{
STIHL FS 40, 50
Instruction Manual
Manual de instrucciones
WARNING
Read Instruction Manual thoroughly before use and follow all safety precautions – improper use can cause serious or fatal injury.
ADVERTENCIA
Antes de usar la máquina lea y siga todas las precauciones de seguridad dadas en el manual de instrucciones – el uso incorrecto puede causar lesiones graves o mortales.
Instruction Manual 1 - 43
Manual de instrucciones 44 - 90
English
Contents
Printing inks contain vegetable oils, paper can be recycled.
Printed on chlorine-free paper Original Instruction Manual
© ANDREAS STIHL AG & Co. KG, 2015 0458-546-8621-D. VA2.M14. 0000001050_017_GB
Guide to Using this Manual |
2 |
Safety Precautions and Working |
|
Techniques |
3 |
Approved Combinations of Cutting |
|
Attachment, Deflector, Handle and |
|
Harness |
14 |
Mounting the Loop Handle |
15 |
Mounting the Deflector |
15 |
Mounting the Cutting Attachment |
16 |
Fuel |
19 |
Fueling |
20 |
Starting / Stopping the Engine |
22 |
Operating Instructions |
24 |
Cleaning the Air Filter |
25 |
Engine Management |
25 |
Adjusting the Carburetor |
26 |
Spark Plug |
26 |
Engine Running Behavior |
27 |
Rewind Starter |
27 |
Storing the Machine |
28 |
Maintaining the Mowing Head |
28 |
Inspections and Maintenance by |
|
Dealer |
32 |
Maintenance and Care |
33 |
Main Parts |
35 |
Specifications |
36 |
Maintenance and Repairs |
37 |
Disposal |
38 |
STIHL Incorporated Federal |
|
Emission Control Warranty |
|
Statement |
38 |
STIHL Incorporated California
Exhaust and Evaporative
Emissions Control Warranty
Statement
Trademarks
|
Allowonlypersonswhofullyunderstand |
|
this manual to operate your trimmer. |
40 |
To receive maximum performance and |
satisfaction from your STIHL trimmer, it |
42is important that you read, understand and follow the safety precautions and the operating and maintenance instructions in chapter "Safety Precautions and Working Techniques" before using your trimmer. For further information you can go to www.stihlusa.com.
Contactyour STIHLdealer or theSTIHL distributor for your area if you do not understandanyoftheinstructionsinthis manual.
WARNING
Because a trimmer is a high-speed cutting tool some special safety precautionsmustbeobservedtoreduce the risk of personal injury. Careless or improperusemaycauseseriousoreven fatal injury.
Makesureyourunitisequippedwiththe properdeflector,handleandharnessfor the type of cutting attachment being used. Always wear proper eye protection.
{This instruction manual is protected by copyright. All rights reserved, especially the rights to reproduce, translate and process with electronic systems.
FS 40, FS 40 C, FS 50, FS 50 C |
1 |
English
Guide to Using this Manual
Pictograms
The meanings of the pictograms attached to or embossed on the machine are explained in this manual.
Dependingonthemodelconcerned,the following pictograms may be on your machine.
Fuel tank for gasoline and engine oil mixture
Press to operate decom- pression valve
Manual fuel pump
Press to operate manual fuel pump
Filler hole for gear lubricant
Air intake summer mode
Air intake winter mode
Handle heating
Symbols in Text
Many operating and safety instructions are supported by illustrations.
The individual steps or procedures describedin themanualmaybemarked in different ways:
N A bullet marks a step or procedure.
A description of a step or procedure that refers directly to an illustration may contain item numbers that appear in the illustration. Example:
N Loosen the screw (1). N 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 and signal words described below:
DANGER
Indicates an imminent risk of severe or fatal injury.
WARNING
Indicates a hazardous situation which, if not avoided, could result in severe or fatal injury.
NOTICE
Indicates a risk of property damage, including damage to the machine or its individual components.
Engineering Improvements
STIHL’s philosophy is to continually improve all of its products. As a result, engineeringchangesandimprovements are made from time to time. Therefore, some changes, modifications and improvements may not be covered in this manual. If the operating characteristics or the appearance of your machine differs from those describedinthismanual,pleasecontact your STIHL dealer or the STIHL distributor for your area for assistance.
2 |
FS 40, FS 40 C, FS 50, FS 50 C |
Safety Precautions and
Working Techniques
Because a trimmer is a high-speed, fast-cutting power tool, 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.
The terminology utilized in this manual when referring to the power tool reflects the type of cutting attachments that may be mounted on it. The term "trimmer" is used to designate an FS unit that is equipped with a nylon line head or a headwithflexibleplasticblades(i.e.,the PolyCut head).
WARNING
As more fully explained later in these Safety Precautions, to reduce the risk of personal injury, make sure your unit is equipped with the proper handle, harness and deflector for the type of cutting attachment you are using. Use only cutting attachments that are specifically authorized by STIHL for use on your FS model. 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 this trimmer.
