Stihl 85 Manual

							
10 English / USAFS 80, FS 80 R, FS 85, FS 85 R
During Operation
Holding and controlling the power 
tool
Always hold the unit firmly with both 
hands on the handles while you are 
working. Wrap your fingers and thumbs 
around the handles. !Warning!Never attempt to operate 
your power tool with one 
hand. Loss of control of 
the power tool resulting in 
serious or fatal injury may 
result. To reduce the risk 
of cut injuries, keep hands and feet away 
from the cutting attachment. Never 
touch a moving cutting attachment with 
your hand or any other part of your body.
!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. For better footing, clear 
away scrub and cuttings. Be extremely 
cautious when working on slopes or 
uneven ground.
!Warning
To reduce the risk of injury from loss of 
control, never work on a ladder or on any 
other insecure support. Never hold the 
cutting attachment above waist height. Working conditions
Operate and start your power tool only 
outdoors in a well ventilated area. 
Operate it under good visibility and 
daylight conditions only. Work carefully.
!Warning!
As soon as the engine is 
running, this product 
generates toxic exhaust 
fumes containing 
chemicals such as 
unburned hydrocarbons 
(including benzene) and carbon 
monoxide that are known to cause 
respiratory problems, cancer, birth 
defects, or other reproductive harm. 
Some of the gases (e.g. carbon 
monoxide) may be colorless and 
odorless. To reduce the risk of serious or 
fatal injury/illness from inhaling toxic 
fumes, never run the machine indoors or 
in poorly ventilated locations.
!Warning!
If the vegetation being cut or the 
surrounding ground is coated with a 
chemical substance (such as an active 
pesticide or herbicide), read and follow 
the instructions and warnings that 
accompanied the substance at issue.
002BA055 KN
002BA054 KN 
						

							
11
FS 80, FS 80 R, FS 85, FS 85 R English / USA
!Warning!
Inhalation of certain dusts, especially 
organic dusts such as mold or pollen, 
can cause susceptible persons to have 
an allergic or asthmatic reaction. 
Substantial or repeated inhalation of 
dust and other airborne contaminants, in 
particular those with a smaller particle 
size, may cause respiratory or other 
illnesses. Control dust at the source 
where possible. Use good work 
practices, such as operating the unit so 
that the wind or operating process 
directs any dust raised by the power tool 
away from the operator. Follow the 
recommendations of EPA/OSHA/
NIOSH and occupational and trade 
associations with respect to dust 
(“particulate matter”). When the 
inhalation of dust cannot be substantially 
controlled, i.e., kept at or near the 
ambient (background) level, the 
operator and any bystanders should 
wear a respirator approved by NIOSH/
MSHA for the type of dust encountered. Operating instructions
!Warning!
Do not operate your power tool using the 
starting throttle lock, as you do not have 
control of the engine speed.
In the event of an emergency, shut off 
the engine immediately – move the slide 
control / stop switch to  0 or  STOP .
!Warning!
The cutting attachment 
continues to rotate for a 
short period after the 
throttle trigger is released 
(flywheel effect).
!Warning!
The rotating cutting attachment may 
fling foreign objects directly or by 
ricochet a great distance. To reduce the risk of eye and other injury 
always wear proper eye protection (see 
the chapter on “Proper Clothing“) and 
ensure that bystanders are at least 50 
feet (15 m) away. To reduce the risk of 
damage to property, also maintain this 
distance from such objects as vehicles 
or windows. Any coworkers who must be 
in the restricted area should also wear 
goggles or protective glasses. Stop the 
engine immediately if you are 
approached.
15m (50ft) 
						

