Stihl Fs 90 R Manual

							FS 90, FS 90 R
English
19 The following STIHL interchangeable 
attachments may be mounted on the 
basic machine:Mounting Bike Handle with Swivelling 
Handle Support
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.
Removing the clamp moldings
NHold the lower clamp (1) and upper 
clamp (2) firmly together.
NRelease 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).
Approved Power Tool 
Attachments
228BA066 KN
BF
FH
FCS
KBKW
HT
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DWWDFKPHQW
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0RXQWLQJWKH%LNH+DQGOH 
						

							FS 90, FS 90 R
English
20 NPull out the wing screw – the 
washer (6) remains on the wing 
screw.
NSeparate the clamp moldings – the 
springs (4 and 5) remain in the 
lower clamp.
Securing the handlebar
NPlace the handlebar (7) in the lower 
clamp (1) so that distance A is no 
more than 15 cm (6 in). 
NPlace the upper clamp in position 
and hold both clamp moldings 
together.
NPush the wing screw through the 
two clamps as far as stop – hold all 
parts together and secure them.NPlace the secured assembly on the 
handle support (8) with the wing 
screw at the side nearest the 
engine.
NPush the wing screw into the handle 
support as far as stop and then 
screw it down – but do not finally 
tighten yet.
NLine up the handlebar at a right 
angle to the drive tube – check 
distance A again.
NTighten down the wing screw firmly.Mounting the control handle
NT a k e  o u t  t h e  s c r e w ( 9 )  –  t h e  n u t ( 1 0 )  
remains in the control handle (11).
NPush the control handle onto the 
handlebar (7) until the holes (13) 
line up – the throttle trigger (12) 
must point towards the gearbox.
NInsert the screw (9) and tighten it 
down firmly.
Fitting the throttle cable
NOTICE
Do not kink the throttle cable or lay it in 
tight radii – make sure the throttle trigger 
moves freely.
1 7A250BA046 KN
002BA234 KN
8 
						

							FS 90, FS 90 R
English
21 NPush the throttle cable (14) into the 
retainers (15).
Adjusting the throttle cable
NCheck adjustment of throttle cable – 
see chapter on "Adjusting the 
Throttle Cable".Swivelling the handlebar
Transport position
NLoosen the wing screw (3) and 
unscrew it until the handlebar (7) 
can be turned clockwise.
NTurn the handlebar 90° and then 
swing the handles down.
NTighten down the wing screw (3) 
firmly.
Working position
NReverse the sequence described 
above to swing the handles up and 
turn the handlebar 
counterclockwise.
Mounting Loop Handle with Barrier Bar
NFit the square nuts (1) in the barrier 
bar (2); the holes must line up.
15
14
15
14
15
250BA002 KN
7
3
002BA650 KN
0RXQWLQJWKH/RRS+DQGOH
2
002BA098 KN
11 
						

							FS 90, FS 90 R
English
22 NPlace the clamp (3) in the loop 
handle (4) and position them both 
against the drive tube (5).
NPosition the clamp (6) against the 
drive tube.
NPlace the barrier bar (2) in position 
as shown.
NLine up the holes.
NInsert the screws (7) in the holes 
and screw them into the barrier 
bar (2) as far as stop.
NGo to "Securing the Loop Handle".Mounting the Loop Handle without 
Barrier Bar
NPlace the clamp (3) in the loop 
handle (4) and position them both 
against the drive tube (5).
NPosition the clamp (6) against the 
drive tube.
NLine up the holes.
NFit 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.
NGo to "Securing the Loop Handle".
Securing the Loop Handle
The loop handle can be adjusted to suit 
the height and reach of the operator and 
the application by changing 
distance (A).
Recommendation: distance (A): 
about 20 cm (8 in)
NSlide the handle to the required 
position.
NLine up the loop handle (4).
NTighten 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.
The sleeve (9) (not fitted on all models) 
must be between the loop handle and 
the control handle.
5 4
002BA099 KN
2
3
6
7
7
8
5
4
1
6
1
3
8
7
002BA614 KN
9
4
A
002BA615 KN 
						

