Stihl Fs 90 R Manual

							FS 90, FS 90 R
English
39 For periods of about 3 months or longer
NDrain and clean the fuel tank in a 
well ventilated area.
NDispose of fuel properly in 
accordance with local 
environmental requirements.
NRun the engine until the carburetor 
is dry – this helps prevent the 
carburetor diaphragms sticking 
together.
NRemove, clean and inspect the 
cutting attachment. Coat metal 
cutting attachments with corrosion 
inhibitor.
NThoroughly clean the machine – pay 
special attention to the cylinder fins 
and air filter.
NStore the machine in a dry and 
secure location – out of the reach of 
children and other unauthorized 
persons.NUse 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.
NSharpen frequently, take away as 
little metal as possible – two or three 
strokes of the file are usually 
enough.
NResharpen 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.
Balancing
NAfter 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 re-
balanced as necessary – STIHL 
recommends a STIHL servicing 
dealer.Storing the MachineSharpening Metal Cutting 
Blades
22
1
2
11
002BA042 KN 
						

							FS 90, FS 90 R
English
40
Placing power tool on the ground
NShut off the engine.
NLay 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.
WARNING
If there are signs of serious wear, 
replace the complete mowing head.
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.
NIf necessary, remove the mowing 
head.
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
NWith the engine running, hold the 
rotating mowing head above the 
grass surface.
NTap 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 2.5cm(1in) long.
STIHL TrimCut
WARNING
To reduce the risk of injury, always shut 
off the engine before adjusting the nylon 
line by hand.
NPull the spool up – rotate it about 1/6 
turn counterclockwise until it 
engages – and allow it to spring 
back.
NPull ends of the lines outward.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 about4 cm (1 1/2 in) of 
fresh line.
Replacing Nylon Line
STIHL PolyCut
A length of nylon line can be fitted to the 
PolyCut in place of the cutting blades.
STIHL DuroCut, STIHL PolyCut
WARNING
To reduce the risk of injury, always shut 
off the engine before refilling the mowing 
head.
NFit nylon line in the 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.
Maintaining the Mowing 
Head
002BA104 KN 
						

							FS 90, FS 90 R
English
41 The mowing head is supplied with 
illustrated instructions for replacing the 
blades. Keep the instructions for the 
mowing head in a safe place.
WARNING
To reduce the risk of injury, always shut 
off the engine before installing the 
blades.
NRemove the mowing head.
NReplace blades as shown in the 
illustrated instructions.
NMount the mowing head on the 
machine.
Maintenance Work
STIHL recommends that you have 
servicing and repair work carried out 
exclusively by an authorized STIHL 
servicing dealer.
Fuel Pickup Body in Tank
NCheck 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.
Inspections and Maintenance 
by Dealer
465BA002 KN 
						

							FS 90, FS 90 R
English
42
Maintenance and Care
The following intervals apply to normal operating conditions only. If your daily work-
ing time is longer or operating conditions are difficult (very dusty work area, etc.), 
shorten the specified intervals accordingly.
before starting work
after finishing work or daily
after each refueling stop
weekly
monthly
every 12 months
if problem
if damaged
as required
Complete machineVisual inspection (condition, leaks)XX
CleanX
Replace any damaged partsXX
Control handle Check operationXX
Air filterVisual inspection XX
CleanXX
ReplaceX
Manual fuel pump (if fitted)CheckX
Have repaired by servicing dealer
1)X
Pickup body in fuel tankHave checked by servicing dealer
1)X
Have replaced by servicing dealer
1)XXX
Fuel tank CleanXX
CarburetorCheck idle adjustment – the cutting 
attachment must not rotateXX
Adjust idle speedX
Spark plugAdjust electrode gapX
Replace after every 100 operating hours
Cooling inletsVisual inspectionX
CleanX
Cylinder fins Clean 
2)X
Valve clearanceCheck and, if necessary, have adjusted 
by dealer after first 139 hours of 
operation
1)X
Have combustion chamber (CARB only)cleaned by servicing dealer
1) after first 
139 hours of operation, then every 150 
hours of operationX 
						

							FS 90, FS 90 R
English
43
Spark arresting screen in mufflerCheckXX
Clean or replaceXX
All accessible screws and nuts (not adjust-
ing screws)RetightenX
Anti-vibration elements (rubber buffers, 
springs)CheckXXX
Have replaced by servicing dealer
1)X
Cutting attachmentVisual inspectionXX
ReplaceX
Check tightnessXX
Metal cutting attachment SharpenXX
Gearbox lubricationCheckX
ReplenishX
Safety labels ReplaceX
1)STIHL recommends an authorized STIHL servicing dealer.2)Remove shroud - see "Spark Arresting Screen in Muffler" The following intervals apply to normal operating conditions only. If your daily work-
ing time is longer or operating conditions are difficult (very dusty work area, etc.), 
shorten the specified intervals accordingly.
before starting work
after finishing work or daily
after each refueling stop
weekly
monthly
every 12 months
if problem
if damaged
as required 
						

