Special safety precau-
tions must be observed
when using a chain saw
because the work goes
faster than with an axe
and a hand saw, because
the chain runs at very
high speeds, and
because the cutters are
extremely sharp.
It is important that you
carefully read the entire
Instruction Manual before
using the machine for the
first time and keep it in a
safe place for future ref-
erence. Non-compliance
with the Instruction Man-
ual may cause serious or
even fatal injury.

MS 261 C-M
English
3
When not using the machine, it must be
laid down in such a way that it does not
endanger anyone. Ensure that the
machine cannot be used without
authorization.
The user is responsible for accidents or
risks involving third parties or their
property.
The machine should only be provided or
loaned to people familiar with this model
and its operation. The Instruction
Manual should always be handed over
with the machine.
Use of machines that emit noise may be
restricted in terms of time by national
and/or on-site, local regulations.
The machine may only be operated by
people who are fit, in good physical
health and in good mental condition. If
you have any condition that might be
aggravated by strenuous work, check
with your doctor before operating a
machine.
If you have a pacemaker: The ignition
system of your machine produces an
electromagnetic field of very low
intensity. An effect on individual
pacemaker types cannot be excluded
entirely. STIHL recommends that you
consult your doctor and the
manufacturer of your pacemaker in
order to avoid health hazards.
Anyone who has consumed alcohol,
medicines affecting their ability to react
or drugs must not operate the machine.
Postpone the work if the weather is bad
(rain, snow, ice, wind) – higher risk of
accidents!
Do not cut any material other than wood
or wooden objects.
The machine must not be used for any
other purposes – risk of accidents!
Only use tools, guide bars, chains, chain
sprockets or accessories that have been
approved by STIHL for this machine or
which are technically equivalent.
Contact a servicing dealer if in doubt.
Only use high-quality tools or
accessories. Otherwise there may be a
risk of accidents or damage to the
machine.
STIHL recommends the use of genuine
STIHL tools, guide bars, chains, chain
sprockets and accessories. These have
been optimized for the product and the
user's requirements.
Never modify the machine in any way,
as this could be extremely dangerous.
STIHL excludes all liability for personal
injury and damage to property caused
while using unauthorized attachments.
Do not use high-pressure cleaners to
clean the machine. The hard water jet
can damage parts of the machine.
Clothing and equipment
Wear proper protective clothing and
equipment.
Clothing which could become trapped in
wood, brush or moving parts of the
machine should not be worn. Do not
wear a scarf, tie or jewelry when
operating the machine. Long hair must
be tied up and covered (headscarf, cap,
helmet, etc.).
Wear safety glasses or a face shield and
"personal" hearing protection – e. g., ear
defenders.
STIHL can supply a comprehensive
range of protective clothing and
equipment.
Transporting the chain saw
Always engage the chain brake and
attach the chain scabbard – even before
transporting the saw for short distances.
When transporting the saw for longer
distances (more than approx. 50 m),
also stop the engine.
Always carry the saw by the handlebar –
with the hot muffler away from your
body, the guide bar must point to the
rear. Avoid touching hot parts of the
machine, especially the surface of the
muffler – risk of burns!
Clothing must be sturdy
and snug-fitting, but allow
complete freedom of
movement. Wear snug
fitting clothing with cut-
retardant pads – an over-
all, not a loose-fitting
jacket.
Wear safety boots – with
cut-retardant material,
non-slip soles and steel
toe caps
Wear a hard hat – if
objects could fall on you.
Wear sturdy gloves.

