Stihl FS-MM Instruction Manual

STIHL FS-MM

WARNING

Read Instruction Manual thoroughly
before use and follow all safety
precautions – improper use can
cause serious or fatal injury.

ADVERTENCIA

Antes de usar la máquina lea y siga
todas las precauciones de
seguridad dadas en el manual de
instrucciones – el uso incorrecto
puede causar lesiones graves o
mortales.

Instruction Manual
Manual de instrucciones

Instruction Manual
1 - 21

Manual de instrucciones
22 - 43

Contents

English

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

Techniques 3
Approved MultiEngines 10
Approved Combinations of Cutting

Attachment and Deflector 11
Fitting, removing the MultiTool 12
Mounting the Deflector 13

Original Instruction ManualPrinted on chlorine-free paper

Mounting the Cutting Attachment 13
Starting / Stopping the Engine 15
Storing the Machine 15
Maintaining the Mowing Head 16
Maintenance and Care 17
Main Parts 18
Specifications 19
Maintenance and Repairs 19
Disposal 20
Trademarks 20

Printing inks contain vegetable oils, paper can be recycled.

Allow only persons who fully understand
the manuals of the MultiEngine (YARD
BOSS®) and trimmer MultiTool
attachment to operate this power tool
combination.

To receive maximum performance and
satisfaction from your STIHL MultiTool, it
is important that you read, understand
and follow the safety precautions and
the operating and maintenance
instructions in chapter "Safety
Precautions and Working Techniques"
before using your MultiTool. For further
information you can go to
www.stihlusa.com.

Contact your STIHL dealer or the STIHL
distributor for your area if you do not
understand any of the instructions in the
two manuals.

WARNING

Because a MultiEngine (YARD BOSS®)
equipped with a trimmer MultiTool
attachment is a power tool with a
relatively fast turning attachment, some
special safety precautions must be
observed to reduce the risk of personal
injury. Careless or improper use may
cause serious or even fatal injury.

© ANDREAS STIHL AG & Co. KG, 2019

0458-480-8621-A. VA0.A19.

0000006509_010_GB

FS-MM

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

1

English

469BA028 KN

+

+

MultiSystem

In the STIHL MultiSystem, various
MultiEngines and MultiTools are
combined to form a machine. In this
Instruction Manual, the functional unit of
MultiEngine and MultiTool is referred to
as a machine.

Accordingly, the instruction manuals for
the MultiEngine and the MultiTool
constitute the entire Instruction Manual
for the machine.

Always read both manuals carefully
before using your machine for the first
time and keep them safe for future
reference.

Guide to Using this Manual

Pictograms

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

Symbols in Text

Many operating and safety instructions
are supported by illustrations.

The individual steps or procedures
described in the manual may be marked
in different ways:

N A bullet marks a step or procedure.
A description of a step or procedure that

refers directly to an illustration may
contain item numbers that appear in the
illustration. Example:

N Loosen the screw (1).
N Lever (2) ...

In addition to the operating instructions,
this manual may contain paragraphs
that require your special attention. Such
paragraphs are marked with the
following symbols and signal words:

DANGER

Indicates a hazardous situation that, if
not avoided, will result in death or
serious injury.

WARNING

Indicates a hazardous situation that, if
not avoided, could result in death or
serious injury.

NOTICE

Indicates a risk of property damage,
including damage to the machine or its
individual components.

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. Therefore,
some changes, modifications and
improvements may not be covered in
this manual. If the operating
characteristics or the appearance of
your machine differs from those
described in this manual, please contact
your STIHL dealer or the STIHL
distributor for your area for assistance.

2

FS-MM

English

Safety Precautions and
Working Techniques

Because a MultiEngine
(YARD BOSS®)
equipped with a trimmer
attachment is a high­speed power tool, special
safety precautions must
be observed to reduce
the risk of personal injury.

It is important that you
read, fully understand
and observe the following
safety precautions and
warnings. Read the
instruction manuals and
the safety precautions of
your MultiEngine and
MultiTool periodically.
Careless or improper use
may cause serious or
fatal injury.

Have your STIHL dealer show you how
to operate your power tool. Observe all
applicable local safety regulations,
standards and ordinances.