FS 40, FS 40 C, FS 50, FS 50 C
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 rotating line or blade comes in contact with your body, it will cut you. When it comes in contact with solid foreign objects such as rocks or bits of metal, it may fling them directly or byricochetinthedirectionofbystanders or the operator. Striking such objects could damage the cutting attachment. Thrown objects, including broken heads or blades, may result in serious or fatal injury to the operator or bystanders.
Use your trimmer equipped with the appropriate cutting attachment only for cutting grass and similar material.
WARNING
Do not use it for other purposes, since misuse may result in personal injury or property damage, including 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.
English
WARNING
Toreducetheriskofinjurytobystanders 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 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 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.Ifyouhaveanyconditionthat mightbeaggravatedbystrenuouswork, check with your doctor before operating this machine.
3
English
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 whitefinger 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 factorsinthedevelopmentofwhitefinger 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
The deflector provided with your power tool will not protect the operator from all foreign objects (gravel, glass, wire, etc.)
thrown back by the rotating cutting attachment. Thrown objects may also ricochet and strike the operator.
WARNING
To reduce the risk of injury to your eyes never
operate your power tool unless wearing goggles or properly fitted protec- tive glasses with adequate top and side protection complying with ANSI Z87 "+" (or your applicable national stand- ard). 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.
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.
4 |
FS 40, FS 40 C, FS 50, FS 50 C |
Always wear heavy duty work gloves (e.g. made of leather or other wear resistant material) when handling the machine, blade and the cutting attachment. Heavy-duty, nonslip gloves improve your grip and help to pro- tect 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.
THE POWER TOOL
For illustrations and definitions of the power tool parts see the chapter on "Main Parts."
WARNING
Nevermodifythispowertoolinanyway. Only attachments supplied by STIHL and expressly approved by STIHL for
FS 40, FS 40 C, FS 50, FS 50 C
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. For the cutting attachments authorized by STIHL for your unit, see the chapter "Approved Combinations of Cutting Attachment, Deflector, Handle and Harness"intheinstructionmanualorthe STIHL "Cutting Attachments, Parts & Accessories" catalog.
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.Checkin particularthat 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. Incaseofdoubt,haveitcheckedbyyour STIHL servicing dealer.
THE USE OF THE POWER TOOL
Transporting the Power Tool
WARNING
To reduce the risk of injury from loss of control and blade or line contact, never carry or transport your power tool with the cutting attachment moving.
English |
389BA019 KN |
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 shut off the engine and make surethecuttingattachmenthasstopped before putting a trimmer down. When transporting it in a vehicle, properly secure it to prevent turnover, fuel spillage and damage to the unit.
Fuel
Your STIHL power tool uses an oilgasoline mixture for fuel (see the chapter on "Fuel" of your instruction manual).
5
English
WARNING
Gasoline is an extremely flammable fuel. If spilled and ignited by a spark or other ignition source, it can cause fire and seri-
ous 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 combusti- ble fuel vapor may escape from the fuel system.
Fueling Instructions
WARNING
To reduce the risk of serious injury from burns, never attempt to refuel the unit until it has been completely removed from the operator.
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 capon yourpowertool carefully so asto allow any pressure build-up in the tank to release slowly. Neverremovethe fuel filler cap while the engine is running.
6
Selectbare groundforfuelingandmove 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.
WARNING
Inordertoreducetheriskoffuelspillage and fire from an improperly tightened fuel cap, correctly position and tighten the fuel cap in the fuel tank opening.
Toolless cap with grip
001BA220 KN
To do this with this STIHL cap, raise the griponthetopofthecapuntilitisupright at a 90° angle. Insert the cap in the fuel
tank opening with the raised positioning marks on the grip of the cap and on the fuel tank opening lining up. Using the grip, press the cap down firmly while turning it clockwise as far as it will go (approx. 1/4 turn).
Fold the grip flush with the top of the cap. Check
the cap for tightness. If the grip does not lie com- pletely flush with the cap and the detent on the grip does not fit in the corre- sponding recess in the filler opening, or if the cap is loose in the filler open- ing, the cap is not properly seated and tight- ened and you must repeat the above steps.
Misaligned, damaged or broken cap
NIfthecapdoesnotdropfullyintothe openingwhenthepositioningmarks line up and/or if the cap does not tighten properly when twisted, the baseofthecapmaybeprematurely rotated (in relation to the top) to the closed position. Such misalignment can result from handling, cleaning or an improper attempt at tightening.
FS 40, FS 40 C, FS 50, FS 50 C
001BA227 KN |
Left: |
Base of cap in closed posi- |
|
tion (with open space) |
Right: |
Base of cap correctly posi- |
|
tioned for installation |
001BA226 KN |
NTo return the cap to the open position for installation, turn the cap (with the grip up) until it drops fully intothetankopening.Next,twistthe capcounterclockwiseasfarasitwill go (approx. 1/4 turn) – this will twist the base of the cap into the correct position. Then, twist the cap clockwise, closing it normally.
