Stihl Fs 450 K Manual

							10 English / USA
FS 300, FS 350, FS 400, FS 450, FS 480 California and some other authorities, 
for instance, have published lists of 
substances known to cause cancer, 
reproductive toxicity, etc.
Control dust and fumes at the source 
where possible. In this regard use good 
work practices and follow the 
recommendations of OSHA/NIOSH and 
occupational and trade associations. 
When the inhalation of toxic dust and 
fumes cannot be eliminated, the 
operator and any bystanders should 
always wear a respirator approved by 
NIOSH/MSHA for the type of dust and / 
or fumes encountered.!
Warning!
The muffler and other parts of the engine 
(e.g. fins of the cylinder, spark plug) 
become hot during operation and remain 
hot for a while after stopping the engine. 
To reduce risk of burns do not touch the 
muffler and other parts while they are 
hot. 
Do not cut any material other than grass, 
brush and wood. The cutting tools may 
be used only for the operations 
described in your manual.Always hold the clearing saw firmly with 
both hands. Wrap your fingers tightly 
around the handles, keeping the 
handles cradled between your thumb 
and forefinger. Keep your hands in this 
position to have your clearing saw under 
control at all times. Make sure your 
clearing saw handles and grip are in 
good condition and free of moisture, 
pitch, oil or grease.
!
Warning!
Never attempt to operate any clearing-
saw with one hand. Loss of control of the 
clearing saw resulting in serious or fatal 
injury may result. 
!
Warning!
Do not overreach. Keep proper footing 
and balance at all times. Special care 
must be taken in slippery conditions (wet 
ground, snow) and in difficult, overgrown 
terrain. Watch for hidden obstacles such 
as tree stumps, roots and ditches to 
avoid stumbling. Be extremely cautious 
when working on slopes or uneven 
ground. 
000BA014 
						

							11 FS 300, FS 350, FS 400, FS 450, FS 480English / USA
!
Warning!
Before cutting, inspect the 
area for stones, glass, 
pieces of metal, trash or 
other solid objects. The 
cutting attachment could 
throw objects of this kind.
!
Warning!
When using rigid blades, avoid cutting 
close to fences, sides of buildings, tree 
trunks, stones or other such objects that 
could cause the clearing saw to kick out 
or could cause damage to the blade. 
STIHL recommends use of the nylon line 
heads or PolyCut head for such jobs. In 
addition, be alert to an increased 
possibility of ricochets in such situations.
!
Warning!
This clearing saw is normally to be used 
at ground level with the cutting attach-
ment parallel to the ground. Use of a 
clearing saw above ground level or with 
the cutting attachment perpendicular to 
the ground may increase the risk of 
injury, since the cutting attachment is 
more fully exposed and the clearing saw 
may be more difficult to control. Never 
use your clearing saw as a hedge 
trimmer.Do not operate using the starting throttle 
lock as you do not have control of the 
engine speed. See section of your 
owners manual on the proper use of the 
slide control.
If the cutting tool or deflector becomes 
clogged or stuck, always turn off the 
engine and make sure the cutting tool 
has stopped before cleaning. Grass, 
weeds, etc. should be cleaned off the 
cutting tool at regular intervals.
!
Warning!
During cutting, check the tightness and 
the condition of the cutting tool at regular 
intervals. If the behavior of the tool 
changes, stop the engine immediately, 
and check the nut securing the tool for 
tightness and the cutting tool for cracks 
and damage. Replace cracked, bent, 
warped, damaged or dull cutting tools 
immediately. Such tools may shatter at 
high speed and cause serious or fatal 
injury.
!
Warning!
A loose blade may cause the blade to 
vibrate, crack, break or come off the 
clearing saw, which may result in serious 
or fatal injury. Make sure that the blade 
is properly tightened. Use the wrench 
supplied or one of sufficient length to 
obtain the proper torque. If the blade 
loosens after being properly tightened, 
stop work immediately. The retaining nut 
may be worn or damaged and should be 
replaced. Never use unauthorized parts 
to secure the blade. If the blade 
continues to loosen, see your STIHL 
dealer. Never use a clearing saw with a 
loose blade.
Do not attach any blade to a unit without 
proper installation of all required parts. 
Never use unauthorized parts to secure 
the blade. Failure to use the proper parts 
may cause the blade to fly off and 
seriously injure the operator or 
bystanders. 
						

