Sachs SA 290 User manual

TAKING DOWN THE ENGINE
Remove a ll connections fr om engi ne 10 f rame or unit (cables. electric connect ions etc.).
Un scr ew exhaust muffler, i. e. manifold and brocket.
Remove t he en gine and clean t horoughly before taki ng down.
When giving the engine a general overhaul, components should be removed in the
sequ
ence indicated.
Fig. 1
Fig. 2
6
Exhoust muffler, corburettor on d
el ec tric s tart er
Fi g. 1
Sc r ew dow n engine on Ihe as-
sembly jig with 2 he)(090n head
bolts M 10 )( 40, as shown in Ihe
adjoining ill ustration.
Re move intake silencer (I).
Un s cr ew adapte r flange cnd
lake off cover plate (21 or un-
screw intake si l encer (Fig. 302,
p. 53) with c
over pl ale.
Pull o ff impul se pipe ( 4) .
Remove co rbur ellor (3).
Rem ove insulating sleeves and
insula ting f lange.
If th ere is on intake stack be-
t we en cor burettor and cylinder,
r
emove it on ly if necessary.
Unscrew electric
starter.
Re coil s tart e r, st ar ter hub
and fa n
Fig. 2
Detach recoil sl arter .
Unlod; nut
in Ihe sl or l er hub (1).
Hold starler hub with retaining
l ever (2, r epai r too l no. 6), un-
screw the nut and r emove sta rter
h
ub with spring ring and washer.
Nol e:
In
the case of the Fairba n ks recoil starte r rel ease nu t, hold starter h ub with strap
span n er and unscrew nut.
I~ the case of the. recoil starter with friction iows rele<lse nut, hold sl orte r hub with
pin spanner (r epair tool no. 7) ond unscr ew il.
T oke off storle r hub with spring ring and washer.
Remove th~ cylindrical pin and .the beor i n!;! ro ll er fr om the magneto flywheel (Fair-
banks r eCOil starter) resp. 2 bearing rollers (recoil star t er with friction jaws).
Toke
off cove r disc (3).
Unsc rew fan and remove gasket.
Cover plat e and fan hou ling
Fig. J
Un screw fixin~ clip (3) for igni-
tion lead (n ot In the case of 75 W
eq uipment) a nd cover (1).
Detach le ads at termina ls 1, 2
and 3 of the term in al box {5} and
rem ove fan housing (4 ).
Note :
Rem
ove cov er fl anges on fan
housing f or electric start er con-
nectian, if fitted.
T
ak e core of dowel tu bes.
Nole :
Remove
shor t-circuiting button
on ly if necessary.
Remove rub
be r cop (2) and
sho rt-circuiting builon.
D
eta ch short-circuiting lead fr om
insulator.
Remounl pa rts in reverse orde r.
Magnelo flywh ee l
Fig. 4
Fi t pro tective cop (reroir tool no.
4) to thr eaded end 0 crankshaft.
Fit retaining lever (1, repair tool
no.
6) 10 m agneto flywheel and
pull off the fl yw h ee l by m eans of
the extr acto r (2, repai r too l no.5).
Fig. ~
7

Fig. 6
8
Labyrinth ring ond ormature
bo se plote
Fig. 5
Uns!;rew lab yrinth ring (5).
Pull ig nition lead with spring out
of th e spar k plug le rminal {61,
pull off rubber sleeve {l } and
rubber cap (2) and screw out the
igni
li on lead socket.
Unscrew armature bose plate (4)
and remove it together with igni-
tion lead (not in Ihe case of 75 W
equi pment) and insulaling tube
(w it h lead).
Remove
Woodruff key.
Cylinder head , cylinder and
piston
Fig. 6
Unscrew cylinder head a nd cy-
linder.
Pull off cylinder wi thoul twisting
(danger of breaking pi ston
rings).
Remove cylinder
fl ange goskel.
Note:
The SACHS
SA 280 A and SA 280
cylinders ca n be rebored three
limes,
and those of Ihe SA 290
and SA 340 C twice. Use appro-
priate p is ton (see Spore Ports
lisl ).
When fitting new or r ep l acement
cy li nders and pistons, care
should be laken to ensure Ihol
Ihe colored spot on Ihe crown
of the piston is Ihe some color os
Ihal in Ihe induction port of Ihe
cyl i nder (i . e. red or white ).
Place cylinder on home-mo de
sloll ed wooden board (1 ).
Cover Ihe crankcase , t oke a utlh o
two wire cirdips. If necessary,
force
oul gudgeon ein wi th gud-
geon pin e)(traclor (3, repair tool
no. 1)
and inserl (2, repair tool
no.
2).
When filting the sleel bond, core
should be token 10 ensure Ihat
the pi ston rings are in their Woo-
ves (danger of breaking piston
rings).
Remove slotted wo
ode n board .
Cronkcose ond crank shaft
Fig . 7
Unscrew 6 he)(ogon socket heod
screws fr om crankcase.
Note:
When dismant li ng Ihe crankcase ,
have a look
at the loble of
crankshaft bearing s on poge 10.
Split crankcase by to pp ing Ihe
crankcase half power takeoff
side sl ig hl ly wi th a rubb er ham-
me r.
Remove cra nk !;ose half power
lakeoff side and gasket.
Toke core of dowel lubes.
Unscrew screw ed nipple (1) and
oil dra in cock {2}.
Unscrewcrankcase half magneto
side from the assembly ii! aod
heat i li a 100...150 0 C 212...
302
0 Fl for removing the cra
nk-
shaft (grooved boll bearing).
Tok e oul crankshaft.
Clean all parts thoroughly, check
for
wear and replace when ne-
cessary.
Use only genuine SACHS s par es.
9

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WORK ON INDIVIDUAL PARTS
SACHS special ext racting tool for cra nk shaft oil seals
(without dismantling the e ngin e)
FICHTEL & SACHS AG have developed a special extracting 1001 by means of which
damaged oil seals ca n be replaced without a major disassembly of Ihe engine being
necessary.
Engine troubles caused by leaking or damaged oil seo ls can thus be remedied in a
relatively short lime.
When re plac ing oil seals, Ihe following poinls sho ul d be borne in mind:
Extracting oil se al s
Fig.8
Be fo re extracting oil sea l be sure
to es tablish installation dimen-
sion x, a or y, in order that the
new oil seal can be fitted 10 the
some dimension.
Note:
If the corr ect installation dimen-
sion is not adhered to, engine
troubl es may occ ur by closed o il
bores in the crankcase or by
rotating
par ts moving against
other parts.
F'll. 9
If Ihe oil seal is laded towards
outside by means
of a collar (a)
or other locking element, it can·
not be extracted.
/
fig . 8
/
11