							
12 English / USAFS 80, FS 80 R, FS 85, FS 85 R
!Warning!Before you start work, 
examine the area for 
stones, glass, fence wire, 
metal, trash or other solid 
objects. The cutting 
attachment could throw 
objects of this kind.
!Warning!
This trimmer/brushcutter is normally to 
be used at ground level with the cutting 
attachment parallel to the ground. Use of 
a trimmer/brushcutter 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 power tool may be more difficult 
to control.
!Warning!
During cutting, check the tightness and 
the condition of the cutting attachment at 
regular short intervals with the engine 
and attachment stopped. If the behavior 
of the  attachment changes during use, 
stop the engine immediately, wait until 
the cutting attachment stops, and check 
the nut securing the attachment for 
tightness and the blade or head for 
cracks, wear and damage. 
!Warning!
A loose blade or head may vibrate, 
crack, break or come off the trimmer/
brushcutter, which may result in serious 
or fatal injury. Make sure that the cutting 
attachment is properly tightened. Use 
the wrench supplied or one of sufficient 
length to obtain the proper torque. If the 
blade or head loosens after being 
properly tightened, stop work 
immediately. The retaining nut may be 
worn or damaged and should be 
replaced. If the blade or head continues 
to loosen, see your STIHL dealer. Never 
use a trimmer/brushcutter with a loose 
cutting attachment.
!Warning!
Replace a cracked, damaged or worn-
out head or a cracked, bent, warped, 
damaged, dull or worn out blade 
immediately, even if damage is limited to 
superficial cracks. Such  attachments 
may shatter at high speed and cause 
serious or fatal injury.
!Warning!
When using rigid blades, avoid cutting 
close to fences, sides of buildings, tree 
trunks, stones or other such objects that 
could cause the power tool to kick out or 
could cause damage to the blade. 
STIHL recommends use of the nylon line 
heads for such jobs. In addition, be alert 
to an increased possibility of ricochets in 
such situations.
!Warning!
If the head, blade or deflector becomes 
clogged or stuck, always shut off the 
engine and make sure the cutting 
attachment has stopped before 
cleaning. Grass, weeds, etc. should be 
cleaned off the blade or from around the 
head at regular intervals.
!Warning!
To reduce the risk of unintentional 
rotation of the cutting attachment and 
injury, always shut off the engine and 
remove the spark plug boot before 
replacing the cutting attachment. To 
reduce the risk of injury, always shut off 
the engine before adjusting the length of 
the nylon line on manually adjustable 
mowing heads.
!Warning
The gearbox becomes hot during 
operation. To reduce the risk of burn 
injury, do not touch the gear housing 
when it is hot. 
						

							
13
FS 80, FS 80 R, FS 85, FS 85 R English / USA
!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. 
!Warning!
To reduce the risk of fire and burn injury, 
keep the area around the muffler clean. 
Remove excess lubricant and all debris 
such as pine needles, branches or 
leaves. Let the engine cool down sitting 
on concrete, metal, bare ground or solid 
wood away from any combustible 
substances.
!Warning!
Never modify your muffler. The muffler 
could be damaged and cause an 
increase in heat radiation or sparks, 
thereby increasing the risk of fire and 
burn injury. You may also permanently 
damage the engine. Have your muffler 
serviced and repaired by your STIHL 
servicing dealer only. Catalytic converter
!Warning!
Some STIHL power tools 
are equipped with a 
catalytic converter, which 
is designed to reduce the 
exhaust emissions of the 
engine by a chemical 
process in the muffler. Due to this 
process, the muffler does not cool down 
as rapidly as conventional mufflers when 
the engine returns to idle or is shut off. 
To reduce the risk of fire and burn 
injuries, the following specific safety 
precautions must be observed.
!Warning!
Since a muffler with a catalytic converter 
cools down less rapidly than conven-
tional mufflers, always set your power 
tool down in the upright position and 
never locate it where the muffler is near 
dry brush, grass, wood chips or other 
combustible materials while it is still hot. 
!Warning!
An improperly mounted or damaged 
cylinder housing or a damaged/
deformed muffler shell may interfere 
with the cooling process of the catalytic 
converter. To reduce the risk of fire or 
burn injury, do not continue work with a 
damaged or improperly mounted 
cylinder housing or a damaged/
deformed muffler shell. 
Your catalytic converter is furnished with 
screens designed to reduce the risk of 
fire from the emission of hot particles. 
Due to the heat from the catalytic 
reaction, these screens will normally 
stay clean and need no service or 
maintenance. If you experience loss of 
performance and you suspect a clogged 
screen, have your muffler maintained by 
a STIHL servicing dealer.
      
