Stihl FS 90 Owner Manual

{
STIHL FS 90
Instruction Manual
English
© ANDREAS STIHL AG & Co. KG, 2015
0458-260-0121-D. VA0.G15.
0000000800_024_GB
Printed on chlorine-free paper
Printing inks contain vegetable oils, paper can be recycled.
Original Instruction Manual
Contents
Guide to Using this Manual
Safety Precautions and Working
Techniques
Approved Combinations of Cutting
Attachment, Deflector, Handle and
Harness
Approved Power Tool Attachments
Mounting the Bike Handle
Mounting the Loop Handle
Adjusting the Throttle Cable
Fitting the Carrying Ring
Mounting the Deflector
Mounting the Cutting Attachment
Fuel
Fueling
Fitting the Harness
Balancing the Machine
Starting / Stopping the Engine
Transporting the Unit
Operating Instructions
Cleaning the Air Filter
Adjusting the Carburetor
Spark Plug
Engine Running Behavior
Lubricating the Gearbox
Storing the Machine
Sharpening Metal Cutting Blades
Maintaining the Mowing Head
Inspections and Maintenance by
Dealer
Maintenance and Care
Minimize Wear and Avoid Damage
{
FS 90, FS 90 R
2
2
12
13
14
16
17
18
18
19
22
23
24
24
26
28
30
30
30
31
32
32
32
33
33
Main Parts
Specifications
Maintenance and Repairs
Disposal
EC Declaration of Conformity
39
40
42
42
42
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
35
36
38
This instruction manual is protected by copyright. All rights reserved, especially the rights to reproduce, translate and process
with electronic systems.
1
English
Guide to Using this Manual
WARNING
Pictograms
The meanings of the pictograms
attached to the machine are explained in
this manual.
Depending on the model concerned, the
following pictograms may be attached to
your machine.
Fuel tank; fuel mixture of
gasoline and engine oil
Operate decompression
valve
Manual fuel pump
Operate manual fuel
pump
Tube of grease
Intake air: Summer
operation
Intake air: Winter
operation
Handle heating
2
Symbols in text
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.
Safety Precautions and
Working Techniques
Some special safety precautions must be
observed to reduce the
risk of personal injury
when operating this
power tool because of the
very high speed of its cutting attachment.
It is important that you
read the instruction manual before first use and
keep it in a safe place for
future reference. Nonobservance of the
instruction manual may
result in serious or even
fatal injury.
Observe all applicable local safety
regulations, standards and ordinances.
If you have not used this type of power
tool before: Have your dealer or other
experienced user show you how to
operate your machine or attend a
special course in its operation.
Minors should never be allowed to use a
power tool.
Keep bystanders, especially children,
and animals away from the work area.
When the power tool is not in use, shut it
off so that it does not endanger others.
Secure it against unauthorized use.
The user is responsible for avoiding
injury to third parties or damage to their
property.
FS 90, FS 90 R
English
Do not lend or rent your power tool
without the instruction manual. Be sure
that anyone using it understands the
information contained in this manual.
servicing dealer. Use only high quality
tools and accessories in order to avoid
the risk of accidents and damage to the
machine.
The use of noise emitting power tools
may be restricted to certain times by
national or local regulations.
STIHL recommends the use of genuine
STIHL tools and accessories. They are
specifically designed to match the
product and meet your performance
requirements.
To operate the power tool you must be
rested, in good physical condition and
mental health.
If you have any condition that might be
aggravated by strenuous work, check
with your doctor before operating a
power tool.
Persons with pacemakers only: The
ignition system of your power tool
produces an electromagnetic field of a
very low intensity. This field may
interfere with some pacemakers. STIHL
recommends that persons with
pacemakers consult their physician and
the pacemaker manufacturer to reduce
any health risk.
Do not operate the power tool if you are
under the influence of any substance
(drugs, alcohol) which might impair
vision, dexterity or judgment.
Depending on the cutting attachment
fitted, use your power tool only for
cutting grass, wild growth, shrubs,
scrub, bushes, small diameter trees and
similar materials.
Do not use your power tool for any other
purpose because of the increased risk of
accidents.
Only use cutting attachments and
accessories that are explicitly approved
for this power tool model by STIHL or
are technically identical. If you have any
questions in this respect, consult a
FS 90, FS 90 R
Never attempt to modify your power tool
in any way since this may increase the
risk of personal injury. STIHL excludes
all liability for personal injury and
damage to property caused while using
unauthorized attachments.
Do not use a pressure washer to clean
the unit. The solid jet of water may
damage parts of the unit.
The deflector on this power tool cannot
protect the operator from all objects
thrown by the cutting attachment
(stones, glass, wire, etc.). Such objects
may ricochet and then hit the operator.
Clothing and Equipment
Wear proper protective clothing and
equipment.
Clothing must be sturdy
but allow complete freedom of movement. Wear
snug-fitting clothing, an
overall and jacket combination, do not wear a
work coat.
Avoid clothing that could
get caught on branches
or brush or moving parts
of the machine. Do not
wear a scarf, necktie or
jewelry. Tie up and confine long hair (e.g. with a
hair net, cap, hard hat,
etc.).
Wear steel-toed safety
boots with non-slip soles.
Sturdy shoes with non-slip soles may be
worn as an alternative only when using
mowing heads.
WARNING
To reduce the risk of eye
injuries, wear snug-fitting
safety glasses in accordance with European
Standard EN 166. Make
sure the safety glasses
are a good fit.
Wear a face shield and make sure it is a
good fit. A face shield alone does not
provide adequate eye protection.
Wear hearing protection, e.g. earplugs
or ear muffs.
Wear a safety hard hat for thinning
operations, when working in high scrub
and where there is a danger of head
injuries from falling objects.
Wear heavy-duty work
gloves made of durable
material (e.g. leather).
3
English
STIHL offers a comprehensive range of
personal protective clothing and
equipment.
Transporting by vehicle: Properly secure
your power tool to prevent turnover, fuel
spillage and damage.
Transporting the Power Tool
Fueling
Gasoline is an extremely
flammable fuel. Keep
clear of naked flames. Do
not spill any fuel – do not
smoke.
Before Starting
Check that your power tool is properly
assembled and in good condition – refer
to appropriate chapters in the instruction
manual.
–
Check the fuel system for leaks,
paying special attention to visible
parts such as the tank cap, hose
connections and the manual fuel
pump (on machines so equipped). If
there are any leaks or damage, do
not start the engine – risk of fire.
Have your machine repaired by a
servicing dealer before using it
again.
–
Use only an approved combination
of cutting attachment, deflector,
handle and harness. All parts must
be assembled properly and
securely.
–
Slide control / stop switch must
move easily to STOP or 0.
–
Smooth action of throttle trigger
lockout (if fitted) and throttle trigger
– the throttle trigger must return
automatically to the idle position.
–
Check that the spark plug boot is
secure – a loose boot may cause
arcing that could ignite combustible
fumes and cause a fire.
–
Check cutting tool or attachment for
correct and secure assembly and
good condition.
Always shut off the engine before
refueling.
Do not fuel a hot engine – fuel may spill
and cause a fire.
002BA079 KN
Open the fuel cap carefully to allow any
pressure build-up in the tank to release
slowly and avoid fuel spillage.
Always turn off the engine.
Carry the unit hanging from the shoulder
strap or properly balanced by the drive
tube.
To reduce the risk of cut injuries, fit
transport guard on the cutting
attachment, even when carrying the tool
for short distances – see also
"Transporting the Unit".
To reduce the risk of serious burn injuries, avoid
touching hot parts of the
machine, including the
gearbox housing.
4
Fuel your power tool only in wellventilated areas. If you spill fuel, wipe
the machine immediately – if fuel gets on
your clothing, change immediately.
After fueling, tighten
down the fuel tank cap as
securely as possible.
This reduces the risk of unit vibrations
causing the fuel cap to loosen or come
off and spill quantities of fuel.
To reduce the risk of serious or fatal
burn injuries, check for fuel leakage. If
fuel leakage is found, do not start or run
the engine until leak is fixed.
FS 90, FS 90 R
English
–
Never attempt to modify the controls
or safety devices in any way.
–
Keep the handles dry and clean –
free from oil and dirt – for safe
control of the power tool.
–
Adjust the harness and handle(s) to
suit your height and reach. See
chapters on "Fitting the Harness"
and "Balancing the
Trimmer/Brushcutter".
To reduce the risk of accidents, do not
operate your power tool if it is damaged
or not properly assembled.