Fin. 10
f ig .
11
Fitting the oil s eal
12
Fi g. l0
Place the extracting tool in posi-
tion in such a way that the two
hooks
(4) gr ip behind the sheet
steel rim of the oil seal. Pre-ten-
sion the two legs (2) evenly with
cylinder
head screws (1), taking
core lhat shaft (5) and thrust
screw
(3) are in alignment.
Screw in thrust screw and extrac t
oil seal.
Fig . 11
If the gop between shaft and
sheet steel rim of oil seal is too
narrow and the extracting tool
cannot completely be placed in
position, toke off one leg of the
extracting tool
and insert both
hooks
(1) in inclined position.
Remount leg and exlract oil seal
as described under Fig. 10,
Note :
tf the oil seal has gal st uck (oxi -
dation). the sheet steel rim may
break, Therefore it is advisable
to knock the oil seal out of its
force fit by means of a tube.
Fig. 12
Before fitting the oil seal, fill the
space around the tension spring
with a litt
le heat-resisting grease
and lightly smear the seal ing lip.
Ta protect the sealing lip of the
oil seal from
damage caused by
sharp edges on the shaft, use
shell sleeve.
If necessary, put
smooth adhesive t
ape around
sharp edges.
Pl ace oil seal in position and
press it in by means of a suitable
tube, taking
core of exact instal-
lation dimension x, a and y
(Fig.
8).
The oil seal must not be tilted
when being pressed
in.
Changing cranksha ft bearings
Heat crankcase halves to about 100 ... 150· C (212 ... 302· Fl. Remove outer race of
bearing and cran k shaft oi ls seals.
Insert new outer race of roller bearing into the warm crankcase half until they strike
a stop. Press
in oil sea l (with sealing lip inwards) until they ore flush.
Press in new grooved ball bearing into the worm crankcase half on the magneto
side un t il it strikes a stop. Press in crankshaft oil sea l until flush only after the crank-
case halves have been screwed together.
Have a look
at the table of crankshaft bearings on page 10.
Removal of inner race
of roller bearing and
grooved ball bearing
Fig. 13
Puil off inner race (1) and groov-
ed boll bearing (S) by means of
the appropriate extractor shells
(10 and 7), clamping rings (9 and
8) and withdrawal tool (11; re-
pair tool no. 17 to 23).
Remove compensating washers
(2), shim (3), spacer (4) or spacer
bush.
Fig. 13
13

T ype of engine
SACHS SA 280 A
280
290
S AC HS SA 280
290
SACHS SA 280
290
340 C
C ra nkshaft
,',
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Note:
"
I'i
3
3
Fig. IS
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i-.) 0., U,
000
33 3
33 3
Ven ion
S-piece cran kshaft (with cover plates )
1 magneto side cronk pin
2 spacer bush (21.4
mm long. with electric storter,
23.4
mm long, without electric slorler)
o
3
3
o
•
9..:
"
a
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3 washer (2 mm thick; only for measuring, then 10 be removed)
1 power takeoff side cronk pin
F ig. 16
3'piece cranksh af t f or engine wi th cy lindrical roller bearing
(NJ 205 E e3 lS ) on m agneto side
1 magneto si de c ra nk pin
2 washer (2 mm thick)
3 spacer (5 mm th ick, bevel pointing towards crankshaft web)
4
washer (1.5 mm th ick, bevel pointing towards cr ankshaft web )
5
power t akeoff side cronk pin
fig. 17
3-piece crankshaft for engine with grooved boll bearing
(6305 C3) on magne to side
1 magneto si de cronk pin
2 spa c er (5 mm thick, bevel pointing towards cranksha ft web)
3 washer (1.5 mm thick, bevel pointing towards crankshaft web)
4 power t akeo ff side cr ank pin
For the
eng ines SACHS SA 280, SA 290 and SA 340 C on ly the 3.piece cronkshaft
ond for SACHS SA 280 A only the 5-pi ece crankshaft will be supplied for replacement purposes.
Pay attention to the above table when mounting the crankshaft.

Removal and replacement of small end bushing
Whe n ta rrying 01.11 repairs to engines it wi ll sometimes be necessary to r ep l ace the
sm all end bushing of the co nn ecting rod. A special 1001 has been de signed for this
purpose ( rep air tool no. 9) .
A special reoming attachment is required when reaming out a newly fitted bushing,
cnd this h as been developed in collaboration with the Germon firm of Hunger (re-
pair too ls no. 10, 11 , 12 and 13).
The following procedure should be adopt ed when replacing a small end bushing:
F ig . 18
fig. 19
16
Removing small end bushing
Fig. 18
F ix the gui de roil 11/, as i ll ustrat-
ed, adjust it in fe olion 10 the
connecting rod,
cnd light ly se-
cure it by meons of two washers
(2) and two nuts ( 3),
Press gui de ra il uniformly agai n st
the two st uds and tighten nuts (3) .
Clomp the connecting r od by
means of eccentri c pins
(9) and
press out the small end bushing
as follows:
Insert withdrawal boll (4) with
guide bush (5) and pressure bush
(6) into the small end bushing.
Fit holding sleeve (7), screw the
nut
(S) and press ou t the small
end bushing.
Inserting repl
ac em ent bushing
fig . 19
When in serting the replace m ent
bushing (k), core should be lake n
to ensure that both oil holes (i n
the bushing and in the connect·
ing rod) are in alignment.
Carefully insert withdrawal tool
Ie) with ,ressure bush ( g) into
small en bushing (kj.
Fit guide bush (f) and holding
sleeve (h ), screw the nut (i) and
press in the bushing Ik) so that it
projects equally on both sides.
Centering the c onn ecting rod
Fill. 20
Mount su ppor t Ir) with guide
bush (g) on guide rail (0 ) and
screw it tig h t.
Insert reamer (t), shonk foremost,
in to the guide bush (g) and accu'
rately center the connecting r od
(v) with the aid of the toper .
Care should be token not to dis·
place the connecting r od axially
or radia lly.
Then bring eccentric pin (w)
lightly into contact with the can·
necting rod and secure it with
nut
(x).
Press eccentric pin (y) firmly
against connecting rod and t ig h-
ten nut (z).
Reaming the sma ll end bushing
Fig. 21
(ove r the crankcase.
The front adjusting nut
(q) of the
reamer is provided wi th mark·
ings: each division corresponds
to 0.02 mm (0.00079 in .).
In se rt reamer and, with the aid
C?f adjusting nu ts (q and pI, ad·
tust it to the diameter of the bore
of the small end bushing.
~ 'S 4 0$ 4 . "
Fill. 20
-
fig. 21
Rem ove rea'!l~r. from the bushing, sla ck en lock nut (p), alter position of adjusting n ut
(q) by one diVIS ion, and secure the blodes wi th lock nut ( p).
The s.mall end bushing can now be r eamed car efully with the aid of the adjustable
reaming tool (I) and the addi tion of oil or paraffin.
Check the fit with the aid of the gudgeon pin.
~eaming should be continu ed un til the oi l ed gudgeon pin sl ides wi th a d ose Ms uckingM
fit thr
ough the r eamed small end bushing.
Bore tolerance for the bushing =
(/J 18 t g:g~ mm
0708 +0 .000 78.
. 66 +0.00118 In. dia.
FICHTEL & SACHS AG, 8720 SCHWEINFURT, GERMANY
supply this special reaming tool in two venions or individual c ompon ents if required.
Relevant prospectuses are available from us on reques t.
17

Fairbanks recoil st arter
The recoil starter is available for clockwise or anti-clockwise starting direction.
II can also be subsequently con verted for the other storting direction.
The illu stration below shows the two start in g directions.
Fig. 22
Recoil starter for engine running Recoil starter for engine running
in clockwise direction in anti-clockwise direction
Fig. 23
18
(as seen on the power take-off side of the crankshaft)
Dismantling
Fig. 23
Unscrew the housing.
Pu l lout the cord as shown in the
illustrotion. Withdraw knot from
sl
orter han dle and undo il.
Remove tubular
ri yet (01. beering
pl ate (b) and starter hand le (c),
and let cord run bock completely.
Remove retainer (d) and cover
plate (e).
Fig . 24
Remoye compression spring (f),
friction disc (gl, drive assembly
(h ), ond second friction disc.
Carefully toke out pulley (i ). Toke
core not to let the co il spring
under
it jump out.
Detad! starter cord from pulley.
Take oul coil spring by han d.
Ass embly
Fig. 25
Lubric ate the coil sprinlil and the
piyot pin
(k) l ig htly wi th Moly-
c ote before assembling.
Note:
For clockwise starting direction,
insert coil spring
as shown in il-
lustration. For anti-clockwise
starling direction insert coil
spr ing the other way round.
Check if coil spring lies flat and
even.
Bend the
end of the spring up-
wards a little.
Fig. 26
Fit the cord into the pulley, as
shown tn the tllustrattOn, and
wind it on, according to the start-
ing direction.
Fit pulley on to pivot pin and
engage the end of the spring in
the pulley according to the start-
ing direction.
Replace st arter handle, bearing
plate and tubulor riyet (see Fig.
23) in position on the starte r
cord, knot the end of the cord
and pull it into the handle.
Fig. 2~
rlS 4 Q!.4 ,.
Fig. 2S
Fig. 26
•
19

