Stihl 45 C Owners Manual

							HS 45
English
9
WARNING
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.
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, switch off 
the engine immediately – move the slide 
control / stop switch to 0 or STOP.
WARNING
The cutter blades continue to move for a 
short period after the throttle trigger is 
released (flywheel effect.)
Accelerating the engine while the blades 
are blocked increases the load and will 
cause the clutch to slip continuously. 
This may result in overheating and 
damage to important components (e.g. 
clutch, polymer housing components) – 
which can then increase the risk of injury 
from the blades moving while the engine 
is idling.
WARNING
Before you start work, examine the 
hedge area for stones, fence wire, metal 
or other solid objects which could 
damage the cutter blades.
Take particular care when cutting 
hedges next to or against wire fences. 
Do not touch the wire with the cutting 
blades. When working close to the 
ground, make sure that no sand, grit or 
stones get between the cutter blades.
Striking solid foreign objects such as 
stones, fence wire or metal could 
damage the cutting attachment and may 
cause blades to crack, chip or break. 
STIHL does not recommend the use of 
your power tool when cutting in areas 
where the blades could contact such 
objects.
WARNING
Observe the cutting blades at all times – 
do not cut any areas of the hedge that 
you cannot see. When cutting the top of 
a taller hedge, check the other side of 
the hedge frequently for bystanders, 
animals and obstructions.
DANGER As soon as the engine is 
running, this product gen-
erates toxic exhaust 
fumes containing chemi-
cals, such as unburned 
hydrocarbons (including 
benzene) and carbon 
monoxide, that are 
known to cause respira-
tory problems, cancer, 
birth defects, or other 
reproductive harm. Some 
of the gases (e.g. carbon 
monoxide) may be color-
less and odorless. To 
reduce the risk of serious 
or fatal injury / illness 
from inhaling toxic fumes, 
never run the machine 
indoors or in poorly venti-
lated locations
Your power tool is not 
insulated against electric 
shock. To reduce the risk 
of electrocution, never 
operate this power tool in 
the vicinity of any wires or 
cables (power, etc.) 
which may be carrying 
electric current. 
						

							HS 45
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10
WARNING
If the cutting tool 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.
Check the cutting blades at regular short 
intervals during operation, or 
immediately if there is a noticeable 
change in cutting behavior:
–Shut off the engine.
–Wait until the cutting blades have 
come to a complete standstill.
–Check condition and tightness, look 
for cracks.
–Check sharpness.
–Replace damaged or dull cutting 
tools immediately, even if they have 
only superficial cracks.
WARNING
The gearbox becomes hot during 
operation. To reduce the risk of burn 
injury, do not touch the gear housing 
when it is hot.
WARNING
Never modify your muffler. Any 
modification could cause an increase in 
heat radiation, sparks or sound level, 
thereby increasing the risk of fire, burn 
injury or hearing loss. You may also 
permanently damage the engine. Have 
your muffler serviced and repaired by 
your STIHL servicing dealer only.
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. 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 (e.g. the trunk of a felled 
tree) away from any combustible 
substances.
WARNING
An improperly mounted or damaged 
cylinder housing or a 
damaged/deformed muffler shell may 
interfere with the cooling process of the 
muffler. 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 muffler is furnished with a spark 
arresting screen designed to reduce the 
risk of fire from the emission of hot 
particles. Never operate your unit with a 
missing or damaged spark arresting 
screen. If your gas/oil mix ratio is correct 
(i.e., not too rich), this screen will 
normally stay clean as a result of the 
heat from the muffler 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. Some state or federal laws or 
regulations may require a properly maintained spark arrestor for certain 
uses. See the "Maintenance, Repair and 
Storing" section of these Safety 
Precautions. Remember that the risk of 
a brush or forest fire is greater in hot or 
dry conditions.
WARNING
After Finishing Work
Always clean dust and dirt off the 
machine – do not use any grease 
solvents for this purpose.
Spray the blades with STIHL resin 
solvent. Start and run the engine briefly 
so that the solvent is evenly distributed. Some STIHL power tools 
are equipped with a cata-
lytic converter, which is 
designed to reduce the 
exhaust emissions of the 
engine by a chemical pro-
cess in the muffler. Due 
to this process, the muf-
fler does not cool down 
as rapidly as conven-
tional mufflers when the 
engine returns to idle or 
is shut off. To reduce the 
risk of fire and burn inju-
ries when using a 
catalytic converter, 
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 com-
bustible materials while it 
is still hot.
      