NIf your cap still does not tighten properly, it may be damaged or broken; immediately stop use of the unit and take it to your authorized STIHL dealer for repair.
Screw Cap
WARNING
Unit vibrations can cause 
an improperly tightened fuel filler cap to loosen or come off and spill quanti-
ties of fuel. In order to reduce the risk of fuel spillage and fire, tighten the fuel filler cap by hand as securely as possible.
See also the "Fueling" chapter in your Instruction Manual for additional information.
Before Starting
WARNING
Alwayscheck yourpowertool forproper condition and operation before starting, particularly the throttle trigger, throttle trigger lockout, stop switch, cutting attachment, deflector and harness. The throttle trigger must move freely and always spring back to the idle position. Never attempt to modify the controls or safety devices. Never use a power tool that is damaged or not properly maintained.
WARNING
Check fuel system for leaks, especially the visible parts, e.g., filler cap, hose connections,manualfuelpump(onlyfor powertoolsequippedwithamanualfuel pump). Do not start the engine if there are leaks or damage – risk of fire! Have the machine repaired by a servicing dealer before using it.
English
WARNING
Do not attach any cutting attachment to a unit without proper installation of all required parts. Failure to use the proper parts may cause the blade or head to fly off and seriously injure the operator or bystanders.
WARNING
Thecuttingattachmentmustbeproperly tightened and in safe operating condition. Inspect for loose parts (nuts, screws, etc.) Replace damaged heads before using the power tool.
Keep the handles clean and dry at all times; it is particularly important to keep themfreeofmoisture,pitch,oil,fuelmix, grease or resin in order for you to maintain a firm grip and properly control your power tool.
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.
FS 40, FS 40 C, FS 50, FS 50 C |
7 |
English
WARNING
To reduce the risk of personal injury to the operator
from blade or line contact and thrown objects, make sure your unit is equipped with the proper deflector, handle and harness for the type of cutting attachment being used (see chart in the chapter on "Approved Combi- nations of Cutting Attachment, Deflector, Handle and Harness").
Keep the deflector (and the attached skirt where appropriate) adjusted properly at all times (see chapters on "Mounting the Deflector" and "Mounting the Cutting Attachment" of your instruction manual).
Arrows on the deflector (as seen from the underside of the deflector) show the correctdirectionofrotationofthecutting attachment (counterclockwise). When
viewedfromabove,however,thecutting attachmentrotatesclockwise(seearrow embossed on top of deflector).
Adjust the hand grip and harness (if you arewearing one)to suityoursize before starting work. The machine should be properly balanced as specified in your instructionmanualforpropercontroland less fatigue in operation. To be better prepared in case of an emergency, practise releasing the unit from the harness as quickly as possible.
Starting
Start the engine at least 10 feet (3 m) from the fueling spot, outdoors only.
Forspecificstartinginstructions,seethe 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
Toreducetheriskofinjuryfrombladeor line contact, be absolutely sure that the cuttingattachmentisclearofyou and all otherobstructionsandobjects,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 cutting attachment.
Once the engine has started, immediately blip the throttle trigger, whichshouldreleasethestartingthrottle and allow the engine to slow down to idle.
With the engine running only at idle, attach the power tool to the spring hook of your harness (see appropriate chapter of this manual).
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 attachment, do not use your unit with incorrect idle adjustment. At correct idle speed, the cutting attachment should not move. For directions on how to adjust idle speed, see the appropriate section of your instruction manual.
8 |
FS 40, FS 40 C, FS 50, FS 50 C |
If you cannot set the correct idle speed, have your STIHL dealer check your power tool and make proper adjustments and repairs.
WARNING
This unit is equipped with an ignition system that is normally in operational readiness. After the stop switch is used to stop the engine, it automatically springsbacktothe"on"positioninorder toalloweasierrestarting.Iftheengineis warm, it may be possible to start it by simply pulling the starter rope, with no further adjustments. To reduce the risk of injury, be particularly alert to keep children away from the unit.
During Operation
Holding and Controlling the Power Tool
002BA054 KN
Always hold the unit firmly with both hands on the handles while you are working. Wrap your fingers and thumbs around the handles, keeping the handles cradled between your thumb and forefinger. Keep your hands in this position to have your power tool under control at all times. Make sure your trimmer handles and grips are in good condition and free of moisture, pitch, oil, fuel mix or grease.
FS 40, FS 40 C, FS 50, FS 50 C
WARNING
To reduce the risk of injury from loss of control,neverworkonaladderoronany other insecure support. Never hold the cutting attachment above waist height.
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 attach- ment. Never touch a moving cutting attach- ment with your hand or any other part of your body.
WARNING
Do not overreach. Keep proper footing and balance at all times. Special care mustbetakeninslipperyconditions(wet ground,snow)andindifficult,overgrown terrain.Watchforhiddenobstaclessuch as tree stumps, roots and ditches to avoidstumbling.Forbetterfooting,clear away scrub and cuttings. Be extremely cautious when working on slopes or uneven ground.
