STIHL MS 191 T Owner's Manual
STIHL MS 191 T
STIH)
Instruction Manual
Manual de instrucciones
Warning!
To reduce the risk of kickback injury use
STIHL reduced kickback bar and STIHL PMN
(3/8" Picco) or PM1 (3/8" Picco) chain
depending on sprocket pitch or other available
low kickback components.
Advertencia!
Para reducir el riesgo de lesionarse como
resultado de un culatazo, utilice la barra de
contragolpe reducido y la cadena PMN (Picco
de 3/8 pulg) o PM1 (Picco de 3/8 pulg) de
STIHL, dependiendo de la rueda dentada
usada y de otros componentes reductores de
contragolpe.
Read and follow all safety precautions in
Instruction Manual – improper use can cause
serious or fatal injury.
Lea y siga todas las precauciones de
seguridad dadas en el manual de
instrucciones – el uso incorrecto puede causar
lesiones graves o mortales.
Contents
English / USA
Guide to Using this Manual .............. 2
Some Important Safety
Precautions for Chain Saw Users ..... 3
Safety Precautions ........................... 5
Mounting the Bar and Chain ........... 22
Tensioning the Saw Chain .............. 23
Checking Chain Tension ................. 23
Fuel ................................................ 24
Fueling ............................................ 25
Printing inks contain vegetable oils;
paper can be recycled.
Chain Lubricant .............................. 25
Filling Chain Oil Tank ...................... 26
Checking Chain Lubrication ........... 26
Chain Brake .................................... 27
Information Before You Start .......... 28
Starting / Stopping the Engine ........ 28
Operating Instructions .................... 32
Taking Care of Guide Bar ............... 33
Cleaning the Air Filter ..................... 33
Motor Management ........................ 34
Adjusting the Carburetor ................ 34
Spark Arresting Screen*
in Muffler ......................................... 36
Checking the Spark Plug ................ 36
Replacing Starter Rope /
Printed on chlorine-free paper.© ANDREAS STIHL AG & Co. KG, 2003
Rewind Spring ................................ 37
Storing the Machine ........................ 38
Checking and Replacing
Chain Sprocket ............................... 38
Maintaining and Sharpening
Saw Chain ...................................... 39
Maintenance Chart ......................... 43
Parts and Controls .......................... 45
Specifications ................................. 47
* see “Guide to Using this Manual“
Special Accessories ....................... 48
Ordering Spare Parts ..................... 48
Maintenance and Repairs .............. 49
STIHL Incorporated Federal and
California Emission Control
Warranty Statement ........................ 50
This manual contains operating and
safety instructions for all STIHL
MS 191 T series power saws.
The STIHL MS 191 T chainsaw is
designed especially for tree
maintenance, tree surgery and other
cutting work in confined spaces.
Allow only persons who understand this
Manual to operate your chainsaw.
To receive maximum performance and
satisfaction from your STIHL chainsaw,
it is important that you read and
understand the maintenance and safety
precautions, starting on page 3, before
using your chainsaw. Contact your
STIHL dealer or the STIHL distributor for
your area if you do not understand any
of the instructions in this Manual.
!Warning!
Because a chainsaw is a high-speed
wood-cutting tool, some special safety
precautions must be observed as with
any other power saw to reduce the risk
of personal injury.
Careless or improper use may cause
serious or even fatal injury.
STIHL's philosophy is to continually
improve all of its products. As a result,
engineering changes and improvements
are made from time-to-time. If the
operating characteristics or the
appearance of your chainsaw differs
from those described in this Manual,
please contact your STIHL dealer for
information and assistance.
STIHl
0458 163 3021. M1. L3. PM. Printed in USA
1MS 191 T
English / USA
Guide to Using this Manual
Pictograms
All the pictograms attached to the
machine are shown and explained in
this manual.
The operating and handling instructions
are supported by illustrations.
Symbols in text
The individual steps or procedures
described in the manual may be marked
in different ways:
: Step or procedure without direct
reference to an illustration.
Description of step or procedure that
refers directly to the illustration and
contains item numbers that appear in
the illustration.
Example:
Loosen the screw (1)
Lever (2) ...
In addition to the operating instructions,
this manual may contain paragraphs
that require your special attention. Such
paragraphs are marked with the
symbols described below:
Warning where there is a risk of an
accident or personal injury or
serious damage to property.
Warning where there is a risk of
damaging the machine or individual
components.
Note or hint which is not essential
for using the machine, but may
improve the operator’s understanding of the situation and result
in better use of the machine.
Note or hint on correct procedure in
order to avoid damage to the
environment.
Equipment and features
This instruction manual refers to
several models with different
features. Components that are not
installed in all models and related
applications are marked thus *.
Such components are available as
special accessories from your
STIHL dealer.
Engineering improvements
STIHL’s philosophy is to continually
improve all of its products. As a result,
engineering changes and improvements
are made from time to time. If the
operating characteristics or the
appearance of your machine differ from
those described in this manual, please
contact your STIHL dealer for
assistance.
Therefore, we cannot be responsible for
changes, modifications or
improvements not covered in this
manual.
2
MS 191 T
Some Important Safety Precautions for Chain Saw Users
English / USA
A.
A Summary of Warnings on
kickback and other Selected
Risks – Taken Primarily from
ANSI B 175.1 (See also “Safety
Precautions“ section of this
Owner’s Manual)
!Warning!
Kickback may occur when the nose or
tip of the guide bar touches an object, or
when the wood closes in and pinches
the saw chain in the cut. Tip contact in
some cases may cause a lightning fast
reverse reaction, kicking the guide bar
up and back towards the operator.
Pinching the saw chain along the top of
the guide bar may push the guide bar
rapidly back towards the operator. Either
of these reactions may cause you to lose
control of the saw which could result in
serious personal injury.
Section 5.11 of ANSI B 175.1-2000 sets
certain performance and design criteria
related to chainsaw kickback. STIHL has
developed a color code system using
green and yellow to help you select a
powerhead, bar and chain combination
that complies with the kickback
requirements of the ANSI Standard.
See the sections entitled "Safety
Precautions" and "Specifications" of this
manual.
Do not rely exclusively upon the safety
devices built into your saw. As a
chainsaw user, you should take several
steps to keep your cutting jobs free from
accident or injury.
1. With a basic understanding of
kickback, you can reduce or
eliminate the element of surprise.
Sudden surprise contributes to
accidents.
2. Keep a good firm grip on the saw
with both hands, the right hand on
the rear handle, and the left hand on
the front handle, when the engine is
running. Use a firm grip with thumbs
and fingers encircling the chainsaw
handles. A firm grip will help you
reduce kickback and maintain
control of the saw. Don't let go.
3. Make sure the area in which you are
cutting is free from obstructions. Do
not let the nose of the guide bar
contact a log, branch, or any other
obstruction that could be hit while
you are operating the saw.
4. Cut at high engine speeds.
5. Do not overreach or cut above
shoulder height.