MS 261 C-M
English
4
In vehicles: Properly secure your
machine to prevent turnover, damage
and fuel spillage.
Refueling
Switch off the engine before refueling.
Never refuel the machine while the
engine is still hot – the fuel may spill over
– risk of fire!
Open the fuel filler cap carefully so that
any excess pressure is relieved
gradually and fuel does not splash out.
The machine may only be refueled in a
well ventilated place. Clean the machine
immediately if fuel is spilled. Change
your clothes immediately if they are
contaminated with fuel.
This helps reduce the risk of unit
vibrations causing an incorrectly
tightened filler cap to loosen or come off
and spill quantities of fuel.
Before starting
Check that saw is properly assembled
and in good condition – refer to
appropriate chapters in the Instruction
Manual:
–Functional chain brake, front hand
guard
–Correctly mounted guide bar
–Correctly tensioned chain
–The throttle trigger and throttle
trigger lockout must move easily –
throttle trigger must return
automatically to the idle position
when released
–The master control lever must be
easy to push towards STOP or †
and then spring back to the run
position F
–Check that the spark plug boot is
secure. A loose boot can lead to
flying sparks which may ignite the
escaping fuel/air mixture – risk of
fire!
–Never attempt to modify the controls
or safety devices
–Keep the handles dry and clean –
free from oil and pitch – for safe
control of the chain saw.
The chain saw should only be used if it
is in full working order – risk of accident!
Starting the engine
Move at least 3 meters away from the
place at which the machine was refueled
and never start the machine in enclosed
spaces.
The machine may only be used on level
ground. Ensure a firm and secure
footing and hold the machine firmly. The
cutting wheel must not touch any objects
and must not touch the ground, because
it may begin to rotate when the machine
is started.
The machine is operated by only one
person – there should not be any other
person within the working area – not
even when starting the machine.
Lock the chain with the chain brake
before starting – risk of injury due to
rotating chain!
Do not drop-start the engine – start as
described in the Instruction Manual.
Do not start the chain saw if the chain is
in a cut.
Holding and guiding the machine
Always hold the chain saw firmly with
both hands: Right hand on the rear
handle – even if you are left-handed. To
ensure reliable control, wrap your
thumbs tightly around the handlebar and
handle.
Gasoline is an extremely
flammable fuel – keep
clear of naked flames and
fire – do not spill any fuel
– no smoking.
Place the cliplock filler
cap (bayonet-type) in
position, turn as far as
stop and fold the cliplock
down.
Check for fuel leakage
while refueling and during
operation. Never start the
engine if fuel has been
spilled or is leaking –
Fatal burns may result!
001BA087 LÄ

MS 261 C-M
English
5
During work
Ensure you always have a firm and safe
footing.
In the event of impending danger or in
an emergency, switch off the engine
immediately and push the master control
lever to STOP or †.
The machine is operated by only one
person. There should not be any other
person within the working area.
Never let the machine run unattended.
When the engine is running: Note that
the chain continues to rotate for a short
period after your let go of the throttle
trigger – coasting effect.
Exercise caution with slippery surfaces,
water, snow, ice, steep slopes, uneven
ground or green wood that has just been
stripped of its bark – danger of slipping!
Use caution with tree stumps, roots,
ditches – danger of stumbling!
Do not work alone – keep within calling
distance of others in case help is
needed.
More care and attention than usual are
required when wearing ear protection –
warning sounds (shouts, alarms, etc.)
cannot be heard properly.
Take breaks in due time in order to
prevent tiredness and exhaustion – risk
of accidents!
Keep easily combustible materials
(e. g., wood chips, bark, dry grass, fuel)
away from hot exhaust gases and hot
mufflers – risk of fire! Mufflers with
catalytic converters can become
especially hot.
Ensure proper ventilation when working
in trenches, hollows or other confined
areas. Toxic fumes can kill!
If you feel sick, if you have a headache,
vision problems (e. g., your field of vision
gets smaller), hearing problems,
dizziness or inability to concentrate, stop
work immediately. Such symptoms may
be caused by an excessively high
concentration of exhaust emissions,
among other things – risk of accident!
Dust (e. g., sawdust), fumes and smoke
produced while using the machine may
be hazardous to health. Wear a dust
mask if dust is generated.
Examine the saw chain periodically at
short intervals and as soon as you note
any tangible changes:
–Switch off the engine; wait until the
saw chain is stationary
–Check condition and secure fitting
–Ensure that the cutting blades are
sharp
Never touch the saw chain when the
engine is running. If the saw chain
becomes jammed by an object, switch
off the engine immediately before
attempting to remove the object – risk of
injury!
To change the saw chain, switch off the
engine – risk of injury!
No smoking when working with or near
the machine - risk of fire! Combustible
fuel vapor may escape from the fuel
system.
If the machine 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 – refer also to the
section "Before starting". Check the fuel
system for leaks and make sure the
safety devices are working properly.
Never continue using a power tool that is
not in perfect working order. Consult a
servicing dealer if in doubt.
Check for correct idling, so that the saw
chain stops moving when the throttle
trigger is released. Have the machine
repaired by a STIHL servicing dealer if
the saw chain continues to move
nevertheless.
Reactive forces
The most common reactive forces are:
kickback, pushback and pull-in.
Dangers of kickback
Your power tool produces
toxic exhaust fumes as
soon as the engine is
running. These gases
may be colorless and
odorless and may contain
unburnt hydrocarbons
and benzene. Never run
the engine indoors or in
poorly ventilated areas,
even if your model is
equipped with a catalytic
converter.
Kickback can result in
fatal cuts.