If you use a shoulder strap or full
harness: Practice removing and putting
down the power tool as you would in an
emergency. To avoid damage, do not
throw the power tool to the ground when
practicing.
Start the engine.
Start the engine at least 3 meters from
the fueling spot, outdoors only.
Place the unit on firm ground in an open
area. Make sure you have good balance
and secure footing. Hold the unit
securely. The cutting attachment must
be clear of the ground and all other
obstructions because it may begin to run
when the engine starts.
FS 90, FS 90 R
Your power tool is a one-person unit. To
reduce the risk of injury from thrown
objects, do not allow other persons
within a radius of 15 meters of your own
position – even when starting.
Models with bike handle
To reduce the risk of
injury, avoid contact with
the cutting attachment.
Do not drop start the
power tool – start the
engine as described in
the instruction manual.
Note that the cutting
attachment continues to
run for a short period
after you let go of the
throttle trigger – flywheel
effect.
Check idle speed setting: The cutting
attachment must not rotate when the
engine is idling with the throttle trigger
released.
To reduce the risk of fire, keep hot
exhaust gases and hot muffler away
from easily combustible materials (e.g.
wood chips, bark, dry grass, fuel).
002BA055 KN
Check protective devices (e.g.
deflector for cutting attachment,
rider plate) for damage or wear.
Always replace damaged parts. Do
not operate your machine with a
damaged deflector or worn rider
plate (lettering and arrows no longer
legible).
Right handle on control handle, left hand
on left handle.
Models with loop handle
002BA080 KN
–
On models with a loop handle and
barrier bar, left hand on loop handle,
right hand on control handle, even if you
are left-handed.
During Operation
Holding and Controlling the Power Tool
Always hold the power tool firmly with
both hands on the handles.
Make sure you always have good
balance and secure footing.
Make sure you always have good
balance and secure footing.
In the event of impending danger or in
an emergency, switch off the engine
immediately by moving the slide control
/ stop switch to STOP or 0.
5
English
15m (50ft)
The cutting attachment may catch and
fling objects a great distance and cause
injury - therefore, do not allow any other
persons within a radius of 15 meters of
your own position. To reduce the risk of
damage to property, also maintain this
distance from other objects (vehicles,
windows). Even maintaining a distance
of 15 meters or more cannot exclude the
potential danger.
The correct engine idle speed is
important to ensure that the cutting
attachment stops rotating when you let
go of the throttle trigger.
Check and correct the idle speed setting
regularly. If the cutting attachment
continues to rotate when the engine is
idling, have the machine checked by
your servicing dealer. STIHL
recommends an authorized STIHL
servicing dealer.
Take special care in slippery conditions
(ice, wet ground, snow), on slopes or
uneven ground.
Watch out for obstacles: Roots and tree
stumps which could cause you to trip or
stumble.
Always stand on the ground while
working, never on a ladder, work
platform or any other insecure support.
Be particularly alert and cautious when
wearing hearing protection because
your ability to hear warnings (shouts,
alarms, etc.) is restricted.
6
To reduce the risk of accidents, take a
break in good time to avoid tiredness or
exhaustion.
Work calmly and carefully – in daylight
conditions and only when visibility is
good. Stay alert so as not to endanger
others.
Your power tool produces
toxic exhaust fumes as
soon as the engine is
running. These fumes
may be colorless and
odorless and contain
unburned hydrocarbons
and benzol. Never run
the engine indoors or in
poorly ventilated locations, even if your model
is equipped with a catalytic converter.
To reduce the risk of serious or fatal
injury from breathing toxic fumes,
ensure proper ventilation when working
in trenches, hollows or other confined
locations.
To reduce the risk of accidents, stop
work immediately in the event of
nausea, headache, visual disturbances
(e.g. reduced field of vision), problems
with hearing, dizziness, deterioration in
ability to concentrate. Apart from other
possibilities, these symptoms may be
caused by an excessively high
concentration of exhaust gases in the
work area.
To reduce the risk of fire, do not smoke
while operating or standing near your
power tool. Note that combustible fuel
vapor may escape from the fuel system.
The dusts, vapor and smoke produced
during operation may be dangerous to
health. If the work area is very dusty or
smoky, wear a respirator.
If your power tool is subjected to
unusually high loads for which it was not
designed (e.g. heavy impact or a fall),
always check that it is in good condition
before continuing work – see also
"Before Starting".
Check the fuel system in particular for
leaks and make sure the safety devices
are working properly. Do not continue
operating your power tool if it is
damaged. In case of doubt, consult your
servicing dealer.
Do not operate your power tool in the
starting throttle position – engine speed
cannot be controlled in this position.
To reduce the risk
of injury from
thrown objects,
never operate the
unit without the
proper deflector for
the type of cutting
attachment being
used.
Operate your power tool so that it
produces a minimum of noise and
emissions – do not run the engine
unnecessarily, accelerate the engine
only when working.
FS 90, FS 90 R
English
Inspect the work area:
Stones, pieces of metal
or other solid objects may
be thrown more than 15
meters and cause personal injury or damage
the cutting attachment
and property (e.g. parked
vehicles, windows).
The gearbox becomes
hot during operation. To
reduce the risk of burn
injury, do not touch the
gearbox housing.
Sharpen metal cutting attachments
regularly as specified.
When using mowing heads
Unevenly sharpened metal cutting
attachments cause out-of-balance
which can impose extremely high loads
on the machine and increase the risk of
breakage.
Special care must be taken when
working in difficult, over-grown terrain.
Equip the deflector with the additional
components specified in the instruction
manual.
Dull or improperly sharpened cutting
edges can put a higher load on the
cutting attachment and increase the risk
of injury from cracked or broken parts.
When cutting high scrub, under bushes
and hedges: Keep cutting attachment at
a minimum height of 15 cm to avoid
harming small animals.
Use only the deflector with properly
mounted line limiting blade to ensure the
mowing lines are automatically trimmed
to the approved length.
Always shut off the engine before
leaving the unit unattended.
To reduce the risk of injury, always turn
off the engine before adjusting the nylon
line of manually adjustable mowing
heads
Check the cutting attachment at regular
short intervals during operation or
immediately if there is a noticeable
change in cutting behavior:
–
Turn off the engine. Hold the unit
firmly and wait for the cutting
attachment to come to a standstill.
–
Check condition and tightness, look
for cracks.
–
Check sharpness.
–
Replace damaged or dull cutting
attachments immediately, even if
they have only superficial cracks.
Using the unit with over-long nylon
cutting lines reduces the engine's
operating speed. The clutch then slips
continuously and this causes
overheating and damage to important
components (e.g. clutch, polymer
housing components) – and this can
increase the risk of injury from the
cutting attachment rotating while the
engine is idling.
Using metal cutting attachments
Clean grass and plant residue off the
cutting attachment mounting at regular
intervals – remove any build up of
material from the cutting attachment and
deflector.
STIHL recommends the use of original
STIHL metal cutting attachments. They
are specifically designed to match your
model and meet your performance
requirements.
To reduce the risk of injury, shut off the
engine before replacing the cutting
attachment.
Metal cutting attachments rotate at very
high speed. The forces that occur act on
the machine, the attachment and the
material being cut.
FS 90, FS 90 R
Inspect metal cutting attachments for
cracks or warping after every contact
with hard objects (e.g. stones, rocks,
pieces of metal). To reduce the risk of
injury, remove burrs and other visible
build-ups of material (use a file) because
they may become detached and be
thrown at high speed during operation.
If a rotating metal cutting attachment
makes contact with a rock or other solid
object there is a risk of sparking which
may cause easily combustible material
to catch fire under certain
circumstances. Dry plants and scrub are
also easily combustible, especially in hot
and dry weather conditions. If there is a
risk of fire, do not use metal cutting
attachments near combustible
materials, dry plants or scrub. Always
contact your local forest authority for
information on a possible fire risk.
Do not continue using or attempt to
repair damaged or cracked cutting
attachments by welding, straightening or
modifying the shape (out of balance).
This may cause parts of the cutting
attachment to come off and hit the
operator or bystanders at high speed
and result in serious or fatal injuries.
7
English
To reduce the above-mentioned risks
when using a metal cutting attachment,
never use a metal cutting attachment
with a diameter larger than specified. It
must not be too heavy. It must be
manufactured from materials of
adequate quality and its geometry must
be correct (shape, thickness).