6. Follow manufacturer's sharpening
and maintenance instructions for
the saw chain.
7. Only use replacement bars and
chains specified by the
manufacturer or the equivalent.
8. Reduced kickback bars and low
kickback chains are designed to
reduce the risk of kickback injury.
Ask your STIHL dealer about these
devices.
B.
Other Safety Precautions
!Warning!
1. Do not operate a chainsaw with one
hand! Serious injury to the operator,
helpers, bystanders, or any
combination of these persons may
result from one-handed operation. A
chainsaw is intended to be used
with two hands.
2. Do not operate a chainsaw when
you are fatigued.
3. Use safety footwear; snug-fitting
clothing; protective gloves; and eye,
hearing, and head protection
devices.
3MS 191 T
English / USA
4. Use caution when handling fuel.
Move the chainsaw at least 10 feet
(3 m) from the fueling point before
starting the engine.
5. Do not allow other persons to be
near the chainsaw when starting or
cutting with the chainsaw. Keep
bystanders and animals out of the
work area.
6. Do not start cutting until you have a
clear work area, secure footing, and
a planned retreat path from the
falling tree.
7. Keep all parts of your body away
from the saw chain when the engine
is running.
8. Before you start the engine, make
sure that the saw chain is not
contacting anything.
9. Carry the chainsaw with the engine
stopped, the guide bar and saw
chain to the rear, and the muffler
away from your body.
10. Do not operate a chainsaw that is
damaged, improperly adjusted, or
not completely and securely
assembled. Be sure that the saw
chain stops moving when the
throttle trigger is released.
11. Shut off the engine before setting
the chainsaw down.
12. Use extreme caution when cutting
small size brush and saplings
because slender material may catch
the saw chain and be whipped
toward you or pull you off balance.
13. When cutting a limb that is under
tension be alert for springback so
that you will not be struck when the
tension in the wood fibers is
released.
14. Keep the handles dry, clean, and
free of oil or fuel mixture.
15. Operate the chainsaw only in wellventilated areas.
16. Do not operate a chainsaw in a tree
unless you have been specifically
trained to do so.
17. All chainsaw service, other than the
items listed in the Owner's Manual
maintenance instructions, should be
performed by competent chainsaw
service personnel.(For example, if
improper tools are used to remove
the flywheel or if an improper tool is
used to hold the flywheel in order to
remove the clutch, structural
damage to the flywheel could occur
and could subsequently cause the
flywheel to burst).
18. When transporting your chainsaw,
use the appropriate chain guard
(scabbard).
Other important safety precautions are
contained in the body of the Owner's
Manual especially in the General Safety
Precautions.
Note:
When using a chainsaw for logging
purposes, refer to the Code of Federal
Regulations, Parts 1910 and 1928.
4
MS 191 T
Safety Precautions
English / USA
This top handle chainsaw is designed
specifically for tree surgery and
maintenance in the tree.
Due to the special
compact handle design
(closely spaced
handles), there is an
increased risk of injury
from loss of control.
(Cut injuries due to uncontrolled reactive
forces of the chainsaw or leg injuries due
to the saw “dropping” at the end of the
cut.)
For this reason these
special chainsaws
should be used only for
work in a tree by
persons who are trained
in special cutting and
working techniques and who are
properly secured (lift bucket, ropes,
safety harness).
Regular chainsaws (with wider spaced
handles) are recommended for all other
cutting work at ground level.
!Warning!
Working in a tree requires the use of
special cutting and working techniques
which must be observed in order to
reduce the increased risk of personal
injury.
Never work in a tree unless you have
received specific, professional training
for such work, including training in the
use of the safety and other climbing
equipment, such as harnesses, ropes,
belts, climbing irons, snap hooks,
carabiners, etc.
!Warning!
The use of any chainsaw
may be hazardous. The
saw chain has many
sharp cutters. If the
cutters contact your flesh,
they will cut you, even if the chain is not
moving. At full throttle, the chain speed
can reach 45 mph (20 m/s).
It is important that you
read, fully understand and
observe the following
safety precautions and
warnings.
Read the owner's manual and the safety
instructions periodically.
!Warning!
Reactive forces, including kickback, can
be dangerous. Careless or improper use
of any chainsaw may cause serious or
fatal injury. Pay special attention to the
section on reactive forces.
All safety precautions that are generally
observed when working with an axe or a
hand saw also apply to the operation of
chainsaws. However, because a
chainsaw is a high-speed, fast-cutting
power tool, special safety precautions
must be observed to reduce the risk of
personal injury.
Have your STlHL dealer show you how
to operate your chainsaw. Observe all
applicable local safety regulations,
standards and ordinances.
!Warning!
Minors should never be allowed to use a
chainsaw. Bystanders, especially
children, and animals should not be
allowed in the area where a chainsaw is
in use. Never let the saw run
unattended.
Do not lend or rent your chainsaw
without the owner's manual. Be sure that
anyone using your saw reads and
understands the information contained
in this manual.
Different models may have different
parts and controls. See the appropriate
section of your owner's manual for a
description of the controls and function
of the parts of your model saw. Safe use
of a chainsaw involves
1. the operator
2. the saw
3. the use of the saw.
5MS 191 T
English / USA
THE OPERATOR
Physical Condition
You must be in good physical condition
and mental health and not under the
influence of any substance (drugs,
alcohol) which might impair vision,
dexterity or judgment.
Do not operate a chainsaw when you
are fatigued. Be alert - If you get tired
while operating your chainsaw, take a
break. Tiredness may result in loss of
control. Working with any chainsaw can
be strenuous. If you have any condition
that might be aggravated by strenuous
work, check with your doctor before
operating a chainsaw.
!Warning!
Prolonged use of chainsaws (or other
machines) exposing the operator to
vibrations may produce whitefinger
disease (Raynaud's phenomenon) or
carpal tunnel syndrome.
These conditions reduce the hand's
ability to feel and regulate temperature,
produce numbness and burning sensations and may cause nerve and
circulation damage and tissue necrosis.
All factors which contribute to whitefinger disease are not known, but cold
weather, smoking and diseases or
physical conditions that affect blood
vessels and blood transport, as well as
high vibration levels and long periods of
exposure to vibration are mentioned as
factors in the development of whitefinger
disease. In order to reduce the risk of
whitefinger disease and carpal tunnel
syndrome, please note the following:
– Many STIHL models are available
with an anti-vibration (“AV”) system
designed to reduce the transmission of vibrations created by the
engine and cutting attachment to
the operator's hands. An AV system
is recommended for those persons
using chainsaws on a regular or
sustained basis.
– Wear gloves and keep your hands
warm. Heated handles, which are
available on most STIHL powerheads, are recommended for cold
weather use.
– Keep the saw chain sharp and the
saw, including the AV system, well
maintained. A dull chain will
increase cutting time, and pressing
a dull chain through wood will
increase the vibrations transmitted
to your hands. A saw with loose
components or with damaged or
worn AV buffers will also tend to
have higher vibration levels.