rl s ' O ~ 4 ':O
Fig. 27
Recoil starter with friction jaws
Fig. 27
Fit friction disc, drive assembly
(with proiections in starting dI-
rection for clockwise starting di-
rection, see arrow in illustration;
for anti-clockwise
sta r ti ng direc-
tion fit drive assembly counter-
wise), second friction disc and
compression spring on to pivot
pin.
Pl ace cov er plate in position and
insert retainer.
With the aid of the cord, tension
the pulley 1...2 turns so that the
starter grip is pulled bock unt il
it encounters the stop.
Let cord run back.
Fit the housing
in position and
screw tight.
The recoil starter
is available for clockwise or anti-clockwise starting direction.
It can be subsequently converted for the other starting direction, if the driving levers
are exchanged for the required direction of rotation.
The illustration below shows both start ing directions.
F&54l0 , 121
Fip.28
Recoil starter for engine running
in clockwise direction
,,
-•
Recoil starter f er engine running
in enli-clockwise direction
(as seen on the
power lake-off side of the crankshaft)
20
Dismontling
Fig. 29
Screw off cover plete (b).
Remove retaining ring (g), paek-
ing discs, spring disc, friction
disc,
bearer (xl with drive levers
and pocking discs.
Fig. 30
Pu ll out cord opprOK . 50 em (19.7
in .) and hold the pulley with a
hom
e-mode retaining cl ip (see
ad ioining illustration).
Fi g. 31
Remove retaining bolt from star-
ter handle and open cl am ping
sleeve
(m) br tappi ng with ham-
mer. Pull of retaining bolt and
starter handle from slarter cord.
Remove retaining clip
again and
lei cord run bock completely.
Fig. 2'1
\
Fig . 30
21

nsu, ., u
Fig. 32
FtS ')(1"15
fig . 33
22
Fig. 32
Carefully take aut the. pull.ey,
taking ta re that the cod spring
u nder it does nat jump aut.
Detach starter
tord from pulley.
Take out
spacer ring (n) ond
ring (g ).
f ig. 33
The best way 10 take a ut th e cod
spring is to strike the storter
housing with the
open side
downwards on
th e work bench.
Broke the ejecting coi l spr
in g
with the start
er housing.
Nole:
If the slorling disc must be re·
placed or in serted for the ot h er
starting direcl io n heat the bush
well, lei ilcoo l and then remove it.
As se mbly
Fig. 3-1
F it the slarling disc 50 that the
bent.up clip
(h) lies in Ihe.slarl.
ing direction shortly afler In sert·
ing the spr in g, and the recesses
(x) cl ip into place in Ihe corres·
ponding ri b.on the bollom of Ihe
starter hOUSing.
Press bush up aga in sl slop (use
only new bushes).
Fig. 35
lubricate the coil spring with
Molycole b efore assembling.
Note :
For clockw
is e starting direction
(
B) insert co il spring as shown in
( b) , and for an l i· clockwise slort·
ing direction (A) as in (a)wilh the
tubul
ar rivet (collar facing dow n·
wards).
The first coil
of the coil sp ring
must lie oulside the
plate ( h, Fig.
34), whereas all ot h er coils mu st
f it ins i de.
Ensure tha t coil spring lies pe r·
fectly even.
Insert spacer ring (n, Fig. 32 ).
Insert contact ring (g, Fi g. 32 ) so
Ihot the riveting of the spring
lies snugly in th e gr oaye of the
contact ring.
Fig. 36
When filling the pulley, attach
Ihe end of Ihe spring to the driv.
ing pin
of the pulley.
Tension pulley/coil spring in di·
rection of cord exil unlil stop is
encountered. Release coil spring
1...2 turns until the recess for the
soldering nipple
in the pulley
rests n
ear the cord duct of the
housing.
lub ri cate the cord l ig htly w it h
Molycote
before assemb ling.
F
it rubber grip on 10 cl amping
sleeve, loy double loop of cord
around retain er boll (see F ig 31)
and secure wilh clamping sleeve.
Pull retainer bolt into rubber grip
and lei starter cord run bode.
__ " __ o.! f&S .... ."u
Fill . 36
Fit on padeing rings, beore r with dr iv in g lever, and inserl Ihe angled ends of the
driving leve
rs inio the recesses of the pulley.
Fit friction disc, sp ring disc, podeing rings and re la iner ring.
Remove packing rings from u
nder th e bearer, should the d ri ving levers not move out-
wards when sl ar ling.
The bearer should have a tolerance of 0.1 .. .0.2 mm (0.0039 ...0.0079 in.).
Screw on cover plate (b, Fi g. 29) with 4 cylindrical screws M 5 x 12 and was her s.
23

Recoil starter with pawls
The recoil starter is available for clockwise or anti-clockwise starting direction.
It can also be subsequently converted for the other starting direction.
The illustrat
io n below shows the two starting directions.
-
Fig. 37
Recoil starter for engine running Recoil star t er for engine running
in clockWIse directIon in ant i-clockwise direction
Fi g. 38
2'
(as seen on the power take-off side of the crankshaft)
Di smantling
F i ~. 38
Toke out broke sprmg (5).
shims, spring ring, friction plate
(3). washer 0. 1 mm (0.0039 in.)
thi ck and starter pawls (land 4) .
Screw off labyrinth ring (2).
Fig. 39
Pull ou t starter cord opprox.
50 cm (19 in.) and hold pulley
with
home-made retaining clip
(11·
Toke clamping ring wi th clamp-
ing taper out of starter handle.
Withdraw clamping toper from
clamping ring
and detach cord.
Remove clamping ring and st ar-
ter handle with st op from cord.
Remove retaining clip (\) an d let
starter cord run bock completel y.
Carefully to ke aut pulley wi th
coil spring, taking
core not to l et
coil spring jump out.
Toke core of disc (3, Fig. 41).
Remove cord from pulley.
Fig. 40
Rai~e spring end to t oke out coil
spring.
Hold
(o il sp ri ng firmly with both
thumbs (see illustration)
and, by
raising
each thumb, let out spring
on alternate side s.
Note :
Repl ace bush ./2, Fig. 42) only if
necessary, u Sing the ex trac t or
shells (r epai r tool no. 19).
Toke core of tolerance nng In
bush (2, Fig. 42).
Assembly
fig. 41
Before assembling, grease coil
spr ing with Aero-SHELL-Grease
14 and f ill the 4 lubricating
grooves
in the pulley with the
same lubri cant .
Insert coil spr ing with end of
spring (2) in stud ( 1) and fit in
coil by coil.
Ensure that the coil spring lies
flat
and even.
Note:
For clockwise starting direction,
insert coil spring
as shown in il-
lustration, f or anti-clockwise di-
rection insert coil spring rever-
sel y.
Fi f!. 39
Fi g. 41
~
1
2
25