							FS 90, FS 90 R
English
441Fuel Filler Cap
2Carburetor Adjusting Screws
3Starter Grip
4Spark Plug Boot
5Muffler with Spark Arresting Screen
6Bike Handle
7Throttle Trigger
8Slide Control
9Throttle Trigger Lockout
10Throttle Cable Retainer
11Carrying Ring
12Manual Fuel Pump
13Choke Knob
14Air Filter Cover
15Fuel Tank
16Machine Support
17Handle Support
18Wing Screw
19Loop Handle
20Barrier Bar
#Serial Number
Main Parts
418
#
13
7
981120
19
8
79
6
17
101110
15
16
14
5
1
2
12
3
249BA069 KN 
						

							FS 90, FS 90 R
English
45
Definitions
1 Fuel Filler Cap
For closing the fuel tank.
2 Carburetor Adjusting Screws
For tuning the carburetor.
3 Starter Grip
The grip of the pull starter, for 
starting the engine.
4 Spark Plug Boot
Connects the spark plug with the 
ignition lead.
5 Muffler with Spark Arresting Screen
Muffler reduces engine exhaust 
noise and diverts exhaust gases 
away from operator.
Spark arresting screen is designed 
to reduce the risk of fire.
6 Bike Handle
For easy control of the machine with 
both hands during cutting work.
7 Throttle Trigger
Controls the speed of the engine.
8 Slide Control
For starting throttle, run and stop. 
Keeps the choke partially open 
during starting and switches off the 
ignition to stop the engine.
9 Throttle Trigger Lockout
Must be depressed before the 
throttle trigger can be activated.
10 Throttle Cable Retainer
Secures the throttle cable to the 
drive tube.
11 Carrying Ring
Connects the trimmer/brushcutter to 
the harness.12 Manual Fuel Pump
Provides additional fuel feed for a 
cold start.
13 Choke Knob
Eases engine starting by enriching 
mixture.
14 Air Filter Cover
Encloses and protects the air filter 
element.
15 Fuel Tank
For fuel and oil mixture.
16 Machine Support
For resting machine on the ground.
17 Handle Support
Connects the shaft and bike handle.
18 Wing Screw
Locks handlebar in selected 
position.
19 Loop Handle
For easy control of machine during 
cutting work.
20 Barrier Bar
Helps keep user's feet and legs 
clear of the cutting tool.
1Mowing Head
2Deflector for Mowing Heads
3Line Limiting Blade
4Deflector with Skirt for all Mowing 
Attachments
5Skirt
6Metal Mowing Tool
002BA114 KN
1
3
45
3
64 12 
						

							FS 90, FS 90 R
English
46
Definitions
1 Mowing Head
The cutting attachment, i. e. 
mowing head, for different 
purposes.
2 Deflector for Mowing Heads
The deflector is designed to reduce 
the risk of injury from foreign objects 
flung backwards toward the 
operator by the cutting attachment 
and from contact with the cutting 
attachment.
3 Line Limiting blade
Metal blade at the deflector in order 
to keep the line of the mowing head 
at the proper length.
4 Deflector with Skirt for all Mowing 
Attachments
The deflector is designed to reduce 
the risk of injury from foreign objects 
flung backwards toward the 
operator by the cutting attachment 
and from contact with the cutting 
attachment. Is not designed to 
contain fragmented metal blades.
5Skirt
The skirt at the bottom of the 
deflector must be utilized as 
described in the chapter "Mounting 
the Deflector".
6 Metal Mowing Tool
The cutting attachment, i. e. blade, 
made from metal for different 
purposes.7Circular Saw Blade
8Limit Stop for Circular Saw Blade
Definitions
7 Circular Saw Blade
Cutting attachment made of metal 
for cutting wood.
8 Limit Stop for Circular Saw Blade
Is designed to position the 
brushcutter steady against the 
wood in order to reduce the risk of 
injury from loss of control from 
reactive forces such as thrust out.
EPA / CEPA
The Emission Compliance Period 
referred to on the Emissions 
Compliance Label indicates the number 
of operating hours for which the engine 
has been shown to meet Federal 
emission requirements.
Category
CARB
The Emission Compliance Period used 
on the CARB-Air Index Label indicates 
the terms:
Engine
Single cylinder four-stroke engine with 
mixture lubrication
002BA186 KN
8
7
6SHFLILFDWLRQV
$   KRXUV
%   KRXUV
& KRXUV
([WHQGHG   KRXUV
,QWHUPHGLDWH   KRXUV
0RGHUDWH   KRXUV 
						