– Maintain a firm grip at all times, but
do not squeeze the handles with
constant, excessive pressures, take
frequent breaks.
All the above mentioned precautions do
not guarantee that you will not sustain
whitefinger disease or carpal tunnel
syndrome. Therefore, continual and
regular users should monitor closely the
condition of their hands and fingers.
If any of the above symptoms appear,
seek medical advice immediately.
!Warning!
The ignition system of your unit
produces an electromagnetic field of a
very low intensity. This field may interfere with some pacemakers. To reduce
the risk of serious or fatal injury, persons
with pacemaker should consult their
physician and the pacemaker manufacturer before operating this tool.
Proper Clothing
Clothing must be sturdy
and snug-fitting, but allow
complete freedom of
movement. Avoid loosefitting jackets, scarves,
neckties, jewelry, flared or
cuffed pants, unconfined long hair or
anything that could be come entangled
with the saw or brush. Wear overalls or
jeans with reinforced cut retardant
inserts or cut retardant chaps.
6
MS 191 T
English / USA
Protect your hands with
gloves when handling
saw and saw chain.
Heavy-duty, nonslip
gloves improve your grip
and protect your hands.
Good footing is most
important in chainsaw
work . Wear sturdy boots
with nonslip soles. Steeltoed safety boots suitable
for climbing in trees are
recommended. To reduce the risk of
injury to your eyes never operate a
chainsaw unless wearing goggles or
properly fitted safety glasses with
adequate top and side protection
complying with ANSI Z 87.1.
Wear an approved safety
hard hat to protect your
head.
Chainsaw noise may
damage your hearing.
Always wear sound barriers (ear plugs
or ear mufflers) to protect your hearing.
Continual and regular users should have
their hearing checked regularly. Any
crew member in the cutting area should
also wear proper protective clothing,
especially hard hats, to protect their
heads.
THE SAW
For illustrations and definitions of the
parts of the chainsaw see the chapter on
“Main Parts of Saw”.
!Warning!
Never modify a chainsaw in any way.
Only attachments and parts supplied by
STIHL or expressly approved by STIHL
for use with the specific STIHL saw
models are authorized. Although certain
unauthorized attachments are useable
with the STIHL powerhead, their use
may, in fact, be extremely dangerous.
THE USE OF THE SAW
Transporting the chainsaw
!Warning!
Always stop the engine before putting a
chainsaw down or carrying it. Carrying a
chainsaw with the engine running is
extremely dangerous. Accidental
acceleration of the engine can cause the
chain to rotate.
001BA061 LÄ
By hand: When carrying your saw by
hand, the engine must be stopped and
the saw must be in the proper position.
Grip the top handle and place the muffler
away from the body. The chain guard
(scabbard) should be over the chain and
guide bar, which should point
backwards.
By vehicle: When transporting in a
vehicle, keep chain and bar covered with
the chain guard. Properly secure your
saw to prevent turnover, fuel spillage
and damage to the saw.
7MS 191 T
English / USA
Preparation for the use of the saw
Take off the chain guard and inspect for
safety in operation. For assembly, follow
the procedure described in the chapter
“Mounting the Bar and Chain” of your
owner's manual.
STIHL Oilomatic chain, guide bar and
sprocket must match each other in
gauge and pitch. Before replacing any
bar and chain, see the sections on
“Specifications”, kickback and the
ANSI B 175.1-2000 chainsaw kickback
standard in this manual. Since longer
bars add weight and may be more
difficult to control, select the shortest bar
that will meet your cutting needs. Check
the throttle trigger and throttle trigger
interlock for smooth action - throttle
trigger must return automatically to idle
position. The master control lever /stop
switch must move easily to stop and $.
Your chainsaw is equipped with a chain
catcher. It is designed to reduce the risk
of personal injury in the event of a
thrown or broken chain. From time to
time the catcher may be damaged or
removed.
To reduce the risk of personal injury, do
not operate a chainsaw with a damaged
or missing catcher. Inspect antivibration
buffers periodically. Replace damaged,
broken or excessively worn buffers
immediately, since they may result in
loss of control of the saw.
A “sponginess” in the feel of the saw,
increased vibration or increased
“bottoming” during normal operation
may indicate damage, breakage or
excessive wear. Buffers should always
be replaced in sets. If you have any
questions as to whether the buffers
should be replaced, consult your STIHL
servicing dealer.
Fueling
Your STIHL chainsaw uses an oil-gasoline mixture for fuel (see chapter “Fuel”
of your owner's manual).
!Warning!
Gasoline is an extremely flammable fuel.
If spilled or ignited by a spark or other
ignition source, it can cause fire and
serious burn injury or property damage.
Use extreme caution when handling
gasoline or fuel mix.
Do not smoke or bring any
fire or flame near the fuel
or the chainsaw. Note that
combustible fuel vapors
may be vented from the
fuel system.
8
MS 191 T
English / USA
Fueling Instructions
Fuel your chainsaw in well-ventilated
areas, outdoors only. Always shut off the
engine and allow it to cool before
refueling. Gasoline vapor pressure may
build up inside the fueltank of a two cycle
engine depending on the fuel used, the
weather conditions, and the venting
system of the tank. In order to reduce the
risk of burns or other personal injury
from escaping gas vapor and fumes,
remove the fuel filler cap on the STIHL
product carefully so as to allow any
pressure build-up in the tank to release
slowly. Never remove fuel filler cap while
the engine is running.
Select bare ground for fueling and move
at least 10 feet (3 m) from fueling spot
before starting the engine.
Wipe off any spilled fuel before starting
your saw, and check for leakage.
!Warning!
Check for fuel leakage while refueling
and during operation. If fuel or oil
leakage is found, do not start or run the
engine until leak is fixed and spilled fuel
has been wiped away. Take care not to
get fuel on your clothing. If this happens,
change your clothing immediately.
!Warning!
Unit vibrations can cause an improperly
tightened fuel cap to loosen or come off
and spill quantities of fuel. In order to
reduce risk of fuel spillage and fire,
tighten the fuel cap by hand with as
much force as possible.
The screwdriver end of
the STIHL combination
wrench or other similar
tool can be used as an aid
in tightening slotted fuel
caps.
Starting
The chain brake must be engaged when
starting the saw.
!Warning!
Your chainsaw is a one-person saw.
Do not allow other persons to be near
the running chainsaw. Start and operate
your saw without assistance. For
specific starting instructions, see the
appropriate section of the owner's
manual. Proper starting methods reduce
the risk of injury. Do not drop start.
001BA062 LÄ
This method is very dangerous because
you may lose control of the saw. Place
the chainsaw on firm ground or other
solid surface in a clear area. Maintain
good balance and secure footing.
!Warning!
