Stihl 108 User Guide
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OperatingInstructions Duringbreak-in period A factory newmachine shouldnotbe run athigh revs(fullthrottle offload) forthe first three tankfillings. Thisavoids un necessary highloads during thebreak-in period. As allmoving partshave tobedin during thebreak-in period,the frictional resistances intheengine are greater duringthisperiod. The engine develops itsmaximum power afterabout 5to 15 tank fillings. 40 During operation After longperiod offull-throttle operation, allowengine torunforawhile atidling speed sothat theheatinthe engine canbedissipated byflow of cooling air.This protects engine mounted components (ignition, carburetor) fromthermal overload. After finishing work Storing forshort period: Toavoid condensation, fillthe fuel tank andkeep theunit inadry place until youneed itagain. Storing foralong period: Drain andclean thefuel tank run engine untilcarburetor is dry. Checktightness ofnuts andscrews (not adjusting screws)atregular inteNals andretighten asnecessary.
CheckingSparkPlug Cleaning AirFilter 1 (~2---\(~ '-=~=======*A:5 8..:1Ilgo Ifengineisdown onpower, difficult tostartorruns poorly atidling speed, first check thespark plug. • Remove sparkplug- see Ifengine doesnt start: • Clean dirtyspark plug. • Check electrode gap- itshould be0.5mmlO.020(A) readjustifnecessary. • Useonly suppressed sparkplugs of the approved type. Rectify faultswhich havecaused fouling ofspark plug: Incorrect carburetor setting,toomuch oil infuelmix, dirty airfilter, unfavorable running conditions, e.g.operating at part load. • Fitanew spark plugafter approx. 100operating hours- or earlier ifthe electrodes are badly eroded. • Ifthereisa noticeable loss of engine power: • Setchoke leverto .L- • Grip tab(2)andpullthe filter cover(1)offthe carburetor. • Clean awayloose dirtfrom around thefilter. 41
LubricatingGearboxLubricatingDriveShaft 0110 2 t 5 3 4 •Removethefoam element (3)•Checkgrease levelafterabout•Check filmoflubricant once and thefeltelement (4). every50hours ofoperation. ayear. •Wash thefilter elementsinfresh,•Unscrew thefiller plug (1). non-flammable cleaningsolution •Ifnogrease canbeseen onthe insi-•Mark theend ofthe gear head on (e.g. warm soapy water) andthen deofthe filler plug, screw thetube thedrive tube. dry. (2)ofSTIHL gearlubricant •Release theclamp screws (1). 0781 1201117 intothefiller hole. •Pullthegear head (2)offthe Replace damaged partsoffilter. •Squeeze greaseintothegear drivetube. housing -about 5-10g(1/4 oz), •Place thefeltelement inthe filter base (5)first and then Donot completely fillthe the foam element. gearhousing withgrease. •Fitthe filter cover (1)-itmustsnap into position. •Refit thefiller plug andtightenit down firmly. 42
SharpeningCuttingTools D 31 :)2()0«([Jr--() o 3 •Resharpen onlywhen allcutting edges (1)onbothsides ofthe bladeare dull: This ensures balanced wear. Grass cutting blade230-4 Never straighten orweld abent or cracked cuttingblade- itmight shatter andcause serious orfatal injury. o •Push shaft(3)intothedrive tube tumittoandfrountil distance Ais lessthan 30mm (1.2). • Slide thedrive tubeinto the gear head - turndrive shaft(4)backand forth untilmark isreached. • Line upthe gear head. • Tightendown theclamp screws. • Ifshaft hasturned blue,fita new one. • Pulltheshaft (3)out ofthe drive tube. • UseSTIHL multipurpose grease 07811201109 tocoat dryareas of the shaft: Do not apply toomuch grease never pump grease intothe drive tube. t ~3 :)0«([Jr--() Toavoid out-at-balance: • Resharpen thecutters (2)uniformly -do not alter thecontour of the parent blade(3) inanyway. •After resharpening about5times, have blade checked onSTIHL balancer 59108502600 and rebalanced asnecessary. 43
~Ao ~c mB~,---~-----a'i:;:;.., 3 2 =:JJ.......__4__ Sharpencorrectly •Ifslightlydull: Use flatfile(4)0814 2123310 Incaseofmore serious wearor nicks: Resharpen withagrinder maintain asharpening angleof 30° (A)onthe cutting edge(1). • Fileback thecutting edge parallel tothe lines (B)(see illustration). • Resharpen frequently,take away aslittle material as possible -two orthree strokes ofthefileare usually enough. 44 Grasscutting blade230-8 Never straightenorweldabent or cracked cuttingblade- itmight shatter andcause serious orfatalinjury. • Resharpen whenthetips ofthe cutting edges(1)have worn down toabout 1mm/3/64 (A). Toavoidout-of-balance: •Resharpen thecutters (2) uniformly -do not alter thecontour of the parent blade(3)inany way. • After resharpening about5times, have blade checked onSTIHL balancer 59108502600 and rebalanced asnecessary. Measurements andangles for resharpening Leave clearance of2mm/5/64(B) between cuttingedgeandparent blade - R1should be2mm/5/64. Radius R2 is2.5mmf7164andis obtained automatically ifyou usethe specified fileand maintain afiling angle of 30° (C). Cutting edge (0)mustbeexactlyinline with center ofblades mounting hole.