        
         
              
						

							
14 English / USAFS 80, FS 80 R, FS 85, FS 85 R
USING THE CUTTING 
ATTACHMENTS
For an illustration of the various cutting 
attachments and instructions on proper 
mounting see the chapter on Mounting 
the Cutting Attachments in your 
instruction manual.
!Warning!
To reduce the risk of severe or fatal 
injury from blade contact and/or loss of 
control, never attempt to use a metal 
blade on an FS model for which it is not 
authorized.
Using the Mowing Heads
Do not use with mowing line longer than 
the intended length. With a properly 
mounted deflector, the built-in line-
limiting blade will automatically adjust 
the line to its proper length.  
Using the unit with an overly long nylon 
cutting line increases the load on the 
engine and reduces its operating speed. 
This causes the clutch to slip 
continuously and results in overheating 
and damage to important components 
(e.g. clutch, polymer housing 
components). Such damage could, 
among other things, cause the cutting 
attachment to rotate at idle. Mowing heads are to be used only on 
trimmer/brushcutters equipped with a 
line-limiting blade in the deflector in 
order to keep the line at the proper 
length (see Parts and Controls chapter 
in your instruction 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 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 
polymer 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 (TapAction).
000BA015 KN 
						

							
15
FS 80, FS 80 R, FS 85, FS 85 R English / USA
STIHL PolyCut mowing head
Uses either nylon lines or nonrigid, 
pivoting polymer blades.
!Warning!
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. STIHL FixCut mowing head
Uses pre-cut lengths of nylon line. 
Observe wear indicators.
Do not continue using the mowing head 
if the raised moldings (1) on the base are 
missing or worn – see right illustration 
above. The mowing head may otherwise 
shatter and flying objects could result in 
injury to the operator or bystanders. 
Install a new mowing head.
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 (especially the 
darkly shaded area) of a rotating blade 
comes in contact with a solid rigid 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 to the 
right or to the rear.
This kickout (blade thrust) may cause 
loss of control of the power tool 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.
002BA177 KN
002BA135 KN 
						

							
16 English / USAFS 80, FS 80 R, FS 85, FS 85 R
Using the Grass Cutting Blade
All kinds of grass and weeds can be 
easily cut with the grass cutting blade. 
The power tool is swept in an arc similar 
to a scythe.
!Warning!
To reduce the risk of serious or fatal 
injury from blade breakage, never 
attempt to use this blade 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. When the 
cutting edges on one side become dull, 
the blade can be turned over to utilize 
the cutting edges on the other side. The 
8-tooth  grass cutting blade is 
recommended for cutting fern or reed.
Both types of grass cutting blade have to 
be resharpened when all cutting edges 
are dull.
Using the Brush Knife
When fitted to the power tool, 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 – 
but keep the tool below waist height at 
all times. 
!Warning!
Exercise  extreme caution  when using 
this method of cutting. The higher the 
cutting attachment is off the ground, the 
greater the risk of loss of control and of 
cuttings being thrown sideways. Use the power tool like a scythe to cut 
grass, i.e. sweep it to and fro 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 blade 
fragments may seriously or fatally injure 
the operator or bystanders. To reduce 
the risk of injury, avoid contact with hard 
or solid foreign objects such as stones, 
rocks or pieces of metal. 
!Warning!
When cutting young saplings or other 
woody materials up to 2 cm (3/4) in 
diameter, use the left side of the blade to 
avoid kickout situations (see section 
on “Risk of kickout (blade thrust) with all 
rigid cutting blades”). Do not attempt to 
cut woody material with a larger 
diameter, since the blade may catch or 
jerk the power tool forward. This may 
cause damage to the blade or power tool 
or loss of control of the power tool, 
resulting in personal injury.  Use a 
circular saw blade for such work. 
!Warning!
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).
000BA020 KN
002BA066 KN 
						