Be sure that the guide bar and chain are
clear of you and all other obstructions
and objects, including the ground. When
the engine is started, the engine speed
with the starting throttle lock engaged
will be fast enough for the clutch to
engage the sprocket and turn the chain,
if the chainbrake is not engaged. If the
running chain near the upper quadrant
of the bar nose touches any object, it
may cause kickback to occur (see
section on reactive forces).
9MS 191 T
English / USA
To reduce this risk, always engage the
chain brake before starting. Never
attempt to start the chainsaw when the
guide bar is in a cut or kerf. When you
pull the starter grip, do not wrap the
starting rope around your hands. Do not
allow the grip to snap back, but guide the
starter rope slowly back to permit the
rope to rewind properly. Failure to follow
this procedure may result in injury to
hand or fingers and may damage the
starter mechanism.
Important adjustments
!Warning!
To reduce the risk of personal injury from
loss of control or contact with the
running chain, do not use a saw with
incorrect idle adjustment. At correct idle
speed, the chain should not rotate. For
directions to adjust idle speed, see the
appropriate section of your owner's
manual . If you cannot set the correct
idle speed, have your STIHL dealer
check your saw and make proper
adjustments or repairs.
!Warning!
Proper tension of the chain is extremely
important. In order to avoid improper
setting, the tensioning procedure must
be followed as described in your
manual. Always make sure the
hexagonal nut(s) for the sprocket cover
is (are) tightened securely after
tensioning the chain. Never start the saw
with the sprocket cover loose.
Check chain tension once more after
having tightened the nut(s) and
thereafter at regular intervals (whenever
the saw is shut off). If the chain becomes
loose while cutting, shut off the engine
and then tighten. Never try to tighten the
chain while the engine is running! After
adjusting a chain, start the saw, let the
engine run for a while, then switch
engine off and recheck chain tension.
Working Conditions
!Warning!
The chainsaw produces
poisonous exhaust gases
as soon as the engine
starts. These gases may
be odorless and invisible. Operate your
chainsaw outdoors only in a well
ventilated area.
To reduce the risk of serious or fatal
injury from inhaling such poisonous
gases, never work indoors or in
enclosed spaces since you may inhale
poisonous fumes.
!Warning!
Use of this product (including
sharpening the saw chain) can generate
dust, mists and fumes containing
chemicals known to cause respiratory
disease, cancer, birth defects, or other
reproductive harm. If you are unfamiliar
with the risks associated with the
particular dust, mist or fume at issue,
consult your employer, governmental
agencies such as OSHA and NIOSH
and other sources on hazardous
materials. California and some other
authorities, for instance, have published
lists of substances known to cause
cancer, reproductive toxicity, etc.
Control dust (such as sawdust), mists
(such as oil mist from chain lubrication)
and fumes at the source where possible.
In this regard use good work practices
and follow the recommendations of
OSHA / NIOSH and occupational and
trade associations.
10
MS 191 T
English / USA
When the inhalation of toxic dust, mists
and fumes cannot be eliminated, the
operator and any bystanders should
always wear a respirator approved by
NIOSH / MSHA for the type substance at
issue.
!Warning!
Breathing asbestos dust is dangerous
and can cause severe or fatal injury,
respiratory illness or cancer. The use
and disposal of asbestos containing
products have been strictly regulated by
OSHA and the Environmental Protection
Agency. Do not cut or disturb asbestos,
asbestos containing products (e.g.
asbestos containing drywall or other
construction products), or products such
as pipes which are wrapped or covered
with asbestos insulation. If you have any
reason to believe that you might be
cutting asbestos, immediately contact
your employer or a local OSHA
representative.
Operate the saw under good visibility
and daylight conditions only. Don't work
alone. Keep within calling distance of
others in case help is needed. Helpers at
the cutting site must also wear protective
clothing (such as hard hat) and stand
well clear of the branches being cut.
Be particularly cautious and alert while
wearing hearing protection because
such equipment may restrict your ability
to hear sounds indicating danger (calls,
signals, warnings, etc.).
!Warning!
Take extreme care in wet and freezing
weather (rain, snow, ice). Put off the
work when the weather is windy, stormy
or rainfall is heavy.
!Warning!
Clear the area where you are working.
Avoid stumbling on obstacles such as
stumps, roots or rocks and watch out for
holes or ditches. Be extremely cautious
when working on slopes or uneven
ground. There is increased danger of
slipping on freshly debarked logs.
Operate your chainsaw so that it
produces a minimum of noise and
emissions - do not run engine
unnecessarily and accelerate the engine
only for cutting. In order to keep control
of your saw, always maintain a firm
foothold. Never work on a ladder, or on
any other insecure support. Never use
the saw above shoulder height. Never
attempt to operate the saw with one
hand.
!Warning!
Never work in a tree unless you have
received specific, professional training
for such work, are properly secured
(such as lift bucket or tackle and harness
system), have both hands free for
operating the chainsaw in a cramped
environment and have taken
precautions to avoid injury from falling
obstacles.
11MS 191 T
English / USA
The use of climbing aids, such as spikes
or climbing irons, also require special
training. Always secure the chainsaw
with a rope (tie to hinged ring) and attach
it to the lifeline. Cordon off the work area
in order to reduce the risk of injuries and
damage to bystander or property (e.g.
motor vehicles) property from falling
branches.
001BA081 KN
001BA082 KN
!Warning!
To reduce risk of
electrocution, take extra
precautions when cutting
near power lines. Have
the power switched off
before starting cutting
work in the immediate vicinity of power
lines.
Cutting Instructions
Always hold the saw firmly with both
hands when the engine is running. Place
your left hand on the front handle bar
and your right hand on rear handle and
throttle trigger. Left-handers should
follow these instructions too. Wrap your
fingers tightly around the handles,
keeping the handles cradled between
your thumb and forefinger. With your
hands in this position, you can best
oppose and absorb the push, pull and
kickback forces of your saw without
losing control (see section on reactive
forces). Make sure your chainsaw
handles and grip are in good condition
and free of moisture, pitch, oil or grease.
!Warning!
To reduce the risk
of serious or fatal
injury to the
operator or
bystanders, never
use the saw with one hand.
You cannot control reactive forces and
you may lose control of the saw, which
can result, e.g., in the bar and chains
kating or bouncing along the limb or log.
This rule against one handed operation
applies also for those compact saws
designed for use in confined spaces.
Position the chainsaw in such a way that
your body is clear of the cutting attachment whenever the engine is running.
Stand to the left of the plane of the
cutting attachment.
!Warning!
Do not operate your chainsaw with the
starting throttle lock engaged. Cutting
with the starting throttle lock engaged
does not permit the operator proper
control of the saw or chain speed. Begin
cutting with the saw at full throttle,
engage the bumper spike firmly in the
wood (if possible) and then continue
cutting. Always work with the bumper
spike so that you have better control of
the saw. If you work without the bumper
spike saw may pull you forwards
suddenly.
12
MS 191 T
English / USA
!Warning!
