Stihl 85 Manual

							
30 English / USAFS 80, FS 80 R, FS 85, FS 85 R
STIHL AutoCut
:
Hold the rotating mowing head 
above the ground – tap it on the 
ground once – about  1 1/4 (3 cm)  
fresh line is advanced. 
The blade on the deflector trims 
overlong line to the correct length – 
avoid tapping head more than once at a 
time.
Line feed operates only if  both lines 
still have a minimum length of  1 
(2.5 cm) .
All other mowing heads
Refer to the instructions supplied with 
the mowing head. To reduce the risk of injury, always 
shut off the engine before adjusting 
the nylon line by hand.
Replacing Nylon Line or Cutting 
Blades
Refer to the instructions supplied with 
the mowing head.
Mounting Metal Cutting Tools
Remove the  skirt and blade  from 
the mowing head deflector before 
mounting
grass cutting blade 230-4  (1),
grass cutting blade 230-8  (2),
or brush knife  (3) – see “Mounting 
the Deflector”
Fit the appropriate  limit stop before 
mounting the circular saw blade 200 
(4,5)  – see “Mounting the Deflector”. :
Lay your machine on its back with 
the gearhead facing upward.
Cutting edges of  (1) and (3) may 
point in either direction.
Cutting edges of  (2), (4) and (5) 
must  point clockwise.
Direction of rotation is marked by 
arrow on inside of cutting head 
deflector or limit stop. 
						

							
31
FS 80, FS 80 R, FS 85, FS 85 R English / USA
: Place the cutting tool  (6) on the 
thrust plate  (7).
Collar  (see arrows)  must locate in  
cutting tool’s mounting hole.
: Slip thrust washer  (8) and rider 
plate  (9) over the output shaft  (10).
: Block the output shaft and
: Screw the mounting nut  (11) with 
the combination wrench  (12) onto 
the output shaft counterclockwise 
and tighten down firmly.
If the mounting nut is too loose, 
fit a new one.
Removing cutting tool
: Block the output shaft.
: Unscrew the nut clockwise.
: Removing the cutting tool –  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 quality two-stroke 
air cooled engine oil.
Use mid-grade unleaded gasoline with a 
minimum octane rating of  89 (R+M/2). If 
the octane rating of the mid-grade 
gasoline in your area is lower, use 
premium unleaded fuel. 
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 
nationally recognized high-quality 
unleaded gasoline! Use only STIHL two-stroke engine oil or 
equivalent high-quality two-stroke 
engine oils that are designed for use 
only in air cooled two-cycle engines. 
We recommend  STIHL 50:1 two-stroke 
engine oil since it is specially formulated 
for use in STlHL engines.
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, 
chainsaws, 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 canister from 
your vehicle and place the canister on 
the ground before filling. Do not fill fuel 
canisters that are sitting in or on a 
vehicle.
The canister should be kept tightly 
closed in order to avoid any moisture 
getting into the mixture.
The machine‘s fuel tank and the canister 
in which fuel mix is stored should be 
cleaned as necessary.
Fuel 
						

							
32 English / USAFS 80, FS 80 R, FS 85, FS 85 R
Fuel mix ages
Only mix sufficient fuel for a few days 
work, not to exceed 3 months of storage. 
Store in approved fuel-canisters only. 
When mixing, pour oil into the canister 
first, and then add gasoline. Close the 
canister and shake it vigorously by hand 
to ensure proper mixing of the oil with 
the fuel.       
Dispose of empty mixing-oil canisters 
only at authorized disposal locations.
Before 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.
In order to reduce the risk of burns 
or other 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.
After fueling, tighten fuel cap  as 
securely as possible  by hand. Change the fuel pick up body every 
year.
Before storing your machine for a long 
period, drain and clean the fuel tank and 
run engine until carburetor is dry.
Gaso-
line
Oil (STIHL 50:1 or 
equivalent high-quality oils)
US gal. US fl.oz 12.6
2 1/2 6.4
512.8
Fueling
389BA031 KN389BA032 KN 
						

