Stihl HL 90 User manual

Instruction Manual
Manual de instrucciones
Warning!
Read and follow all safety precautions in
Instruction Manual – improper use can cause
serious or fatal injury.
Advertencia!
Lea y siga todas las precauciones de
seguridad dadas en el manual de
instrucciones – el uso incorrecto puede
causar lesiones graves o mortales.
STIH)
STIHL HL 90
BA_U1_86_02.fm Seite 0 Mittwoch, 18. April 2007 1:20 13

1HL 90 K
English / USA
BA_SE_212_003_01_03.fmPrinted on chlorine-free paper.
Printing inks contain vegetable oils; paper can be recycled.
© ANDREAS STIHL AG & Co. KG, 2008 0458 445 8621 A. M1. C8. PM. Printed in USA
STIHl
Contents
Guide to Using this Manual .............. 2
Safety Precautions and
Working Techniques ......................... 3
Using the Hedge Trimmer .............. 13
Mounting the Gearbox .................... 14
Adjusting the Throttle Cable ........... 15
4-MIX Engine .................................. 16
Fuel ................................................ 16
Fueling ............................................ 17
Starting / Stopping
the Engine ...................................... 18
Operating Instructions .................... 21
Cleaning the Air Filter ..................... 21
Motor Management ........................ 21
Adjusting the Carburetor ................ 22
Spark Arresting Screen in Muffler ... 23
Checking the Spark Plug ................ 24
Lubricating the Gearbox ................. 25
Replacing Starter Rope
and Rewind Spring ......................... 26
Storing the Machine ........................ 29
Sharpening Instructions .................. 29
Inspections and Maintenance
by Dealer ........................................ 29
Maintenance Chart ......................... 30
Main Parts and Controls ................. 32
Specifications ................................. 34
Special Accessories ....................... 35
Maintenance and Repairs ............... 35
STIHL Incorporated
Federal Emission Control
Warranty Statement ........................ 36
STIHL Incorporated California
Exhaust and Evaporative Emissions
Control Warranty Statement ........... 38
Trademarks .................................... 40
Allow only persons who understand this
manual to operate your hedge cutter.
To receive maximum performance and
satisfaction from your STIHL hedge
cutter, it is important that you read and
understand the maintenance and safety
precautions, starting on page 3, before
using your hedge cutter.
Contact your STIHL dealer or the STIHL
distributor for your area if you do not
understand any of the instructions in this
manual.
!Warning!
Because a hedge cutter is a high-speed
cutting tool some special safety
precautions must be observed to reduce
the risk of personal injury.
Careless or improper use may cause
serious or even fatal injury.
STIHL's philosophy is to continually
improve all of its products. As a result,
engineering changes and improve-
ments are made from time to time. If the
operating characteristics or the
appearance of your hedge cutter differs
from those described in this manual,
please contact your STIHL dealer for
information and assistance.

2
English / USA
HL 90 K
Pictograms
All the pictograms attached to the
machine are shown and explained in
this manual.
The operating and handling instructions
are supported by illustrations.
Symbols in text
The individual steps or procedures
described in the manual may be marked
in different ways:
:A bullet marks a step or procedure
without direct reference to an
illustration.
A description of a step or procedure that
refers directly to an illustration may
contain item numbers that appear in the
illustration.
Example:
Loosen the screw (1)
Lever (2) ...
In addition to the operating instructions,
this manual may contain paragraphs
that require your special attention. Such
paragraphs are marked with the
symbols described below:
Warning where there is a risk of an
accident or personal injury or
serious damage to property.
Caution where there is a risk of
damaging the machine or its
individual components.
Note or hint which is not essential
for using the machine, but may
improve the operator’s under-
standing of the situation and result
in better use of the machine.
Note or hint on correct procedure in
order to avoid damage to the
environment.
Equipment and features
This instruction manual may refer to
several models with different
features. Components that are not
installed on all models and related
applications are marked with an
asterisk (*). Such components may
be available as special accessories
from your STIHL dealer.
Engineering improvements
STIHL’s philosophy is to continually
improve all of its products. As a result,
engineering changes and improvements
are made from time to time. If the
operating characteristics or the
appearance of your machine differ from
those described in this manual, please
contact your STIHL dealer for
assistance.
Therefore some changes, modifications
and improvements may not be covered
in this manual.
Guide to Using this Manual