Never touch a chain with your hand or
any part of your body when the engine is
running, even when the chain is not
rotating. The chain continues to rotate
for a short period after the throttle trigger
is released.
!Warning!
The muffler and other parts of the engine
(e.g. fins of the cylinder, spark plug)
become hot during operation and remain
hot for a while after stopping the engine.
To reduce risk of burns do not touch the
muffler and other parts while they are
hot.
!Warning!
Do not cut any material other than wood
or wooden objects. Use your chainsaw
for cutting only. It is not designed for
prying or shoveling away limbs, roots or
other objects. When sawing, make sure
that the saw chain does not touch any
foreign materials such as rocks, fences,
nails and the like. Such objects may be
flung off, damage the saw chain or
cause the saw to kickback.
Do not underbuck freely hanging limbs
because the chain may get pinched and
cause kickback and loss of control. Take
special care when cutting shattered
wood because of the risk of injury from
slivers being caught and thrown in your
direction.
Don't put pressure on the saw when
reaching the end of a cut. The pressure
may cause the bar and rotating chain to
pop out of the cut or kerf, go out of
control and strike the operator or some
other object. If the rotating chain strikes
some other object, a reactive force may
cause the moving chain to strike the
operator.
001BA034 KN
To r e duc e risk of falls, keep rotating
saw chain well clear of harness and
lifelines to avoid them being severed. It
is essential to use a double lifeline.
Check condition of harness, belts and
ropes at regular frequent intervals.
Always pull the saw out of the cut with
the chain running.
After finishing a cut, activate the chain
brake to lock the chain or shut down the
engine before moving the saw to
another position in the tree.
13MS 191 T
English / USA
Reactive forces including kickback
!Warning!
Reactive forces may occur any time the
chain is rotating. Reactive forces can be
dangerous! In any chainsaw, the
powerful force used to cut wood can be
reversed (and work against the
operator). If the rotating chain is
suddenly stopped by contact with any
solid object like a log or branch or is
pinched, the reactive forces may occur
instantly.
These reactive forces may result in loss
of control which may, in turn, cause
serious or fatal injury. An understanding
of the causes of these reactive forces
may help you avoid loss of control.
The most common reactive forces are
– kickback,
– pushback,
– pull-in.
Kickback
.Kickback may occur
when the moving saw
chain near the upper
quadrant of the bar nose
contacts a solid object or
is pinched.
The reaction of the cutting force of the
chain causes a rotational force on the
chainsaw in the direction opposite to the
chain movement. This may fling the bar
001BA035 KN
up and back in an uncontrolled arc
mainly in the plane of the bar. Under
some cutting circumstances the bar
moves towards the operator, who may
suffer severe or fatal injury.
Kickback may occur, for example, when
the chain near the upper quadrant of the
bar nose contacts the wood or is pinched
during limbing or when it is incorrectly
used to begin a plunge or boring cut.
The greater the force of the kickback
reaction, the more difficult it becomes for
the operator to control the saw. Many
factors influence the occurrence and
force of the kickback reaction. These
include chain speed, the speed at which
the bar and chain contact the object, the
angle of contact, the condition of the
chain and other factors.
The type of bar and saw chain you use
is an important factor in the occurrence
and force of the kickback reaction. Some
STIHL bar and chain types are designed
to reduce kickback forces. STIHL
recommends the use of reduced
kickback bars and low kickback chains.
ANSI B 175.1-2000 chainsaw
kickback standard
Section 5.11 of ANSI standard
B 175.1-2000 sets certain performance
and design criteria related to chainsaw
kickback.
To comply with section 5.11 of ANSI
B 175.1-2000:
a) saws with a displacement of less
than 3.8 cubic inches
– must, in their original condition,
meet a 45° computer derived
kickback angle when equipped with
certain cutting attachments.
– and must be equipped with at least
two devices to reduce the risk of
kickback injury, such as a
chainbrake, low kickback chain,
reduced kickback bar, etc.
14
MS 191 T
English / USA
b) saws with a displacement of 3.8
cubic inches and above
– must be equipped with at least one
device designed to reduce the risk
of kickback injury such as a chain
brake, low kickback chain, reduced
kickback bar, etc.
The computer derived angles for saws
below 3.8 cubic inch displacement are
measured by applying a computer
program to test results from a kickback
test machine.
!Warning!
The computer derived angles of § 5.11
of ANSI B 175.1-2000 may bear no
relationship to actual kickback bar
rotation angles that may occur in real life
cutting situations. Compliance with §
5.11 of ANSI B 175.1-2000 does not
automatically mean that in a real life
kickback the bar and chain will rotate at
most 45°.
!Warning!
In order for powerheads below 3.8 cubic
inch displacement to comply with the
computed kickback angle requirements
of § 5.11 of ANSI B 175.1-2000 use only
the following cutting attachments:
– bar and chain combinations listed
as complying in the “Specifications”
section of the owner's manual or
– other replacement bar and chain
combinations marked in
accordance with the standard for
use on the powerhead or
– replacement chain designated “low
kickback saw chain”
1)
.
!Warning!
There are potential powerhead and bar
combinations with which low kickback
saw chains can be used which have not
been specifically certified to comply with
the 45° computer derived kickback
angle of § 5.11 of ANSI B 175.1-2000.
Some low kickback chains have not
been tested with all powerhead and bar
combinations. STIHL offers a variety of
bars and chains. STIHL reduced
kickback bars and low kickback chains
are designed to reduce the risk of
kickback injury. Other chains are
designed to obtain higher cutting
efficiency or sharpening ease but may
result in higher kickback tendency.
STIHL has developed a color code
system to help you identify the STIHL
reduced kickback bars and low kickback
chains. Cutting attachments with green
warning decals or green labels on the
packaging are designed to reduce the
risk of kickback injury.
1)
“Low kickback saw chain” is a chain
which has met the kickback
performance requirements of § 5.11.2.4
of ANSI B 175.1-2000 (Safety
Requirements for Gasoline-Powered
Chain Saws) when tested on a selected
representative sample of chainsaws
below 3.8 cubic inch displacement
specified in ANSI B 175.1-2000.
15MS 191 T
English / USA
The matching of green decaled
powerheads under 3.8 cubic inch
displacement with green labeled bars
and green labeled chains gives
compliance with the computed kickback
angle requirements of ANSI B 175.12000 when the products are in their
original condition. Products with yellow
decals or labels are for users with
extraordinary cutting needs and
experience and specialized training for
dealing with kickback.
STIHL recommends the use of its
green labeled reduced kickback bars,
green labeled low kickback chains
and a STIHL Quickstop chain brake
for both experienced and in experienced chainsaw users.
Please ask your STlHL dealer to
properly match your powerhead with the
appropriate bar/chain combinations to
reduce the risk of kickback injury. Green
labeled bars and chains are
recommended for all powerheads. See
your “STIHL Bar and Chain Information”
leaflet for details.
!Warning!