MS 261 C-M
English
6
Kickback occurs when the saw is
suddenly thrown up and back in an
uncontrolled arc towards the operator.
Kickback occurs if, for example,
–the saw chain in the area of the
upper quarter of the guide bar nose
unintentionally comes into contact
with wood or a solid object – e. g.,
unintentionally touches another limb
during limbing
–the saw chain at the nose of the
guide bar is pinched in the cut
QuickStop chain brake:
This device reduces the risk of injury in
certain situations – it cannot prevent
kickback. When activated, the chain
brake stops the saw chain within a
fraction of a second –
See the section "Saw chain" in this
Instruction Manual.
Reducing the risk of kickback
–Work cautiously and methodically
–Hold the chain saw firmly with both
hands and maintain a secure grip
–Always cut at full throttle
–Be aware of the location of the guide
bar nose
–Do not cut with the guide bar nose
–Be especially careful with small,
tough limbs, undergrowth and
offshoots – the saw chain may
become caught in them
–Never cut several limbs at once
–Do not lean too far forward
–Do not cut above shoulder height
–Use extreme caution when re-
entering a previous cut
–Do not attempt plunge cuts if you
are not experienced in this cutting
technique
–Be alert for shifting of the log or
other forces that may cause the cut
to close and pinch the chain
–Always cut with a correctly
sharpened, properly tensioned saw
chain – the depth gauge setting
must not be too large
–Use low-kickback saw chains as
well as narrow-radius guide bars
Pull-in (A)
When the chain on the bottom of the bar
– overbucking – is suddenly pinched,
caught or encounters a foreign object in
the wood, the chain saw may suddenly
be drawn forward toward the log – to
avoid this, engage the bumper spike
firmly in the wood.
001BA036 KN
001BA257 KN
001BA037 KN
A