)J4_- 22 Sharpencorrectly •Ifslightlydull: Use flatfile(4)08142123310 Incase ofmore serious wearor nicks: Resharpen withagrinder. • Fileback thecutting edge parallel tothe lines (E) (see illustration). • Resharpen frequently,take away aslittle material as possible -two orthree strokes of the fileare usually enough. Brushknite250 Neverstraighten orweld a bentor cracked brushknife- itmight shatter and cause serious orfatal injury. • Only sharpen the cutting edges (1)atthe pointed tips -do not sharpen curved cutting edges (2)eveniftheyare nicked inplaces. Toavoid out-at-balance: •Resharpen cuttingedges uniformly - use thesharpening template 0457 3422629 provided. • After resharpening about 5 times, haveblade checked on ST-U::iLbalancer59108502600 andrebalanced asnecessary. 45
)n3- Sharpencorrectly •Ifslightlydull:Use flat file(3)0814 2123310- Incaseofmore serious wearor nicks:Resharpen withagrinder maintain asharpening angleof 30 0(A) onthe cutting edge(1). • Fileback thecutting edge parallel tothe lines onthe sharpen ing template. • Resharpen frequently,take away aslittle material as possible -two orthree strokes of the fileare usually enough. 46 ay I! ~) I--.-:-,-,I \ \ Circular sawblade 200(chisel tooth) Neverstraightenorweldabentor cracked circularsawblade -it might shatter andcause serious orfatalinjury. Sharpening circularsaw bladeonthe unit • Cutavertical slitinthe top ofatree stump -lean theunit against thestump sothat thesaw blade restsinthe slil. • Turn theblade withonehand while resharpening - Weargloves! Sharpen correctly •Fileonly theside plate (1). • Ifslightly dull:Use file holder (2)5605 7504343 and matching 5.5mmdia. round file(3) 08114118108. l0case ofmajororvery irregular wear: Use anelectric grinder. • Fileright andleft-hand teeth inthedirection ofsel.
54 B~ •Fileatthe angle marked onthe file holder: Filing angle is15°(A) fileshould slopeupward at an angle of5° (B). • Resharpen frequently,take away aslittle material as possible -two orthree strokes of the fileare usually enough. Resetting theteeth Ifthesaw blade doesnotcutfreely or binds inthe cut: Check setofteeth - • Hold thesaw set (4)4020 8935000 against thesaw blade (5)-ifthere is agap (C)between thetooth and saw set:see Resetting theteeth. • Ifthe tooth justtouches thesaw set: Clearance 0is1 mm (3/64) andthe set iscorrect. Resetting correctlytheteeth • Fitnotch ofsaw set (4)over the tooth(6) -blade thickness 1.5mm (about 1/16). Maintain theangle of 90° (E)and keeptoexisting direction ofset. • Push thesaw setdownward until the sloRing side (F)ofthe notch,butts, against thesaw blade. • Check setofteeth again. Circular sawblade 200 (scratcher tooth) Never straighten orweld abent or cracked circularsawblade - itmight shatter andcause serious orfatal injury. 47
ReplacingStarterRope andRewind Spring 2~ 00 5 -6 0 ]ID__2_- Sharpen correctly •Fileonly theback ofthe tooth (1). • Ifslightly dull:Use flat file(2)0814 2123310. Incase ofmore serious wearor nicks: Resharpen withagrinder untilthetips(3)ofthe teeth are restored tofull sharpness. • Resharpen frequently,takeaway as little material aspossible -two or three strokes ofthe fileare usually enough. • Donot alter tooth profile. Removing rewindstarter •Layyour brushculler onitsback with thegear head facing up. •Remove thefour screws (1)from the machine support(2)and liftit away. • Take outthe screws (3). • Remove thestarter cover (4) together withrewind starter mechanism. Replacing abroken starterrope •Take outthescrew (5). • Remove thewasher (6). • Remove therope rotorvery carefully -the rewind spring is seatedinthestarter coverand may popoutand cause injuryif care isnot taken. 48
•Remove remaining ropefrom rotor thread thenew rope - 3.5mm x800mm (0.14x31.5) into therotor andsecure itwith asimple overhand knot. • Thread otherend-from inside -through therope guide bush inthestarter coverandtheundersi de ofthe starter gripand secure with special knot(7). • Coat roperotor bearing bore with non-resinous oil. • Slide rotorontostarter post turn itback andforth until anchor loop (8)ofrewind spring engages. • Fitscrew andwasher andtighten down firmly. Go toTensioning rewindspring. a=2mm(O,08in) Replacing abroken rewindspring • Lubricate thenew spring withafew drops ofnon-resinous oil- do not open thewire retainer! • Remove therope rotor -as described inReplacing abroken starter rope. • Reitloveparts ofold spring. • Fitthe new spring - position outerspring loop inthe recess -the wire retainer slipsoff in thisprocess. 49