WARNING

As more fully explained later in these
Safety Precautions, to reduce the risk of
personal injury, make sure your unit is
equipped with the proper deflector for
the type of cutting attachment you are
using. Use only cutting attachments that
are specifically authorized by STIHL for
use on your MultiEngine model.

WARNING

Do not lend or rent your power tool
without the instruction manuals of your
MultiEngine and MultiTool. Be sure that
anyone using it understands the
information contained in these manuals.

WARNING

The use of this machine may be
hazardous. If the rotating line or polymer
blade comes in contact with your body, it
will cut you. When it comes in contact
with solid foreign objects such as rocks
or bits of metal, it may fling them directly
or by ricochet in the direction of
bystanders or the operator. Striking such
objects could damage the cutting
attachment and may cause polymer
blades to crack, chip or break. Thrown
objects, including broken heads or
blades, may result in serious or fatal
injury to the operator or bystanders.

Use your MultiEngine equipped with the
appropriate MultiTool only for cutting
grass.

WARNING

Do not use it for other purposes, since
misuse may result in personal injury or
property damage, including damage to
the machine.

WARNING

Minors should never be allowed to use
this power tool. Bystanders, especially
children, and animals should not be
allowed in the area where it is in use.

WARNING

To reduce the risk of injury to bystanders
and damage to property, never let your
power tool run unattended. When it is
not in use (e.g. during a work break),
shut it off and make sure that
unauthorized persons do not use it.

Most of these safety precautions and
warnings apply to the use of all STIHL
power tools. Different models may have
different parts and controls. See the
appropriate section of your MultiEngine
and MultiTool instruction manuals for a
description of the controls and the
function of the parts of your model.

Safe use of a power tool involves

1. the operator

2. the power tool

3. the use of the power tool.

THE OPERATOR

Physical Condition
You must be in good physical condition

and mental health and not under the
influence of any substance (drugs,
alcohol, etc.) which might impair vision,
dexterity or judgment. Do not operate
this machine when you are fatigued.

WARNING

Be alert – if you get tired, take a break.
Tiredness may result in loss of control.
Working with any power tool can be
strenuous. If you have any condition that
might be aggravated by strenuous work,
check with your doctor before operating
this machine.

FS-MM

3

English

Proper Clothing

WARNING

To reduce the risk of injury, the operator
should wear proper protective apparel.

The deflector provided with your power
tool will not protect the operator from all
foreign objects (gravel, glass, wire, etc.)
thrown back by the rotating cutting
attachment. Thrown objects may also
ricochet and strike the operator.

WARNING

Clothing must be sturdy
and snug-fitting, but allow
complete freedom of
movement. Wear long
pants made of heavy
material to help protect
your legs. Do not wear
shorts, sandals or go
barefoot.

Avoid loose-fitting jackets, scarfs,
neckties, jewelry, flared or cuffed pants,
unconfined long hair or anything that
could become caught on branches,
brush or the moving parts of the unit.
Secure hair so it is above shoulder level.

To reduce the risk of
injury to your eyes never
operate your power tool
unless wearing goggles
or properly fitted protec­tive glasses with
adequate top and side
protection complying with
ANSI Z87 "+" (or your
applicable national stand­ard). To reduce the risk of
injury to your face STIHL
recommends that you
also wear a face shield or
face screen over your
goggles or protective
glasses.

Power tool noise may
damage your hearing.
Wear sound barriers (ear
plugs or ear mufflers) to
protect your hearing.
Continual and regular
users should have their
hearing checked
regularly.

Be particularly alert and
cautious when wearing
hearing protection
because your ability to
hear warnings (shouts,
alarms, etc.) is restricted.

Always wear heavy duty
work gloves (e.g. made of
leather or other wear
resistant material) when
handling the cutting
attachment. Heavy-duty,
nonslip gloves improve
your grip and help to pro­tect your hands.

Good footing is very
important. Wear sturdy
boots with nonslip soles.
Steel-toed safety boots
are recommended.

For further instructions on proper
clothing see the safety precautions in
the instruction manual of the
MultiEngine you are using.

THE POWER TOOL (MULTIENGINE
EQUIPPED WITH TRIMMER
MULTITOOL)

For illustrations and definitions of the
power tool parts see the chapter on
"Main Parts.”