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.
English
WARNING
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.
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 dustandotherairbornecontaminants,in particular those with a smaller particle size, may cause respiratory or other illnesses. Control dust at the source
9
English
where possible. Use good work practices, such as operating the unit so that the wind or operating process directsanydustraisedbythepowertool 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 neartheambient(background)level,the operator and any bystanders should wear a respirator approved by NIOSH/MSHA for the type of dust encountered.
Operating Instructions
WARNING
Donotoperateyourpowertoolusingthe starting throttle lock, as you do not have control of the engine speed.
In the event of an emergency, switch off the engineimmediately– movetheslide control / stop switch to 0 or STOP.
WARNING
The rotating cutting attachment may fling foreign objects directly or by ricochet a great distance.
15m (50ft)
Toreducetheriskofeyeandotherinjury always wear proper eye protection (see the chapter on "Proper Clothing") and
10
ensure that bystanders are at least 15 m (50 feet) away. To reduce the risk ofdamagetoproperty,alsomaintainthis distance from such objects as vehicles or windows. Even maintaining a minimum distance of 15 meters cannot exclude all potential risks. Any coworkers who must be in the restricted area should also wear goggles or protective glasses. Stop the engine immediately if you are approached.
WARNING
Inspect the work area: To reduce the risk of injury, remove stones, pieces of
metal and other solid objects which could be thrown 15 meters or more
by the cutting attachment
or damage the cutting
attachment or other prop- erty (e.g. parked vehicles, windows).
WARNING
This trimmer is normally to be used at ground level with the cutting attachment parallel to the ground. Use of a trimmer above ground level or with the cutting attachment perpendicular to the ground may increase the risk of injury, since the cuttingattachmentismorefullyexposed and the power tool may be more difficult to control.
WARNING
During cutting, check the tightness and theconditionofthecuttingattachmentat 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 head for cracks, wear or other damage.
WARNING
A loose head may vibrate, crack, break or come off the trimmer, 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 head loosens after being properly tightened, stopworkimmediately.Theretainingnut maybewornordamagedandshouldbe replaced. If the blade or head continues toloosen,seeyourSTIHLdealer.Never use a trimmer with a loose cutting attachment.
WARNING
Replace a cracked, damaged or wornout head or a cracked, bent, warped, damaged, dull or worn out blade immediately,evenifdamageislimitedto superficial cracks. Such attachments may shatter at high speed and cause serious or fatal injury.
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.
FS 40, FS 40 C, FS 50, FS 50 C
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 theenginebeforeadjustingthelengthof 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.
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
Themufflerandotherpartsoftheengine (e.g. fins of the cylinder, spark plug) becomehotduringoperationandremain hot for a while after stopping the engine. Toreduceriskofburns,donottouchthe 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 (away from any combustible substances, such as dry brush, grass or wood chips.
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.Ifyourgas/oilmixratioiscorrect (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 experiencelossofperformanceandyou suspect a clogged screen, have your muffler maintainedby aSTIHLservicing dealer. Some state or federal laws or regulations may require a properly maintained spark arrestor for certain uses.Seethe"Maintenance,Repairand Storing" section of these Safety Precautions. Remember that the risk of a brush or forest fire is greater in hot or dry conditions.
English
USING THE CUTTING ATTACHMENT
For an illustration of the various cutting attachments and instructions on proper mounting see the chapter on "Mounting the Cutting Attachment" 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 this trimmer.
Using the Mowing Heads
Do not use with mowing line longer than the intended length. With a properly mounted deflector, the built-in linelimiting 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 engineandreducesitsoperatingspeed. 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.
FS 40, FS 40 C, FS 50, FS 50 C |
11 |
English
002BA354 KN
Mowing heads are to be used only on trimmers equipped with a line-limiting bladeinthedeflectorinordertokeepthe line at the proper length (see "Main Parts" 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 arenoplantsalongtheedgeofthelawn. 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 AutoCut mowing head
Nylon cutting cord advances automatically when tapped against the ground (TapAction).
STIHL PolyCut mowing head
Uses nonrigid, pivoting polymer blades.
1 |
KN |
|
002BA073 |
||
|
|
KN |
2 |
002BA074 |
|
Donotcontinue using thePolyCutif one of the circular holes (1; arrow) becomes visible or if the projecting rim (2; arrow) has worn away. Install a new mowing head.
WARNING
To reduce the risk of accidents from shattered blades, avoid contact with stones, metal and similar solid objects. Check PolyCut blades for cracks at regular intervals. If a crack is found on one blade, always replace all blades.
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 mayotherwiseshatterandflyingobjects could result in injury to the operator or bystanders. Install a new mowing head.
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 partsformaintenanceandrepair.Useof non-STIHL parts may cause serious or fatal injury.
Strictly follow the maintenance and repair instructions in the appropriate sections of your instruction manual.
12 |
FS 40, FS 40 C, FS 50, FS 50 C |
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 notdescribedinyourinstructionmanual. Have such work performed by your STIHL servicing dealer only.