							
33
FS 80, FS 80 R, FS 85, FS 85 R English / USA
The type and style of harness depend on 
the market.
Shoulder Strap
: Put on the shoulder strap ( 1). 
: Adjust the length of the strap so that 
the spring hook ( 2) is about a hand’s 
width below your right hip. 
: Balance the brushcutter.
The use of the harness is described in 
chapter “Approved Combinations of 
Cutting Tool, Deflector, Handle and 
Harness”.
Full harness
: Put on the full harness  (1).
: Adjust length until the spring hook 
(2) is about a hand’s width below 
your right hip.
: Balance the brushcutter.
The use of the harness is described in 
chapter “Approved Combinations of 
Cutting Tool, Deflector, Handle and 
Harness”.
Attaching Harness to Brushcutter
: Attach the spring hook ( 1) to the 
clamp ( 2) (carrying ring) on the drive 
tube.
Fitting the HarnessBalancing the Brushcutter 
						

							
34 English / USAFS 80, FS 80 R, FS 85, FS 85 R
:
Loosen the screw ( 3).
Balancing the Machine
The machine has to be balanced to suit 
the cutting tool you are using.
Carry out the following steps to reach 
the condition described under “Point of 
balance”:
: Slide the clamp up or down the drive 
tube. Tighten the screw moderately. 
Let go of the machine and check to 
see how it is balanced. Point of balance
A Mowing tools
Mowing heads, grass cutting blades 
and brush knife should just touch 
the ground.
B Circular saw blades should hover about 8 in (20 cm) 
above the ground.
When the correct point of balance is 
reached:
: Tighten down the clamp screw 
firmly.
Disconnecting Brushcutter from 
Harness
Depending on the type of spring hook 
(carabiner):
:Press down the bar on the spring 
hook ( 1) and take the clamp (2) off 
the hook.
A
002BA034 KN
B
002BA035 KN 
						

							
35
FS 80, FS 80 R, FS 85, FS 85 R English / USA
Controls
Control handle on bike handle
Throttle trigger interlock (
1)
Throttle trigger ( 2) 
Slide control ( 3) Control handle on drive tube
Throttle trigger interlock (
1)
Throttle trigger ( 2) 
Slide control ( 3)
Positions of slide control
STOP -O  (4) – engine off – the ignition is 
switched off
#  – normal run position ( 5) – the engine 
is running or can start
START  (6 ) - the ignition is switched on, 
the engine can start Symbol on slide control
h
  ( 7 ) – stop symbol and arrow – to stop 
the engine, push the slide control in 
direction of arrow on stop symbol ( h ) to 
STOP -O .
Starting
: Hold down the throttle trigger 
interlock and squeeze the throttle 
trigger.
: While holding both levers in this 
position, move the slide control to  
START  and hold it there.
: Now release the throttle trigger, 
slide control and trigger interlock in 
that order. This is the  starting 
throttle position .
Starting / Stopping 
the Engine
3STOP
56
4
7
002BA182 KN
1
2
STARTSTOP-
3
STOP
2
5
6
4
7
002BA181 KN
START
STOP-
1 
						

							
36 English / USAFS 80, FS 80 R, FS 85, FS 85 R
:
Set the choke knob ( 8):
For cold start to      
g
For warm start to     e 
– also use this position if engine has 
been running but is still cold
: Press fuel pump bulb ( 9) at least five 
times – even if the bulb is already 
filled with fuel. :
Place the unit on the ground: It must 
rest securely on the engine support 
and deflector. 
Check that the cutting tool is not 
touching the ground or any other 
obstacles.
: Make sure you have a firm footing.
: Hold the unit with your left hand and 
press it down  firmly – your thumb 
should be under the fan housing.
Do not stand or kneel on the drive 
tube! :
Pull the starter grip slowly with your 
right hand until you feel it engage 
and then give it a brisk strong pull. 
Do not pull out the starter rope to full 
length – it might otherwise break.
: Do not let the starter grip snap back. 
Guide it slowly back into the housing 
so that the starter rope can rewind 
properly.
: Continue cranking until engine runs.
393BA017 KN
8
8
393BA018 KN
9
002BA038 KN
002BA040 KN357BA033 KN 
						