							FS 90, FS 90 R
English
23 Some machine versions are equipped 
with a throttle cable adjuster on the 
control handle.
A properly adjusted throttle cable is the 
precondition for correct operation in the 
full throttle, starting throttle and idle 
positions.
Adjust the throttle cable only after the 
unit is fully assembled – the control 
handle must be in the normal operating 
position.
NUse a suitable tool to push the slide 
to the end of the slot (see 
illustration).
NPress down the throttle trigger 
lockout (1) and squeeze the throttle 
trigger (2) (full throttle) – this sets 
the throttle cable correctly.The carrying ring comes standard with 
the machine or is available as a special 
accessory.
For position of carrying ring see "Main 
Parts".
NPlace the clamp (1) against the 
drive tube with the tapped hole on 
the left (viewed from engine).
NSqueeze the two ends of the clamp 
together and hold in that position.
NInsert the M6x14 screw (2).
NLine up the carrying ring.
NTighten down the screw firmly.
Mounting the Deflector
1Deflector for mowing attachments
2Deflector for mowing heads
Deflectors (1 and 2) are both mounted to 
the gearbox in the same way.
NPlace the deflector on the gearbox 
flange.
NInsert the screws (3) and tighten 
them down firmly.
Adjusting the Throttle Cable
002BA163 KN
STOP
249BA017 KN1 2
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002BA142 KN
1
2
1
0RXQWLQJWKHHIOHFWRU
002BA380 KN
2
1
3
3 
						

							FS 90, FS 90 R
English
24
Fitting the Skirt and Blade
WARNING
These parts must be fitted to the 
deflector (1) when you use a mowing 
head.
NSlide the lower guide slot of the skirt 
(4) onto the deflector (1) – it must 
snap into position.
NPush the blade (5) into the upper 
guide slot on the skirt and line it up 
with the first hole.
NInsert the screw and tighten it down 
firmly.
Mounting the Limit Stop
WARNING
Always fit the limit stop (6) when you use 
a circular saw blade.
NPosition the limit stop (6) on the 
gearbox flange.
NInsert the screws (7) and tighten 
them down firmly.
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.
Mounting Hardware for Cutting 
Attachments
The mounting hardware supplied 
depends on the cutting attachment that 
comes as original equipment with the 
new machine.
Machine supplied with mounting 
hardware
Mowing heads and metal cutting 
attachments may be mounted.
4
1
54
002BA103 KN
7
002BA382 KN
6
0RXQWLQJWKH&XWWLQJ
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002BA104 KN 
						

							FS 90, FS 90 R
English
25 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
NPull the hose (1) off the shaft (2).
Machine supplied without mounting 
hardware
Only mowing heads may be used which 
mount directly to the shaft (2).
Blocking the Shaft
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.
NInsert the stop pin (6) or 
screwdriver (6) in the hole (7) in the 
gearbox as far as stop – and apply 
slight pressure.
NRotate shaft, nut or cutting 
attachment until the stop pin slips 
into position and blocks the shaft.Removing the Mounting Hardware
NBlock the shaft.
NUse the combination wrench (1) to 
loosen and remove the nut (2) 
clockwise (left-hand thread).
NTake the thrust washer (3) off the 
shaft (4). Do not remove the thrust 
plate (5).
Mounting the Cutting Attachment
WARNING
Use a deflector that matches the cutting 
attachment – see "Mounting the 
Deflector".
2
002BA164 KN
13
4
5
2
002BA266 KN
6
7
2
002BA330 KN6
3
4
2
271BA057 KN
1
5 
						

							FS 90, FS 90 R
English
26 Fitting Mowing Head with Screw 
Mounting
Keep the instruction leaflet for the 
mowing head in a safe place.
NScrew the mowing head 
counterclockwise on to the shaft (1) 
as far as stop.
NBlock the shaft.
NTighten down the mowing head 
firmly.
NOTICE
Remove the tool used to block the shaft.
Removing the Mowing Head
NBlock the shaft.
NUnscrew the mowing head 
clockwise.
Mounting Metal Cutting Attachment
Keep the leaflet and packaging of the 
metal cutting attachment in a safe place.
WARNING
Wear protective gloves to reduce the 
risk of direct contact with the sharp 
cutting edges.
Mount only one metal cutting 
attachment.
Check direction of rotation of cutting 
attachment
Cutting attachments with 3 or 4 teeth (1, 
3) 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 2, 4 and 5 must point 
clockwise.
WARNING
Direction of rotation is indicated by an 
arrow on the inside of the deflector.
NPlace the cutting attachment (6) on 
the thrust plate (7).
WARNING
Collar (see arrow) must engage the 
cutting attachment's mounting hole.
Securing the cutting attachment
NFit the thrust washer (8) – convex 
side must face up.
NFit the rider plate (9).
NBlock the shaft (10).
NUse the combination wrench (12) to 
screw the mounting nut (11) on to 
the output shaft counterclockwise 
and tighten it down firmly.
1
002BA385 KN 
						