MS 261 C-M
English
7
Pushback (B)
When the chain on the top of the bar –
underbucking – is suddenly pinched,
caught or encounters a foreign object in
the wood, the chain saw may suddenly
be driven straight back toward the
operator – to avoid this:
–Do not allow the top of the guide bar
to become jammed
–Do not twist the guide bar in the cut
Be very careful
–with freely hanging limbs
–with trunks that are under tension
between other trees because they
fell unfavorably
–when working in windbreaks
In these cases, do not use a chain saw –
use a hoist, winch or dragline instead.
Pull out trunks that are lying about and
have been cut free. Whenever possible,
deal with them in open areas.
Deadwood (brittle, rotten or dead wood)
poses a substantial, highly
unpredictable hazard. It is extremely
difficult or even practically impossible to
recognize the danger. Use aids such as
winches or draglines.
Always be especially careful when
felling timber near roads, railway lines,
power lines etc. If necessary, notify
police, power companies or railway
authorities.
Sawing
Do not use the starting throttle position
for cutting. Engine speed cannot be
controlled with the throttle trigger in this
position.
Work calmly and methodically – only
with good lighting and visibility. Do not
endanger others – stay alert at all times.
Use the shortest possible guide bar: The
chain, guide bar and chain sprocket
must match each other and your saw.
Make certain that all parts of your body
are well clear of the extended range of
travel of the saw chain.
Always pull the saw out of the cut with
the saw chain running.
Use the chain saw only for sawing – not
for prying or shoveling away limbs or
roots.
Do not underbuck freely hanging limbs.
Be careful when cutting shattered wood
– risk of injury from slivers being caught
and thrown in your direction!
Make sure your saw does not touch any
foreign materials: Stones, nails, etc. may
be flung off and damage the saw chain –
the saw may kick back unexpectedly.
On slopes, always stand above or to the
side of the trunk or felled tree. Watch out
for rolling trunks.
When working above ground level:
–Always use a lift bucket
–Never use the machine while
standing on a ladder or in a tree
–Never use the machine in unsteady
locations
–Never cut above shoulder height
–Never use the machine with one
hand
Begin cutting with the saw at full throttle
and engage the bumper spike – then
saw.
001BA038 KN
B
001BA082 KN
001BA033 KN

MS 261 C-M
English
8
Never use the chain saw without the
bumper spike, the saw may pull you
forward suddenly. Always engage the
bumper spike securely.
At the end of the cut, the chain saw is no
longer supported by the cutting
attachment in the cut. The machine's
weight must be borne by the user – risk
of loss of control!
Felling
Felling may only be carried out by
persons who have had special training.
Persons who are not experienced chain
saw users should carry out neither
felling nor limbing – increased risk of
accidents!
Comply with national regulations
regarding felling technique.
Only persons who are engaged in felling
may be present in the felling area.
Make certain that no one is endangered
by the falling tree – motor noise can
drown out shouting.
The distance to the next worksite must
be at least 2 1/2 tree lengths.
Determining direction of fall and escape
paths
Select a gap in the timber stand into
which the tree can be felled.
Pay special attention to the following
points:
–the natural inclination of the tree
–unusually heavy limb structure,
asymmetrical growth, damage to
tree
–wind direction and speed – do not
fell trees in high winds
–direction of slope
–neighboring trees
–snow load
–Take the general condition of the
tree into account – be especially
careful with trunk damage or
deadwood (brittle, rotten or dead
wood)
Adirection of fall
Bescape paths
–Establish escape paths for each
worker – approx. 45° diagonally
backwards
–Clear escape paths, eliminate
obstacles
–Put down tools and equipment at a
safe distance – but not on the
escape paths
–When felling, stand only to the side
of the falling trunk and only move
back laterally onto the escape route
–Plan escape routes on slopes
parallel to the slope
–When getting out of the way, watch
out for falling branches and the
crown area
001BA088 LÄ
2
/
12
11
/
12
B
001BA040 KN
A45°
45°
B

MS 261 C-M
English
9
Preparing the work area at the trunk
–Clear the work area at the trunk of
branches, brush and other
obstacles – secure footing for all
workers
–Carefully clear the base of the trunk
(e. g., with an axe) – sand, stones
and other foreign objects will dull the
saw chain
–Remove large buttresses: remove
the largest buttress first – saw first
vertically, then horizontally – only if
the tree is in sound condition
Making a felling notch
With the help of the gunning sight on the
shroud and fan housing of the chain
saw, it is possible to check the direction
of fall when cutting the felling notch.
When making the felling notch, orient
the chain saw so that the gunning sight
points precisely in the direction in which
you want the tree to fall.
Several possibilities are permissible
when it comes to the sequence of
horizontal and diagonal cuts – observe
national regulations with regard to felling
technique.
The felling notch (C) determines the
direction of fall.
STIHL recommends the following
procedure:
NMake a horizontal cut – in doing so,
check the direction of fall with the
gunning sight
NStart a diagonal cut at an
approx. 45° angle
NCheck the felling notch – then
correct the felling notch, if
necessary
Important:
–Felling notch at right angle to
direction of fall
–As close to the ground as possible
–cut to a depth of approx. 1/5 to 1/3
of the diameter of the trunk
Sapwood cuts
With long-fibered wood, sapwood cuts
prevent the sapwood from splintering
when felling the trunk – saw both sides
of the trunk at the level of the felling
notch base to approx. 1/10 of the
diameter of the trunk – with thicker
trunks, not more than the width of the
guide bar.
Do not use sapwood cuts on diseased
trees.
001BA146 KN
001BA153 KN
001BA143 KN
C
C
001BA150 KN