To reduce the risk of injury, a metal
cutting attachment not manufactured by
STIHL must not be heavier, thicker,
have a different shape or a diameter
larger than the largest metal cutting
attachment approved by STIHL for this
power tool model.
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).
8
Continual and regular users should
monitor closely the condition of their
hands and fingers. If any of the above
symptoms appear (e.g. tingling
sensation in fingers), seek medical
advice.
Maintenance and Repairs
Service the machine regularly. Do not
attempt any maintenance or repair work
not described in the instruction manual.
Have all other work performed by a
servicing dealer.
STIHL recommends that you have
servicing and repair work carried out
exclusively by an authorized STIHL
servicing dealer. STIHL dealers are
regularly given the opportunity to attend
training courses and are supplied with
the necessary technical information.
Only use high-quality replacement parts
in order to avoid the risk of accidents
and damage to the machine. If you have
any questions in this respect, consult a
servicing dealer.
STIHL recommends the use of genuine
STIHL replacement parts. They are
specifically designed to match your
model and meet your performance
requirements.
To reduce the risk of injury, always shut
off the engine before carrying out any
maintenance or repairs or cleaning the
machine. – Exception: Carburetor and
idle speed adjustments.
stop switch is on STOP or 0 since there
is otherwise a risk of fire from
uncontained sparking.
To reduce the risk of fire, do not service
or store your machine near open flames.
Check the fuel filler cap for leaks at
regular intervals.
Use only a spark plug of the type
approved by STIHL and make sure it is
in good condition – see "Specifications".
Inspect the ignition lead (insulation in
good condition, secure connection).
Check the condition of the muffler.
To reduce the risk of fire and damage to
hearing, do not operate your machine if
the muffler is damaged or missing.
Do not touch a hot muffler since burn
injury will result.
Vibration behavior is influenced by the
condition of the AV elements – check the
AV elements at regular intervals.
Symbols on Deflectors
An arrow on the deflector shows the
correct direction of rotation of the cutting
attachments.
Some of the following symbols are
applied to the outside of the deflector to
indicate the approved combination of
cutting attachment and deflector.
Deflector may be used
with mowing heads.
Do not turn the engine over on the
starter with the spark plug boot or spark
plug removed unless the slide control /
FS 90, FS 90 R
English
Mowing Head with Nylon Line
Deflector may be used
with grass cutting blades.
Deflector must not be
used with mowing heads.
Do not use deflector with
brush knives, shredder
blades, grass cutting
blades or circular saw
blades.
Deflector may be
used with mowing heads. Not
approved for use
with brush
knives, shredder
blades or circular
saw blades.
Deflector may be
used with mowing heads – do
not use metal cutting attachments.
Use a shoulder strap.
N
With the engine running, attach the
machine to the shoulder strap.
Grass cutting blades and brush knives
must always be used in combination
with a shoulder strap.
Circular saw blades must always be
used in combination with a full harness
with a quick-release system.
000BA015 KN
Do not use deflector with
brush knives, shredder
blades or circular saw
blades.
N
Nylon line achieves a soft cut for edging
and trimming around trees, fence posts,
etc. – less risk of damaging tree bark.
The mowing head comes with an
instruction leaflet. Refill the mowing
head with nylon line as described in the
instruction leaflet.
WARNING
To reduce the risk of serious injury,
never use wire or metal-reinforced line in
place of the nylon line.
STIHL FixCut
Harness / Strap
Check the wear limit marks!
The harness is included in the scope of
supply or available as a special
accessory.
FS 90, FS 90 R
9
English
It is important to follow the maintenance
instructions for the PolyCut mowing
head.
If the raised moldings (1) on the
base of the attachment are worn as
shown in the illustration (above
right), do not continue using the
mowing head. Install a new one.
There is otherwise a risk of injury
from thrown parts of the head.
Never use wire in place of the nylon
mowing line – risk of injury.
Grass Cutting Blade
Risk of kickback with metal cutting
attachments
STIHL Polycut Mowing Head with
Polymer Blades
For mowing unobstructed edges of
meadows (without posts, fences, trees
or similar obstacles).
002BA049 KN
Check the wear limit marks!
If one of the wear limit marks on the
PolyCut mowing head is worn through
(arrow): Do not continue using the
mowing head. Install a new one. There
is otherwise a risk of injury from thrown
parts of the head.
10
WARNING
Increased risk of kickback when the tool
hits an obstacle within the black area.
WARNING
When using metal cutting attachments (grass
cutting blade, brush knife,
circular saw blade), there
is the risk of kickback
when the tool hits a solid
object (tree trunk, branch,
tree stump, stone and the
like). The machine is
flung back – against the
direction of rotation of the
tool.
000BA020 KN
N
The mowing head comes with
instruction leaflets. Equip the mowing
head with polymers blades or nylon line
as described in the instruction leaflets.
002BA135 KN
The PolyCut can also be equipped with
mowing line in place of the polymer
blades.
Use for grass and weeds only – sweep
the brushcutter in an arc like a scythe.
WARNING
Improper use may damage the grass
cutting blade – risk of injury from thrown
parts.
FS 90, FS 90 R
English
Exercise extreme caution when using
this method of cutting. The higher the
cutting attachment is off the ground, the
greater the risk of injury from cuttings
being thrown sideways.
Brush Knife
002BA355 KN
For cutting matted grass, wild growth
and scrub and thinning young stands
with a stem diameter of no more than
2 cm – do not cut thicker stems – risk of
accidents.
Use the brushcutter like a scythe (sweep
it to the right and left) at ground level
when cutting grass and thinning young
stands.
Warning! Improper use of a brush knife
may cause it to crack, chip or shatter –
risk of injury from thrown parts.
To reduce the risk of injury it is essential
to take the following precautions:
–
Avoid contact with stones, rocks,
pieces of metal and other solid
foreign objects.
002BA509 KN
FS 90, FS 90 R
To reduce the risk of blade damage,
avoid contact with stones and the
ground. Resharpen the blade properly in
good time – dull teeth may result in the
blade cracking and shattering and
causing serious injury.
When felling, maintain a distance of at
least two tree lengths from the next
felling site.
Risk of kickout
–
Never cut wood or shrubs with a
stem diameter of more than 2 cm –
use a circular saw blade for such
work.
–
Inspect the brush knife at regular
short intervals for signs of damage.
Do not continue working with a
damaged brush knife.
–
Resharpen the brush knife regularly
and whenever it has dulled
noticeably, and have it balanced if
necessary (STIHL recommends a
STIHL servicing dealer).
The risk of kickout is highest in the black
area of the blade: Do not use this area of
the circular saw blade for cutting.
Circular Saw Blade
To cut wild growth and scrub, lower the
brush knife down onto the growth to
achieve a shredding effect – always
keep the cutting attachment below hip
level during this process.
WARNING
002BA068 KN
Resharpen the grass cutting blade
according to instructions when it has
dulled noticeably.
Suitable for cutting shrubs and trees with
a maximum stem diameter of 4 cm.
Before starting the cut, accelerate the
engine up to full throttle. Perform cut
with uniform pressure.
There is also a risk of kickout when
using the lighter shaded areas of the
blade: These areas of the blade should
only be used by experienced operators
with specialized training.
STIHL recommends that you use the
non-shaded area of the circular saw
blade. Always start the cut with this area
of the blade.
Use circular saw blades only with a
matching limit stop of the correct
diameter.
11
English
Approved Combinations of Cutting Attachment, Deflector, Handle and Harness
Cutting Attachment
Deflector, Limit Stop
2
1
Handle
Harness/Shoulder Strap
19
14
20
3
4
5
6
7
8
10
25
24
25
24
25
21
16
15
9
23
22
20
21
17
22
11
18
13
22
26
681BA118 KN
12
12
FS 90, FS 90 R
English
Select correct combination from the
table according to the cutting
attachment you intend to use.
12 Scratcher tooth circular saw blade
200
(200 mm dia.)
13 Chisel tooth circular saw blade 200
(200 mm dia.)
WARNING
Non-metal grass cutting blades, brush
knives and circular saw blades are not
approved.
Cutting Attachments
14
15
16
17
1
2
3
4
5
6
STIHL SuperCut 20-2
STIHL AutoCut C 25-2
STIHL AutoCut 25-2
STIHL TrimCut 31-2
STIHL FixCut 25-2
STIHL PolyCut 20-3
Metal cutting attachments
7
Grass cutting blade 230-2
(230 mm dia.)
8
Grass cutting blade 230-4
(230 mm dia.)