Use of other, non-listed bar/chain
combinations may increase kickback
forces and increase the risk of kickback
injury. New bar/chain combinations may
be developed after publication of this
literature, which will, in combination with
certain powerheads, comply with § 5.11
of ANSI B 175.1-2000. Check with your
STI HL dealer for such combinations.
!Warning!
Do not mount a bow guide on any STIHL
chainsaw.
Any chainsaw equipped with a bow
guide is potentially very dangerous. The
risk of kickback is increased with a bow
guide because of the increased kickback
contact area. Low kickback chain will not
significantly reduce the risk of kickback
injury when used on a bow guide.
001BA036 KN
Devices for reducing the risk of
kickback injury
STIHL recommends the use of the
STIHL Quickstop chain brake on your
power-head with green labeled reduced
kickback bars and low kickback chains.
Quickstop™ chain brake:
STIHL has developed a chain stopping
system designed to reduce the risk of
injury in certain kickback situations. It is
called a Quickstop chain brake. The
Quickstop is available as standard
equipment on your STIHL chainsaw and
is available for installation on most older
STIHL saws. Ask your dealer to retrofit
your older model saw with a chain brake.
When a kickback occurs, the guide bar
may rotate around the front handle.
16
MS 191 T
English / USA
If the cutting position is such that the
operator's left hand is gripping the front
handle behind the hand guard, and if the
left hand rotates around the front handle
and contacts the front hand guard, which
is the Quickstop activating lever, this
contact will activate the Quickstop . The
chain brake on most new model STIHL
chainsaws can also be activated by
inertia. See the chapter entitled “Chain
Brake” of your owner's manual.
!Warning!
Never operate your chainsaw without a
front hand guard. In a kickback situation
this guard helps protect your left hand or
other parts of your body. In addition,
removal of the hand guard on a saw
equipped with a chain brake will
deactivate the chain brake.
!Warning!
No Quickstop or other chain brake
device prevents kickback. These
devices are designed to reduce the risk
of kickback injury, if activated, in certain
kickback situations. In order for the
Quickstop to reduce the risk of kickback
injury, it must be properly maintained
and in good working order. See the
chapter entitled “Chain Brake” and
“Maintenance, Repair and Storing” of
your owner's manual. In addition, there
must be enough distance between the
bar and the operator to ensure that the
Quickstop has sufficient time to activate
and stop the chain before potential
contact with the operator.
!Warning!
An improperly maintained chain brake
may increase the time needed to stop
the chain after activation, or may not
activate at all. If the chain brake does not
function correctly, stop using the saw
immediately. Take the saw to your local
STIHL servicing dealer! Do not use the
saw until the problem has been rectified
(see the section “Chain Brake”).
!Warning!
Never run the chainsaw above idle
speed for more than 3 seconds when the
chain brake is engaged or the chain is
pinched or otherwise caught in the cut.
Clutch slippage can cause excessive
heat, leading to severe damage of the
motor housing, clutch and oiler
component and may interfere with the
operation of the chain brake. If clutch
slippage in excess of 3 seconds has
occured, allow the motor housing to cool
before proceeding and check the
operation of your chain brake as
described in the chapter entitled “Chain
Brake”. Make also sure that the chain is
not turning at idle speed (see above
“Important Adjustments”).
Reduced kickback bar
STIHL green labeled reduced kickback
bars are designed to reduce the risk of
kickback injury when used with STIHL
green labeled low kickback chains.
!Warning!
When used with other, more aggressive
chains, these bars may be less effective
in reducing kickback, and may result in
higher kickback forces.
Low kickback chain
Some types of saw chain have specially
designed components to reduce the
force of nose contact kickback. STIHL
has developed low kickback chain for
your powerhead.
17MS 191 T
English / USA
!Warning!
A dull or improperly sharpened chain
may reduce or negate the effects of the
design features intended to reduce
kickback energy. Improper lowering or
sharpening of the depth gauges or
shaping of the cutters may increase the
chance and the potential energy of a
kickback. Always cut with a properly
sharpened chain.
!Warning!
Reduced kickback bars and low
kickback chains do not prevent
kickback, but they are designed to
reduce the risk of kickback injury. They
are available from your STIHL dealer.
!Warning!
Even if your saw is equipped with a
Quickstop chain brake, a reduced
kickback bar and/or low kickback chain,
this does not eliminate the risk of injury
by kickback. Therefore, always observe
all safety precautions to avoid kickback
situations.
To avoid kickback
The best protection from personal injury
that may result from kickback is to avoid
kickback situations:
1. Hold the chainsaw firmly with both
hands and maintain a secure grip.
2. Be aware of the location of the guide
bar nose at all times.
3. Never let the nose of the guide bar
contact any object. Do not cut limbs
with the nose of the guide bar. Be
especially careful when cutting
small, tough limbs, small size brush
and saplings which may easily catch
the chain.
4 Don't overreach.
5. Don't cut above shoulder height.
6. Begin cutting and continue at full
throttle.
7. Cut only one log at a time.
8. Use extreme caution when re-
entering a previous cut.
9. Do not attempt to plunge cut if you
are not experienced with these
cutting techniques.
10. Be alert for shifting of the log or
other forces that may cause the cut
to close and pinch the chain.
11. Maintain saw chain properly. Cut
with a correctly sharpened, properly
tensioned chain at all times.
12. Stand to the side of the cutting path
of the chainsaw.
A
A = Pull-in:
Pull-in occurs when the chain on the
bottom of the bar is suddenly stopped.
The chain on the bottom of the bar stops
when it is pinched, caught or encounters
a foreign object in the wood. The
reaction of the chain pulls the saw
forward and may cause the operator to
lose control. Pull-in frequently occurs
when the bumper spike of the saw is not
held securely against the tree or limb
and the chain is not rotating at full speed
before it contacts the wood.
!Warning!
Use extreme caution when cutting small
size brush and saplings which may
easily catch a chain and pull you off
balance.
To avoid pull-in
1. Always start a cut with the chain
rotating at full speed and the
bumper spike in contact with the
wood.
2. Pull-in may also be prevented by
using wedges to open the kerf or
cut.
001BA037 KN
18
MS 191 T
English / USA
B
B = Pushback:
Pushback occurs when the chain on the
top of the bar is suddenly stopped when
it is pinched, caught or encounters a
foreign object in the wood. The reaction
of the chain drives the saw straight back
toward the operator and may cause loss
of saw control. Pushback frequently
occurs when the top of the bar is used
for cutting.
To avoid pushback
1. Be alert to forces or situations that
may cause material to pinch the top
of the chain.
2. Do not cut more than one log at a
time.
3. Do not twist the saw when withdrawing the bar from a plunge cut or
underbuck cut because the chain
can pinch.
!Warning!
This chainsaw equipped with a top
handle is designed specifically for tree
surgery and maintenance. Due to the
special handle design (closely spaced
handles), there is an increased risk of
injury from loss of control.