MS 261 C-M
English
10
Felling cut
Give a warning cry of "timber!" before
making the felling cut.
NMake the felling cut (D) slightly
higher than the horizontal cut of the
felling notch
–Exactly horizontal
–approx. 1/10 of the diameter of the
trunk must remain standing
between the felling cut and the
notch = bridge
Insert wedges in the felling cut in time –
use only wedges made of wood, light
metal or plastic – no steel wedges. Steel
wedges damage the saw chain and can
cause kickback.
The bridge (E) functions as a hinge to
guide the tree to the ground.
–Never saw through the bridge while
felling – otherwise the tree with fall
in a direction other than the one
planned – risk of accident!
–With rotten trunks, leave a wider
bridge
Immediately before felling the tree, give
out a second warning cry of "timber!".
Thin trunks: simple fan cut
NEngage the spiked bumper behind
the hinge. Pivot the chain saw
around this point – only as far as the
bridge – the spiked bumper rolls
against the trunk.
001BA144 KN
D
D
001BA145 KN
E
E
001BA147 KN

MS 261 C-M
English
11
Large diameter trunks: sectioning
method
Use the sectioning method if the
diameter of the trunk exceeds the length
of the chain saw guide bar.
1. First cut
The nose of the guide bar should
enter the wood just behind the hinge
– hold the chain saw absolutely
horizontally and swing it as far as
possible – use the spiked bumper as
a pivot point – reposition the chain
saw as little as possible.
2. While repositioning for the next cut,
keep the guide bar fully engaged in
the cut in order to avoid an uneven
felling cut – apply the spiked bumper
again, etc.
3. Insert wedge (3)
4. Last cut: Position the chain saw as
for the simple fan cut – do not saw
through the bridge!
Special cutting techniques
Plunge-cutting and heartwood cutting
require training and experience.
Plunge-cutting
–for felling leaners
–for relieving cuts during bucking
–for DIY projects
Nuse a low kickback chain and be
especially cautious
1. Begin the cut by applying the lower
portion of the guide bar nose – do
not use the upper portion – risk of
kickback! Cut until the depth of the
kerf is twice the width of the guide
bar
2. Swing the saw slowly into the
plunge-cutting position – risk of
kickback or pushback!
3. Make the plunge cut very carefully –
danger of pushback!
Heartwood cut
–if the diameter of the trunk exceeds
twice the length of the guide bar
–if a piece of heartwood remains
uncut on large diameter trunks
001BA148 KN
1
4
2
12
3
001BA179 KN