        
          
             
						

							HS 45
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11 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 
section of your instruction manual. 
Please also refer to the maintenance 
chart in this manual.
WARNING
Always stop the engine and make sure 
that the cutting blades are 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 spark plug 
terminal 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 
ignition wire 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. 
Your muffler is equipped with a spark-
arresting screen to reduce the risk of 
fire; never operate your power tool if the 
screen is missing, damaged or clogged. 
Remember that the risk of a brush or 
forest fire is greater in hot or dry 
weather.
In California, it is a violation of § 4442 or 
§ 4443 of the Public Resources Code to 
use or operate gasoline-powered tools 
on forest-covered, brush-covered or 
grass-covered land unless the engine’s 
exhaust system is equipped with a 
complying spark arrester that is 
maintained in effective working order. The owner/operator of this product is 
responsible for properly maintaining the 
spark arrester. Other states or 
governmental entities/agencies, such as 
the U.S. Forest Service, may have 
similar requirements. Contact your local 
fire agency or forest service for the laws 
or regulations relating to fire protection 
requirements.
WARNING
Never repair damaged cutting attach-
ments by welding, straightening or 
modifying the shape. This may cause 
parts of the cutting blades to come off 
and result in serious or fatal injuries.
Keep the cutting blades sharp. Tighten 
all nuts, bolts and screws, except the 
carburetor adjustment screws, after 
each use.
Do not clean your machine with a 
pressure washer. The solid jet of water 
may damage parts of the machine.
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 this 
manual. 
						

							HS 45
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12
Cutting Season
Observe country-specific or municipal 
rules and regulations for cutting hedges.
Do not use your power tool during other 
people's normal rest periods.
Cutting Sequence
Use lopping shears or a chain saw to cut 
out thick branches first.
Cut both sides of the hedge first, then 
the top.
Disposal
Do not throw cuttings in the garbage can 
– they can be composted!
Working Technique
Vertical Cut
Swing the cutting blade from the bottom 
upwards in an arc – lower the nose of the 
blade, move along the hedge and then 
swing the blade up again in an arc.
Any working position above head height 
is tiring. To minimize the risk of 
accidents, work in such positions for 
short periods only.Horizontal Cut
Hold the cutter bar at an angle of 0° to 
10° as you swing the hedge trimmer 
horizontally.
Swing the cutting blade in an arc 
towards the outside of the hedge so that 
the cuttings are swept to the ground.Using the Unit 
						

							HS 45
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13 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 two-stroke air 
cooled engine oil.
Use mid-grade unleaded gasoline with a 
minimum octane rating of 89 ((R+M)/2) 
and no more than 10% ethanol content.
NOTICE
Fuel with an octane rating below 89 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 damage the 
engine. For this reason STIHL 
recommends that you use only quality 
unleaded gasoline!
NOTICE
Gasoline with an ethanol content of 
more than 10% can cause running 
problems and major damage in engines 
and should not be used.
For further details, see 
www.STIHLusa.com/ethanol
The ethanol content in gasoline affects 
engine speed – it may be necessary to 
readjust the carburetor if you use fuels 
with various ethanol contents.
WARNING
To reduce the risk of personal injury 
from loss of control and/or contact with 
the running cutting tool, do not use your 
unit with an incorrect idle adjustment. At 
correct idle speed, the cutting tool 
should not move.
If your machine’s idle speed is 
incorrectly adjusted, have your 
authorized STIHL servicing dealer 
check your machine and make the 
proper adjustments and repairs.
The idle speed and maximum speed of 
the engine change if you switch from a 
fuel with a certain ethanol content to a 
fuel with a much higher or lower ethanol 
content.
This problem can be avoided by always 
using fuel with the same ethanol 
content.
To ensure the maximum performance of 
your STIHL engine, use a high quality 2-
cycle engine oil. To help your engine run 
cleaner and reduce harmful carbon 
deposits, STIHL recommends using 
STIHL HP Ultra 2-cycle engine oil or ask 
your dealer for an equivalent fully 
synthetic 2-cycle engine oil. 
To meet the requirements of EPA and 
CARB we recommend to use STIHL HP 
Ultra oil.
STIHL MotoMix
STIHL recommends the use of STIHL 
MotoMix. STIHL MotoMix has a high 
octane rating and ensures that you 
always use the right gasoline/oil mix 
ratio.STIHL MotoMix uses STIHL HP Ultra 
two-stroke engine oil suited for high 
performance engines.
For further details, see 
www.STIHLusa.com/ethanol
If not using MotoMix, use only STIHL 
two-stroke engine oil or equivalent high-
quality two-stroke engine oils that are 
designed for use in air cooled two-cycle 
engines.
The use of non-seasonal gasoline 
blends may increase the potential for 
pressure to build in the fuel tank during 
operation. For example, using a winder 
blend during the summer will increase 
pressure in the fuel tank. Always use 
gasoline blends appropriate to the 
season, altitude and other 
environmental factors.
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, 
chain saws, mopeds, etc.).
WARNING
Take care when handling gasoline. 
Avoid direct contact with the skin and 
avoid inhaling fuel vapor. When filling at 
the pump, first remove the container 
from your vehicle and place the 
container on the ground before filling. To 
reduce the risk of sparks from static 
discharge and resulting fire and/or 
explosion, do not fill fuel containers that 
are sitting in or on a vehicle or trailer.
The container should be kept tightly 
closed in order to limit the amount of 
moisture that gets into the mixture.
Fuel 
						