9
Grass cutting blade 230-8
(230 mm dia.)
10 Grass cutting blade 250-40 Spezial
(250 mm dia.)
The following STIHL attachments may
be mounted to the basic power tool:
WARNING
For safety reasons only the cutting
attachments, deflectors, handles and
harnesses shown in each row of the
table may be used together. No other
combinations are permitted because of
the risk of accidents.
Mowing heads
Approved Power Tool
Attachments
Deflectors, Limit Stop
Deflector for mowing heads
Deflector with
skirt and blade, for mowing heads
Deflector without skirt and blade, for
metal cutting attachments 7 to 11
18 Limit stop for circular saw blades
FH
HT
FCS
BF
SP
SP 10
Handles
19
20
21
22
Loop handle
Loop handle with
barrier bar
Bicycle handle
Harness
23
24
25
26
Shoulder strap may be used
Shoulder strap must be used
Full harness may be used
Full harness must be used
228BA065 KN
Approved Combinations
11 Brush knife 250-3
(250 mm dia.)
FS 90, FS 90 R
13
English
HL 0°1)
HL 135° 2)
HT 1)
SP 1) 4)
SP 10 1)
Application
Pick tines
Edger
Power scythe,
adjustable
Long reach hedge
trimmer
Hedge trimmer,
adjustable
Pole pruners
Special harvester
Special harvester
1)
Unsuitable for models with bike
handle
2)
Limited suitability for models with
bike handle
3)
It is not necessary to use the
shoulder strap
4)
Use the handle hose supplied with
the machine
14
N
Pull out the wing screw – the
washer (6) remains on the wing
screw.
Mounting Bike Handle with Swivelling
Handle Support
N
Separate the clamp moldings – the
springs (4 and 5) remain in the
lower clamp.
The machine is supplied with the
swiveling handle support already
mounted on the shaft. To mount the
handlebar it is necessary to remove the
clamp moldings.
Securing the handlebar
Mounting the Bike Handle
A
7
Removing the clamp moldings
1
N
Hold the lower clamp (1) and upper
clamp (2) firmly together.
N
Release the wing screw (3) – the
clamps are loose once the wing
screw has been released. They are
pushed apart by the two
springs (4 and 5).
250BA046 KN
Attachment
BF
FCS 2) 3)
FH
N
Place the handlebar (7) in the lower
clamp (1) so that distance A is no
more than 15 cm (6 in).
N
Place the upper clamp in position
and hold both clamp moldings
together.
N
Push the wing screw through the
two clamps as far as stop – hold all
parts together and secure them.
FS 90, FS 90 R
English
Mounting the control handle
14
15
8
15
14
002BA234 KN
250BA002 KN
15
N
Place the secured assembly on the
handle support (8) with the wing
screw at the side nearest the
engine.
N
N
Take out the screw (9) – the nut (10)
remains in the control handle (11).
Push the control handle onto the
handlebar (7) until the holes (13)
line up – the throttle trigger (12)
must point towards the gearbox.
Insert the screw (9) and tighten it
down firmly.
N
Push the wing screw into the handle
support as far as stop and then
screw it down – but do not finally
tighten yet.
N
N
Line up the handlebar at a right
angle to the drive tube – check
distance A again.
N
N
Tighten down the wing screw firmly.
Push the throttle cable (14) into the
retainers (15).
Adjusting the throttle cable
N
Check adjustment of throttle cable –
see chapter on "Adjusting the
Throttle Cable".
Fitting the throttle cable
NOTICE
Do not kink the throttle cable or lay it in
tight radii – make sure the throttle trigger
moves freely.
FS 90, FS 90 R
15
English
Swivelling the handlebar
Mounting the Loop Handle
Transport position
2
4
Mounting Loop Handle with Barrier Bar
3
3
5
2
6
002BA099 KN
7
002BA650 KN
7
Loosen the wing screw (3) and
unscrew it until the handlebar (7)
can be turned clockwise.
N
Turn the handlebar 90° and then
swing the handles down.
N
Tighten down the wing screw (3)
firmly.
N
Place the clamp (3) in the loop
handle (4) and position them both
against the drive tube (5).
N
Position the clamp (6) against the
drive tube.
N
Place the barrier bar (2) in position
as shown.
N
Line up the holes.
N
Insert the screws (7) in the holes
and screw them into the barrier
bar (2) as far as stop.
N
Go to "Securing the Loop Handle".
1
002BA098 KN
N
1
N
Fit the square nuts (1) in the barrier
bar (2); the holes must line up.
Working position
N
16
Reverse the sequence described
above to swing the handles up and
turn the handlebar
counterclockwise.
FS 90, FS 90 R
English
Mounting the Loop Handle without
Barrier Bar
7
8
Securing the Loop Handle
Adjusting the Throttle Cable
Some machine versions are equipped
with a throttle cable adjuster on the
control handle.
7
8
4
A properly adjusted throttle cable is the
precondition for correct operation in the
full throttle, starting throttle and idle
positions.
A
Adjust the throttle cable only after the
unit is fully assembled – the control
handle must be in the normal operating
position.
4
9
3
Place the clamp (3) in the loop
handle (4) and position them both
against the drive tube (5).
The loop handle can be adjusted to suit
the height and reach of the operator and
the application by changing
distance (A).
N
Position the clamp (6) against the
drive tube.
Recommendation: distance (A):
about 20 cm (8 in)
N
Line up the holes.
N
N
Fit washers (8) on the screws (7)
and insert the screws in the holes.
Fit the square nuts (1) and screw
them down as far as stop.
Slide the handle to the required
position.
N
Line up the loop handle (4).
N
Tighten down the screws until the
loop handle can no longer be
rotated on the drive tube. If no
barrier bar is fitted – lock the nuts if
necessary.
N
N
Go to "Securing the Loop Handle".
The sleeve (9) (not fitted on all models)
must be between the loop handle and
the control handle.
FS 90, FS 90 R
002BA163 KN
1
N
Use a suitable tool to push the slide
to the end of the slot (see
illustration).
P
STO
2
1
N
249BA017 KN
1
002BA615 KN
6
002BA614 KN
5
Press down the throttle trigger
lockout (1) and squeeze the throttle
trigger (2) (full throttle) – this sets
the throttle cable correctly.
17
English
Fitting the Carrying Ring
Fitting the Skirt and Blade
Mounting the Deflector
The carrying ring comes standard with
the machine or is available as a special
accessory.
Mounting the Deflector
4
1
4
3
1
1
5
002BA103 KN
2
2
002BA142 KN
3
For position of carrying ring see "Main
Parts".
N
Place the clamp (1) against the
drive tube with the tapped hole on
the left (viewed from engine).
N
Squeeze the two ends of the clamp
together and hold in that position.
N
Insert the M6x14 screw (2).
N
Line up the carrying ring.
N
Tighten down the screw firmly.
18
1
2
002BA380 KN
1
Deflector for mowing attachments
Deflector for mowing heads
Deflectors (1) and (2) are both mounted
to the gearbox in the same way.
N
Place the deflector on the gearbox
flange.
N
Insert the screws (3) and tighten
them down firmly.
WARNING
These parts must be fitted to the
deflector (1) when you use a mowing
head.
N
Slide the lower guide slot of the skirt
(4) onto the deflector (1) – it must
snap into position.
N
Push the blade (5) into the upper
guide slot on the skirt and line it up
with the first hole.
N
Insert the screw and tighten it down
firmly.
FS 90, FS 90 R
English
Mounting the Limit Stop
Mounting the Cutting
Attachment
7
3
Placing power tool on the ground
6
002BA382 KN
4
002BA104 KN
5
Always fit the limit stop (6) when you use
a circular saw blade.
N
Position the limit stop (6) on the
gearbox flange.
N
Insert the screws (7) and tighten
them down firmly.
N
Shut off the engine.
N
Lay your power tool on its back so
that the cutting attachment
mounting face is pointing up.
Mounting Hardware for Cutting
Attachments
The mounting hardware supplied
depends on the cutting attachment that
comes as original equipment with the
new machine.
If mounting hardware is packed with
machine
1
2
002BA164 KN
WARNING
Depending on the cutting attachment, it
may be necessary to use the nut (3),
rider plate (4) and thrust washer (5).
These parts are included in a kit
supplied with the machine and are also
available as special accessories.
Removing the transport lock
N
Pull the hose (1) off the shaft (2).
If mounting hardware is not packed with
machine
2
002BA266 KN
Mowing heads and metal cutting
attachments may be mounted.