							
17
FS 80, FS 80 R, FS 85, FS 85 R English / USA
Using the Circular Saw Blade
Circular saw blades are suitable for 
thinning brush and cutting small trees up 
to a diameter of 4 cm (1 1/2”). Do not 
attempt to cut trees with larger 
diameters, since the blade may catch or 
jerk the trimmer/brushcutter forward. 
This may cause damage to the blade or 
loss of control of the power tool and 
result in serious injury.  Use a chain saw 
for such work.
!Warning!
To reduce the risk that the blade will 
crack and/or break, avoid all contact with 
stones, rocks or the ground. Sharpen 
blades in a timely manner as specified – 
dull teeth may cause the blade to crack 
or shatter.
When a trimmer/brushcutter with a 
circular saw blade is used to cut down 
small trees, STIHL recommends that the 
standard deflector be removed and 
replaced by the special limit stop 
deflector (see chapter on “Mounting the 
Deflector”). This limit stop helps to keep 
the unit 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 trimmer/brushcutter against the tree 
during the cutting operation and will 
reduce the risk of loss of control and 
possible kickout (described above and 
briefly again below). 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, as 
shown in the illustration above.
000BA016 KN
002BA214 ST
002BA068 KN 
						

							
18 English / USAFS 80, FS 80 R, FS 85, FS 85 R
!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 the use and control of the 
trimmer/brushcutter.
!Warning!
To reduce the risk of loss of control and 
serious injury to the operator or 
bystanders by a kickout, never use a 
circular saw blade on a trimmer/
brushcutter with a loop handle, but 
rather only on one with a bicycle handle.
When felling small trees, maintain a 
distance of at least two tree lengths from 
the nearest coworker.
!Warning!
In order to reduce the risk of injury from 
thrown objects or operator contact with 
the blade or head, be sure to remount 
the standard deflector when no longer 
using a circular saw blade.
MAINTENANCE, REPAIR AND 
STORING
Maintenance, replacement, or repair 
of the emission control devices and 
systems may be performed by any 
nonroad engine repair establishment 
or individual. However, if you make a 
warranty claim for a component 
which has not been serviced or 
maintained properly or if 
nonapproved replacement parts were 
used, STIHL may deny coverage.
!Warning!
Use only identical STIHL replacement 
parts for maintenance and repair. Use of 
non-STIHL parts may cause serious or 
fatal injury.
Strictly follow the maintenance and 
repair instructions in the appropriate 
sections of your instruction manual.
!Warning!
Always stop the engine and make sure 
that the cutting attachment is stopped 
before doing any maintenance or repair 
work or cleaning the power tool. Do not 
attempt any maintenance or repair work 
not described in your instruction manual. 
Have such work performed by your 
STIHL servicing dealer only. 
Wear gloves when handling or 
performing maintenance on blades.
!Warning!
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 terminal of the proper size. (Note: If 
terminal has detachable SAE adapter 
nut, it must be securely attached.) A 
loose connection between the spark 
plug and the ignition wire connector in 
the boot may create arcing that could 
ignite combustible fumes and cause a 
fire. 
!Warning!
Never test the ignition system with the 
spark plug boot removed from the spark 
plug or with a removed spark plug, since 
uncontained sparking may cause a fire.
!Warning!
Do not operate your power tool if the 
muffler is damaged, missing or modified. 
An improperly maintained muffler will 
increase the risk of fire and hearing loss.  
If your muffler was equipped with a 
spark-arresting screen to reduce the risk 
of fire, never operate your power tool if 
the screen is missing or damaged. 
Remember that the risk of forest fires is 
greater in hot or dry weather. 
						

							
19
FS 80, FS 80 R, FS 85, FS 85 R English / USA
!Warning!
Never repair damaged cutting attach-
ments by welding, straightening or 
modifying the shape. This may cause 
parts of the cutting attachment to come 
off and result in serious or fatal injuries.
Keep blades sharp. Tighten all nuts, 
bolts and screws, except the carburetor 
adjustment screws, after each use.
Store the power tool in a dry and 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 in the 
instruction manual.