Fig. 42
Before inserting pulley, slick. di sc
(3, Fig. 41] 0.8 mm thick (0 . 032 in.)
wilh a little grease into recess of
pulley.
Fit pulley on to bearing bo lt and
insert end of spring (4, Fig . 41] 01
stud (1].
Tension pulley/coil spring in di-
rection of cord exil until slop is
encountered.
Release coil spring
opp rox. 'II
...1 turn until the recess for the
FOH Q lI '" soldering nipple in the pulley
resls near the cord duct of Ihe
fi g. 42 housing.
Again hold the pulley firmly with home-made retaining clip
(1, Fig. 43].
Pull the starler cord through a rag soaked wilh SAE 10 oil before assembling.
fig. 43
Fi g. 44
fjg.43
Note:
When converting starting dlrec-
lion, reposition cord gUide (2)
olso.
Fit starter handle with stop and
clamping ring on to cord.
lay starter cord around clamp-
ing toper and pull it into clamp-
ing ring.
Pull clamping ring inio starter
handle and let starter cord run
bock.
Fi ll. 44
Screw labyrinth ring (2) tight.
lubrica te storler powl bed and
start
er pawls lightly with SAE 10
oil.
Fi t starter p aw ls (1 and 4).
The open side of the starter
pawl seating
and the l ong side
of the starler pawl face in starl-
ing direction.
Fit washer 0 .1 mm (0.0039 in.)
thi ck, friction plate (3), spring
ring
and shims as reqUired.
Insert broke spring
(5].
After mounting Ihe broke spring, Ihe friction plate should have on axial play of
0. 1...0.2 mm (0.0039 ...0.0079 in.).
Correct this ploy by putting shims under Ihe broke spring.
26
Flywheel dynamo ma gneto c ente r ing tool
Replacing the ignition or
lighting ormatur e
fi f!o 45
I. Pass the l eads th rough a hole
in the centering pl ale and
in position in centering plat e.
2. Place centering unit in posi-
tion and tighten hexagon
head screw by hand.
3. Remove foully armatures and
r
eplace by new ones.
4. Pl ace centering ring in posi-
tion, press newly fitted arma-
lure against Ihis ring and ligh-
ten both screws. After removal
of the centering ring the gop
between armature core and
magne to flywheel w il l be of
the correct width.
Note:
--
, .. .*,.
The F & S centering tool will not
be supplied
any more when the
present stock
is exhausted. F ig . 45
New ignition or lighting armatures have to be fitted according to the installation
instructions whi ch are attached to BOSCH spore parts.
In order to ob tain the maximum ignition and lighting power it is recommended to
maintain the
gop of 0.25...0.35 mm (0.0098 ...0.0138 in. ) between the armature poles
and the flywheel under any circumstances.
Replacing the contact breaker
The contact
breake r should be changed when the contacls, the slider or the pivot pin
are badly worn; also when the bearing bush is warn or if the contact arm or the spring
is damaged.
1. Unscrew cutout l ead, and, if fitted, noting correct sequence of insulating washers
for connector
angle brocket in cont act carrier.
2. Remove r etainer and contact arm from pivot pin (take care of shimming washers ].
3. Unscrew fillister head screw and remove contact car rier.
4. Unscrew pivot pin from armature bose plate.
New ports should be fitted
in reverse order, proceeding as follows:
Caulk the pivot pin
after screwing in.
Use only the contact breaker assembly specified for this engine.
When fitted in position, the contacts on the contact arm must not be displ aced or
ti lted.
Apply BOSCH Ft1 v 8
grease to bearing before fitting.
Smear BOSC H Ft 1 v 4 grease on the felt lubricating pod and greaser wedge in the
slider. (BOSCH
grease is obtainable in tubes from all BOSCH suppliers.]
Do not allow any grease or oil to reach the contacts.
Replocing the condenser
I. Unsolder both leads.
2. Push the de fective condenser out of the arma ture bose plate with 0 wooden dowel.
3.
Re move the sealing caulk from the hole with a triangular scraper.
4. Insert new condenser
and ca ref ull y caulk again.
5. Solder both cables to their terminals.
27

Replacing the magneto housing or the flywheel
2- ->~·
fi~. 46
fig . 47
Fig. 46
Screw ou t4recessed head screws
in flywheel.
Screw in 4 hexagon heod screws
(1) alternately (with equipments
wi thout gear ring for elec-
tric
starte r the 4 staybalts must
be removed before) ond press
out flywheel (2).
Note:
When replacing the magneto
housing of the 6 V 36 W equip-
ment, screw out contact-breake r
hub
and insert it ogoin into the
new housing,
as described under
Fig.
53.
Torque: 0.6 ... 0.8 kpm (4.3 ... 5.8 ft.
lb.).
Fig. 47
Unscrew retaining strip (2) and
t ake aut cam (I),
Fill annular groove (3) wi th heat-
resisting grease and grease cam
support in flywheel.
Insert cam (1
), fit retaining strip
(2) and screw tight with 3 cylin-
der head screws M 4 x 5 and
washers.
Take retaining ring
(5), flyweight
(4) and thrust ring below off
bearing pin.
Grease bearing pin and bearing
surface for flyweight in flywheel
with heat-res
isti ng grease.
Fit thrust washer (0.3 mm thi ck) on bearing pin, hang spring (6) into place in flyweight.
Fit flyweight on bearing pin (m us t engage with cam) and secure with retaining ring (5 ).
Cam an d flyweight must always be free-moving.
Note:
On equipments wi th gear r in g for electric start er there are two markings in the
magneto housing: -40x' (for
40 W equipment) and -7 5xH (for 75 W equipment).
The flywheel should be fitted
in such a way that the bores in the flywheel are perfectly
in line with the bores in the housing.
On engine without electric starter, fit appropriate magneto housing (see Spare Parts
List) according to equipment (40 W or 75 W) in such a way that the bores in the hous-
ing are perfectly in line with the bores in the flywheel.
Pr ess in the flywheel.
Degrease 4 Philips screws M 6 x 10 with Tri, apply LOCTITE to them and screw them in.
Tightening torque 0.9 ... 1.1 kpm (6.5 ...8.0 ft. Ib,),
28
I
J
'I
Carburettor
The type of carburettor, the jet size and the jet adjustment are determined by means
of tests
in the factory. The adjustment de termined in this way gives the best results,
and it is therefore not advisable to alter it.
No alteration of the carburettor setting should be mode os long as the eng ine turns
over quietly
and smoothly when idling, accelerates steadily when the th rottle is
opened, and gives its full output at full revs without choking. If the engine pounds or
runs uneven ly , or the exhaust gas is black, the m ix ture is too rich. Repeated spitting or
coughing, or back fi ring with a blue flame stabb ing from the carbureltor coupled with
difficult starting, indicates
that the mixture is too wea k.
When running with the correct corburettor ad jus tment, a clean air fi lt er and a suitable
sparking
pl ug with the correct thermal value, the insulator of the sparking plug should
be brown in colour. Sooty
or wet plugs indicate ri ch mi xture, whereas white insulator
points to the mixture being too
weak.
Special core should be token to ensure that the corburetlor setting is never too low,
as at low throttle insufficient lubricant will be conveyed to the moving parts of the
engine. With a two-stroke engine the
carburettor setting should always be sufficient
to provide
adequate lubrication.
Correct carburettor settings will help to ensure economic and trouble-free running of
the engine.
Adjusting the carbureltar for special climat ic conditions
When using the
engine at al ti tudes above 1Qoo metres (3280 ft.), adiustments of the
carbure ttor setting will be required. As the air density is reduced at high altitudes,
the
supp ly of gasol ine to the corburellor should be restricted by changing the main jet.
Starling
On Tillotson diaphragm carburellors the choke is incorporated in the carburettor
itself.
The choke should be used to facilitate starting from cold. It should not be us ed for
starting when the engine
is worm ond it should be pa rtially or fully closed only for
starting the cold engine.
When the choke is closed, a higher vacuum is caused in the mixing ch amber, so that a
richer fuel/air
mix ture is obtained. Once the engine has started, the choke should be
slowly
opened.
The Tillotson diaphragm carburettor can function in any position and has two di a-
phragms (the HO-7 A type and the HO-13 A type h ave three diaphragms): a control
diaphragm for proportioning the fuel feed to the engine and a pump diaphragm
(HO -7 A and HD - l3 A h ave two pump diaphragms) for drawing the fuel from the tank.
CarbureHor adjustment
The Tillotson
carburellor is the first corburellor us ed for SACHS engines which has ad-
justable jets. If
engine troubles occur and the jets have to be readjusted, the following
points should be noted:
1. To adjust the carburettor correctly for maximum ou tput (full load), the engine
should be thoroughly wormed up.
2. WHh adjustable jets, core should be token not to use too leon a fuel/air mixture
(see also
page 41).
3. The adjusting screws for the je ts must never be screwed too tight ly to the right
(i. e. closed) in the jet seat, as this will deform the seat.
4. The main jet is marked " Wan d the idling jet is marked "l" on the carburetto r
housing.
29