3HL 90 K
English / USA
Because a hedge trimmer
is a high-speed, fast-
cutting power tool with
sharp cutting blades,
special safety precautions
must be observed to
reduce the risk of
personal injury.
It is important that you
read, fully understand and
observe the following
safety precautions and
warnings. Read the
instruction manual and
the safety precautions periodically.
Careless or improper use may cause
serious or fatal injury.
Have your STIHL dealer show you how
to operate your power tool. Observe all
applicable local safety regulations,
standards and ordinances.
!Warning!
Do not lend or rent your power tool
without the instruction manual. Be sure
that anyone using it understands the
information contained in this manual.
!Warning!
The use of this machine may be
hazardous. If the cutting tool comes in
contact with your body, it will cut you.
Use your hedge trimmer only for cutting
hedges, shrubs, scrub, bushes and
similar material. It must not be used for
any other purposes, since such misuse
may result in an accident or damage to
the machine.
!Warning!
Minors should never be allowed to use
this power tool. Bystanders, especially
children, and animals should not be
allowed in the area where it is in use.
!Warning!
To reduce the risk of injury to bystanders
and damage to property, never let your
power tool run unattended. When it is
not in use (e.g. during a work break),
shut it off and make sure that
unauthorized persons do not use it.
Most of these safety precautions and
warnings apply to the use of all STIHL
hedge trimmers. Different models may
have different parts and controls. See
the appropriate section of your
instruction manual for a description of
the controls and the function of the parts
of your model.
Safe use of a hedge trimmer involves
1. the operator
2. the power tool
3. the use of the power tool.
THE OPERATOR
Physical Condition
You must be in good physical condition
and mental health and not under the
influence of any substance (drugs,
alcohol, etc.) which might impair vision,
dexterity or judgment. Do not operate
this machine when you are fatigued.
!Warning!
Be alert – if you get tired, take a break.
Tiredness may result in loss of control.
Working with any power tool can be
strenuous. If you have any condition that
might be aggravated by strenuous work,
check with your doctor before operating
this machine.
Safety Precautions and
Working Techniques

4
English / USA
HL 90 K
!Warning!
Prolonged use of a power tool (or other
machines) exposing the operator to
vibrations may produce whitefinger
disease (Raynaud's phenomenon) or
carpal tunnel syndrome.
These conditions reduce the hand's
ability to feel and regulate temperature,
produce numbness and burning
sensations and may cause nerve and
circulation damage and tissue necrosis.
All factors which contribute to white-
finger disease are not known, but cold
weather, smoking and diseases or
physical conditions that affect blood
vessels and blood transport, as well as
high vibration levels and long periods of
exposure to vibration are mentioned as
factors in the development of whitefinger
disease. In order to reduce the risk of
whitefinger disease and carpal tunnel
syndrome, please note the following:
Most STIHL power tools are available
with an anti-vibration (“AV”) system
designed to reduce the transmission of
vibrations created by the machine to the
operator's hands. An AV system is
recommended for those persons using
power tools on a regular or sustained
basis.
Wear gloves and keep your hands
warm.
Keep the AV system well maintained. A
power tool with loose components or
with damaged or worn AV buffers will
tend to have higher vibration levels.
Maintain a firm grip at all times, but do
not squeeze the handles with constant,
excessive pressure. Take frequent
breaks.
All the above-mentioned precautions do
not guarantee that you will not sustain
whitefinger disease or carpal tunnel
syndrome. Therefore, continual and
regular users should closely monitor the
condition of their hands and fingers. If
any of the above symptoms appear,
seek medical advice immediately.
!Warning!
The ignition system of the STIHL unit
produces an electromagnetic field of a
very low intensity. This field may
interfere with some pacemakers. To
reduce the risk of serious or fatal injury,
persons with a pacemaker should
consult their physician and the
pacemaker manufacturer before
operating this tool.
Proper Clothing
!Warning!
To reduce the risk of injury, the operator
should wear proper protective apparel.
!Warning!
To reduce the risk of injury
to your eyes never
operate your power tool
unless wearing goggles or
properly fitted protective
glasses with adequate top
and side protection complying with ANSI
Z 87.1 (or your applicable national
standard). To reduce the risk of injury to
your face STIHL recommends that you
also wear a face shield or face screen
over your goggles or protective glasses.
!Warning!
Power tool noise may
damage your hearing.
Wear sound barriers (ear
plugs or ear mufflers) to
protect your hearing.
Continual and regular
users should have their hearing checked
regularly.
Be particularly alert and cautious when
wearing hearing protection because
your ability to hear warnings (shouts,
alarms, etc.) is restricted.

