Stihl 108 User Guide
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@8 [\6 ::==::...,5 3 7 4 Circularsawblade 200 (chisel andscratcher tooth) Fitthe appropriate stop before mounting circularsawblade. Fitting thestop seechapter Mounting the Deflector. 30 Mounting circularsawblade •Layyour brushcutter onitsback with thegear head facing up. • Position sawblade (3)on the thrust plate(4)- teeth mustpointinclockwise direction. • Slipthethrust washer (5) andrider plate(6)over the drive shaft (7). •Block thedrive shaft. • Screw mounting nut (8)counterclockwise onto drive shaftandtighten down securely. Releasing mountingnut •Block thedrive shaftand unscrew themounting nut clockwise. Ifthe mounting nutbecomes slackdue to frequent loosening andretightening, fit a new one.
Fuel Yourtwo-strokeenginerequires a mixture ofbrand-name gasolineand quality two-stroke engineoilwith the classificationTe. Useregular branded unleaded gasoline with aminimum octanenumber of 90 ROZ (U.S.A./Canada: pumpoctane min. 89!). Iftheoctane number ofthe regular gradegasoline inyourarea is lower us5=lpremium unleaded fuel. Fuel withalower octane number may result inpreignition (causingpinging) which isaccompanied byan increasein engine temperature. This,inturn, increases therisk ofthe piston seizure and damage tothe engine. The chemical composition ofthe fuel is also important. Somefueladditives not only detrimentally affectelastomers (carburetor diaphragms, oilseals, fuel lines etc.), butmagnesium castingsas well. This could cause running problems or even damage theengine. Forthis reason itisessential thatyou useonly name branded fuels! Use only STIHL two-stroke engineoilor equivalent brandedtwo-stroke air-cooled engine oilswith theclassification TCfor mixing. We recommend STIHL 50:1two-stroke engine oilsince itis specially formulated for use inSTIHlengines. Themixratio with STIHloilis50:1(50 parts gasoline to 1part oil),or 25:1(25parts gasoline to 1 part oil)with other branded two-stroke air-cooled engineoils. Do not use BIAor TCW(two-stroke water cooled) mixoils! Take carewhen handling gasoline. Avoid directcontact withtheskin and avoid inhaling fuelvapour. The canister shouldbekept tightly closed inorder toavoid anymoisture getting intothemixture. The fueltank andthecanister inwhich fuel mixisstored should becleaned from timetotime. Fuel mixages: Only mixsufficient fuelforafew days work, nottoexceed 30days ofstorage. Store inapproved safetyfuel-canisters only. When mixing, pouroilinto the canister first,andthen addgasoline. Gaso- STIHL Otherbranded line engineoil TCoils 50:125:1 Liters Liters(cc) Liters (cc) 1 0.02 (20)0.04 (40) 5 0.10(100) 0.2(200) 10 0.20(200) OA(400) 15 ,:-0.30(300) 0.6(600) 20 OAO(400) 0.8(800) 25 0.50(500) 1.0 (1000) Gaso- STIHL Otherbranded line engineoil TCoils 50:125:1 US gal. US fl.oz USfl.oz 1 2.6 5.1 21/26A12.8 5 12.8 25.6 31
FuelingFittingtheHarness Beforefueling, cleanthefiller capand the area around it toensurethatnodirt falls intothetank. Always thoroughly shakethemixture in the canister beforefueling yourmachi ne. Change thefuel pick upbody every year. Before storing yourmachine foralong period, drainandclean thefuel tank and run engine untilcarburetor is dry. Modelswithaloop handle comewithout a harness (available asspecial acces sory forthese models). Shoulder strap Useofthe carrying strapisdescribed in chapters SafetyPrecautions and Selecting theCutting Tool. Warning!Inordertoreduce therisk of bums orother personal injuryfromesca ping gasvapor andfumes, remove the fuel filler capcarefully soastoallow any pressure build-up inthetanktorelease slowly. WarningAfter fueling, tightenfuelcap assecurely aspossiblebyhand. 32 •....,.Put onthe shoulder strap(1). Adjust lengthuntilthespring hook (3)rests against yourrighthip.
Fullharness • Putonthe fullharness (2). • Adjust lengthuntilthespring hook (3)rests against yourrighthip. Use ofthe carrying strapisdescribed inchapters SafetyPrecautions and Selecting theCutting Tool. Balancing thebrushcutter • Attach thespring hook (3)totheclamp(4)onthe drive shaft slacken thescrew (5). • Slide theclamp upordown the drive shaft. • Tightenthe screw moderately. • Letgoofthe brush cutter andcheck toseehowitisbalanced: mowing heads,FixedLineHead and brush knifemust restlightly onthe ground. Circular sawblades muststay abottt30cm/1ft(A)clear ofthe ground. • Tightenthe screw firmly. 33
Starting 1 •Observe safetyprecautions -see section SafetyPrecautionsinthis manual. • Hold down thethrottle trigger interlock (1)and squeeze the throttle trigger(2). • Move theslide control (3) toSTART position. • Now release thethrottle trigger, slide control andtrigger interlock inthatorder=Thisisthe starting-throttle position. 34 Ifengineiscold: Setthechoke lever(4)to.L Ifengineiswarm: Set thechoke lever(4)to... Also usethissetting ilengine hasbeen running but isstillcold. • Puttheunit onthe ground: Itmust restsecurely onthe engine support anddeflector. Checkthat the cutting tool isnottouching the ground orany other obstacles. • Make sureyouhave afirm looting: Holdtheunit with youleft hand andpress itdown firmly yourthumb shouldbeunderthe housing. • Donot stand orkneel onthe drive shaft!