Only mowing heads may be used which
mount directly to the shaft (2).
FS 90, FS 90 R
19
English
Blocking the Shaft
Fitting Mowing Head with Screw
Mounting
Removing the Mounting Hardware
Keep the instruction leaflet for the
mowing head in a safe place.
2
6
6
2
The output shaft (2) must be blocked
with the stop pin (6) or screwdriver (6) to
mount or remove cutting tools. These
parts come standard with the machine or
are available as special accessories.
Insert the stop pin (6) or
screwdriver (6) in the hole (7) in the
gearbox as far as stop – and apply
slight pressure.
N
Rotate shaft, nut or cutting
attachment until the stop pin slips
into position and blocks the shaft.
4
1
5
271BA057 KN
N
3
N
Block the shaft.
N
Use the combination wrench (1) to
loosen and remove the nut (2)
clockwise (left-hand thread).
N
Take the thrust washer (3) off the
shaft (4). Do not remove the thrust
plate (5).
Screw the mowing head
counterclockwise on to the shaft (1)
as far as stop.
N
Block the shaft.
N
Tighten down the mowing head
firmly.
N
Mounting the cutting attachment
WARNING
Use a deflector that matches the cutting
attachment – see "Mounting the
Deflector".
20
002BA385 KN
7
002BA330 KN
1
NOTICE
Remove the tool used to block the shaft.
Removing the Mowing Head
N
Block the shaft.
N
Unscrew the mowing head
clockwise.
FS 90, FS 90 R
English
Mounting Metal Cutting Attachments
WARNING
WARNING
Direction of rotation is indicated by an
arrow on the inside of the deflector.
Keep the leaflet and packaging of the
metal cutting tool in a safe place.
If the mounting nut has become too
loose, fit a new one.
NOTICE
WARNING
14
Wear protective gloves to reduce the
risk of direct contact with the sharp
cutting edges.
Remove the tool used to block the shaft.
Removing the Metal Cutting Attachment
Mount only metal cutting attachments.
13
Check direction of rotation of cutting
attachment
WARNING
11
Wear protective gloves to reduce the
risk of direct contact with the sharp
cutting edges.
10
8
12
9
681BA161 KN
3
1
2
N
4
5
Place the cutting attachment (8) on
the thrust plate (9).
N
Block the shaft.
N
Unscrew the mounting nut
clockwise.
N
Remove cutting attachment and its
mounting hardware from the
gearbox – but do not remove the
thrust plate (9).
6
7
Cutting attachments with 2, 3 or
4 blades (2, 4, 5) may point in either
direction – these cutting attachments
must be turned over regularly to help
avoid one-sided wear.
The cutting edges of cutting
attachments 1, 3, 6 and 7 must point
clockwise.
FS 90, FS 90 R
681BA042 KN
WARNING
Collar (see arrow) must engage the
cutting attachment's mounting hole.
Securing the cutting attachment
N
Fit the thrust washer (10) – convex
side must face up.
N
Fit the rider plate (11).
N
Block the shaft (12).
N
Use the combination wrench (14) to
screw the mounting nut (13) on to
the output shaft counterclockwise
and tighten it down firmly.
21
English
Fuel
Your engine requires a mixture of
gasoline and engine oil.
WARNING
For health reasons, avoid direct skin
contact with gasoline and avoid inhaling
gasoline vapor.
If your machine is equipped with a
catalytic converter, you must use
unleaded gasoline.
NOTICE
A few tankfuls of leaded gasoline will
greatly reduce the efficiency of the
catalytic converter.
Examples
Gasoline
Liters
1
5
10
15
20
25
Gasoline with an ethanol content of
more than 10% can cause running
problems in engines with a manually
adjustable carburetor and should not be
used in such engines.
N
STIHL recommends the use of STIHL
MotoMix. This ready-to-use fuel mix
contains no benzol or lead, has a high
octane rating and ensures that you
always use the right mix ratio.
Engines equipped with M-Tronic deliver
full power when run on gasoline with an
ethanol content of up to 25% (E25).
Storing Fuel
STIHL MotoMix uses STIHL HP Ultra
two-stroke engine oil for an extra long
engine life.
Use only high-quality two-stroke engine
oil – preferably STIHL HP, HP Super or
HP Ultra, which are specially formulated
for use in STIHL engines. HP Ultra
guarantees high performance and a
long engine life.
STIHL MotoMix
MotoMix is not available in all markets.
Mixing Fuel
NOTICE
Unsuitable fuels or lubricants or mix
ratios other than those specified may
result in serious damage to the engine.
Poor quality gasoline or engine oil may
damage the engine, sealing rings, hoses
and the fuel tank.
Gasoline
Use only high-quality brand-name
gasoline with a minimum octane rating
of 90 – leaded or unleaded.
22
Engine oil
These engine oils are not available in all
markets.
Use only STIHL 50:1 two-stroke engine
oil for the fuel mix in models with a
catalytic converter.
STIHL engine oil 50:1
Liters
(ml)
0.02
(20)
0.10
(100)
0.20
(200)
0.30
(300)
0.40
(400)
0.50
(500)
Use a canister approved for storing
fuel. Pour oil into canister first, then
add gasoline and mix thoroughly.
Store fuel only in approved safety-type
fuel canisters in a dry, cool and safe
location protected from light and the sun.
Fuel mix ages – only mix sufficient fuel
for a few weeks work. Do not store fuel
mix for longer than 30 days. Exposure to
light, the sun, low or high temperatures
can quickly make the fuel mix unusable.
STIHL MotoMix may be stored for up to
2 years without any problems.
N
Thoroughly shake the mixture in the
canister before fueling your
machine.
Mix Ratio
STIHL 50:1 two-stroke engine oil: 50
parts gasoline to 1 part oil
WARNING
Pressure may build up in the canister –
open it carefully.
N
Clean the fuel tank and canister
from time to time.
FS 90, FS 90 R
English
Dispose of remaining fuel and cleaning
fluid properly in accordance with local
regulations and environmental
requirements.
Filling Up with Fuel
Fueling
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).
N
Preparations
Fill up with fuel.
N
N
Before fueling, clean the filler cap
and the area around it to ensure that
no dirt falls into the tank.
Position the machine so that the
tank cap faces up.
2709BA004 KN
266BA028 KN
Closing the filler cap
N
Place the cap in the opening.
N
Turn the cap clockwise as far as
stop and tighten it down as firmly as
possible by hand.
2709BA003 KN
Opening the filler cap
FS 90, FS 90 R
N
Turn the cap counterclockwise until
it can be removed from the tank
opening.
N
Remove the cap.
23
English
Full Harness
Fitting the Harness
Balancing the Machine
The type and style of the
harness/shoulder strap depend on the
market.
Attaching the unit to the harness
1
The use of the shoulder strap is
described in the chapter on "Approved
Combinations of Cutting Attachment,
Deflector, Handle and Harness".
3
Shoulder Strap
2
002BA228 KN
1
N
Put on the harness (1) and close the
locking plate (3).
N
Adjust the length of the strap – with
the machine attached, the
carabiner (2) must be about a
hand's width below your right hip.
2
002BA441 KN
N
N
Put on the shoulder strap (1).
N
Adjust the length of the strap so that
the carabiner (2) is about a hand’s
width below your right hip.
N
Balance the machine – see
"Balancing the Machine".
24
Balance the machine – see
"Balancing the Machine".
The type and style of the harness and
carabiner (spring hook) depend on the
market.
N
Attach the carabiner (1) to the
carrying ring (2) on the drive tube.
FS 90, FS 90 R
English
Floating positions
A
002BA034 KN
Detaching the unit from the harness
Mowing tools (A) such as mowing
heads, grass cutting blades and brush
knives
N
Loosen the screw (3).
Balancing the brushcutter
B
The unit is balanced differently,
depending on the cutting attachment
used.
Proceed as follows until the conditions
specified under "Floating positions"
have been met:
N
Adjust the carrying ring.
N
Tighten the screw moderately.
N
Allow the unit to hang freely.
N
Check the position obtained.
FS 90, FS 90 R
002BA035 KN
N
should just touch the ground.
N
Press down the bar on the
carabiner (1) and pull the carrying
ring (2) out of the carabiner.
Circular saw blades (B)
N
should "hover" about 20 cm (8 in)
above the ground.
When the correct floating position has
been reached:
N
Tighten down the screw on the
carrying ring firmly.