							12 English / USA
FS 300, FS 350, FS 400, FS 450, FS 480!
Warning!
Keep hands and feet 
away from cutting tool. 
Never touch a rotating 
cutting tool with your hand 
or any part of your body. It 
continues to rotate for a 
short period after the throttle trigger is 
released (flywheel effect).
Important adjustments
!
Warning!
To reduce the risk of personal injury from 
loss of control or contact with the 
running cutting tool, do not use a cutting 
tool with incorrect idle adjustment. At 
correct idle speed, the cutting tool 
should not move. For directions on how 
to adjust idle speed, see the appropriate 
section of your owners manual.
If you cannot set the correct idle speed, 
have your STIHL dealer check your 
clearing saw and make proper 
adjustments and repairs.
MAINTENANCE, REPAIR AND 
STORINGMaintenance, replacement, or repair 
of the emission control devices and 
systems may be performed by any 
nonroad engine repair establishment 
or individual. However if you claim 
warranty coverage for a component 
which has not been serviced or 
maintained properly or if 
nonapproved replacement parts were 
used, STIHL may deny warranty.!
Warning!
Use only identical STIHL replacement 
parts for maintenance and repair. Use of 
non-STIHL parts may cause serious or 
fatal injury.
Follow the maintenance and repair 
instructions in the appropriate section of 
your owners manual. Please refer to the 
maintenance chart on the last pages of 
this manual.
!
Warning!
Always stop the engine and make sure 
that the cutting tool is stopped before 
doing any maintenance or repair work or 
cleaning the clearing saw. Do not 
attempt any maintenance or repair work 
not described in your owners manual. 
Have such work performed at your 
STIHL service shop only. 
Wear gloves when handling or doing 
maintenance on blade.
!
Warning!
Never repair damaged cutting attach-
ments by welding, straightening or 
modifying the shape. This may cause 
parts of the cutting tool to come off and 
result in serious or fatal injuries.
!
Warning!
To reduce the risk of fire and burn 
injuries, check fuel filler cap for leaks at 
regular intervals. Use the specified 
spark plug and make sure it and the 
ignition lead are always clean and in 
good condition. Always press spark plug 
boot snugly onto spark plug boot of the 
proper size. (Note: If boot has 
detachable SAE adapter nut, it must be 
attached.) A loose connection between 
spark plug boot and ignition wire 
connector in the boot may create arcing 
that could ignite combustible fumes and 
cause a fire.  
						

							13 FS 300, FS 350, FS 400, FS 450, FS 480English / USA
!
Warning!
Never test the ignition system with 
ignition wire boot removed from spark 
plug or with unseated spark plug, since 
uncontained sparking may cause a fire.
!
Warning!
Do not operate your clearing saw if the 
muffler is damaged, missing or modified. 
An improperly maintained muffler will 
increase the risk of fire and hearing loss. 
Never touch a hot muffler or burn will 
result. If your muffler was equipped with 
a spark-arresting screen to reduce the 
risk of fire (e.g. in the USA, Canada and 
Australia), never operate your clearing 
saw if the screen is missing or damaged. 
Do not modify or remove any part of the 
muffler or spark arresting screen. 
Remember that the risk of forest fires is 
greater in hot or dry weather.
Keep cutting tool sharp. Tighten all nuts, 
bolts and screws, except the carburetor 
adjustment screws, after each use.
Additionally, the daily maintenance 
schedule for your clearing saw set forth 
in your STIHL Owners Manual should 
be strictly followed.For any maintenance please refer to the 
maintenance chart and to the warranty 
statement near the end of this manual. 
Store clearing saw in a dry, high or 
locked location out of reach of children.
Before storing for longer than a few 
days, always empty the fuel tank. See 
chapter Storing the machine.
USING THE CUTTING TOOLSFor an illustration of the various cutting 
tools and instructions on proper 
mounting see the chapter on mounting 
the cutting tools in your owners 
manual.
Using the mowing heads
Do not use with mowing line longer than 
the intended diameter. With a properly 
mounted guard, the built-in cutter will 
automatically adjust the line to its proper 
length. Overly long lines can overload 
the engine, resulting in damage to the 
clutch mechanism and nearby parts. 
002BA018 LÄ 
						