5HL 90 K
English / USA
Always wear gloves when
handling the machine and
the cutting tool. Heavy-
duty, nonslip gloves
improve your grip and
help to protect your
hands.
Clothing must be sturdy
and snug-fitting, but allow
complete freedom of
movement. Wear long
pants made of heavy
material to help protect
your legs. Do not wear shorts, sandals
or go barefoot.
Avoid loose-fitting jackets,
scarfs, neckties, jewelry,
flared or cuffed pants,
unconfined long hair or
anything that could
become caught on
branches, brush or the moving parts of
the unit. Secure hair so it is above
shoulder level.
Good footing is very
important. Wear sturdy
boots with nonslip soles.
Steel-toed safety boots
are recommended.
Wear an approved safety
hard hat to reduce the risk
of injury to your head
when there is a danger of
head injuries.
THE POWER TOOL
For illustrations and definitions of the
power tool parts see the chapter on
“Main Parts and Controls”.
!Warning!
Never modify this power tool in any way.
Only attachments supplied by STIHL or
expressly approved by STIHL for use
with the specific STIHL model are
authorized. Although certain
unauthorized attachments are useable
with STIHL power tools, their use may, in
fact, be extremely dangerous.
If this tool is subjected to unusually high
loads for which it was not designed (e.g.
heavy impact or a fall), always check
that it is in good condition before
continuing work. Check in particular that
the fuel system is tight (no leaks) and
that the controls and safety devices are
working properly. Do not continue
operating this machine if it is damaged.
In case of doubt, have it checked by your
STIHL servicing dealer.
THE USE OF THE POWER TOOL
Transporting the Power Tool
!Warning!
To reduce the risk of injury from blade
contact, never carry or transport your
power tool with the cutter blades
moving.
It may be carried only in a horizontal
position. Grip the shaft in a manner that
the machine is balanced horizontally.
Keep the hot muffler away from your
body and the cutting attachment behind
you.
!Warning!
Always switch off the engine and fit the
scabbard over the cutter blades before
transporting the power tool over long
distances. When transporting it in a
vehicle, properly secure it to prevent
turnover, fuel spillage and damage to the
unit.
002BA247 KN

6
English / USA
HL 90 K
Fuel
Your STIHL power tool uses an oil-
gasoline mixture for fuel (see the chap-
ter on “Fuel” of your instruction manual).
!Warning!
Gasoline is an extremely
flammable fuel. If spilled
and ignited by a spark or
other ignition source, it
can cause fire and serious
burn injury or property
damage. Use extreme caution when
handling gasoline or fuel mix.
Do not smoke or bring any fire or flame
near the fuel or the power tool. Note that
combustible fuel vapor may escape from
the fuel system.
Fueling Instructions
!Warning!
Fuel your power tool in well-ventilated
areas, outdoors. Always shut off the
engine and allow it to cool before
refueling. Gasoline vapor pressure may
build up inside the fuel tank depending
on the fuel used, the weather conditions
and the tank venting system.
In order to reduce the risk of burns and
other personal injury from escaping gas
vapor and fumes, remove the fuel filler
cap on your power tool carefully so as to
allow any pressure build-up in the tank
to release slowly. Never remove the fuel
filler cap while the engine is running.
Select bare ground for fueling and move
at least 10 feet (3 m) from the fueling
spot before starting the engine. Wipe off
any spilled fuel before starting your
machine.
!Warning!
Check for fuel leakage while refueling
and during operation. If fuel leakage is
found, do not start or run the engine until
the leak is fixed and any spilled fuel has
been wiped away. Take care not to get
fuel on your clothing. If this happens,
change your clothing immediately.
Different models may be equipped with
different fuel caps.
Cap with grip
!Warning!
In order to reduce the risk of fuel spillage
and fire from an improperly tightened
fuel cap, correctly position and tighten
the fuel cap in the fuel tank opening.
To do this with this STIHL
cap, raise the grip on the
top of the cap until it is
upright at a 90° angle.
Insert the cap in the fuel
tank opening with the
triangular marks on the grip of the cap
and on the fuel tank opening lining up.
Using the grip, turn the cap firmly
clockwise as far as it will go (approx. a
quarter turn).
Fold the grip flush with the
top of the cap. If the grip
does not lie completely
flush with the cap and the
detent on the grip does
not fit in the
corresponding recess in the filler neck,
the cap is not properly seated and
tightened and you must repeat the
above steps.