WARNING
Use the specified spark plug, and make sure it and the ignition lead are always clean and in good condition. Always press the spark plug boot snugly onto the spark plug terminal of the proper size. (Note: If the terminal has a 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 systemby pulling the starter rope with the spark plug boot removed from the spark plug or with a removedspark plug,sincetheignitionis normally in the "on"position and there is a risk that uncontained sparking may cause a fire.
WARNING
Do not operate your power tool if the mufflerisdamaged,missingormodified. An improperly maintained muffler will increasetheriskoffireandhearingloss. Your muffler is equipped with a sparkarresting screen to reduce the risk of
FS 40, FS 40 C, FS 50, FS 50 C
English
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 governmentalentities/agencies,suchas 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
Neverrepairdamaged orbroken heads. This may cause parts of the cutting attachment to come off and result in serious or fatal injuries.
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 the instruction manual.
13
English
Approved Combinations of Cutting Attachment, Deflector, Handle and Harness
Cutting Attachment |
Deflector |
Handle |
Harness |
1 |
2 |
6 |
|
|
|
|
|
3 |
|
7 |
8 |
4 |
5 |
|
|
546BA014 KN
Approved Combinations
The complete combination includes:
–Cutting attachment
–Deflector
–Handle
–Harness/shoulder strap (special accessory)
Select correct combination from the table according to the cutting attachment you intend to use.
WARNING
For safety reasons no other combinations are permitted – risk of accidents.
Cutting Attachments
Mowing heads
1STIHL AutoCut C 5-2
2 STIHL AutoCut 5-2
3 STIHL FixCut 5-2
4 STIHL DuroCut 5-2
5 STIHL PolyCut 6-3
Deflector
6Deflector with blade for mowing heads
Handle
7 Loop handle
Harness
8Shoulder strap may be used
WARNING
Based on the cutting attachment being used:
Choose the proper deflector in order to reduce the risk of injury from thrown objects and contact with the cutting attachment.
Makesureyourunitisequippedwiththe proper handle and harness in order to reduce the risk of injury from loss of control and contact with the cutting attachment.
Do not use rigid polymer blades, metal cutting attachments or circular saw blades on this unit.
Only mowing heads may be used on loop-handled trimmers with a curved drive tube.
14 |
FS 40, FS 40 C, FS 50, FS 50 C |
Mounting the Loop Handle
Your new power tool comes with the loop handle mounted on the drive tube, but it must be turned and lined up to suit your requirements.
Adjusting the loop handle
1 |
2 |
KN |
|
|
546BA003 |
Versions with screw (FS 40)
NUse a screwdriver or the combination wrench to loosen the screw (1) on the handle.
Versions with star knob (FS 50)
NLoosen the star knob (2) on the handle.
All versions
A
546BA004 KN
The loop handle can be adjusted to suit theheightandreach ofthe operatorand the application by changing
distance (A).
Recommended distance (A): about 6 in (15 cm)
NSlide the handle to the required position.
NTightendownthescreworstarknob sothatthehandlecannotberotated on the drive tube.
545BA004 KN
NTurn the handle to the vertical position.
FS 40, FS 40 C, FS 50, FS 50 C
English
Mounting the Deflector
2 
1 
232BA066 KN
4 
3 |
KN |
|
546BA005 |
NPush the deflector (1) over the clamp (2) as far as stop.
NInsertthenut (3)inthehexrecessin the deflector – make sure the holes line up.
NInsertthescrew (4)withwasherand tighten it down firmly.
15
English
Mounting the Cutting
Attachment
Placing power tool on the ground
546BA016 KN
N Switch off the engine.
NLay your trimmer on its back with theloophandleandshroudpointing downand the outputshaftfacingup.
Thrust plate
1
3
2 4
232BA033 KN
The thrust plate is shipped with the PolyCut 6-3 and FixCut 5-2. It is only required for these mowing heads.
STIHL AutoCut 5-2 mowing head, STIHL AutoCut C 5-2 mowing head
NPull the thrust plate (1), if fitted, off the shaft (2).
STIHL PolyCut 6-3 mowing head, STIHL FixCut 5-2 mowing head
NSlip the thrust plate (1) over the shaft (2) and engage the hex recess (3) on the external hexagon (4).
Block the shaft.
|
6 |
6 |
|
|
KN |
5 |
546BA017 |
|
NTo block the shaft, insert a suitable tool (5) through the holes (6) in the deflector and thrust plate – turn the thrust plate back and forth if necessary.
Fitting Mowing Head with Screw Mounting
Keep the instruction leaflet for the mowing head in a safe place.
16 |
FS 40, FS 40 C, FS 50, FS 50 C |
1 |
002BA385 KN |
NScrew the mowing head counterclockwise on to the shaft (1) as far as stop.
N Block the shaft.
NTighten down the mowing head firmly.
NOTICE
Remove the tool used to block the shaft.
Removing the Mowing Head
N Block the shaft.