							14 English / USA
FS 300, FS 350, FS 400, FS 450, FS 480 A damaged clutch may cause a cutting 
attachment to rotate at idle speed and 
increase the risk of personal injury from 
loss of control and from contact with the 
cutting tool.
The STIHL SuperCut, TrimCut, AutoCut 
and PolyCut mowing heads produce a 
clean and tidy finish.
They are to be used only on brush-
cutters equipped with a limiter blade in 
the deflector in order to keep the line at 
the proper length (see Parts and 
Controls chapter of this manual).If the lawn edges are planted with trees 
or bordered by a fence etc., it is best to 
use a nylon line head. It achieves a 
softer cut with less risk of damaging 
tree bark etc. than with the polymer 
blades.
However, the polymer bladed STIHL 
PolyCut produces a better cut if there 
are no plants along the edge of the lawn. 
Sharpening is not necessary and worn 
grass cutting blades are easily replaced.
!
Warning!
To reduce the risk of serious injury, 
never use wire or metal-reinforced line 
or other material in place of the nylon 
cutting lines. Pieces of wire could break 
off and be thrown at high speed toward 
the operator or bystanders.
STIHL SuperCut mowing head
Fresh line is advanced automatically. 
Frayed line is replaced by a simple 
adjustment (see instruction sheet 
supplied with mowing head).
STIHL TrimCut mowing head
Frayed line is replaced by a simple 
adjustment (see instruction sheet 
supplied with mowing head).STIHL AutoCut mowing head
Nylon cutting cord advances 
automatically when tapped against the 
ground.
STIHL PolyCut mowing head
Uses either nylon lines or nonrigid 
plastic blades.
Important!
Three rectangular wear limit marks are 
applied to the base (periphery) of the 
PolyCut. To reduce the risk of serious 
injury from breakage of the head or 
blades, the PolyCut must not be used 
when it has worn as far as one of these 
marks. It is important to follow the 
maintenance instructions supplied with 
the head!
000BA015 KN
002BA177 KN 
						

							15 FS 300, FS 350, FS 400, FS 450, FS 480English / USA
Using the grass cutting bladeAll kinds of grass and weeds can be 
easily cut with the grass cutting blade. 
The clearing saw is swept in an arc 
similar to a scythe.!
Warning!
To reduce the risk of serious or fatal 
injury never attempt to cut woody 
materials.
The 4-tooth grass cutting blade is 
intended to cut grass and weeds. It has 
4 cutting knives with cutting edges on 
both sides, i.e. front and rear.The 8-tooth grass cutting blade is 
recommended for cutting fern or reed.
Both blades have to be resharpened 
when all cutting edges are dull.
Using the brush knifeWhen fitted to the clearing saw, the 
brush knife is suitable for applications 
ranging from cutting matted grass to 
clearing weeds, wild growth and scrub.
To cut wild growth and scrub, lower the 
rotating brush knife down onto the 
growth to achieve a chopping effect. Use 
the clearing saw like a scythe to cut 
grass, i.e. sweep it to and for in an arc.!
Warning!
When cutting woody materials, use the 
left side of the blade to avoid kickout 
(blade thrust) situations.
!
Warning!
Improper use of a brush knife may cause 
it to crack, chip or shatter. Thrown parts may seriously injure the 
operator or bystanders. To reduce the 
risk of personal injury it is essential to 
take the following precautions:
Avoid contact with hard or solid foreign 
objects such as stones, rocks or pieces 
of metal.
Never cut wood or shrubs with a stem 
diameter of more than 2 cm (3/4) - 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 (when it has dulled noticeably).
!
Warning!
When cutting young saplings or other 
woody materials up to 2 cm (3/4) in 
diameter, use left side of the blade to 
avoid kickout situations (see 
appropriate section in this manual). Do 
not attempt to cut woody material with a 
larger diameter, since the blade may 
catch or jerk the clearing saw forward. 
This may cause damage to the blade or 
clearing saw or loss of control of the 
clearing saw, resulting in personal injury.
000BA020 KN
002BA066 KN 
						