001BA038 KN
For this reason this special chainsaw
should be used only for work in a tree by
persons trained in special cutting and
working techniques. This type of
chainsaw is not designed for cutting
work on the ground, such as felling and
bucking. Because this chainsaw is not
intended for use on the ground, this
manual does not contain instructions for
felling or for limbing and bucking felled
trees. For instructions on these
techniques when using other STIHL
chainsaw models, see the owners’
manuals for these saws or the STIHL
Chainsaw Safety Manual, which is
available free from your STIHL servicing
dealer.
A
1
2
B
B
2
1
A
Cutting techniques:
– Cut straight through thin limbs.
– Support and secure heavy
branches with ropes.
– Limbs under strain create risk of
pinching! Always start relieving cut
(1) at compression side (A). Then
make bucking cut (2) at tension side
(B).
– If the saw pinches, stop the engine
and remove it from the limb.
If conditions allow, work from a lift
bucket.
001BA066 KN
001BA067 KN
19MS 191 T
English / USA
!Warning!
Be extremely cautious when cutting
limbs under tension (spring poles). The
limbs could spring back toward the
operator and cause loss of control of the
saw and severe or fatal injury to the
operator. Only properly trained
professionals should work in an area
where the trees and limbs are tangled.
Working in blowdown areas is extremely
hazardous.
MAINTENANCE, REPAIR AND
STORAGE
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 claim
warranty for a component which has
not been serviced or maintained
properly or if nonapproved
replacement parts were used, STIHL
may deny warranty.
Never operate a chainsaw that is
damaged, improperly adjusted or not
completely or securely assembled.
Follow the maintenance and repair
instructions in the appropriate section of
your owner's manual, especially those in
the chapters “Mounting the bar and
chain”, “Maintaining and Sharpening”,
and “Chain Brake”.
Only parts supplied or approved by
STIHL for the specific model are
authorided.
Although other parts may fit, their use, in
fact, may be extremely dangerous.
!Warning!
Always stop the engine and ensure that
the chain is stopped before making any
adjustments, maintenance or repair
work, changing the saw chain or
cleaning the saw. Do not attempt any
maintenance or repair work not
described in your owner's manual. Have
such work performed at your STIHL
service dealer only.
!Warning!
Never test the ignition system with
ignition wire connector removed from
spark plug or with unseated spark plug,
since uncontained sparking may cause
a fire.
!Warning!
To reduce the risk of fire and burn injury,
use only spark plugs authorized by
STIHL. 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 connection between
spark plug terminal and ignition wire
connector in the boot may create arcing
that could ignite combustible fumes and
cause a fire. Keep the spark plug clean,
and make sure the ignition lead is in
good condition.
20
MS 191 T
English / USA
!Warning!
Do not operate your chainsaw if the
muffler is damaged, missing or modified.
An improperly maintained muffler will
increase the risk of fire and hearing loss.
Never touch a hot muffler or a burn will
result. If your muffler was equipped with
a spark-arresting screen to reduce the
risk of fire (e. g. in the USA, Canada
and Australia), never operate your saw if
the screen is missing or damaged.
Remember that the risk of forest fires is
greater in hot or dry weather. Keep the
chain, bar and sprocket clean; replace
worn sprockets or chains. Keep the
chain sharp.
You can spot a dull chain when easy-tocut wood becomes hard to cut or burn
marks appear on the wood. Keep the
chain at proper tension. Tighten all nuts,
bolts and screws except the carburetor
adjustment screws after each use.
!Warning!
In order for the chain brake on your
STIHL chainsaw to properly perform its
function of reducing the risk of kickback
and other injuries, it must be properly
maintained. Like an automobile brake, a
chainsaw chain brake incurs wear each
time it is engaged.
The amount of wear will vary depending
upon usage, conditions under which the
saw is used and other factors. Excessive
wear will reduce the effectiveness of the
chain brake and can render it
inoperable. For the proper and effective
operation of the chain brake the brake
band and clutch drum must be kept free
of dirt, grease and other foreign matter
which may reduce friction of the band on
the drum.
For these reasons, each STIHL
chainsaw should be returned to trained
personnel such as your STIHL servicing
dealer for periodic inspection and
servicing of the brake system according
to the following schedule: Heavy usage every three months, Moderate usage twice a year, Occasional usage annually.
The chainsaw should also be returned
immediately for maintenance whenever
the brake system cannot be thoroughly
cleaned or there is a change in its
operating characteristics.
For any maintenance please refer to the
maintenance chart and to the warranty
statement near the end of this manual.
The daily maintenance schedule for your
chainsaw set forth in your STIHL
owner's manual should be strictly
followed.
Store chainsaw in a dry and secure
place and away from children.
Before storing for longer than a few
days, always empty the fuel tank.
21MS 191 T
English / USA
Mounting the Bar and Chain
(Front Chain Tensioner)
1
a
t = a : 2
You can run chains of different pitches
on this chainsaw – depending on the
chain sprocket (see “Specifications”):
The chain pitch (1) must match the pitch
of the sprocket and the guide bar (for
Rollomatic). The drive link gauge (2)
must match the bar groove width (3).
The pitch is marked on the chain
sprocket and guide bar in inches
(e.g. 3/8 or .325). The groove width
is marked on the guide bar in
millimeters (e.g. 1.6).
If non-matching components of the
wrong pitch or drive link gauge are
run together on the same machine
they may be damaged beyond
repair after a short period of
operation.
2
3
001BA105 KN
: Unscrew the nut and remove the
chain sprocket cover.
5
: Turn screw (4) counterclockwise
until the tensioner slide (5) butts
against left end of housing slot.
4
001BA127 KN
: Disengage the chain brake: Pull the
hand guard (6) back toward the front
handle.
001BA128 KN
Wear work gloves to protect your
hands from the sharp cutters.
: Fit the chain – start at the bar nose.
6
001BA108 KN
143BA003 KN
22
MS 191 T
English / USA
9
: Fit the guide bar over the studs (7) –
cutting edges on top of bar must
point to right – and engage the peg
of the tensioner slide in the locating
hole (8) –- place the chain over
sprocket (9) at the same time.
: Now turn tensioning screw (10)
clockwise until there is very little
chain sag on the underside of the
bar –- and the drive link tangs are
located in the bar groove.
: Refit the sprocket cover and screw
on the nut only fingertight.
: Go to “Tensioning the Saw Chain”.
7
7
8
10
Tensioning the Saw Chain
(Front Chain Tensioner)
1
001BA111 KN
Retensioning during cutting work:
: Shut off the engine and then loosen
the nut.
: Hold the bar nose up.
: Use screwdriver to turn the
tensioning screw (1) clockwise until
the chain fits snugly against the
underside of the bar.
: While still holding the bar nose up,
tighten down the nut firmly.
: Follow instructions in chapter
"Checking Chain Tension".
A new chain has to be retensioned more
often than one that has been in use for
some time.
Check chain tension frequently – see
chapter "During Operation".