Tillotson diaphragm ca rbur etlo r
Fiq .48
I Ho.e nipple
2 Fuel pump body
3 Fuel pump diap hragm
3 A In let "alve on pu mp
di aphragm
3 BOutl et valve on p um p
diaphragm
4 Fuel pump ga.ke t
5 Di aphragm hous in g gasket
(; Control <flomber
7 Ad iu.ting sCrew lo r idling j et
8 Impulse passage
9 Id ling iet orilice
30
lOA Idling outlet pO$Soge
10 BBy_pass p o"ag e
11 Bunerily valve
12 Main iet orif ic e
13 Corburettor housing
14 Throato l corb urenor Ive ntur i)
15 Main luel o ull et
16 Choke
17 fuel passage from pu mp
to control chamber
18 Inl et needle and .eat
1 8ACopper seal
19 Adiusting screw lor main iet
" .. .. ,"
20 In let compre .. i on sp ring
21 Inl et conlrol lever
22 Pivot pin
Z3 Venl hole
24 Di ap hragm hous in g
25 Diaphragm
26 Air <flamber
V Filter go.k.,
28 Fu el stmine,
'l'I Filter housing sere '"
3(} Fuel chamt.er
31 Pu ls ation chamber
32 Fuel fil ter housing
Initial adjustm en t
Jet adjuslmenl should first
be done when the engine is cold. Proceed as follows: Close
both jets and open the adjusting screw of the main jel and the ad iusling screw of the
idling jet again 10 the values given in the carburettor chart (see technical data). Turn
Ihe idling odiustment screw so for bock: that it is no longer in conlact with the butterfly
valve lever; then tu rn the scr ew in again about one whale turn, so that th e butterfly
valve is slight ly open.
N ow stortthe engine and allow it to warm up (open Ihe choke as soon as the engine
starts up).
Final adjustment: see section -Test-running the engine"
Maintenance of the carburellor
At ceria in intervals every carburetlor must be disassembled, cleaned and overhauled.
All exterior dirt should be cleaned off with gasoline before disassembly. The holes,
ducts, passages and jets must not be cleaned with hard objects (e . g. wire or drill),
but should only be rinsed with gasoline and cleaned with compressed air (remove
diaphragms before blowing through). Before assembly, check that all carburetto r
components (especially jet
se ats and diaphragms) are in proper working order.
Checking and cleaning the fuel filter in good time helps to achi eve satisfactory func·
tioning of the carburellor and longer engine service life.
Special maintencmce instructions
1. If pump failure occurs, always check (before removing the pump diaphragm) the
impulse pipeline for leakage and blockage.
2. When filling the inlet control lever and the compression spring (see illustration),
take care thai both ends of Ihe spring are bedded in the spring seats.
3. Th e compression spring musl not be stretched, as the spring pressure is accurately
adjusted to Ihe carbureltor.
4. The inlel control lever is cor-
rectly inserted when it is atthe
same level as the bottom of
the di aphra!m chamber (see
arrows on il uslration).
5. Th e inlet needle should close
just when the inlet control le-
ver is flush with the boltom of
the enamber. If not, Ihe lever
should be adjusted by bend-
in g it a liltle (an the in let
needle side).
6.
When assembling Ihe carbu-
retlor, make sure that main
diaphragm , gasket and cast-
ing of the housing are care-
fu l ly inserted into the cast-on
centering pins; similarly, the
gasket, fuel
diaphragm and
fuel pump body are adjusted
by means of the same kind of
centering pins.
The gaskets at both dia·
phragms are in eaen case po·
sitioned on that side of the
diaphragm which faces the
carburellor housing.
,"' " .. "
Fig. 49
31

Decarbonizing the exhaust muffler , cylinder and cylinder head
Whe n dealing wi th com pla in ts and repoirs, the following should be bor ne in min d:
In every engi ne a p ropo rtion of th e lubrication oil is burnt ond forms carbon which,
in a two-stroke engine, is deposited chiefly on the piston (fown, in the transfer port of
the cylinder and in the exh aust mu ff ler. The corbon should be removed ofter every
200 running hours, at the lotest when the e ng ine performance drops or when, even
wi th correct corburellor setting, the engine lends 10 four-stroke.
Fi g. 50
Exhaust muffler
Fig. 50
The exha ust muffler cannot be
dis ma ntled for cl eaning.
Corban deposils may be burnt
off by heating the muffler 10 red
heat by me an s of a weld i ng torch
or in a fo rge fire.
I
No modifications should be mode to the exhaust muffler, as any such alterations
wi ll be detrimental to performance, fuel consumption and wi ll increase engine
noise. Modifications of any kind to the exhaust muffler are in any case illegal
a
nd constitute a puni sh abl e offence.
Cylinder he ad
Un screw the cylinder head and re m ove the carbon deposits from the in si de of I he
combusti on chamber with a screwd ri ver. Take care not to da mag e the surface of
the cham ber .
Cylinder
port s
Place piston at bottom dead ce nter.
Remove
carbon deposits in exhaust port ond transfer ports with a screwdriver.
Care fu lly place piston at top dead center and remove loose carbon.
Piston
Care fully r emove only th e thick er carbon deposits (fla ke s) from the piston crown.
Do
nottfy to sc rap e th e pi ston crown to a bright m eta ll ic co ndition.
32
ASSEMBLING THE ENGINE
Crankca se and cronkshoft
Fi g. 51
Before assembling, fill the groov-
es of the sholt seah with gr ease
(Alvonio 3 ).
Note:
When assembling
crankcase hal-
v es , hove a look 01 the table on
crankshaft bear ings on page 15 .
On engines equipped with
grooved boll bearing on the
magneto side, he at the in ner
race of the grooved boll beoring
and insert c ra nk sha ft into the
crankcase half.
Insert both dowe l tubes and
place gasket in position.
Fit
the p. t. a. cra nkca se half
(heat up inner
rir>g on engines
equipped wi th grooved boll
bearing) and screw t he two hal-
ves together by mea ns of 4 hexa-
gon socket head screws M 8 x 35
and 2 hexagon socket head
screws M 8 x 60 (on SACHS SA
340 C, 2 hexa gon socket head
screws M 8 x 65) and sp ring wa-
shers.
Tightening
torque 2.2 .. 2.4 kpm
(15.9 ... 17.4 fl. lb .).
Sc rew magneto side c ran kcase
half to assembly ji g wilh two
he xagon he ad screws M lOx 40.
Screw in scr ewed nipple II) and
oil dr ain co ck (2) with sea .
Fig. 52
A ft er having screwed the crank-
case hal ves together, press in
cr ankshaft ail seals on power
takeoff and on magneto side
from outside until
flu sh (see illus-
tration).
Fig. 51
Fig. 52
33
•