25
English
Control handle on shaft
Starting
7
Operating elements
4
STOP-
Starting / Stopping the
Engine
STOP
Control handle on handlebar
4
5
7
ST
6
6
START
3
START
STOP-
5
N
Press the throttle trigger lockout and
throttle trigger in succession
N
Hold both triggers down
N
Move the slide control to START
and hold it in position too
N
Release the throttle trigger, slide
control and throttle trigger lockout in
succession = starting throttle
position
2
3
1
002BA181 KN
OP
1
2
3
Throttle lever lock
Throttle trigger
Slide control
1
2
3
Throttle lever lock
Throttle trigger
Slide control
Slide control positions
4
5
6
STOP-0 – engine off – ignition is
switched off
Operating position F – Run – engine
is running or can start
START – Start – the ignition is
switched on – the engine can be
started
Symbol on slide control
7
26
8
h – Stop sign and arrow – to switch
off the engine, push the slide control
in the direction of the arrow at the
stop sign (h) to STOP-0
249BA057 KN
1
002BA182 KN
2
9
N
Set the choke knob (8)
g If the engine is cold
e If the engine is warm – even if the
engine has already run but is still
cold
N
Press the manual fuel pump
bulb (9) at least 5 times - even when
bulb is filled with fuel
FS 90, FS 90 R
English
Starting
Switching off the engine
N
Push the slide control in the
direction of the arrow at the stop
sign h to STOP-0
At very low temperatures
N
Grab the starter grip with your right
hand
N
Pull the starter grip slowly until you
feel it engage and then give it a
brisk, strong pull
NOTICE
Do not pull out the starter rope
completely – risk of breakage!
N
N
Lay the machine on the ground in a
secure position: It must rest on the
engine support and the deflector for
the cutting attachment
N
(if present): Remove the transport
guard on the cutting attachment
N
The cutting attachment must not touch
the ground or any other objects – risk of
accident!
N
Assume a firm stance – possibilities:
standing, bending or kneeling
N
Press the machine firmly against
the ground with the left hand – do
not touch the throttle trigger or
throttle trigger lockout while doing
so – your thumb should be under the
fan housing
NOTICE
Do not stand or kneel on the shaft!
FS 90, FS 90 R
N
Do not let the starter grip snap back
– guide it slowly back into the
housing so that the starter rope can
rewind properly
crank until the engine starts – at the
latest after the fifth time the starter
rope is pulled, turn the choke knob
to e
continue cranking
As soon as engine is running:
N
Blip the throttle trigger = disengage
starting throttle position – the slide
control jumps to run F – engine
begins to idle
N
Press the throttle trigger slightly
N
Let the engine warm up briefly
If the engine does not start
Choke knob
If the choke knob was not returned to e
in time after the engine turned over for
the first time, then the engine has
flooded.
N
Turn the choke knob to e.
N
Move the slide control, throttle
trigger interlock and throttle trigger
to the starting throttle position
N
Start the engine – to do this, pull the
starter rope briskly – 10 or 20 pulls
may be needed
Once the engine is running
N
Blip the throttle trigger, the slide
control jumps to run ?F – the engine
begins to idle
WARNING
If the engine still does not start
If the carburetor has been set correctly,
the cutting attachment should not rotate
when the engine is idling!
N
Set slide control to STOP-0
N
Remove the spark plug - see "Spark
plug"
The machine is now ready for use.
N
Dry the spark plug
27
English
Crank the engine several times with
the starter – to clear the combustion
chamber
N
Replace the spark plug – see "Spark
plug"
N
Set the slide control to START
N
Turn the choke knob to e – even if
the engine is cold!
N
Restart the engine
Adjusting the throttle cable
N
Check throttle cable adjustment –
see "Adjusting the throttle cable"
Transporting the Unit
Using a transport guard
The type of transport guard used
depends on the type of metal cutting
attachment supplied with the machine.
Transport guards are also available as
special accessories.
681BA270 KN
N
If a brush knife is fitted:
Fitting the transport guard for grass
cutting blades 230 and brush knives
After refueling, press the manual
fuel pump bulb at least five times –
even if it is full of fuel.
N
Set choke lever depending on
engine temperature
N
Restart the engine
The transport guard can be used for
grass cutting blades up to 230 mm
(9.1 in.) in diameter and for brush knife
250-3.
681BA269 KN
N
681BA268 KN
If the tank has been drained completely
If a grass cutting blade 230 is fitted:
28
FS 90, FS 90 R
English
1.
N
681BA275 KN
681BA271 KN
2.
Unhook the retainer on the transport
guard and swing outward
681BA280 KN
681BA272 KN
If a grass cutting blade 250 is fitted:
Fitting the transport guards for grass
cutting blades 250 and circular saw
blades
681BA279 KN
N
Fit the transport guard (1) to the
cutting attachment from below.
If a circular saw blade is fitted:
2.
N
681BA281 KN
The transport guard (1) can be used for
grass cutting blades with a diameter of
250 mm (9.8 in.) and the transport
guard (2) for circular saw blades with a
diameter of 200 mm (7.9 in.) .
FS 90, FS 90 R
Fit the transport guard (2) to the
cutting attachment from below,
ensuring that the stop is centered in
the recess.
2
681BA278 KN
1
N
Hook the retainer onto the hook of
the transport guard
29
English
After a long period of full throttle
operation, allow the engine to run for a
short while at idle speed so that engine
heat can be dissipated by the flow of
cooling air. This protects enginemounted components (ignition,
carburetor) from thermal overload.
30
Setting the idle speed
4
1
2
N
Turn the choke knob to g
N
Take out the screw (1) and remove
the filter cover (2).
N
Clean away loose dirt from around
the filter.
N
N
Grip the filter element (3) at the
cutout (arrow) in the filter
housing (4) and remove it.
Let the engine warm up for approx.
3 min
N
Fit a new filter element. As a
temporary measure you can knock it
out on the palm of your hand or blow
it out with compressed air. Do not
wash.
Slowly turn idle speed screw (LA)
clockwise until the engine runs
smoothly – the cutting attachment
must not rotate
Cutting attachment turns when idling
N
After Finishing Work
Storing for a short period: Wait for the
engine to cool down. Empty the fuel tank
and keep the machine in a dry place,
well away from sources of ignition, until
you need it again. For longer out-ofservice periods – see "Storing the
Machine".
The carburetor of the machine has been
adjusted for optimum performance and
fuel efficiency in all operating states at
the factory.
If there is a noticeable loss of engine
power
A factory-new machine should not be
run at high revs (full throttle off load) for
the first three tank fillings. This avoids
unnecessary high loads during the
break-in period. As all moving parts
have to bed in during the break-in
period, the frictional resistances in the
engine are greater during this period.
The engine develops its maximum
power after about 5 to 15 tank fillings.
During Operation
Adjusting the Carburetor
266BA027 KN
During break-in period
Cleaning the Air Filter
273BA006 KN
Operating Instructions
N
Replace damaged parts.
Installing the filter
N
Install the filter element in the filter
housing and fit the cover.
N
Insert the screw and tighten it down
firmly.
LA
Engine stops when idling
N
Turn the idle speed screw (LA)
slowly counterclockwise until the
cutting attachment stops moving –
then turn another 1/2 to 3/4 turn in
the same direction
WARNING
If the cutting attachment continues to
keep rotating in idle even after
adjustment, have the machine checked
by a servicing dealer.
FS 90, FS 90 R
English
If the engine is down on power,
difficult to start or runs poorly at idle
speed, first check the spark plug.
N
Fit a new spark plug after about 100
operating hours – or sooner if the
electrodes are badly eroded. Install
only suppressed spark plugs of the
type approved by STIHL – see
"Specifications".
Removing the spark plug
N
Move the slide control to STOP-0.
A
N
Clean dirty spark plug.
N
Check electrode gap (A) and
readjust if necessary – see
"Specifications".
N
Rectify the problems which have
caused fouling of the spark plug.
1
2
002BA446 KN
N
Installing the Spark Plug
000BA039 KN
Checking the spark plug
Spark Plug
Possible causes are:
249BA063 KN
1
Pull off the spark plug boot (1).
N
Unscrew the spark plug.
Too much oil in fuel mix.
–
Dirty air filter.
–
Unfavorable running conditions.
N
Screw the spark plug (2) into the
cylinder and fit the boot (1) (press it
down firmly).
1
000BA045 KN
N
–
WARNING
If the spark plug comes with a
detachable adapter nut (1), screw the
adapter onto the thread and tighten it
down firmly to reduce the risk of arcing
and fire.