							FS 90, FS 90 R
English
47
Ignition System
Electronic magneto ignition
Fuel System
All position diaphragm carburetor with 
integral fuel pump
Weight
Overall length
FeaturesUsers of this unit should carry out only 
the maintenance operations described 
in this manual. STIHL recommends that 
other repair work be performed only by 
authorized STIHL servicing dealers.
Warranty claims following repairs can be 
accepted only if the repair has been 
performed by an authorized STIHL 
servicing dealer using genuine STIHL 
replacement parts.
Genuine STIHL parts can be identified 
by the STIHL part number, the 
{ logo and, in some cases, by 
the STIHL parts symbol K. The 
symbol may appear alone on small 
parts. Displacement: 28.4 cc 
(1.72 cu.in)
Bore: 38 mm (1.50 in)
Stroke: 25 mm (0.98 in)
Engine power to 
ISO 8893:0.95 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 
(0.004 in)
Exhaust valve: 0.10 mm 
(0.004 in)
Spark plug (resistor 
type): Bosch USR 7 AC
Electrode gap: 0.5 mm (0.02 in)
Fuel tank capacity: 0.53 l (17.9 fl.oz)
Dry, without cutting attachment and 
deflector
FS 90: 5.8 kg (12.8 lbs)
FS 90 R: 5.5 kg (12.1 lbs)without cutting 
attachment 1800 mm (71 in)
R Loop handle
Z Spark arresting screen in muffler
Maintenance and Repairs 
						

							FS 90, FS 90 R
English
48 Observe all country-specific waste 
disposal rules and regulations.
STIHL products must not be thrown in 
the garbage can. Take the product, 
accessories and packaging to an 
approved disposal site for environment-
friendly recycling.
Contact your STIHL servicing dealer for 
the latest information on waste disposal.
Not for California
Your Warranty Rights and Obligations
The U.S. Environmental Protection 
Agency (EPA) and STIHL Incorporated 
are pleased to explain the Emission 
Control System Warranty on your 
equipment type engine. In the U.S. new 
1997 and later model year small off-road 
equipment engines must be designed, 
built and equipped, at the time of sale, to 
meet the U.S. EPA regulations for small 
non road engines. The equipment 
engine must be free from defects in 
materials and workmanship which 
cause it to fail to conform with U.S. EPA 
standards for the first two years of 
engine use from the date of sale to the 
ultimate purchaser.
STIHL Incorporated must warrant the 
emission control system on your small 
off-road engine for the period of time 
listed below provided there has been no 
abuse, neglect or improper maintenance 
of your small off-road equipment engine.
Your emission control system includes 
parts such as the carburetor and the 
ignition system. Also included may be 
hoses, and connectors and other 
emission-related assemblies.
Where a warrantable condition exists, 
STIHL Incorporated will repair your 
small off-road equipment engine at no 
cost to you, including diagnosis (if the 
diagnostic work is performed at an 
authorized dealer), parts, and labor.Manufacturer's Warranty Coverage
In the U.S., 1997 and later model year 
small off-road equipment engines are 
w a r r a n t e d  f o r  t w o  y e a r s .  I f  a n y  e m i s s i o n -
related part on your engine is defective, 
the part will be repaired or replaced by 
STIHL Incorporated free of charge.
Owner's Warranty Responsibilities
As the small off-road equipment engine 
owner, you are responsible for the 
performance of the required 
maintenance listed in your instruction 
manual. STIHL Incorporated 
recommends that you retain all receipts 
covering maintenance on your small off-
road equipment engine, but STIHL 
Incorporated cannot deny warranty 
solely for the lack of receipts or for your 
failure to ensure the performance of all 
scheduled maintenance.
Any replacement part or service that is 
equivalent in performance and durability 
may be used in non-warranty 
maintenance or repairs, and shall not 
reduce the warranty obligations of the 
engine manufacturer.
As the small off-road equipment engine 
owner, you should be aware, however, 
that STIHL Incorporated may deny you 
warranty coverage if your small off-road 
equipment engine or a part has failed 
due to abuse, neglect, improper 
maintenance or unapproved 
modifications.
You are responsible for presenting your 
small off-road equipment engine to a 
STIHL service center as soon as a 
problem exists. The warranty repairs will 
be completed in a reasonable amount of 
time, not to exceed 30 days.
Disposal
000BA073 KN
67,+/,QFRUSRUDWHG)HGHUDO
(PLVVLRQ&RQWURO:DUUDQW\
6WDWHPHQW