Piston
Nol
e:
In case Ihere are pistons with square-pro fil ed and l-profiled rings, fil the l oller in lo
Ihe upper recess (l eg points upward).
Heat piston to 70... 80· ( (158 ... 1 76· F) and fit it in position on the connecting r od by
means of th e fixing bo1l. Arr ow on piston crown must point 10 the exhaus l.
In se rt gudgeon pin - wi th the aid of withdr awal 1001 (3, Fig. 6) and inserti on bush (2,
Fig. 6 ), if necessary.
Use slolled
board (I, Fig. 6).
(o ver Ih e crankcase, fi l Ihe two wire ci rcl ips, making su re Ihal they ar e corre c tl y
seale d.
Cy lind er and cy lin de r he ad
Scrape off th e projecting ends of the gas ke t.
locate Ihe cy linder flange gaskel wilh Ihe graphiled side facing the cr ankcase.
Put pist on on slot led wooden board (1, Fi g. 6), lightly oi l the cylinder and place il in
pasilion
over the pislo n, laking core not 10 rolale Ihe cy linder, olherwise il might
damage the piston ri ng s.
Remove sl olle d bOard and secure cylinder wi lh 4 nuts M 10. These nuls should be
tightened
diago nally, with 0 torque 01 4.6 .. .4.8 kpm (33.3...34.7 I t. lb.) f or SW 14
(1 4 mm across fl als) and a torque 012. 0...2.2 kpm (14.7 ... 15.9 It . lb.) for SW 17 (17 mm
ac ross Ilals).
Fit the cylinder head (decompressor lowards power takeoff side) and secure il wilh
4 hexagon h ead boilS M 10 x 55 (in the case of the SACHS SA 340 C with 6 screws
M 8 x 60). Ti ghten bolts diago nally wilh a torque of 4.6...4.8 kpm (33.3...34.7 ft . lb .) for
M 10 x 55 and with a lorque 0 12 .2 ...2.6 kpm (15.9... 18.8 fl. lb.) for M 8 x 60.
Armature base plate and labyrinth ring
Inserl Woodruff key inio crankshaft.
Pass the insula ti ng lube with lead and the ignition l ead (nol in the ca se of 75 W
eq uipment) throu gh th e holes in the crankcase. Place armature bose p late (4, Fig. 5)
in pos
it i on so tha t the marks (3, Fig. 5) are li ned up, and secure it wi th 3 fillist er head
screws M 5 x 12 and washers.
Torque 0.4...0.5 kpm (2.9...3.6
It . lb ).
Not e:
N ew armature bo se plales hove no li ming mark and should be adjust ed by means
of the longitudinal slots.
Put socket with r ubber cop (2, Fi g. 5) on ig nit io n l ead and scr ew it in la the cra nkcase.
Fit ru bber sleeve (I, Fi g. 5) on Ihe ignit io n tead. Hong spring into ig nition lead (laking
car e I hat the sp ring ge ls inlo conl act wi th the core of the ignition lead) and inserl inlo
spar k plug t er mina l.
Inse rt labyrinth ri ng (5, Fig. 5) and secure it with 4 fillisler head screws M 5 x 4.
Magneto flywheel
On equipments 12 V 40 W and 12 V 75 W, check flyweight for ignition setting and com
for free movement
and fill annular groove in com bore wi th heat -resisling grease.
Degrease the t aper of the crankshaft and Ihe magneto flywheel (on equipmen ls 12 V
40 Wan d 12 V 75 W take care of lubrica nl applied).
F it on magn eto housing wi th screwed in flywheel, making sure that the W oodru ff key
engage s accurate ly with Ih e groove in Ihe flywheel.
Note:
Fig. 53
The contact-breaker hub of ma9-
neta flywheel with screwed In
contact- br ea k er hub musl be so
posilioned thai the mark wL
w
on
anti-clockwise rota ti ng m agneto
flywheel and Ihe mar k ~ R· on
clockwise rotating magneto flr.-
whe el is li ned up with Ihe ho e
marked
"Rl W in the magneto
housing.
fig. 54
T oke core when filling m agneto
flywheel on to keyway thol th e
grooves marked OR"
and "l" en-
gage correctly, i. e. use groove
marked WL" for mognelo fly -
wheel ro
latin g anti -clockwise.
'" "'~,
Fif! . 54
35

Ignition $etting
Fig. 55
Ignition ti ming:
6 V 36 W equipment
4.0 ... 4.5 mm before TDC
(0.15748...0. 1771 in.)
12 V 40 or 75 W equipmen t
Stopped engine:
0.3...0.5 mm before TDC
(0.0118...0.0197 in.)
0.2 ... 0.4 mm before TDC
(0.0079...0.0157 in.)
(SACHS SA 340 C)
Running engine:
4.1...4.7 mm before TOC
(0.1969...0.2205 in.)
Contod-breaker gop:
0.4 ±0.05 mm
(0.01575 ± 0.00196 in.)
Pole shoe gop:
6 V 36 W equipment
16 .. ,19 mm
(0 .62992...0.74803 in.)
12 V 40 W equipment
Stoppe d engine: 32...36 mm
(1.2598 ... 1.4173 in.)
Running
engine: 14 ... 18 mm
(0.5512...0.7087 in.)
12 V 75 W equipment
Slopped engine: 25 ... 29 mm
(0 .9843...1.1417 in.)
Running engine: 7 .. 11 mm
(0.2756... 0.4331 in.)
Gouge:
Ignition timing gouge or depth
gouge, 0.4 mm (0.016 in.),
feeler gauge.
The magne to flywheel is provi ded with two punched marks.
" 0" is in line wi th I he mark on Ihe housing when the piston is at top dead center.
" M" indicates the fi ring po sition.
When fitting new ignition systems or systems without marks, the top dead center and
firing pos iti on should be determined with the aid of the ignition timing gauge and
su i tably marked.
It is adv i sable to check the ignition setting every lime the engine is insp ected, since the
perform
anc e of Ihe enQ ine depends on this and trouble with the lights is not in-
frequently du e to fa ul ty Ignition setting.
At the
sam e t im e also c he ck the spa rk gop of the sparking plug (0.5 mm) (0.020 in.).
36
Adiustment procedure for ignition setting:
Magneto fly wheel with ignition control
Slopp ed e ngine:
1. When cam is in its highest position, adjust contact-breoker cl e arance (b, Fig. 56 or
57) to 0.4 ± 0.05 mm (0 .016 ± 0.002 in.).
2. Turn the magneto flywheel in the rever se direction of rotat i on and determine the
firing positi on w it h the aid of the ignition timing gouge.
3. In this positi on the contacts should now begin to open. If nol, then the firing time
can be ad jus ted by turning the armature bose plate. This can be done by means of
t he longitudinal slots.
4. Turning the armature bose plate in reverse direction of rotation advances the
ignition,
and in the di rection of rotation retards the ignition.
5. When Ihe setting is adiusted, screw Ihe armature base plate firmly inlo position.
6. If the ignition setting is correctly car ried out, the pole shoe gap (0, Fig . 56) should
measure be t ween 32 ... 36 mm (1 .2598 ... 1.4173 in.), and the pale shoe gap (a, Fig. 57)
be t ween 25 ... 'E mm (0 .9843...1.1417 in.).
Magneto flywheel wilh scre we d on conlact breaker hub
1. When com is in its highest position, adjust contac t- breaker clearance (b, Fig. 56) to
0.4 ±0.05 mm (0.016 ± 0.002 in .).
2. Turn the magneto fl ywheel in the reverse direction of rotation until the mar k (M)
on the magneto flywheel is in line with the mark on the housing.
3. Rotate ormature base plate until gop be t ween pole shoe and ar mature core (a, F ig.
56) is adjusted to 16 ... 19 mm (0.62992...0.74803 in . ).
4. When the setting is adjusted, screw the armature bose plate firmly into position.
5.
In this position the contac ts should begin to open. If nat, the firing time can be
adjus t ed by turning the cont act-breaker hub (Fig. 53). Th is can be done by means
of the longitudi na l slots.
6. Turning the contact- breake r hub in the oppos i te direction of rotation retards th e
ignition,
and in the direction of rota tion advances the ignition.
37