WARNING

Never modify this power tool in any way.
Only attachments supplied by STIHL
and expressly approved by STIHL for
use with the specific STIHL MultiEngine
are authorized. Although certain
unauthorized attachments are useable
with STIHL power tools, their use may,
in fact, be extremely dangerous.

For the cutting attachments authorized
by STIHL for your unit, see the chapter
"Approved Combinations of Cutting
Attachment and Deflector" in the
instruction manual or the STIHL "Cutting
Attachments, Parts & Accessories"
catalog.

If this tool is subjected to unusually high
loads for which it was not designed (e.g.
heavy impact or a fall), always check
that it is in good condition before
continuing work. Check in particular that
the fuel system is tight (no leaks) and
that the controls and safety devices are

4

FS-MM

English

469BA060 KN

002BA590 KN

working properly. Do not continue
operating this machine if it is damaged.
In case of doubt, have it checked by your
STIHL servicing dealer.

THE USE OF THE POWER TOOL
(MULTIENGINE EQUIPPED WITH
TRIMMER MULTITOOL)

Transporting the Power Tool

WARNING

To reduce the risk of injury from loss of
control and line contact, never carry or
transport your power tool with the cutting
attachment moving.

WARNING

Always switch off the engine and make
sure the working tool has stopped before
putting a power tool down.

WARNING

When transporting it in a vehicle,
properly secure it to prevent turnover,
fuel spillage and damage to the unit.

Before Starting

WARNING

Always check your power tool for proper
condition and operation before starting.
Never attempt to modify the controls or
safety devices.

WARNING

Never use a power tool that is damaged
or not properly maintained.

WARNING

Do not attach any cutting attachment to
a unit without proper installation of all
required parts. Failure to use the proper
parts may cause a blade or head to fly
off and seriously injure the operator or
bystanders.

WARNING

To reduce the risk
of personal injury
to the operator
from polymer
blade or line con­tact and thrown
objects, make sure
your unit is
equipped with the
proper deflector
for the type of cut­ting attachment
being used (see
chart in the chap­ter on "Approved
Combinations of
Cutting Attach­ment and
Deflector".)

Keep the deflector adjusted properly at
all times (see chapters on "Mounting the
Deflector" and "Mounting the Cutting
Attachment" of your instruction manual).

Grip the power tool by the carrying
handle with the attachment facing
forward.

WARNING

To reduce the risk of burn injury, do not
touch hot parts of the machine and the
gear housing when they are hot.

FS-MM

WARNING

The cutting attachment must be properly
tightened and in safe operating
condition. Inspect for loose parts (nuts,
screws, etc.) and for cracked or
damaged heads. Replace damaged
heads before using the power tool.

Keep the handles clean and dry at all
times; it is particularly important to keep
them free of moisture, pitch, oil, fuel mix,
grease or resin in order for you to
maintain a firm grip and properly control
your power tool.

Arrows on the deflector (A) (as seen
from the top) show the correct direction
of rotation of the cutting attachment.
When viewed from above, however, the
cutting attachment rotates
counterclockwise.

5

English

9911BA010 KN

469BA045 KN

Starting

WARNING

Start the engine at least 10 feet (3 m)
from the fueling spot, outdoors only.

Start and operate your power tool
without assistance. For specific starting
instructions, see the appropriate section
of your MultiEngine and MultiTool
manuals. Place the power tool on firm
ground or other solid surface in an open
area. Maintain good balance and secure
footing.

WARNING

To reduce the risk of injury from loss of
control, be absolutely sure that the
working tool is clear of you and all other
obstructions and objects, including the
ground, because when the engine starts
at starting-throttle, engine speed will be
fast enough for the clutch to engage and
move the working tool.

Once the engine has started,
immediately blip the throttle trigger,
which should release the starting throttle
and allow the engine to slow down to
idle.

WARNING

Your power tool is a one-person
machine. Do not allow other persons in
the general work area, even when
starting.

See also the safety precautions on
Starting in the instruction manual of the
MultiEngine.

Set of wheels

Use the MultiTool on the MultiEngine
only in combination with a set of wheels
(special accessory).