NUnscrew the mowing head clockwise.
Fitting Mowing Head without Screw Mounting
Keep the instruction leaflet for the mowing head in a safe place.
STIHL AutoCut 5-2
4
2 |
3 |
|
1 |
|
KN |
3 |
232BA054 |
|
NFit the spring (1) in the mowing head (2).
NWind the mowing line (3) on to the spool (4).
NThread the nylon line through the sleevesandfitthespoolinthehead.
Theindividualstepsaredescribedinthe instruction sheet supplied.
English
8
2
7
5
6 
232BA053 KN
NSlip the mowing head (2) over the shaft (5)andengagehexrecess (7) on the external hexagon (6).
NFit the cap (8) on the mowing head
– screw it clockwise on to the shaft as far as stop and tighten it down firmly.
FS 40, FS 40 C, FS 50, FS 50 C |
17 |
English
STIHL AutoCut C 5-2
8 
2 ES
2 |
9 |
Schnur/LINE |
|
|
1 |
681BA018 KN
NSlip the mowing head (2) on to the shaft – as AutoCut 5-2.
NTurn the spool (9) clockwise until the two arrow heads line up – secure the spool in this position.
NInsertthecap (8)inthespool,press it down as far as stop and turn it clockwise at the same time.
NTurn the cap until you feel resistance and then tighten it down
firmly by hand.
STIHL PolyCut 6-3 |
10 |
11 |
5 |
681BA019 KN |
N Fit the thrust plate on the shaft.
NInsert the nut (10) in the mowing head.
NScrew the mowing head (11) clockwise on to the shaft (5) as far as stop.
N Block the shaft.
NTighten down the mowing head firmly.
WARNING
If the mounting nut has become too loose, fit a new one.
NOTICE
Remove the tool used to block the shaft.
STIHL FixCut 5-2 |
|
|
5 |
|
|
4 |
|
|
1 |
|
KN |
|
|
|
|
2 |
232BA074 |
|
|
NSlip the thrust plate (2) over the shaft.
NPlace the mowing head on the thrust plate (2).
WARNING
Collar (see arrows) must engage the mowing head's mounting hole.
NPush the thrust washer (3) over the shaft (1) so it is seated on the base.
N Block the shaft.
NUse the combination wrench (5) (special accessory) to screw the mounting nut (4) on to the output shaft and tighten it down firmly.
WARNING
If the mounting nut has become too loose, fit a new one.
18 |
FS 40, FS 40 C, FS 50, FS 50 C |
NOTICE
Remove the tool used to block the shaft.
Remove the mowing head.
STIHL AutoCut
N Hold the mowing head steady.
N Unscrew the cap counterclockwise.
STIHL PolyCut
N Block the shaft.
NUnscrew the mowing head counterclockwise.
STIHL FixCut
N Block the shaft.
NUse the combination wrench (special accessory) to loosen and unscrew the mounting nut counterclockwise from the output shaft.
FS 40, FS 40 C, FS 50, FS 50 C
Fuel
This engine is certified to operate on unleaded gasoline and the STIHL twostroke engine oil at a mix ratio of 50:1.
Your engine requires a mixture of highquality gasoline and two-stroke air cooled engine oil.
Usemid-gradeunleadedgasolinewitha minimum octane rating of 89 ((R+M)/2) and no more than 10% ethanol content.
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.),butmagnesiumcastingsand catalytic converters as well. This could cause running problems or even damage the engine. For this reason STIHL recommends that you use only high-quality unleaded gasoline!
Gasoline with an ethanol content of more than 10% can cause running problems and major damage in engines and should not be used.
The ethanol content in gasoline affects engine running 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
English
unit with incorrect idle adjustment. At correct idle speed, the cutting tool should not move.
Ifyourpowertoolshowsanincorrectidle adjustment, have your STIHL dealer check your power tool and make 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 another fuel with a much higher or lower ethanol content.
This problem can be avoided by always using fuel with the same ethanol content.
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.
WerecommendSTIHLHPUltra2-Cycle Engine Oil since it is specially formulated for use in STIHL engines.
Do not use BIA or TCW rated (twostroke water cooled) mix oils or other mixoilsthatstatetheyareforuseinboth 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 containeronthegroundbeforefilling.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.
19
English
The container should be kept tightly closed in order to limit the amount of moisture that gets into the mixture.
The machine‘s fuel tank should be cleaned as necessary.
Fuel mix ages
Only mix sufficient fuel for a few days 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 mixing of the oil with the fuel.
Gaso- |
Oil (STIHL 50:1 or equiva- |
line |
lent high-quality oils) |
US gal. |
US fl.oz. |
12.6
2 1/2 |
6.4 |
512.8
Dispose of empty mixing-oil containers only at authorized disposal locations.
Fueling |
|
Preparations |
002BA418 KN |
|
Toolless filler cap (with folding grip) |
547BA045 KN
NBefore fueling, clean the filler cap andtheareaaroundittoensurethat no dirt falls into the tank.