~oo~ ((\\3)) 2 •Pullthestarter gripslowly withyour right hand untilyoufeel itengage and then give itabrisk strong pull. Do not pull outstarter ropemore than 70cm (27)- itmight break. Do not letthe starter gripsnap back -guide itslowly intothe housing sothat thestarter rope can rewind properly. When engine beginstofire: Ifengine iscold: Set choke lever(4) to- andcontinue cranking untilengine runs. Ifengineiswarm: Continue crankinguntilengine runs_ Assoon aswarm engine runs: • Blipthethrottle trigger(2)- the slide control (3)moves tothe runpositionI,and theengine returns toidling speed. • Make~urecarburetor iscorrectly adj,usted-cutting toolmust not rotate whenengine isidling. Your brushcutter isready for operation. 35
Toshutdown engine: • Move slidecontrol (3) toSTOP. At very lowoutside temperatures: Allow engine towarm up As soon asengine runs: • Blipthethrottle trigger- the slide control (3)moves tothe run position I,and theengine returns toidling speed. • Open throttle slightly - warm upengine forshort period. 36 Ifthe engine doesnt start: Ifyoudidnot move thechoke lever to.L quickly enough aftertheengine began tofire, thecombustion chamber is flooded. Remove sparkplugterminal (5)- • Unscrew anddryoffthe spark plug. • Setslide control toSTOP. • Open thethrottle fully. • Pullthestarter ropeseveral timesto clear thecombustion chamber. • Refit thespark plugandconnect the spark plugterminal. • Setslide control toSTART. • Setchoke lever to... even ifengineiscold. • Nowstart theengine. Fuel tank rununtil dryand then refueled • Continue cranking- Engine willnot start immediately because fuelpump hastobe pri med withfuel.
AdjustingCarburetor FS88{I IFS88/I I tL/-1=1 rLrBI~~R I~~~ IfF ~l~ 1~! I L-!@~LAL.... ~ FS108I{ I IFS108I ,I H LJJ ~~~I-R~-LD Thecarburetor hasbeen adjusted for optimum performance underthe barometric pressureandclimatic conditions atthe factory. Basic setting Thissettingisthestarting pointforfine tuning andcanbeused asthe standard setting. •Check airfilter andclean it if necessary. • Carefully screwthehigh speed adjusting screw(H) and lowspeed adjusting screw(L)down ontotheir seats (clockwise) andmake the following adjustments: H Open 1full turn L Open 1full tum • Start theengine andadjust idling speed withtheidle speed adjusting screw LAor LD: cutting toolmust notrotate. This standard setting istheoptimum setting ofthe high speed adjusting screw for normal operation atan altitude of about 300m/1000 Itabove sealevel. Itensures yourmachine willdeliver maximum power,befuel efficient and operate reliably. Itmaybenecessary fine-tunethe carburetor ifoperatingconditionschange, e.g. higher orlower altitudes, extreme changes inhumidity andtemperature or ifyoufitadifferent cuttingtool: Thefinetuning procedures described below ensure maximum performance under t~enewoperating conditions. 37
FS88I,,FS88I! , ~HIii H IrII~@,~R,n ~IILL1-1@ 1Pr=I-- II l-II ---------- FS108(I ,FS108( I , Finetuning •Mount thecutting tool. Machines withcutting head: •Trim linetocorrect length: Lines mustextend asfar asline limiting bladeonthe deflector • Carry outthebasic setting. • Warm upengine byrunning itfor about 1minute atfull throttle and then return toidlespeed. • Back offhigh speed adjusting screw (H)onehalfturn (counterclockwise). • Runengine atfull throttle androtate high speed adjusting screw (H) carefullyclockwise untilyouhear 38 nofurther increaseinRPM back offscrew oneeighth turn. Machines withmetal cutting tool: Atachometer isnecessary forthe following adjustment. Ifnotachometerisavailable,.....,. do not turn screws beyond thebasic setting. • Carry outthebasic setting. • Warm upengine byrunning itfor about 1minute atfull throttle and then return toidle speed. • Back offhigh speed adjusting screw (H)onehalfturn (counterclockwise). • Runengine atfull throttle and rotate highspeed adjusting screw (H)carefullyclockwise until maximum permissible speedof 12,000 RPM isreached. Turning thescrew (H)any further in the clockwise directionwill make thefuel-air mixture too lean - thiscould damage theengine!
FS88 , ,, L rHI@f;jIR II Lj~ IiiL-LA~ FS88II! L rHI@f;jIR I 117=1 l-/~ L-LA~ FS88(I I L rH)@f;j R I 117= l-/@L-I ------ FS 108( I IFS108( IIFS108( II Adjustingidlespeed Itisusually necessary tochange the setting ofthe idle speed adjusting screw (LAorLD)after every correction tothe low speed adjusting screw (L). Engine stopswhileidling Turntheidle speed adjusting screw (LAorLD) clockwise untilengine runs smoothly -cutting tool must notrotate. Cutting toolrotates when engine isidling Turn theidle speed adjusting screw (LA orLD)counterclockwise until cutting toolstops rotating then back offscrew about another onehalftum from that position. Erratic idlingbehavior, poor acceleration Idlesetting istoo lean. Turn thelow speed adjusting screw (L)counterclockwise until engine runsandaccelerates smoothly. Exhaust smokesatidle speed Idlesetting istoo rich. Turn thelow speed adjusting screw (L)clockwise until engine speeddrops. Thenturn screw backonequarter turn and ch~kthat engine still accelerates smoothlywhen you open thethrottle. 39