MS 261 C-M
English
12
–with trees that are difficult to fell
(oak, beech), to make possible to
maintain the planned direction of fall
more precisely and prevent the
heartwood from splintering
–with soft deciduous trees to relieve
tension in horizontal trunks and
prevent slivers of wood from being
torn out of the trunk
NMake the plunge cut very carefully –
danger of pushback! – then swing in
the direction of the arrow
Limbing
Limbing may only be carried by persons
who have had special training. Persons
who are not experienced chain saw
users should carry out neither felling nor
limbing – risk of accidents!
–Use a low-kickback saw chain
–Support the chain saw as much as
possible
–Do not stand on the trunk when
limbing
–Do not cut with the guide bar nose
–Watch out for limbs that are under
tension
–Never cut several limbs at once
Sawing thin wood
–Use a sturdy, stable fixture –
sawhorse
–Do not hold the wood in place with
your foot
–Other persons must neither be
allowed to hold the wood nor help in
any other way
Lying or standing logs under tension
Always make the cuts in the correct
order (first compression side (1), then
tension side (2)), otherwise the chain
saw may pinch or kick back – risk of
injury!
NMake relieving cut in the
compression side (1)
NMake bucking cut in the tension
side (2)
If the bucking cut is made from the
bottom upwards (underbuck) – risk of
pushback!
NOTICE
Lying logs must not touch the ground at
the point where the cut is made –
otherwise the chain will be damaged.
Ripping
Sawing technique without use of the
spiked bumper – risk of pull-in – position
the guidebar at as shallow an angle as
possible – be especially careful –
increased risk of kickback!
1
001BA151 KN
2
1
001BA152 KN
2
001BA189 KN

MS 261 C-M
English
13
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
The machine must be serviced regularly.
Do not attempt any maintenance or
repair work not described in the
Instruction Manual. All other work should
be carried out by a servicing dealer.
STIHL recommends that maintenance
and repair work be carried out only by
authorized STIHL dealers. STIHL
dealers receive regular training and are
supplied with technical information.
Use only high-quality spare parts.
Otherwise, there may be a risk of
accidents or damage to the machine.
Contact a servicing dealer if in doubt.
STIHL recommends the use of genuine
STIHL spare parts. Such parts have
been optimized for the machine and the
user's requirements.
Before starting any maintenance or
repair work and before cleaning the
machine, always stop the engine – risk
of injury! – Exception: adjustment of
carburetor and idle speed.
Do not turn the engine over on the
starter with the spark plug boot removed
or the spark plug unscrewed – risk of fire
due to ignition outside the cylinder!
Do not service or store the machine near
a naked flame – risk of fire due to the
fuel.
Check fuel cap regularly for tightness.
Use only spark plugs that are in perfect
condition and have been approved by
STIHL – see "Specifications".
Inspect ignition lead (insulation in good
condition, secure connection).
Check that the muffler is in perfect
working condition.
Do not use the machine if the muffler is
damaged or missing – risk of fire! –
Hearing damage!
Never touch a hot muffler – risk of burns!
The condition of the antivibration
elements influences vibration behavior –
inspect antivibration elements
periodically.
Inspect chain catcher – replace if
damaged.
Switch off the engine
–to check the chain tension
–to retension the chain
–to change chains
–for remedying malfunctions
Observe sharpening instructions – for
safe and proper handling, always keep
the chain and guide bar in flawless
condition. Keep the chain properly
sharpened, tensioned and well
lubricated.
Change chain, guide bar and chain
sprocket in due time.
Check that the clutch drum is in perfect
working condition.
Always store fuel and chain lubricant
only in the specified type of containers
and ensure they are correctly labeled.

MS 261 C-M
English
14
Avoid direct skin contact with gasoline.
Do not inhale gasoline vapors – danger
to health!
In the event of a chain brake
malfunction, switch off the machine
immediately – risk of injury! Consult a
dealer – do not use the machine until the
malfunction has been remedied, see
"Chain Brake".
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.
STIHL is the only manufacturer in the
industry to produce its own chain saws,
guide bars, saw chains and chain
sprockets.
A cutting attachment consists of the saw
chain, guide bar and chain sprocket.
The cutting attachment that comes
standard is designed to exactly match
the chain saw.
–The pitch (t) of the saw chain (1),
chain sprocket and the nose
sprocket of the Rollomatic guide bar
must match.
–The drive link gauge (2) of the saw
chain (1) must match the groove
width of the guide bar (3).
If non-matching components are used,
the cutting attachment may be damaged
beyond repair after a short period of
operation.
Chain Scabbard
Your saw comes standard with a chain
scabbard that matches the cutting
attachment.
If guide bars of different lengths are
mounted to the saw, always use a chain
scabbard of the correct length which
covers the complete guide bar.
The length of the matching guide bars is
marked on the side of the chain
scabbard.
Guide bars longer than 90 cm require
one scabbard extension. Guide bars
longer than 120 cm require two
scabbard extensions.
Depending on the model, the scabbard
extension either comes standard with
the saw or is available as a special
accessory.
Cutting Attachment
001BA248 KN
1
2
3
a
001BA244 KN