FiA_ Sol
6 V 36 W equipment
(with 4 magnetos!
12 V 40 W equipment
...... '" FiA.57 ..........
12 V 75 Wequipment
(with external ignition coil)
Should the
pole sh oe gop be incorr ec t, it can be corrected by sligh tl y odiusting th e
breaker contacts in the range of OA ± 0.05 mm (0.016 ± 0.002 inl
Fig. 58
38
Fa n hous in g and cover
fill . 58
Insert the two dowel tubes into
the fan housing
(4!, pl ace it in
position and screw it tight wi th
2 nu
ts M a, 2 nuts M 6 and spring
washers.
Not
e:
Fit also cover fl anges for electr ic
starter connec ti on, if provided.
Connect leads 10 screw terminal
(5) as follows:
Connect lighting l ead (yellow) 10
terminal I and 2.
Connect shart-clrcul t lflQ lead
(blad! from short-wcu ihng but-
ton (2) and from dynamo m ag -
neto to terminal 3.
Not e:
With the 12 V 75 W equipment,
connect primary
le ad (blue! from
dynamo magneto and short -ci r-
cuiting lead from short-circuiting
button to terminal 3.
Connect ea r th wire (b rown! in
case
of le ft -hand carbu rettor
from supporting nipple to termi-
nal
4, in case of right-hand car-
bureltar from cover cap to termi-
nal
4.
fig. 59
Connect leads to terminal black
(5) as shown in the illustrotion.
Connect ea rth wire (brow n) fr om
angle suppo rt of Bowden coble
to terminal I .
Connect short-circuiting l ead
(block) from dy namo mO!if n eto to
terminal 2 and to short-circuit
in g
button
(2).
Connect lig hting lead (yellow) 10
terminals 3 an d 4.
Fig, 60
On engines without terminal
blo
ck, pass short-circuiting l ead
through rubber grommet (1.1) and
hole in f an housing a nd screw
the fan housing l
ig htly i nl o
place.
Make sure that short-circuiting
lead
is correctly filled. If the l ead
is too long, there is a r isk that it
will rub against the fan or touch
the cylinder.
Fit short-circ ui ting lead to insu-
lator. Insert short-circuil inQ but-
ton and place r ubber cop In po-
sition.
Fig. 59
Fig. 60
Secure cover (I. Fig. 59 ), ignition lead with rubber sl eeve (1, Fig. 5! and fixing clip
(3, Fig. 59 ) an d ear th lead (b rown, in case of right-hand corburellor) with 3 ' iUister
h ead screws M 6 x 10 and spring woshers.
Fan, s tart er hub, recoil start er
Place fan with gasket in position ond secure it with 4 nu ts M 6 a nd spring washers.
To r que 0.5 ... 0.6 kpm (3.6 ...4.3 fL lb.!.
Place the cover plate
(3, Fig. 2! in position.
Inserl two bearing rollers 4 dio. x a mm into m ag neto fl ywheel.
Not
e:
On engines wi th Fairbanks recoil slorter fit bearing roller 4 dio. x 8 mm (0 . 032 in .) and
cylindrical pi n 4 dia. x 11.5 mm (0.4527 in.!. For recoil slorter with friction iaws in sert
two
bearing rolle rs 4 dio. x 8 mm .
Fi t starter hub (I, Fig. 21, in sert washer and retaining plate.
Pl ace retaining lev er (2, Fig. 2) in position and secure starter hub with hexagon nut
(with collar) M
14 x 1. 5.
Torque 9.0...9.5 kpm (65. 1...6a.7 ft .lb .J.
39

Not e:
For Fairbanks recoil starter, place starter hub wi th washer and retaining plate in
position, hold it with strop s panner a nd secure it with nut M 14 x 1.5.
Torque 5.4...6.0 kpm (39.1 ... <13.<1 ft. lb.).
For reco il starier with friction jaw s, place starter hub ond washer in position, hold il
with pin spanner (repair tool no. 7) and secure it with collar nut M 14 x 1.5.
To r que 5.4 ... 6.0 kpm (39. 1...43.4 ft. lb.).
Secure reco il star ler with 6 nuts M 6 and spring washers.
El ect ri c s tart e r, C(lrbure Hor and intake si lencer
Sc rew on electric starter.
Screw on inertia-pinion type starter with 2 nuts M 8 and spri ng washers.
Screw on solenoid-controlled storler with 2 nuts M 8 and spring washers. Screw
additiona l supporting plate on to crankcase p. t. o. side with two hexagon head
scre
ws M 8 x 20 and washers.
Connect impulse pipe (<I, Fig. 1) to connection on crankcase.
Place on both insulating bushes, insulating flange, carburettar (fi t impulse pipe 10
connection on carburettar) and both fibre washers (hard cloth side towards carbu·
rettor) and screw carburettor firmly in to place with 2 self-locking nuts M 6.
Note:
On SACHS SA 280 A there is on int ake stack between corburetlor and cy linder.
Se~ure cover plate (2, Fig. I) and adapter flange with 3 cylindrical screws '/." x 15 and
spring washers to carburettor and secure intake silencer (I, Fig . 1).
On engines wi th intake silencer (F i g. 302, page 53), secure cover plate ond intake
manifold with 2
cy lindrical screws ".' x 55 and 1 cylindrical 'I,' x 30 and spri ng
washers to carburettor. Secure intake silencer with 2 hexagon screws M 6 x 15 ond
spring washers to fan housing.
Exhaust muffler
Screw on exhaust muffler
or manifold and bradeet respectively.
40
TEST-RUNNING AND RUNNING-IN THE ENGINE
Tesl'running
Start the engine and let it worm up (open the choke as soon 0$ the engine storts up).
Fin ol adjustment
Ad ju st the desired idling speed of the engine by means of the idling adjustment sc rew.
Then slowly vary the selling of the adjusting
~crew of Ihe idling jet.so .thal the engine
speed incr eases smoothly when the throttle IS opened. The mOIn tet IS correctly ad-
justed when the engine gives satisfactory two-stroke operotion under load and only
slight fum es ore discharged from Ihe exhaust (Hl 242 A with fixed main jel). If there
is excessive exhoust smoke under l oad, turn main iet adjusting screw clockwise
(closing) until smoking stops and eng in e runs satisfactorily.
If the idling speed fluctuates too much or is too high, turn the idling jet adjusting screw
anti-clockwise (to open Ihe jet) unlil the engine runs smoothly 01 lo wer speed withoul
beginning to discharge more smoke from the exhaust.
Running-in period
Even the fine ly machined surfaces of pistons and cylinders are not so smooth os the
surfaces of paris which have
been sliding against one ano ther for some time. For
this reason every piston requires to be run in during Ihe initial period of operation.
This does not call for any specia l precautions, however, but simply means that th e
eng in e should not be required to give its maximum output during the firsl 20 ... 30
ru nning hours.
No special gasolineloil mixture
is required during the running-in period, and conse-
quently there is no need to add any special oils.
41

