Stihl 108 User Guide

							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