							HS 45
English
14 The machine‘s fuel tank should be 
cleaned as necessary.
Fuel mix ages
If not using MotoMix, only mix sufficient 
fuel for a few days of work, not to exceed 
30 days of storage. Store in approved 
fuel-containers only. When mixing, pour 
oil into the container first, and then add 
gasoline. Close the container and shake 
it vigorously by hand to ensure proper 
mix of oil and gasoline.
Dispose of empty mixing-oil containers 
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.
WARNING
In order to reduce the risk of fire and 
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.
WARNING
After fueling, tighten fuel cap as securely 
as possible by hand.
Have the fuel pickup body in the tank 
changed once every year.NObserve safety precautions – see 
chapter on "Safety Precautions and 
Working Techniques".
NMove the stop switch (1) to I.
NPress down the lockout lever (2) 
and squeeze the throttle trigger (3) 
– hold both levers in that position.
NPress in the starting throttle lock (4).
NLet go of the lockout lever, throttle 
trigger and starting throttle lock. 
This is the starting throttle position.
NSet the choke lever (5) to Gaso-
lineOil (STIHL 50:1 or equiva-
lent high-quality oils)
US gal. US fl.oz.
12.6
2 1/2 6.4
512.8
Fueling
253BA001 KN
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lif the engine is cold
jfor warm start – also use this posi-
tion if the engine has been running 
but is still cold.
4
3
2
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253BA020 KN
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6
253BA021 KN 
						

							HS 45
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15 NPress the manual fuel pump 
bulb (6) at least five times – even if 
the bulb is filled with fuel.
Cranking
NPlace the unit on the ground.
NRemove the blade scabbard. Check 
that the cutting blades are not 
touching the ground or any other 
obstacles.
NMake sure you have a safe and 
secure footing.
NHold the unit firmly with your left 
hand on the front handle and press 
down.
NPull the starter grip slowly with your 
right hand until you feel it engage 
and then give it a brisk strong pull.
NOTICE
Do not pull out the starter rope all the 
way – it might otherwise break.
NDo not let the starter grip snap back. 
Guide it slowly back into the housing 
so that the starter rope can rewind 
properly.If the engine is cold (choke set tol)
NPull the starter rope five times.
NSet choke lever toj and
Ncontinue cranking until the engine 
runs.
If conditions are unfavorable and the 
engine does not start after 10 pulls with 
the choke lever set toj :
NSet choke tol and pull starter 
rope five times. Set choke toj and 
continue cranking.
If the engine is warm (choke set toj)
NContinue cranking until the engine 
runs.
As Soon as Engine Runs
NBlip the throttle trigger – the engine 
settles down to idle speed.
If the engine stops during warm-up or 
acceleration
NRepeat the starting procedure as 
described under "If the engine is 
cold".
WARNING
Make sure the carburetor is correctly 
adjusted. The cutting blades must not 
move when the engine is idling.
Your machine is now ready for 
operation.
Stopping the Engine
NMove the stop switch toO.
Other Hints on Starting
If the engine does not start
NMake sure all settings are correct 
(choke shutter, throttle trigger in 
starting throttle position, stop switch 
toI).
NRepeat the starting procedure.
If the engine still does not start
NRemove the spark plug – see 
"Spark Plug".
NDry the spark plug.
NOpen the throttle wide.
NCrank the engine several times with 
the starter to clear the combustion 
chamber.
NInstall the spark plug – see "Spark 
Plug".
NMove the stop switch to I.
NSet choke lever toj – even if the 
engine is cold.
NNow start the engine.
253BA022 KN 
						

