STIHL Fs 50 C Manual

							FS 40, FS 40 C, FS 50, FS 50 C
English
29
Installing the Spark Plug
NScrew the spark plug into the 
cylinder.
NPress the spark plug boot with cap 
firmly on to the spark plug.
If the cap has become detached from 
the spark plug boot:NPush the cap on to the spark plug 
boot as far as stop.
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.
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.
Warning!
To reduce the risk of fire and burn injury, 
use only spark plugs authorized by 
STIHL. Always press spark plug boot (1) 
snugly onto spark plug terminal (2) of 
the proper size. (Note: If terminal has 
detachable SAE adapter nut, it must be 
attached.) A loose connection between 
spark plug boot and ignition wire con-
nector in the boot may create arcing that 
could ignite combustible fumes and 
cause a fire.
1
2
000BA071 KN
(QJLQH5XQQLQJ%HKDYLRU 
						

							FS 40, FS 40 C, FS 50, FS 50 C
English
30 To help prolong the wear life of the 
starter rope, observe the following 
points:
NPull the starter rope only in the 
direction specified.
NDo not pull the rope over the edge of 
the guide bushing.
NDo not pull out the rope more than 
specified.
NDo not allow the starter grip to snap 
back, guide it back into the housing 
slowly – see chapter on "Starting / 
Stopping the Engine."
Have a damaged starter rope replaced 
by your dealer before it breaks 
completely. STIHL recommends that 
you have servicing and repair work 
carried out exclusively by an authorized 
STIHL servicing dealer.For periods of 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.
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.
STIHL AutoCut C 5-2
Always check the mowing head for signs 
of wear before replacing the nylon line.
If there are signs of serious wear, 
replace the complete mowing head.
Preparations
NShut off the engine.
NPut the machine on the ground with 
the mowing head facing up.
Disassembling the mowing head and 
removing remaining nylon line
In normal operation, the supply of nylon 
line in the head is used up completely.
Rewind StarterStoring the MachineReplacing Nylon Line 
						

							FS 40, FS 40 C, FS 50, FS 50 C
English
31 NHold the mowing head steady and 
rotate the cap (1) counterclockwise 
until it can be removed.
NPull the spool (2) out of the mowing 
head (3) and remove the remaining 
line.Assembling the mowing head
NFit the empty spool in the mowing 
head.
If the spring (4) has popped out,
Npush it into the spool (2) until it 
engages in position with an audible 
click.
NMount the mowing head – see 
"Mounting the Mowing Head".Winding line onto spool
NUse green-coded nylon line with a 
diameter of 0.08 in (2.0 mm).
NCut two 6ft 6in (2 m) lengths of 
nylon line from the reel (special 
accessory).
NRotate the spool (2) 
counterclockwise until the two arrow 
points are in alignment.
NPush the straight end of each line 
through one sleeve (5) in the 
mowing head (3) until you feel a 
noticeable resistance – and then 
continue pushing as far as stop.
Schnur/LINE  1
681BA021 KN
1
2
3
Schnur/LINE  1
681BA022 KN
24
Schnur/LINE  2
681BA023 KN
5
Schnur/LINE  13
32 
						

							FS 40, FS 40 C, FS 50, FS 50 C
English
32 NHold the mowing head steady.
NRotate the spool counterclockwise 
until the shortest line is about 4 in 
(10 cm).
NIf necessary, cut the longer line to a 
length of about 4 in (10 cm).
The mowing head is now full.
STIHL AutoCut 5-2
Always check the mowing head for signs 
of wear before replacing the nylon line.
If there are signs of serious wear, 
replace the parts concerned or install a 
new mowing head.Preparations
NShut off the engine.
NPut the machine on the ground with 
the mowing head facing up.
Removing remaining nylon line
NOpen the mowing head – hold it 
steady with one hand.
NTurn the cap (1) counterclockwise.
NDisengage the spool (2), take it out 
of the mowing head and remove the 
remaining line.
Winding line onto spool
A prewound spool (special accessory) 
may be used as an alternative to the 
following procedure.NUse green-coded nylon line with a 
diameter of 0.08 in (2.0 mm).
NCut two 10ft (3 m) lengths of nylon 
line from the reel (special 
accessory).
NInsert the ends of each line (3) in the 
holes (4) in the spool.
NBend the ends of the lines over the 
edge of the holes to form a hook.
681BA024 KN
Schnur/LINE  2
Schnur/LINE  1
681BA008 KN
1
2
681BA009 KN
4
3
3 
						

							FS 40, FS 40 C, FS 50, FS 50 C
English
33 NStraighten out the nylon lines and 
wind them tightly on to the spool – 
one nylon line in each chamber.
NEngage the ends of the lines in the 
notches (2).
Assembling the mowing head
Check that the compression spring is 
installed (see "Mounting the Mowing 
Head").NThread the ends of the lines (6) 
through the sleeves (7) and push 
the spool (2) into the head so that it 
snaps into position.
The nylon lines must disengage from the 
notches (5) as the spool is pushed into 
position.
NPull out the ends of the lines as far 
as stop.
NMount the mowing head on the 
machine.
Spark Arresting Screen in Muffler
Spark arresting screen in muffler (not all 
markets)
NIf the engine is down on power, 
check the spark arresting screen in 
the muffler.
STIHL recommends that you have 
servicing and repair work carried out 
exclusively by an authorized STIHL 
servicing dealer.
681BA010 KN
5
5
7
681BA011 KN
2
6
6
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E\HDOHU 
						