MS 261 C-M
English
15
Fitting Chain Scabbard Extension
NPush the scabbard extension and
chain scabbard together – the
lugs (1) must engage in the chain
scabbard.
Removing the chain sprocket cover
NRotate the captive nuts
counterclockwise until they hang
loosely in the sprocket cover.
NRemove the sprocket cover with
captive nuts.
NTurn the screw (1)
counterclockwise until the tensioner
slide (2) butts against the left end of
the housing slot.
Disengaging the chain brake
NPull the hand guard towards the
front handle until there is an audible
click – the chain brake is
disengaged.
Fitting the chain
WARNING
Wear work gloves to protect your hands
from the sharp cutters.
NFit the chain – start at the bar nose.
001BA245 KN
1
1
Mounting the Bar and Chain
5902BA020 KN
1
2
001BA185 KN
001BA186 KN
143BA003 KN

MS 261 C-M
English
16
NFit the guide bar over the studs (1) –
the cutting edges on the top of the
bar must point to the right.
NEngage the peg of the tensioner
slide in the locating hole (2) –- place
the chain over the sprocket (3) at
the same time.
NTurn the tensioning
screw (4)clockwise until there is
very little chain sag on the
underside of the bar – and the drive
link tangs are engaged in the bar
groove.
NRefit the sprocket cover and tighten
the nuts only moderately by hand
(they are finally tightened after the
saw chain is tensioned).
NGo to chapter on "Tensioning the
Saw Chain"
Retensioning during cutting work:
NShut off the engine.
NLoosen the nuts.
NHold the bar nose up.
NUse a screwdriver to turn the
tensioning screw (1) clockwise until
the chain fits snugly against the
underside of the bar.
NWhile still holding the bar nose up,
tighten down the nuts firmly.
NGo to "Checking Chain Tension".
A new chain has to be retensioned more
often than one that has been in use for
some time.
NCheck chain tension frequently –
see chapter on "Operating
Instructions".
NShut off the engine.
NWear work gloves to protect your
hands.
NThe chain must fit snugly against
the underside of the bar and it must
still be possible to pull the chain
along the bar by hand.
NIf necessary, retension the chain.
A new chain has to be retensioned more
often than one that has been in use for
some time.
NCheck chain tension frequently –
see chapter on "Operating
Instructions".
31
1
24
001BA187 KN
Tensioning the Chain
1
133BA024 KN
Checking Chain Tension
143BA007 KN

MS 261 C-M
English
17
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 (R+M)/2.
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)
10.02(20)
5 0.10 (100)
10 0.20 (200)
15 0.30 (300)
20 0.40 (400)
25 0.50 (500)

MS 261 C-M
English
18
Preparing the machine
NBefore fueling, clean the cap and
the area around it to ensure that no
dirt falls into the fuel tank
NAlways position the machine so that
the cap is facing upwards
Opening
NRaise the grip until it is upright.
NTurn the cap counterclockwise
(about a quarter turn).
Marks on tank cap and fuel tank must
line up.
NRemove the cap.
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).
NFill up with fuel.
Closing
Grip must be vertical:
NFit the cap – marks on tank cap and
fuel tank must line up.
NPress the cap down as far as stop.
NWhile holding the cap depressed,
turn it clockwise until it engages in
position.
The marks on the tank cap and fuel tank
are then in alignment.
Fueling
001BA229 KN
001BA236 KN
001BA232 KN
001BA234 KN
001BA237 KN
001BA234 KN
001BA233 KN
001BA231 KN