							FS 90, FS 90 R
English
27
WARNING
If the mounting nut has become too 
loose, fit a new one.
NOTICE
Remove the tool used to block the shaft.
Removing the Metal Cutting Attachment
WARNING
Wear protective gloves to reduce the 
risk of direct contact with the sharp 
cutting edges.
NBlock the shaft.
NUnscrew the mounting nut 
clockwise.
NRemove cutting attachment and its 
mounting hardware from the 
gearbox – but do not remove the 
thrust plate (7).This engine is certified to operate on 
unleaded gasoline and the STIHL two-
stroke engine oil at a mix ratio of 50:1.
Your engine requires a mixture of high-
quality gasoline and two-stroke air 
cooled engine oil.
Use mid-grade unleaded gasoline with a 
minimum octane rating of 89 ((R+M)/2) 
and no more than 10% ethanol content.
Fuel with a lower octane rating may 
increase engine temperatures. This, in 
turn, increases the risk of piston seizure 
and damage to the engine.
The chemical composition of the fuel is 
also important. Some fuel additives not 
only detrimentally affect elastomers 
(carburetor diaphragms, oil seals, fuel 
lines, etc.), but magnesium castings and 
catalytic converters as well. This could 
cause running problems or even 
damage the engine. For this reason 
STIHL recommends that you use only 
high-quality unleaded gasoline!
Gasoline with an ethanol content of 
more than 10% can cause running 
problems and major damage in engines 
and should not be used.
For further details, see 
www.STIHLusa.com/ethanol
The ethanol content in gasoline affects 
engine running speed – it may be 
necessary to readjust the carburetor if 
you use fuels with various ethanol 
contents.
WARNING
To reduce the risk of personal injury 
from loss of control and / or contact with 
the running cutting tool, do not use your 
unit with incorrect idle adjustment. At 
correct idle speed, the cutting tool 
should not move.
If your power tool shows an incorrect idle 
adjustment, have your STIHL dealer 
check your power tool and make proper 
adjustments and repairs.
The idle speed and maximum speed of 
the engine change if you switch from a 
fuel with a certain ethanol content to 
another fuel with a much higher or lower 
ethanol content.
This problem can be avoided by always 
using fuel with the same ethanol 
content.
Use STIHL HP Ultra oil or ask your 
dealer for an equivalent high quality oil 
to ensure the maximum performance of 
the product for the full lifetime.
To meet the requirements of EPA 
40CFR90/1054 we recommend to use 
STIHL HP Ultra oil.
Do not use BIA or TCW rated (two-
stroke water cooled) mix oils or other 
mix oils that state they are for use in both 
water cooled and air cooled engines 
(e.g., outboard motors, snowmobiles, 
chain saws, mopeds, etc.).
Take care when handling gasoline. 
Avoid direct contact with the skin and 
avoid inhaling fuel vapor. When filling at 
the pump, first remove the container 
from your vehicle and place the 
container on the ground before filling. To 
reduce the risk of sparks from static Fuel 
						

							FS 90, FS 90 R
English
28 discharge and resulting fire and/or 
explosion, do not fill fuel containers that 
are sitting in or on a vehicle or trailer.
The container should be kept tightly 
closed in order to limit the amount of 
moisture that gets into the mixture.
The machine’s fuel tank should be 
cleaned as necessary.
STIHL MotoMix
STIHL recommends the use of STIHL 
MotoMix. STIHL MotoMix has a high 
octane rating and ensures that you 
always use the right mix ratio. 
STIHL MotoMix uses STIHL HP Ultra 
two-stroke engine oil suited for high 
performance engines.
For further details, see 
www.STIHLusa.com/ethanol
Fuel mix ages
Only mix sufficient fuel for a few days 
work, not to exceed 30 days of storage. 
Store in approved fuel-containers only. 
When mixing, pour oil into the container 
first, and then add gasoline. Close the 
container and shake it vigorously by 
hand to ensure proper mixing of the oil 
with the fuel.Dispose of empty mixing-oil containers 
only at authorized disposal locations.
Preparations
NBefore fueling, clean the filler cap 
and the area around it to ensure that 
no dirt falls into the tank.
Always thoroughly shake the mixture in 
the canister before fueling your 
machine.
NPosition the machine so that the 
filler cap is facing up.
WARNING
In order to reduce the risk of fire and 
personal injury from escaping gas vapor 
and fumes, remove the fuel filler cap 
carefully so as to allow any pressure 
build-up in the tank to release slowly. Gasoline Oil (STIHL 50:1 or equiva-
lent high-quality oils)
Liters Liters (ml)
10.02(20)
5 0.10 (100)
10 0.20 (200)
20 0.40 (400)
US gal. US fl.oz.
12.6
2 1/2 6.4
512.8
Fueling
266BA028 KN