Use only genuine STIHL wheels. The
use of other wheels may result in
damage to the machine or personal
injury.

The wheels can be locked in different
positions - see notes on "Wheels" in the
MultiEngine instruction manual.

During Operation
Holding and Controlling the Power Tool

Always hold the unit firmly with both
hands on the handles while you are
working. Wrap your fingers and thumbs
around the handles.

WARNING

Never attempt to operate
your power tool with one
hand. Loss of control of
the power tool resulting in
serious or fatal injury may
result. To reduce the risk
of cut injuries, keep
hands and feet away
from the cutting attach­ment. Never touch a
moving cutting attach­ment with your hand or
any other part of your
body.

WARNING

Do not overreach. Keep proper footing
and balance at all times. Special care
must be taken in slippery conditions (wet
ground, snow) and in difficult, overgrown
terrain. Watch for hidden obstacles such
as tree stumps, roots and ditches to
avoid stumbling. For better footing, clear

6

FS-MM

English

15m (50ft)

away scrub and cuttings. Be extremely
cautious when working on slopes or
uneven ground.

WARNING

To reduce the risk of injury from loss of
control, never work on any other
insecure support. Never hold the cutting
attachment above waist height

Working Conditions
Operate and start your power tool only

outdoors in a well-ventilated area.
Operate it under good visibility and
daylight conditions only. Work carefully.

WARNING

If the vegetation being cut or the
surrounding ground is coated with a
chemical substance (such as an active
pesticide or herbicide), read and follow
the instructions and warnings that
accompany the substance at issue.

WARNING

Inhalation of certain dusts, especially
organic dusts such as mold or pollen,
can cause susceptible persons to have
an allergic or asthmatic reaction.
Substantial or repeated inhalation of
dust and other airborne contaminants, in
particular those with a smaller particle
size, may cause respiratory or other
illnesses. Control dust at the source
where possible. Use good work
practices, such as operating the unit so
that the wind or operating process
directs any dust raised by the power tool
away from the operator. Follow the
recommendations of EPA / OSHA /
NIOSH and occupational and trade
associations with respect to dust

FS-MM

("particulate matter"). When the
inhalation of dust cannot be
substantially controlled, i.e., kept at or
near the ambient (background) level, the
operator and any bystanders should
wear a respirator approved by NIOSH /
MSHA for the type of dust encountered.

Operating Instructions

WARNING

Do not operate your power tool using the
starting throttle lock, as you do not have
control of the engine speed.

In the event of an emergency, switch off
the engine immediately – move the slide
control / stop switch to 0 or STOP.

WARNING

The cutting attachment
continues to rotate for a
short period after the
throttle trigger is released
(flywheel effect.)

The rotating cutting attachment may
fling foreign objects directly or by
ricochet a great distance.

To reduce th e risk of eye and other injury
always wear proper eye protection (see
the chapter on "Proper Clothing") and
ensure that bystanders are at least
50 feet (15 m) away. To reduce the risk
of damage to property, also maintain this
distance from such objects as vehicles

or windows. Even maintaining a
minimum distance of 15 meters cannot
exclude the potential risk. Any
coworkers who must be in the restricted
area should also wear goggles or
protective glasses. Stop the engine
immediately if you are approached.

WARNING

Inspect the work area: To
reduce the risk of injury,
remove stones, pieces of
metal and other solid
objects which could be
thrown 50 feet (15 m) or
more by the cutting
attachment or damage
the cutting attachment
and property (e.g. parked
vehicles, windows).

WARNING

This power tool is normally to be used at
ground level with the MultiTool parallel
to the ground. Use of a MultiEngine
above ground level or with the MultiTool
perpendicular to the ground may
increase the risk of injury, since the
cutting attachment is more fully exposed
and the power tool may be more difficult
to control.

WARNING

During cutting, check the tightness and
the condition of the cutting attachment at
regular short intervals with the engine
and attachment stopped. If the behavior
of the attachment changes during use,
stop the engine immediately, wait until
the cutting attachment stops, and check

7

English

002BA354 KN

the nut securing the attachment for
tightness and the attachment for cracks,
wear and damage.