							16 English / USA
FS 300, FS 350, FS 400, FS 450, FS 480Using the circular saw bladeCircular saw blades are suitable for 
thinning brush and cutting small trees up 
to a diameter of 4 cm (1 9/16). Do not 
attempt to cut trees with larger 
diameters, since the blade may catch or 
jerk the clearing saw forward. This may 
cause damage to the blade or loss of 
control of the clearing saw which may 
result in serious injury.When the clearing saw with circular saw 
blade is used to cut down small trees, 
STIHL recommends that the standard 
deflector be removed and replaced by 
the special stop (see chapter circular 
saw blade for mounting instructions). 
This stop helps to keep the clearing saw 
positioned against the tree during the 
cutting process. Inexperienced users 
should place the left side of the stop 
against the tree trunk before beginning 
to cut. This will keep the clearing saw 
against the tree during the cutting 
operation and will reduce the risk of loss 
of control and possible kickout 
(described in the following section).
!
Warning!
In order to reduce the risk of injury from 
thrown objects or from operator contact 
with the cutting tool, be sure to remount 
the standard deflector for all other uses.
Before starting the cut, accelerate the 
engine up to full throttle. Perform cut 
with uniform pressure. STIHL 
recommends that the circular saw blade 
be applied to the right of the tree, using 
the non-shaded area of the blade.
!
Warning!
The risk of kickout is highest when 
cutting in the darker shaded area. To 
reduce the risk of kickout and resulting 
injury, do not use this area of the circular 
saw blade for cutting trees or shrubs. 
Special techniques using the lighter 
shaded areas of the blade to cut shrubs 
and trees should only be used by 
experienced operators with specialized 
training in use and control of the clearing 
saw.
000BA016 KN
000BA012 KN 
						

							17 FS 300, FS 350, FS 400, FS 450, FS 480English / USA
Risk of kickout (blade thrust)
with all rigid cutting blades
!
Warning!
Kickout (blade thrust) is the sudden and 
uncontrolled motion towards the 
operators right or rear that can occur 
when the shaded area of the rotating 
blade comes in contact with a solid 
object like a tree, rock, bush or wall. The 
rapid counterclockwise rotation of the 
blade may be stopped or slowed, and 
the cutting attachment may be thrown in 
an area to the right or to the rear.
This kickout (blade thrust) may cause 
loss of control of the clearing saw and 
may result in serious or fatal injury to the 
operator or bystanders. To reduce the 
risk of injury, extreme caution should be 
used when cutting with the shaded area 
of any rigid blade.
002BA135 KN 
						

							18 English / USA
FS 300, FS 350, FS 400, FS 450, FS 480Cutting toolsMowing heads
  1STIHL SuperCut 40-2
  2STIHL AutoCut 40-2
  3STIHL AutoCut 40-4 
1)
  4STIHL TrimCut 40-2
  5STIHL PolyCut 40-3
Metal mowing tools
  6Grass cutting blade 230-4
  7Grass cutting blade 255-8
  8Brush knife 300-3
Circular saw blades
  9Chisel tooth 
circular saw blade 200
10Scratcher tooth 
circular saw blade 200
11Chisel tooth 
circular saw blade 225 
2)
12Scratcher tooth 
circular saw blade 225 
2)
1)
for FS 450, 450 K, 450 L, 480, 480 K, 
480 L only
2)
for FS 400, 400 K, 400 L, 450, 450 K, 
450 L, 480, 480 K, 480 L only
Deflectors13Deflector for mowing heads 1 to 5
14Deflector with skirt and blade
for mowing heads 1 to 5
15Defector without skirt and blade for 
mowing tools 6 to 8Limit Stops16Limit stop for circular saw 
blades 200
17Limit stop for circular saw 
blades 225Harnesses18Full harness
19Deluxe full harnessEquipmentAmong other parts, the complete unit 
includes:
– Cutting tool
– Deflector or limit stop
– Bike handle
–Harness
Approved CombinationsSelect correct combination from the 
table on the next page on basis of the 
cutting tool.!
For safety reasons only the tools, 
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.
!
To reduce the risk of personal 
injury, take special care to avoid 
contact with the rotating cutting tool.
Approved Combinations of Cutting Tool, Deflector, Stop 
and Harness 
						

							19 FS 300, FS 350, FS 400, FS 450, FS 480English / USA
Cutting tools Deflectors, Limit Stops Harnesses
681FK008681FK001
681FK007
681FK011
5 1
681FK037 KN
4
2
3
681BA004 KN
13
681BA003 KN
14
002BA026 KN002BA006 K
18
19
681FK015
8
681FK014
7
6
681BA005 KN
15
681FK018
681FK016
910
681BA007 KN
16
681FK016
681FK018
11
12
681BA006 KN
17