FS 90, FS 90 R
31
English
Lubricating the Gearbox
For periods of 3 months or longer
If engine running behavior is
unsatisfactory even though the air filter
is clean and the carburetor is properly
adjusted, the cause may be the muffler.
1
Have the muffler checked for
contamination (carbonization) by your
servicing dealer.
STIHL recommends that you have
servicing and repair work carried out
exclusively by an authorized STIHL
servicing dealer.
Storing the Machine
2
233BA010 KN
Engine Running Behavior
N
Check the grease level regularly –
about every 25 hours of operation.
N
Unscrew the filler plug (1). If no
grease can be seen on the inside of
the filler plug, screw the tube (2) of
STIHL gear lubricant (special
accessory) into the filler hole.
N
Squeeze up to 5 g grease into the
gearbox.
NOTICE
Do not completely fill the gearbox with
grease.
32
N
Remove the tube of grease (2).
N
Refit the filler plug (1) and tighten it
down firmly.
N
Drain and clean the fuel tank in a
well ventilated area.
N
Dispose of fuel properly in
accordance with local
environmental requirements.
N
Run the engine until the carburetor
is dry – this helps prevent the
carburetor diaphragms sticking
together.
N
Remove, clean and inspect the
cutting attachment. Coat metal
cutting attachments with corrosion
inhibitor.
N
Thoroughly clean the machine.
N
Clean the air filter.
N
Store the machine in a dry and
secure location – out of the reach of
children and other unauthorized
persons.
FS 90, FS 90 R
English
N
Use a sharpening file (see "Special
Accessories") to sharpen dull
cutting attachments. In case of
more serious wear or nicks:
Resharpen with a grinder or have
the work done by a dealer – STIHL
recommends a STIHL servicing
dealer.
N
Sharpen frequently, take away as
little metal as possible – two or three
strokes of the file are usually
enough.
1
1
2
2
N
After resharpening about 5 times,
check the cutting attachment for
out-of-balance on a STIHL balancer
– see “Special Accessories” – or
have it checked by a dealer and rebalanced as necessary – STIHL
recommends a STIHL servicing
dealer.
Maintaining the Mowing
Head
Placing power tool on the ground
002BA104 KN
Balancing
Sharpening Metal Cutting
Blades
N
Shut off the engine.
N
Lay your power tool on its back so
that the cutting attachment
mounting face is pointing up.
Replacing Nylon Line
Always check the mowing head for signs
of wear before replacing the nylon line.
1
WARNING
2
1
N
002BA083 KN
2
If there are signs of serious wear,
replace the complete mowing head.
Resharpen the teeth (1) uniformly –
do not alter the contour of the parent
blade (2) in any way.
See cutting attachment packaging for
additional sharpening instructions. Keep
the packaging for future reference.
FS 90, FS 90 R
The nylon mowing line is referred to as
"nylon line" or "line" in the following.
The mowing head is supplied with
illustrated instructions for replacing the
nylon line. Keep the instructions for the
mowing head in a safe place.
N
If necessary, remove the mowing
head.
33
English
Adjusting Nylon Line
STIHL SuperCut
Fresh line is advanced automatically if
the remaining line is at least 6 cm
(2 1/2 in) long. The blade on the
deflector trims overlong lines to the
correct length.
STIHL AutoCut
N
With the engine running, hold the
rotating mowing head above the
grass surface.
N
Tap it on the ground once – fresh
line is advanced and the blade on
the deflector trims it to the right
length.
Fresh line is advanced every time the
mowing head is tapped on the ground.
For this reason observe the mowing
head's cutting performance during
operation. If the mowing head is tapped
on the ground too often, the line limiter
blade will unnecessarily cut off unused
lengths of nylon line.
Line feed operates only if both lines are
still at least 2.5 cm (1 in) long.
STIHL TrimCut
WARNING
To reduce the risk of injury, always shut
off the engine before adjusting the nylon
line by hand.
N
N
34
Pull the spool up – rotate it about 1/6
turn counterclockwise until it
engages – and allow it to spring
back.
Repeat the above procedure as
necessary until both lines reach the
limiter blade on the deflector.
Rotating the spool from one stop to the
next advances about 4 cm (1 1/2 in) of
fresh line.
The mowing head is supplied with
illustrated instructions for replacing the
blades. Keep the instructions for the
mowing head in a safe place.
WARNING
Replacing nylon line
To reduce the risk of injury, always shut
off the engine before installing the
blades.
STIHL PolyCut
N
Remove the mowing head.
A length of nylon line can be fitted to the
PolyCut in place of the cutting blades.
N
Replace blades as shown in the
illustrated instructions.
STIHL FixCut, STIHL PolyCut
N
Mount the mowing head on the
machine.
WARNING
To reduce the risk of injury, always shut
off the engine before refilling the mowing
head.
N
Fit nylon line in mowing head as
described in the instructions
supplied.
Replacing Cutting Blades
STIHL PolyCut
Always check the mowing head for signs
of wear before installing new cutting
blades.
WARNING
If there are signs of serious wear,
replace the complete mowing head.
The thermoplastic cutting blades are
referred to as "blades" in the following.
Pull ends of the lines outward.
FS 90, FS 90 R
English
Inspections and Maintenance
by Dealer
Maintenance Work
STIHL recommends that you have
servicing and repair work carried out
exclusively by an authorized STIHL
servicing dealer.
465BA002 KN
Fuel Pickup Body in Tank
N
Check the pickup body in the fuel
tank every year and have it replaced
if necessary.
The pickup body should be positioned in
the area of the tank shown in the
illustration.
FS 90, FS 90 R
35
English
Visual inspection (condition, leaks)
Complete machine
Control handle
X
Clean
Replace any damaged parts
X
Function tests
X
X
X
X
Replace
Manual fuel pump (if present)
X
X
Have checked by a specialist dealer1)
Have them replaced by a servicing
dealer1)
Fuel tank
Clean
Carburetor
Check idle adjustment, cutting attachment must not turn
X
X
X
X
X
Cylinder fins
Valve clearance
36
X
X
Set electrode gap
Cooling air intakes
X
X
Setting the idle speed
Spark plug
X
X
Have repaired by a specialist dealer1)
Fuel pickup body in fuel tank
As required
X
X
Clean
Check
If damaged
If faulty
Yearly
Monthly
X
X
Visual inspection
Air filter
Weekly
Whenever tank is refilled
Before starting work
The following maintenance intervals apply in normal operating conditions. The specified intervals must be shortened accordingly when working for longer than normal
or under difficult cutting conditions (extensive dust, etc.).
At the end of work and/or
daily
Maintenance and Care
X
Replace after every 100 hours of
operation
Visual inspection
X
Clean
Have them cleaned by a servicing dealer
1)
Check and adjust if necessary, once
after 139 hours of operation, by servicing dealer1)
X
X
X
FS 90, FS 90 R
Combustion chamber
Clean after 139 hours of operation, then
every 150 hours of operation, by servicing dealer1)
X
All accessible screws, nuts and bolts (not
Retighten
adjusting screws)
Check
Anti-vibration elements
X
X
X
Replace
Check for secure fit
X
Metal cutting attachments
Sharpen
X
Safety information label
1)
Check
X
X
Cutting attachments
Gear lubrication
X
Have them replaced by a servicing
dealer1)
Visual inspection
X
X
X
X
X
Top up
Replace
As required
If damaged
If faulty
Yearly
Monthly
Weekly
Whenever tank is refilled
Before starting work
The following maintenance intervals apply in normal operating conditions. The specified intervals must be shortened accordingly when working for longer than normal
or under difficult cutting conditions (extensive dust, etc.).
At the end of work and/or
daily
English
X
X
STIHL recommends STIHL servicing dealers
FS 90, FS 90 R
37
English
Minimize Wear and Avoid
Damage
Observing the instructions in this manual
helps reduce the risk of unnecessary
wear and damage to the power tool.
The power tool must be operated,
maintained and stored with the due care
and attention described in this owner's
manual.
servicing dealer. STIHL dealers are
regularly given the opportunity to attend
training courses and are supplied with
the necessary technical information.
Alterations or modifications to the
product not approved by STIHL.
–
Using tools or accessories which
are neither approved or suitable for
the product or are of a poor quality.
–
Using the product for purposes for
which it was not designed.
–
Using the product for sports or
competitive events.