							HS 45
English
16 If fuel tank has been run completely dry 
and then refueled
NPress the manual fuel pump 
bulb (6) at least five times – even if 
the bulb is filled with fuel.
NNow start the engine.
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 the engine to run for a 
short while at idle speed so that engine 
heat can be dissipated by the flow of 
cooling air. This protects engine-
mounted components (ignition, 
carburetor) from thermal overload.
After Finishing Work
Storing for a short period: Wait for the 
engine to cool down. Empty the fuel tank 
and keep the machine in a dry place, 
well away from sources of ignition, until 
you need it again. For longer out-of-
service periods – see "Storing the 
Machine".If there is a noticeable loss of engine 
power
NMove the choke lever tol.
NPress in the tab (1) and swing the 
filter cover (2) down.
NClean away loose dirt from around 
the filter.
6
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2 
						

							HS 45
English
17 NRemove the foam element (3) and 
felt element (4).
NWash the foam element in a clean, 
non-flammable solution (e.g. soapy 
water) and then dry.
NFit a 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.
NReplace any damaged parts.
NFit the foam element (3) in the filter 
cover (2) and the felt element (4) in 
the filter housing (5).
NClose the filter cover so that it snaps 
into position.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.
General Information
The carburetor comes from the factory 
with a standard setting.
This setting provides an optimum fuel-air 
mixture under most operating 
conditions.
Preparations
NShut off the engine.
NCheck the air filter and clean or 
replace if necessary.
NInspect cutting blades and clean if 
necessary (clean, move freely, not 
warped).
Standard Setting
NTurn high speed screw (H) 
counterclockwise as far as stop (no 
more than 3/4 turn).
NTurn the low speed screw (L) 
clockwise as far as stop, then turn it 
back 3/4 turn.
5
2
3
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							HS 45
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18
Adjusting Idle Speed
NCarry out the standard setting.
NStart and warm up the engine.
NAdjust idle speed with the idle speed 
screw (LA) so that the cutting 
blades do not run.
Engine stops while idling
NTurn the idle speed screw (LA) 
slowly clockwise until the engine 
runs smoothly – the cutting blades 
must not run.
Cutting blades run when engine is idling
NTurn the idle speed screw (LA) 
counterclockwise until the cutting 
blades stop moving – then turn it 
another 1/2 to 1 turn in the same 
direction.
WARNING
If the cutting blades continue moving 
when the engine is idling, have your 
power tool checked and repaired by your 
servicing dealer.
Erratic idling behavior, poor acceleration 
(despite correction to setting of LA 
screw).
Idle setting is too leanNT u r n  t h e  l o w  s p e e d  s c r e w ( L )  s l o w l y  
counterclockwise until the engine 
runs and accelerates smoothly.
It is usually necessary to change the 
setting of the idle speed screw (LA) after 
every correction to the low speed 
screw (L).
Fine Tuning for Operation at High 
Altitude
A slight correction of the setting may be 
necessary if engine does not run 
satisfactorily:
NCarry out the standard setting.
NWarm up the engine.
NTurn high speed screw (H) slightly 
clockwise (leaner) – no further than 
stop.
NOTICE
After returning from high altitude, reset 
the carburetor to the standard setting.
If the setting is too lean there is a risk of 
engine damage due to insufficient 
lubrication and overheating.If the engine is down on power, difficult 
to start or runs poorly at idling speed, 
first check the spark plug.
Install a new spark plug after approx. 
100 operating hours or earlier if the 
electrodes are badly eroded/corroded.
The wrong fuel mix (too much engine oil 
in the gasoline), a dirty air filter and 
unfavorable running conditions (mostly 
at part throttle etc.) affect the condition 
of the spark plug. These factors cause 
deposits to form on the insulator nose 
which may degrade performance.
Removing the Spark Plug
NMove the stop switch toO.
NPull off the spark plug boot.
NUnscrew the spark plug.
LA
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