							FS 40, FS 40 C, FS 50, FS 50 C
English
34
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
if required
Complete machineVisual inspection (condition, leaks)XX
CleanX
Control handle Check operationXX
Air filterCleanXX
ReplaceX
Pickup body in fuel tankCheckX
ReplaceXXX
Fuel tank CleanXX
CarburetorCheck idle adjustment – the cutting 
attachment must not turnXX
Readjust idleX
Spark plugReadjust electrode gapX
Replace after every 100 operating hours
Cooling inletsVisual inspectionX
CleanX
Spark arresting screen
2) in mufflerHave checked by dealer
1)X
Have cleaned or replaced by servicing 
dealer
1)XX
All accessible screws and nuts (not adjust-
ing screws)RetightenX 
						

							FS 40, FS 40 C, FS 50, FS 50 C
English
35
Cutting attachmentVisual inspectionXX
ReplaceX
Check tightnessXX
Safety labels ReplaceX
1)STIHL recommends a STIHL servicing dealer.2)not in all versions, market-specific 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
if required 
						

							FS 40, FS 40 C, FS 50, FS 50 C
English
361Loop Handle
2Carrying Ring
3Momentary Stop Switch
4Throttle Trigger Lockout
5Throttle Trigger
6Carburetor Adjusting Screws
7Choke Lever
8Air Filter Cover
9Cap with Spark Plug Boot
10Machine Support
11Fuel Pump
12Fuel Filler Cap
13Fuel Tank
14Starter Grip
15Muffler with Spark Arresting Screen
16Mowing Head
17Line Lmiting Blade
18Deflector
19Drive Tube
#Serial Number
Main Parts
11
546BA009 KN
32
5
4
#
1
7
6
8
9
10
12
13
14
15
17
18
19
16 
						

							FS 40, FS 40 C, FS 50, FS 50 C
English
37
Definitions
1 Loop Handle
For easy control of machine during 
cutting work.
2 Carrying Ring
Connects the unit to the harness.
3 Momentary Stop Switch
Switches the engine's ignition off 
and stops the engine. 
4 Throttle Trigger Lockout
Must be depressed before the 
throttle trigger can be activated.
5 Throttle Trigger
Controls the speed of the engine.
6 Carburetor Adjusting Screws
For tuning the carburetor.
7 Choke Lever
Eases engine starting by enriching 
mixture.
8 Air Filter Cover
Covers and protects the air filter 
element.
9 Cap with Spark Plug Boot
Connects the spark plug with the 
ignition wire.
10 Machine Support
For resting machine on the ground.
11 Fuel Pump
Provides additional fuel feed for a 
cold start.
12 Fuel Filler Cap
For closing the fuel tank.
13 Fuel Tank
For fuel and oil mixture.14 Starter Grip
The grip of the pull starter, for 
starting the engine.
15 Muffler with Spark Arresting Screen
Muffler reduces exhaust noises and 
diverts exhaust gases away from 
operator.
Spark arresting screen is designed 
to reduce the risk of fire.
16 Mowing Head
The cutting attachment, i.e. mowing 
head, for different purposes.
17 Line Limiting Blade
Metal blade on the deflector which 
keeps the line of the mowing head 
at the proper length.
18 Deflector
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.
19 Drive Tube
Encloses and protects the drive 
shaft between the engine and 
bearing housing.
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 two-stroke engine
Specifications
A = 300 hours
B = 125 hours
C= 50hours
Extended = 300 hours
Intermediate = 125 hours
Moderate = 50 hours 
						

							FS 40, FS 40 C, FS 50, FS 50 C
English
38 FS 40, FS 40 C
FS 50, FS 50 C
Ignition System
Electronic magneto ignition
Fuel System
All position diaphragm carburetor with 
integral fuel pump
Weight
dry, without cutting attachment and 
deflector
Overall length
without cutting attachmentContact your STIHL dealer for 
information regarding special 
accessories that may be available for 
your product. Displacement: 1.66 cu. in. 
(27.2 cm
3)
Bore: 1.34 in (34 mm)
Stroke: 1.18 in. (30 mm)
Engine power to 
ISO 8893:0.9 hp (0.7 kW) 
at 8,500 rpm
Idle speed: 2,800 rpm
Cut-off speed (rated): 10,000 rpm
Max. output shaft 
speed (cutting 
attachment): 8,900 rpm
Displacement: 1.66 cu. in. 
(27.2 cm
3)
Bore: 1.34 in (34 mm)
Stroke: 1.18 in. (30 mm)
Engine power to 
ISO 88931.1 hp (0.8 kW) 
at 8,500 rpm
Idle speed: 2,800 rpm
Cut-off speed (rated): 10,000 rpm
Max. output shaft 
speed (cutting 
attachment): 8,900 rpm
Spark plug (resistor 
type): NGK CMR 6 H
Electrode gap: 0.02 in (0.5 mm)Fuel tank capacity: 11.5 fl.oz (0.34 l)
Standard versions
FS 40: 9.7 lbs 
(4.4 kg)
FS 50: 9.7 lbs 
(4.4 kg)
FS 50: with long 
shaft9.9 lbs 
(4.5 kg)
Versions with Easy2Start
FS 40 C: 9.9 lbs 
(4.5 kg)
FS 50 C: 9.9 lbs 
(4.5 kg)
FS 50 C: with long 
shaft10.1 lbs 
(4.6 kg)
FS 40, 
FS 40 C57 in. 
(1450 mm)
FS 50, 
FS 50 C:57 in. 
(1450 mm)
FS 50, 
FS 50 C:with long 
shaft65 in. 
(1650 mm)
Special Accessories