Instruction Manual
FS 91, FS 91 R
English
41
Engine
Single cylinder four-stroke engine with
mixture lubrication
Ignition System
Electronic magneto ignition
Fuel System
All position diaphragm carburetor with
integral fuel pump
Weight
Overall length
Features
Noise and Vibration Data
Cutting Attachment
For details on compliance with Vibration
Directive 2002/44/EC visit
www.stihl.com/vib.
Sound pressure level L
p
to ISO 22868
Sound power level L
w
to ISO 22868
Vibration level a
hv,eq
to ISO 22867
Interchangeable Attachments
The noise and vibration data of the
approved attachments are listed in the
instructions supplied with each
attachment.
The K-factor in accordance with
Directive 2006/42/EC is 2.0 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/s
2
for the vibration level.
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.
Specifications
Displacement: 28.4 cc
Bore: 38 mm
Stroke: 25 mm
Engine power to
ISO 8893:
0.95 kW
(1.3 bhp) at
7,000 rpm
Idle speed: 2,800 rpm
Cut-off speed (rated): 9,500 rpm
Max. output shaft
speed (cutting
attachment): 7,150 rpm
Valve clearance
Inlet valve: 0.10 mm
Exhaust valve: 0.10 mm
Spark plug (resistor
type): Bosch USR 7 AC
Electrode gap: 0.5 mm
Fuel tank capacity: 710 cc (0.71 l)
Dry, without cutting attachment and
deflector
FS 91: 5.8 kg
FS 91 R: 5.5 kg
without cutting
attachment 1800 mm
R Loop handle
with mowing head
FS 91 with bike handle: 95 dB(A)
FS 91 R: 95 dB(A)
with metal mowing
attachment
FS 91 with bike handle: 93 dB(A)
FS 91 R with barrier bar: 93 dB(A)
with mowing head
FS 91 with bike handle: 106 dB(A)
FS 91 R: 106 dB(A)
with metal mowing
attachment
FS 91 with bike handle: 105 dB(A)
FS 91 R with barrier bar: 105 dB(A)
with mowing head
Handle,
left
Handle,
right
FS 91 with bike
handle: 3.4 m/s
2
3.0 m/s
2
FS 91 R: 5.3 m/s
2
5.3 m/s
2
with metal mow-
ing attachment
Handle,
left
Handle,
right
FS 91 with bike
handle: 3.2 m/s
2
2.5 m/s
2
FS 91 R with bar-
rier bar: 3.8 m/s
2
4.3 m/s
2