WARNING

A loose head may vibrate, crack, break
or come off the power tool, which may
result in serious or fatal injury. Make
sure that the cutting attachment is
properly tightened. Use the wrench
supplied or one of sufficient length to
obtain the proper torque. If the head
loosens after being properly tightened,
stop work immediately. The retaining nut
may be worn or damaged and should be
replaced. If the head continues to
loosen, see your STIHL dealer. Never
use a MultiEngine with a loose
MultiTool.

WARNING

Replace a cracked, damaged or worn­out head immediately, even if damage is
limited to superficial cracks. Such
attachments may shatter at high speed
and cause serious or fatal injury.

WARNING

If the head or deflector becomes
clogged or stuck, always shut off the
engine and make sure the cutting
attachment has stopped before
cleaning. Grass, weeds, etc. should be
cleaned off from around the head at
regular intervals.

WARNING

To reduce the risk of unintentional
rotation of the cutting attachment and
injury, always shut off the engine before
replacing the cutting attachment. To

reduce the risk of injury, always shut off
the engine before adjusting the length of
the nylon line on manually adjustable
mowing heads.

WARNING

The gearbox becomes
hot during operation. To
reduce the risk of burn
injury, do not touch the
gear housing when it is
hot.

USING THE CUTTING ATTACHMENT

For an illustration of the various cutting
attachments and instructions on proper
mounting see the chapter on "Mounting
the Cutting Attachment" in your
instruction manual.

WARNING

To reduce the risk of severe or fatal
injury from blade contact and / or loss of
control, never attempt to use a metal
blade on a power tool for which it is not
authorized.

Using the Mowing Heads
Do not use with mowing line longer than

the intended length. With a properly
mounted deflector, the built-in line­limiting blade will automatically adjust
the line to its proper length.

Using the unit with an overly long nylon
cutting line increases the load on the
engine and reduces its operating speed.
This causes the clutch to slip
continuously and results in overheating
and damage to important components
(e.g. clutch, polymer housing

components). Such damage could,
among other things, cause the cutting
attachment to rotate at idle.

Mowing heads are to be used only on
trimmers / brushcutters equipped with a
line-limiting blade in the deflector in
order to keep the line at the proper
length (see "Main Parts" chapter in your
instruction manual).

If the lawn edges are planted with trees
or bordered by a fence etc., it is best to
use a nylon line head. It achieves a
"softer" cut with less risk of damaging
tree bark etc. than polymer blades.

However, the polymer-bladed STIHL
PolyCut produces a better cut if there
are no plants along the edge of the lawn.
Sharpening is not necessary, and worn
polymer blades are easily replaced.

WARNING

To reduce the risk of serious injury,
never use wire or metal-reinforced line
or other material in place of the nylon
cutting lines. Pieces of wire could break
off and be thrown at high speed toward
the operator or bystanders.

8

FS-MM

English

002BA177 KN

STIHL SuperCut mowing head
Fresh line is advanced automatically.

Frayed line is replaced by a simple
adjustment (see instruction sheet
supplied with mowing head).

STIHL AutoCut mowing head
Nylon cutting line advances

automatically when tapped against the
ground (TapAction).

STIHL TrimCut mowing head
Frayed line is replaced by a simple

adjustment (see instruction sheet
supplied with mowing head).

STIHL PolyCut mowing head
Uses either nylon lines or nonrigid,

pivoting polymer blades.
Observe wear indicators.

STIHL FixCut mowing head
Uses pre-cut lengths of nylon line.
Observe wear indicators.

Do not continue using the mowing head
if the raised moldings (1) on the base
are missing or worn – see right
illustration above. The mowing head
may otherwise shatter, and flying
objects could result in injury to the
operator or bystanders. Install a new
mowing head.

MAINTENANCE, REPAIR AND
STORING

Wear gloves when handling or
performing maintenance on blades.

WARNING

Never repair damaged cutting
attachments by welding, straightening or
modifying the shape. This may cause
parts of the cutting attachment to come
off and result in serious or fatal injuries.

Tighten all nuts, bolts and screws,
except the carburetor adjustment
screws, after each use.

Do not clean your machine with a
pressure washer. The solid jet of water
may damage parts of the machine.