–
Consequential damage caused by
continuing to use the product with
defective components.
Maintenance Work
–
Damage to the engine due to
neglect or deficient maintenance
(e.g. air and fuel filters), incorrect
carburetor adjustment or
inadequate cleaning of cooling air
inlets (intake ports, cylinder fins).
–
Corrosion and other consequential
damage resulting from improper
storage.
–
Damage to the machine resulting
from the use of poor quality
replacement parts.
–
Antivibration elements
Parts Subject to Wear and Tear
Some parts of the power tool are subject
to normal wear and tear even during
regular operation in accordance with
instructions and, depending on the type
and duration of use, have to be replaced
in good time. Among other parts, this
includes:
All the operations described in the
"Maintenance Chart" must be performed
on a regular basis. If these maintenance
operations cannot be performed by the
owner, they should be performed by a
servicing dealer.
–
Cutting attachments (all types)
–
Mounting hardware for cutting
attachments (rider plate, nut, etc.)
–
Deflectors for cutting attachments
–
Clutch
STIHL recommends that you have
servicing and repair work carried out
exclusively by an authorized STIHL
–
Filters (air, fuel)
–
Rewind starter
38
Spark plug
If these maintenance operations are not
carried out as specified, the user
assumes responsibility for any damage
that may occur. Among other parts, this
includes:
The user is responsible for all damage
caused by non-observance of the safety
precautions, operating and maintenance
instructions in this manual. This includes
in particular:
–
–
FS 90, FS 90 R
English
Main Parts
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
8
12
7
9
2
3
5
1
#
6
18
10
11
4
14
10
15
17
16
19
9
7
FS 90, FS 90 R
249BA069 KN
20
13
11 8
#
Filler cap
Carburetor adjusting screw
Starter grip
Spark plug boot
Muffler
Two-handed handle bar
Throttle trigger
Slide control
Throttle lever lock
Throttle cable support
Carrying ring
Manual fuel pump
Choke knob
Air filter cover
Fuel tank
Machine support
Handlebar support
Tommy screw
Loop handle
Barrier bar (present depending on
country)
Machine number
39
English
Specifications
3
1
7
8
5
4
1
3
4
002BA394 KN
6
1
2
3
4
5
6
8
Mowing head
Deflector for mowing heads only
Blade
Deflector for all mowing
attachments
Skirt
Metal mowing attachment
Circular saw blade
Limit stop for circular saw blades
only
Engine
002BA395 KN
7
2
Single cylinder four-stroke engine with
mixture lubrication
Displacement:
Bore:
Stroke:
Engine power to
ISO 8893:
28.4 cc
38 mm
25 mm
0.95 kW
(1.3 bhp) at
7,000 rpm
Idle speed:
2,800 rpm
Cut-off speed (rated): 10,200 rpm
Max. output shaft
speed (cutting
attachment):
7,500 rpm
Valve clearance
Inlet valve:
0.10 mm
Exhaust valve:
0.10 mm
Ignition System
Electronic magneto ignition
Spark plug (resistor
type):
Bosch USR 7 AC
Electrode gap:
0.5 mm
Fuel System
All position diaphragm carburetor with
integral fuel pump
Fuel tank capacity:
40
530 cc (0.53 l)
FS 90, FS 90 R
English
Weight
Sound power level Lw to ISO 22868
Dry, without cutting attachment and
deflector
FS 90:
5.8 kg
FS 90 R:
5.5 kg
Overall length
without cutting
attachment
1800 mm
Features
R
Loop handle
Noise and Vibration Data
Cutting Attachment
For further details on compliance with
Vibration Directive 2002/44/EC see
www.stihl.com/vib.
Sound pressure level Lp to ISO 22868
with mowing head
FS 90 with bike handle:
FS 90 R:
with metal mowing
attachment
FS 90 with bike handle:
FS 90 R with barrier bar:
91 dB(A)
91 dB(A)
90 dB(A)
90 dB(A)
with mowing head
FS 90 with bike handle:
FS 90 R:
with metal mowing
attachment
FS 90 with bike handle:
FS 90 R with barrier bar:
104 dB(A)
104 dB(A)
104 dB(A)
104 dB(A)
Vibration measurement ahv,eq to
ISO 22867
Handle,
with mowing head left
FS 90 with bike
handle:
4.6 m/s2
FS 90 R:
5.1 m/s2
with metal mowing attachment
FS 90 with bike
handle:
FS 90 R with barrier bar:
Handle,
right
5.4 m/s2
5.3 m/s2
Handle,
left
Handle,
right
5.3 m/s2
6.1 m/s2
3.5 m/s2
4.9 m/s2
Interchangeable attachment
For version see "Approved Power Tool
Attachments".
Noise and vibration data measurements
include idling and rated maximum speed
in the following ratios.
on FCS, FS, FH and HT
on HL
on BF, SP and KW
1 to 1
1 to 4
1 to 6
Sound power level Lweq to ISO 22868,
3744
FS 90 with bike
handle:
99 dB(A) ... 102 dB(A)
FS 90 R:
99 dB(A) ... 102 dB(A)
Vibration measurement ahv,eq to
ISO 11789, 20643, 22867, 8662
Handle, left
FS 90 with bike
handle:
1-5 m/s2 ... 2.9 m/s2
FS 90 R:
3.4 m/s2 ... 6.8 m/s2
Handle, right
FS 90 with bike
handle:
2.1 m/s2 ... 2.8 m/s2
FS 90 R:
4.1 m/s2 ... 7.0 m/s2
The K-factor in accordance with
Directive 2006/42/EC is 2.5 dB(A) for
the sound pressure level and sound
power level; the K-factor in accordance
with Directive 2006/42/EC is 2.0 m/s2
for the vibration measurement.
REACH
REACH is an EC regulation and stands
for the Registration, Evaluation,
Authorisation and Restriction of
Chemical substances.
For information on compliance with the
REACH regulation (EC) No. 1907/2006
see www.stihl.com/reach.
Sound pressure level Lp to
ISO 11201, 22868
FS 90 with bike
handle:
88 dB(A) ... 95 dB(A)
FS 90 R:
88 dB(A) ... 97 dB(A)
FS 90, FS 90 R
41
English
Users of this machine may only carry out
the maintenance and service work
described in this user manual. All other
repairs must be carried out by a
servicing dealer.
STIHL recommends that you have
servicing and repair work carried out
exclusively by an authorized STIHL
servicing dealer. STIHL dealers are
regularly given the opportunity to attend
training courses and are supplied with
the necessary technical information.
When repairing the machine, only use
replacement parts which have been
approved by STIHL for this power tool or
are technically identical. Only use highquality replacement parts in order to
avoid the risk of accidents and damage
to the machine.
Disposal
EC Declaration of Conformity
Observe all country-specific waste
disposal rules and regulations.
ANDREAS STIHL AG & Co. KG
Badstr. 115
D-71336 Waiblingen
confirms that the product described
below
000BA073 KN
Maintenance and Repairs
STIHL products must not be thrown in
the garbage can. Take the product,
accessories and packaging to an
approved disposal site for environmentfriendly recycling.
Contact your STIHL servicing dealer for
the latest information on waste disposal.
Category:
Make:
Model:
Serial identification:
Displacement:
Brushcutter
STIHL
FS 90
FS 90 R
4180
28.4 cc
conforms to the provisions of Directives
2006/42/EC, 2004/108/EC and
2000/14/EC and has been developed
and manufactured in compliance with
the following standards in the versions
valid at the time of production:
STIHL recommends the use of original
STIHL replacement parts.
EN ISO 11806-1, EN 55012,
EN 61000-6-1
Original STIHL parts can be identified by
the STIHL part number, the {
logo and the STIHL parts symbol K
(the symbol may appear alone on small
parts).
The measured and guaranteed sound
power levels were determined according
to Directive 2000/14/EC, Annex V, using
the ISO 10884 standard.
Measured sound power level
104 dB(A)
Guaranteed sound power level
106 dB(A)
Technical documents deposited at:
ANDREAS STIHL AG & Co. KG
Produktzulassung (Product Licensing)
The year of manufacture and serial
number are applied to the product.
42
FS 90, FS 90 R
English
Done at Waiblingen, 15.08.2014
ANDREAS STIHL AG & Co. KG
Thomas Elsner
Director Group Product Management
FS 90, FS 90 R
43
English
44
FS 90, FS 90 R
0458-260-0121-D
englisch
G
www.stihl.com
*04582600121D*
0458-260-0121-D
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