Always thoroughly shake the mixture in the canister before fueling your machine.
NPosition the machine so that the filler cap is facing up.
WARNING
In order to reduce the risk of fire and personalinjuryfromescapinggasvapor and fumes, remove the fuel filler cap carefully so as to allow any pressure build-up in the tank to release slowly.
One of two different filler caps is installed as standard at the factory.
002BA419 KN
Threaded filler cap
Opening the toolless filler cap
001BA218 KN |
NRaise the grip into an upright position.
20 |
FS 40, FS 40 C, FS 50, FS 50 C |
001BA219 KN |
NTurn the cap counterclockwise (approx. 1/4 turn).
001BA224 KN |
N Remove fuel filler cap.
Refueling
Take care not to spill fuel while fueling and do not overfill the tank.
Closing the toolless filler cap
001BA220 KN
With grip in an upright position:
FS 40, FS 40 C, FS 50, FS 50 C
NInsert the cap – positioning marks onthecapandthefueltankopening must line up.
NThe cap should drop fully into the opening in this position.
001BA221 KN |
NWhilepressingthecapdown,twistit firmly clockwise as far as it will go (approx. 1/4 turn).
001BA222 KN |
N Fold down the grip.
English
Checking for proper closure
001BA223 KN |
NThe lug on the grip must engage entirely in the recess (arrow), and the grip must lie completely flush with the top of the cap.
001BA225 KN
NGrip the cap and check for tightness.
NIf the cap can be moved, it is not properly installed.
Misalignment of the cap parts
NIfthecapdoesnotdropfullyintothe openingwhenthepositioningmarks line up and/or if the cap does not tighten properly when twisted, the base of the cap may be rotated out of position vis-à-vis the top.
NSuch misalignment can result from handling, cleaning or an improper attempt at tightening.
21
English |
001BA227 KN |
Left: |
Base of improperly aligned |
|
cap (with open space) |
Right: |
Base of cap correctly posi- |
|
tioned for installation |
001BA226 KN |
NTo correct a misalignment, turn the cap (with the grip up) until it drops fully into the tank opening.
NTwist the cap counterclockwise as far as it will go (approx. 1/4 turn) – thiswilltwistthebaseofthecapinto the correct position.
NTwist the cap clockwise, closing it normally – see the sections "Closing" and "Checking for proper closure."
NIf your cap still does not tighten properly, it may be damaged or broken; immediately stop use of the unit and take it to your authorized STIHL dealer for repair.
Opening the threaded filler cap
002BA447 KN |
NTurn the cap counterclockwise until it can be removed from the tank opening.
N Remove the filler cap.
Refueling
Take care not to spill fuel while fueling and do not overfill the tank.
Closing the threaded filler cap
002BA448 KN |
N Position cap.
NTurn the cap clockwise as far as it will go and tighten it as securely as possible by hand.
Starting / Stopping the
Engine
Controls
Version with loop handle
3 1
2 |
KN |
|
546BA007 |
1 Throttle trigger lockout
2Throttle trigger
3Stop switch with Run and 0 = Stop positions.
Function of stop switch and ignition system
The stop switch is normally in the Run position, i.e. when it is not depressed: The ignition is switched on – the engine is ready to start. If the stop switch is moved to the 0 position, the ignition is switched off. The ignition is switched on again automatically after the engine stops.
22 |
FS 40, FS 40 C, FS 50, FS 50 C |
Starting the Engine
4 
KN547BA015
NPress the manual fuel pump
bulb (4) at least five times – even if the bulb is filled with fuel.
Cold engine (cold start)
5 |
KN |
|
547BA016 |
NPressinthechokelever (5)andturn it to g at the same time.
Warm engine (warm start)
547BA017 KN
NPressinthechokelever (5)andturn it to <at the same time.
Also use this setting if the engine has been running but is still cold.
Cranking |
547BA018 KN |
NPlacetheunitontheground:Itmust rest securely on the engine support and the deflector. Check that the cutting attachment is not touching the ground or any other obstacles.
NMake sure you have a safe and secure footing.
NHold the unit firmly on the ground with your left hand and press down
– do not touch the throttle trigger or lockout lever.
NOTICE
Do not stand or kneel on the drive tube.
English
547BA020 KN
NHold the starter grip with your right hand.
Version without Easy2Start
NPull the starter grip slowly until you feelitengageandthengiveitabrisk strong pull.
Version with Easy2Start
N Pull the starter grip steadily.
NOTICE
Do not pull out the starter rope all the way – it might otherwise break.
NDonotletthestartergripsnapback. Guideitslowlybackintothehousing so that the starter rope can rewind properly.
N Continue cranking until engine runs.
FS 40, FS 40 C, FS 50, FS 50 C |
23 |
English
As soon as the engine runs
547BA021 KN
NPress down the throttle trigger lockout and open the throttle – the choke knob moves to the run position F. After a cold start, warm up the engine by opening the throttle several times.