ENGINE WITH BOSCH SOLENOID-CONTROLLED
STARTER (Type DO)
Fig. 61
Fig. 61
To remove starter, unscrew 2
nuts
(3) M Bwith spring washers
and t wo screws (1) M 8 x 20 with
washers.
The pini on of the solenoid-controlled star t er (Fig. 61) slides on a coarse thread on the
armature shaft and is first pressed up against the gear rim by means of a shift lever
until it engages with it. The lever is electro-magnetically operated. Shortly ofter
engagement of the pi nion, the switch mounted on the starter automatically closes
- on mechanically operated starters by means of the engaging lever _ the armature
revolves and the pinion screws itself further forward on the coarse thread until it is
ful ly engaged. Even if too th on toolh engagement occurs, fhe switch wi ll close, as
the spring is spring-connected to the guide ring and the lever is there fore not
hindered in its movement; when starting, the armature turns the pinion until it con
engage. As soon as the pinion runs up agains t i ts counterpart, fi rm contact is estab-
lished between it and the armature, and the engine is being started.
If, after starting, the engine begins to overtake the starter, the pinion is uncoupled
from the
armature shaft by on overrunning roller clutch, but remains engaged with
the gear rim until the engaging lever is returned to its initial position by a return
spring.
To enable the starter to come to rest as soon as possible afte r being switched off, and
to enable a new star! to be made shortly afterwards, on armature broke is installed
on the commutator bearing of the starter.
42
ENGINE WITH BOSCH INERTIA-PINION TYPE
STARTER
(Type DG)
Fill. 62
To remove starter, unscrew 2 nuts
(3) M 8 with spr ing washers.
Fig. 62
The pinion of the inertia-pinion type st arter (Fig. 62) slides on a coarse thread on the
arma t ure shaft. In rest position the gear is held bock by spring tension and the pinion
is not engaged. When the starter is operated, the acceleration of the starter and the
inertia of the pinion result in a force which causes the pinion to run along the shaft
and engage with the gear rim. When the pinion has reached the stop on the armature
shaft the drive becomes positive and the engine is turned by the sta rter.
If, after starting, the eng in e begins to overtake the starter, the pinion is uncoupled
from
the ormature shaft by an overrunning roller clutch and is spun bock by spring
pressure into rest pos ition.
Note:
On subsequen t installation of an inertia-pinion type st arter, on ly the magneto housing
wi th steel rim (F & S Port No. 1471 007000) can be used.
43

Operation, mainten an ce and lubric a tion of electric starters
Operoting instructions
Do n
ot leave the storler switched on longer thon 10 seconds without interruption.
Before switching
on again, wail 1 minute to allow the storter 10 cool cnd the bollery
to recover. If there is a grating of teelh, switch off storler immediately and repeat
storling attempt. let go Ihe starter as soon as the engine runs under i ts own powe r.
Should Ihe syslem nol be provided wilh a slarler safety device, never swilcn on Ihe
slarler until the engine or Ihe pinion have come 10 rest, as otherwise damage wi ll be
caused to pinion and gear rim.
If Ihe engine does not start afler some starting attempts, further starting attempts will
serve no
purpose and will only lead 10 exhaustion of the battery. T he faull should be
sough l and remed ied (chack the fuel supply in particular ).
Maintenance
Danger of short circuits a ri ses when work is carried out on t he electrical components
of I he built-in starter. It is therefore strongly recommended, before carrying oul such
work,
that the earth lead be disconnected from the bollery. Do not ploca tools on the
balle r y!
Carbon brush es
The condilion of the corban brushes should be checked periodically. After removing
the
retain ing st rop (2, Fig. 61) of the sliding gear storl er or screwing off the cop (1,
Fig . 62) and taking out the fuse, the compensa ti ng washers and the cap (2, Fig. 62) of
the ine rt ia pi nion t ype st arter, the spring which presses the relevant corban brush on
to the com
mu t ator should be raise d, preferably with a h oo k (take core not to bend
spring to one side and not to raisa it longer than necessary). Now ched:: th at the cor-
ban brushes can easily be moved in their gui des in the brush holder.
The cor
ban brushes and brush holders must be kept free of dust, oil and gr ease. If
th ese paris are dirty or jam, they should be cleaned with a clean gasoline-damped
rag (not with waste wool, as this easily sheds fibres) and well dried.
Do
not sand p aper, file or use knives on the bright ground surface of the corban
brushes. Blowout the brush holders well. If a carbon brush is broken, unsoldered or
so worn thol lhe spring or the soldered-in strand in the brush is in danger of striking
aga in st the brush holder, then it should be replaced. (Use only 80SCH corban
br ushes.) When filling th e corban brushes, core should be taken that the spring does
not strike agains t the brush.
When fitting the cover strop (2, Fig. 61) of the sliding pin io n starter, core should be
laken to ensure that the locking clasp lies on the middle of a web; the sealing strip
gl
ued inio t he strop should clo se lr fil everywhere.
When fitting Ih a cop (2, Fig. 62) a the inerlia pinion type storler, core should be token
10 ensure t hat the ar matu re shaf t is sea ted correctly in the hausinlil and that t he carbon
brushes ore in close con t act with Iha commutator. Fit compensa ting washers and fuse
and screw on cop (1, Fig. 62).
The carbon brushes should 01 a ll events be renewed when the engine is given a gene-
ral overhaul.
Commulator
The c ommutator should have on even, grey-block surf ace, and must be fr ee of dust,
oil
and gre.ase. Soil ed commutators should be cleaned with a dean gasoline .damped
r ag (not Wit h waste wool) and well dried. Commutators which hove become scored
and eccentric musl be re-turned in 0 suitably eq uipped wor kshop. By no means should
a (o m mutator be worked on with sandpaper or a file.
lubricalion
Bo th bea rings of. the star t er are provided with a self-lubricat in g bearing (Compo.
bush). These bearings must not be Qreased or treated wi th grease-d issolving cleaners.
To i nc r ease their service life, the pinion and the gear ri m should be cleaned periodi-
ca ll y wi lh a brush dipped in gasoline and t he n re-greased (graphite gr ease, e. g.
BOSCH Ftl v 13).lf necessary, remove burrs from gear rim and pinion.
44
Starter faults
Wh en fa ults arise it shol,lld be borne in mind tho t their cause n eed not necessarily lie
with the starte r itse lf , nor in the poor electrical connection of the vehicle earthing
points, but olso in the fuel supply. The following remediol hints ore limited to the
actual
sta rter system.
A. When the ignition is twitched on ,
the armature s haft does not rotat e,
or only slowly:
I. Bollery exhausted .
2. Battery defe(tive.
3. Battery te rminals l oose, oxidized,
earth (onnection poor.
4. Starter brushes or terminals have
gr ound (ontoct.
5. Carbon brushes of th e sl arier do not
lie
on the commutator, are jammed
in their guides, are wor n, broke n,
oi l- sm e ar ed or soiled.
6.
St ar ter swit ch damaged (p orts loose,
so
that switch is not o n, burnt out ).
7. Ma gnetic swi t ch of st ar ter damage d
(on
ly with solen oid-controlled
star ter).
8. Loss of cu rrent in l eads too great,
le ads damaged, lead connections
loose.
B.
Armature rotat es, bUI pinion does
not engage :
1. Pinion soiled.
2. Burr on pinion or gear rim.
C. When the ignition is switched on ,
the s larter ormature rolates until
the pinion connect"5, then stops:
1. Battery insufficient ly charged.
2. Pressure of carbon br ushes
insufficient.
3. Mag nelic switcn of starter (only
with solenoid-controlled starter) not
in orde r.
4. loss of current in leads too great .
D. Startor keeps running after switch
is released:
1. St ar t er switch do es not swi t(h off or
magneti( swit ch (only with solenoid-
controlled starte r) sticks.
E. Pinion
does not dis engage after
engine statl$:
I. Pinion or flywheel toot hing badly
soil ed or damaged; return spring
weak or bro ken.
45