7HL 90 K
English / USA
Screw cap
!Warning!
Unit vibrations can cause
an improperly tightened
fuel filler cap to loosen or
come off and spill
quantities of fuel. In order
to reduce the risk of fuel
spillage and fire, tighten the fuel filler cap
by hand as securely as possible.
Before Starting
!Warning!
Always check your power tool for proper
condition and operation before starting,
particularly the throttle trigger, throttle
trigger interlock, stop switch and cutting
tool. The throttle trigger (if applicable)
must move freely and always spring
back to the idle position. Never attempt
to modify the controls or safety devices.
!Warning!
Never use a power tool that is damaged
or not properly maintained.
!Warning!
Check that the spark plug boot is
securely mounted on the spark plug – a
loose boot may cause arcing that could
ignite combustible fumes and cause a
fire.
Keep the handles clean and dry at all
times; it is particularly important to keep
them free of moisture, pitch, oil, grease
or resin in order for you to maintain a firm
grip and properly control your power
tool.
!Warning!
The cutting tool must be properly
tightened and in safe operating
condition. Inspect for loose parts (nuts,
screws, etc.) and for cracked, bent,
warped or damaged blades. Regularly
check the condition and tightness of the
cutter blades – with the engine stopped!
Replace damaged cutter blades before
using the power tool. Always keep
blades sharp.
STIHL recommends that you always
spray the cutter blades with STIHL resin
solvent before starting work - with the
engine stopped! You can obtain this
protective spray from your dealer. Apply
generously.
Starting
Start the engine at least 10 feet
(3 meters) from the fueling spot,
outdoors only.
For specific starting instructions, see the
appropriate section of your manual.
Place the power tool on firm ground or
other solid surface in an open area.
Maintain good balance and secure
footing.
!Warning!
To reduce the risk of injury from blade
contact, be absolutely sure that the
cutting tool is clear of you and all other
obstructions and objects, including the
ground, because when the engine starts
at starting-throttle, engine speed will be
fast enough for the clutch to engage and
move the blades on the cutting tool.
002BA245 KN

8
English / USA
HL 90 K
Once the engine has started,
immediately blip the throttle trigger,
which should release the starting throttle
and allow the engine to slow down to
idle.
!Warning!
Your power tool is a one-person
machine. Do not allow other persons in
the general work area, even when
starting.
!Warning!
To reduce the risk of injury from loss of
control, do not attempt to “drop start”
your power tool.
!Warning!
When you pull the starter grip, do not
wrap the starter rope around your hand.
Do not let the grip snap back, but guide
the starter rope to rewind it properly.
Failure to follow this procedure may
result in injury to your hand or fingers
and may damage the starter
mechanism.
Important Adjustments
!Warning!
To reduce the risk of personal injury from
loss of control or contact with the
running cutting tool, do not use your unit
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 instruction manual.
If you cannot set the correct idle speed,
have your STIHL dealer check your
power tool and make proper
adjustments and repairs.
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.
Place your left hand on hose grip of shaft
and your right hand on rear grip and
throttle trigger. This also applies to left-
handers.
!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 tool. Never touch a
moving cutting tool with your hand or
any other part of your body.
002BA246 KN

9HL 90 K
English / USA
!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 fallen branches, 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, in a tree
or any other insecure support. Never
hold the machine above shoulder
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.
!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.