Checking Chain Tension
170BA000 KN
: Shut off the engine.
: Wear work gloves!
: Chain must fit snugly against the
underside of the bar – and, with the
chain brake disengaged, it must still
be possible to pull the chain along
the bar by hand.
: If necessary, retension the chain.
A new chain has to be retensioned more
often than one that has been in use for
some time.
Check chain tension frequently! –
see chapter "During Operation".
142BA064 KN
23MS 191 T
English / USA
Fuel
This engine is certified to operate on
unleaded gasoline and the STIHL twostroke engine oil at a mix ratio of 50:1.
Your two-stroke 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
nationally recognized high-quality
unleaded gasoline!
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 50:1 two-stroke
engine oil since it is specially formulated
for use in STlHL engines.
Do not use BIA or TCW rated (twostroke 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,
chainsaws, 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.
Gasoline
US gal. US fl.oz
12.6
2 1/2 6.4
512.8
Dispose of empty mixing-oil canisters
only at authorized disposal locations.
Oil (STIHL 50:1 or
equivalent high-quality oils)
24
MS 191 T
English / USA
Fueling
MIX
Before fueling, clean the filler cap and
the area around it to ensure that no dirt
falls into the tank. Always thoroughly
shake the mixture in the canister before
fueling your machine.
In order to reduce the risk of 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.
Use a suitable tool (e.g. screwdriver
end of combination wrench) to
tighten slotted fuel caps.
MIX
170BA007 KN
Change the fuel pickup body
once every year
: Drain the fuel tank.
: Use a hook to pull the fuel pickup
body out of the tank and take it off
the hose.
: Push the new pickup body into the
hose.
: Place the pickup body in the tank.
Chain Lubricant
For automatic and reliable
lubrication of the chain and guide
bar – use only an environmentally
compatible quality chain and bar
lubricant with non-fling additive
or the rapidly biodegradable
STIHL BioPlus is recommended.
Biological chain oil must be resistant
to aging (e.g. STIHL BioPlus) since
it will otherwise quickly turn to resin.
This results in hard deposits that are
difficult to remove, especially in the
area of the chain drive, clutch and
chain. It may even cause the oil
pump to seize.
The service life of the chain and guide
bar depends on the quality of the
170BA008 KN
lubricant. It is therefore essential to use
only a specially formulated chain
lubricant.
25MS 191 T
English / USA
If special chain lubricant is not available,
you may – in an emergency – use an HD
single grade or multigrade engine oil
with a viscosity that suits the prevailing
outside temperature.
Do not use waste oil!
Medical studies have shown that
renewed contact with waste oil can
cause skin cancer. Moreover, waste
is environmentally harmful!
Waste oil does not have the
necessary lubricating properties
and is unsuitable for chain
lubrication.
Filling Chain Oil Tank
: Thoroughly clean the the oil filler
cap and the area around it to ensure
that no dirt falls into the tank.
: Refill the chain oil tank every time
you refuel.
There must still be a small amount of oil
in the oil tank when the fuel tank is
empty.
If the oil tank is still partly full, the reason
may be a problem in the oil supply
system: Check chain lubrication, clean
the oilways, contact your STlHL dealer
for assistance if necessary.
Checking Chain Lubrication
170BA009 KN
The saw chain must always throw off a
small amount of oil.
Never operate your saw without
chain lubrication! If the chain runs
dry, the whole cutting attachment
will be irretrievably damaged within
a very short time. Always check
chain lubrication and oil level in tank
before starting work.
Every new chain has to be broken in for
about 2 to 3 minutes.
After breaking in chain, check chain
tension and adjust if necessary – see
“Checking Chain Tension”.
142BA069 KN
26
MS 191 T
Chain Brake
Locking chain with chain brake
– in an emergency
– for starting
– at idle speed
The chain is stopped and locked when
the hand guard is pushed toward the bar
nose by the left hand – or when the
brake is activated by inertia in certain
kickback situations.
170BA010 KN
Releasing the chain brake
: Pull the hand guard back toward the
front handle.
Always disengage the chain brake
before accelerating the engine and
starting the cut (the only exception
is when you check operation of the
chain brake).
High revs with the chain brake
engaged (chain locked) will quickly
damage the powerhead and chain
drive (clutch, chain brake).
English / USA
The chain brake is activated by the
inertia of the front hand guard
if the kickback force of the saw is high
enough:
The hand guard is accelerated toward
the bar nose – even if your left hand is
not behind the hand guard, e.g. during
felling cut.
The chain brake will operate only if the
hand guard has not been modified in any
way.
Check operation of chain brake
Before starting work:
Run engine at idle speed, engage the
chain brake (push hand guard toward
bar nose). Open the throttle wide for no
more than 3 seconds. The chain must
170BA011 KN
not rotate. The hand guard must be free
from dirt and move freely.
27MS 191 T
English / USA
Chain brake maintenance
The chain brake is subject to normal
wear and tear. It must therefore be
checked and serviced regularly by
trained personnel (e.g. STIHL dealer) at
the following intervals:
Full-time professional
usage:
Semi-professional
usage:
every 3
months
every 6
months
Information Before You Start
STOP
0
The four positions of the
Master Control lever
$ = Engine off –
ignition is switched off.
# = Normal run position –
engine runs or can fire.
To move the Master Control lever from #
to
n or l, press down the throttle
trigger interlock and squeeze throttle
trigger at the same time.
n=Warm start – this position is used to
start a warm engine. The Master
Control lever moves to the normal
run position as soon as the throttle
trigger is squeezed.
l=Cold start – this position is used to
start a cold engine.
Starting / Stopping the Engine
4
2
3
001BA140 KN
Observe safety precautions – see
chapter "Safety Precautions".
: Push hand guard (1) forward:
The chain is now locked.
: Press down trigger interlock (2) and
squeeze throttle trigger (3) at the
same time – hold them in that
position.
: Set Master Control lever (4) to n
and also hold in that position.
: Now release the throttle trigger,
Master Control lever and throttle
interlock in that order. This is the
starting throttle position.
1
170BA012 KN
28
MS 191 T
English / USA
1
1
5
: Set the choke lever (5) to:
for cold start l
for warm start j
(also use this position if engine has
been running but is still cold)
170BA013 KN
: Place your saw on solid ground.
: Make sure you have a firm footing –
check that chain is not touching any
object or the ground.
Bystanders must be well clear of the
general work area of the saw.
: Hold the saw firmly on the ground
with your right hand on the top
handle and your right knee resting
on the filter cover.
70BA014 KN
: Pull the starter grip slowly with your
left hand until you feel it engage –
then give the grip a brisk strong pull
and push down the top handle at the
same time.
: Do not pull out the starter rope to its
full length – it might otherwise
break.
: Do not let the starter grip snap back
– guide it back slowly and vertically
so that the starter rope can rewind
properly.
If the engine is new, pull the starter
several times to prime the fuel system.
70BA014 KN
29MS 191 T
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