WARNING
Make sure the carburetor is correctly adjusted. The cutting attachment must not rotate when the engine is idling.
The machine is now ready for operation.
Stopping the engine
NMovethestopswitchinthedirection of 0 – the engine stops – release the stop switch – it springs back to the run position.
Other Hints on Starting
Engine stalls in cold start position gor under acceleration
NMove the choke knob to <and continue cranking until the engine runs.
Engine does not start in warm start position <
NMove the choke knob to gand continue cranking until the engine runs.
If the engine does not start
N Check that all settings are correct.
NCheck that there is fuel in the tank and refuel if necessary.
NCheck that the spark plug boot is properly connected.
N Repeat the starting procedure. Fuel tank run until completely dry
NAfter refueling, press the manual fuel pump bulb at least five times – even if the bulb is filled with fuel.
NSet the choke knob to suit the engine temperature.
N Start the engine.
Operating Instructions
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 enginemounted components (ignition, carburetor) from thermal overload.
After Finishing Work
Storing for a short period: Wait for the enginetocooldown.Emptythefueltank 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".
24 |
FS 40, FS 40 C, FS 50, FS 50 C |
Cleaning the Air Filter
If there is a noticeable loss of engine power
|
3 |
1 |
2 |
KN |
|
|
547BA022 |
N Move the choke lever (1) to <.
NTurn the screw (2) in the filter cover (3) counterclockwise until the cover is loose.
NEase the filter cover (3) over the choke lever and lift it away.
NClean away loose dirt from around the filter.
4 
547BA023 KN
NReachintotherecess (4)inthefilter housing and take out the felt
filter (5).
NFit a new felt filter element (5). As a temporarymeasureyoucanknockit outonthepalmofyourhandorblow it out with compressed air. Do not wash.
NOTICE
Replace damaged parts.
NFit the felt filter (5) in the filter housing, make sure it is properly seated – the arrow points to the recess.
N Move the choke lever (1) to <.
NFit the filter cover in position, making sure the screw is square. Tighten down the screw.
English
Engine Management
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.
FS 40, FS 40 C, FS 50, FS 50 C |
25 |
English
Adjusting the Carburetor |
Spark Plug |
Checking the Spark Plug
0815BA006 KN
The carburetor has been set at the factory to provide an optimum fuel-air mixture under most operating conditions.
Adjusting Idle Speed
Engine stops while idling
NWarm up the engine for about 3 minutes.
NTurn the idle speed screw (LA) slowly clockwise until the engine runs smoothly – the cutting attachment must not run.
Cutting attachment runs when engine is idling
NTurn the idle speed screw (LA) counterclockwise until the cutting attachment stops moving and then rotate the screw another 1/2 to 3/4 turn in the same direction.
WARNING
Ifthecuttingattachmentcontinuestorun when the engine is idling, have your machine checked and repaired by your servicing dealer.
If engine is down on power, difficult to start or runs poorly at idling speed, first check the spark plug.
Fit a new spark plug after approx. 100 operating hours or earlier if the electrodes are badly eroded.
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 result in trouble in operation.
Removing the Spark Plug
N Shut off the engine.
1
2 
547BA041 KN
N Remove the spark plug boot (1). N Unscrew the spark plug (2).
|
KN |
A |
000BA039 |
|
N Clean dirty spark plug.
NCheck electrode gap (A) and readjust if necessary – see "Specifications."
NUseonlyresistortypesparkplugsof the approved range.
Rectify problems that have caused fouling of spark plug:
–too much oil in fuel mix,
–dirty air filter,
–unfavorablerunningconditions,e.g. operating at part load.
26 |
FS 40, FS 40 C, FS 50, FS 50 C |
1
2
000BA071 KN
WARNING
Toreducetheriskoffireandburninjury, use only spark plugs authorized by STIHL.Alwayspresssparkplugboot(1) snuglyontosparkplugterminal(2)ofthe proper size. (Note: If terminal has detachable SAE adapter nut, it must be securely 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.
Installing the Spark Plug
NScrew the spark plug into the cylinder.
NPress the boot firmly onto the spark plug.
English
Engine Running Behavior |
|
Rewind Starter |
|
|
|
If engine running behavior is unsatisfactory even though the air filter is clean and the carburetor is properly adjusted, the cause may be the muffler.
Have the muffler checked for contamination (carbonization) by your servicing dealer.
STIHL recommends that you have servicing and repair work carried out exclusively by an authorized STIHL servicing dealer.
To help prolong the wear life of the starter rope, observe the following points:
NPull the starter rope only in the direction specified.
NDonotpulltheropeovertheedgeof the guide bushing.
NDo not pull out the rope more than specified.
NDo not allow the starter grip to snap back, guide it back into the housing slowly – see chapter on "Starting / Stopping the Engine."
Have a damaged starter rope replaced by your dealer before it breaks completely. STIHL recommends that you have servicing and repair work carried out exclusively by an authorized STIHL servicing dealer.
FS 40, FS 40 C, FS 50, FS 50 C |
27 |
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