Store the power tool in a dry and high or
locked location out of reach of children.

WARNING

Three rectangular wear limit marks are
applied to the base (periphery) of the
PolyCut. To reduce the risk of serious
injury from breakage of the head or
blades, the PolyCut must not be used
when it has worn as far as one of these
marks. It is important to follow the
maintenance instructions supplied with
the head.

FS-MM

WARNING

Always stop the engine and make sure
that the cutting attachment is stopped
before doing any maintenance or repair
work or cleaning the power tool. Do not
attempt any maintenance or repair work
not described in your instruction manual.
Have such work performed by your
STIHL servicing dealer only.

WARNING

Use only identical STIHL replacement
parts for maintenance and repair. Use of
non-STIHL parts may cause serious or
fatal injury.

9

English

Approved MultiEngines

Only use MultiEngines supplied by
STIHL or expressly approved by STIHL
for use with the MultiTool.

This MultiTool may only be used in
combination with the STIHL MM 56
MultiEngine.

10

FS-MM

Approved Combinations of Cutting Attachment and Deflector

8

1

2

3

5

6

0000-GXX-0425-A1

7

4

Cutting Attachment Deflector

English

Approved Combinations

Select correct combination from the
table according to the cutting
attachment you intend to use.

WARNING

For safety reasons no other
combinations are permitted – risk of
accidents.

Only mowing heads (1, 2, 3, 4, 5, 6)
may be used on the FS-MM MultiTool.

Cutting Attachments

Mowing heads
1 STIHL SuperCut 20-2

2 STIHL AutoCut C 25-2
3 STIHL AutoCut 25-2
4 STIHL FixCut 31-2

FS-MM

5 STIHL TrimCut 31-2
6 STIHL DuroCut 20-2
7 STIHL PolyCut 20-3

Deflector

8 Deflector for mowing heads

WARNING

Based on the cutting attachment being
used:

Choose the proper deflector in order to
reduce the risk of injury from thrown
objects and contact with the cutting
attachment.

Do not use rigid, non-pivoting polymer
blades, metal cutting attachments or
circular saw blades on this unit.

Only mowing heads may be used.

11

English

1

486BA012 KN

2

1

3

486BA013 KN

4

2

9911BA002 KN

1

3

9911BA004 KN

4

1

2

9911BA011 KN

4

9911BA008 KN

3

481BA011 KN

Fitting, removing the
MultiTool

Mounting the MultiTool

Remove the gearbox

N Loosen the clamp screws (1) and

pull the gearbox (2) off the drive
tube.

Remove the deflector

N Loosen the screw (3) and pull the

deflector (4) off the drive tube.

WARNING

Keep the deflector in a safe place and
always refit it before using other
MultiTools – there is otherwise a risk of
accidents.

12

N Push the coupling sleeve (1) onto

the drive tube (2) as far as stop.

The coupling sleeve (1) is properly
positioned when the arrow is in line with
the gap in the flange (4).

N Tighten down the wing screw (3)

firmly.

Removing the MultiTool

N Loosen the wing screw and pull off

the FS-MM.

N Push the deflector (1) onto the drive

tube (2) as far as stop.

N Tighten down the screw (2).

N Push the gearbox (3) into position

and tighten down the clamp
screws (4).

N Tighten the two clamp screws on

the gearbox in the following
sequence:

– Tighten the first screw moderately.
– Tighten the second screw

moderately.

FS-MM

English

2

3

1

9911BA007 KN

9911BA009 KN

2

3

1

002BA569 KN

2

– Tighten down first screw firmly.
– Tighten down second screw firmly.

Mounting the Deflector

Mount the wheel guard.

N Attach the wheel guard to the

gearbox, while doing so, insert the
nose (1) into the recess (2) on the
wheel guard.

N Turn-in and tighten the screw (3).

Mounting the Cutting
Attachment

Placing Power Tool on the Ground

N Shut off the engine.
N Turn the power tool so that the

cutting attachment mounting face is
pointing up.

Blocking the shaft

FS-MM

To mount and remove the cutting
attachments, the shaft (1) must be
blocked with the locking pin (2) or Allen
wrench (2). The parts are included in the
scope of delivery and are available as
special accessories.

13