							
37
FS 80, FS 80 R, FS 85, FS 85 R English / USA
When the engine begins to fire:
: Turn choke knob to  e
and continue cranking.
When the engine begins to fire:
: Blip the throttle trigger immediately 
so that the slide control moves to 
the normal run position  # and the 
engine settles down to idle speed.
Make sure the carburetor is 
correctly adjusted – the cutting tool 
must not rotate when the engine is 
idling.
Your machine is now ready for 
operation.
Stopping the engine
: Push the slide control in direction 
of arrow on stop symbol ( h ) to 
STOP -O .
At very low outside temperatures
As soon as engine runs:
: Blip the throttle trigger to disengage 
the starting throttle position. The 
slide control moves to the normal 
run position  # and the engine settles 
down to idle speed.
: Open the throttle slightly.
: Warm up engine for brief period.
If the engine does not start
Choke knob
If you did not turn the choke knob to  e 
quickly enough after the engine began to 
fire, the combustion chamber has 
flooded.
: Turn choke knob to  e
: Select starting throttle position.
: Start the engine by pulling the 
starter rope firmly. 10 to 20 pulls 
may be necessary.
If the engine still does not start:
: Move the slide control to  STOP-O .
: Pull off the spark plug boot ( 10). :
Unscrew and dry off the spark plug.
: Open the throttle wide.
: Crank the engine several times with 
the starter to clear the combustion 
chamber.
: Refit the spark plug. Connect the 
spark plug boot (press it down 
firmly).
: Move the slide control to  START.
: Set the choke knob to  e –
even if engine is cold.
: Now start the engine.
Throttle cable adjustment
: Check adjustment of throttle cable – 
see chapter on Adjusting the 
Throttle Cable.
Tank run until dry
: After refueling, press the fuel pump 
bulb at least five times – even if bulb 
is filled with fuel.
: Set choke knob according to engine 
temperature.
: Now start the engine.
10
393BA042 KN 
						

							
38 English / USAFS 80, FS 80 R, FS 85, FS 85 R
During break-in period
A factory new machine should not be run 
at high revs (full throttle off load) for the 
first three tank fillings. This avoids 
unnecessary high loads during the 
break-in period. As all moving parts 
have to bed in during the break-in 
period, the frictional resistances in the 
engine are greater during this period. 
The engine develops its maximum 
power after about 5 to 15 tank fillings.
During operation
After a long period of full-throttle 
operation, allow engine to run for a while 
at idle speed so that the heat in the 
engine can be dissipated by flow of 
cooling air. This protects engine-
mounted components (ignition, 
carburetor) from thermal overload.
After finishing work
Wait for engine to cool down. Drain the 
fuel tank. Store the machine in a dry 
place. Check tightness of nuts and 
screws (not adjusting screws) at regular 
intervals and retighten as necessary.
Dirty air filters reduce engine power 
increase fuel consumption and make 
starting more difficult.
If there is a noticeable loss of engine 
power
:
Move choke lever to  g.
: Press in the tab  ( 1 ).
: Ease the filter cover ( 2) over the tab 
and take it away.
: Clean away loose dirt from around 
the filter.
: Remove the foam and felt filter 
elements. :
Wash the foam element in a clean, 
non-flammable cleaning solution 
(e.g. warm soapy water) and then 
dry.
: Fit new felt element. 
As a temporary measure you can 
knock it out on the palm of your 
hand or blow it out with compressed 
air. Do not  wash.
Replace damaged parts!
: Install the foam element ( 3) in the 
filter cover ( 2).
: Place felt element ( 4) (lettering 
facing inward) in filter housing ( 5).
: Fit filter cover so that it snaps into 
position.
Operating Instructions Cleaning the Air Filter
355BA014 KN
2
1
2
3355BA031 KN
45
355BA032 KN 
						

							
39
FS 80, FS 80 R, FS 85, FS 85 R English / USA
Exhaust emissions are controlled by the 
design of the fundamental engine 
parameters and components (e.g. 
carburation, ignition, timing and valve or 
port timing) without the addition of any 
major hardware.
The carburetor comes from the factory 
with a standard setting.
This setting provides an optimum fuel-air 
mixture under most operating 
conditions.
With this carburetor it is only possible to 
adjust the engine idle speed within fine 
limits.!
Standard Setting
:Shut off the engine.
: Mount FS cutting tool,  Power Tool 
Attachment or CombiTool.
: Check the air filter and replace if 
necessary.
: Check adjustment of throttle cable –
adjust if necessary – see Adjusting 
the Throttle Cable.
: Turn high speed screw  (H) 
counterclockwise  (max. 
3/4 turn) as 
far as stop.
: Carefully screw the low speed 
screw  (L) down onto its seat. Then 
open it  one turn counterclockwise.
: Start and warm up the engine.
: Adjust idle speed with the idle speed 
screw  (LA) so that the cutting tool 
does not rotate.
Fine Tuning
A slight correction of the setting of the 
high speed screw  (H) may be necessary 
if engine power is not satisfactory when 
operating at high altitude or at sea level 
or after changing the cutting tool.
Motor Management Adjusting the Carburetor
265BA024 KN
LA
HL 1
3 / 4