Sachs SA 340 - Page 21

Initial adjustment
Jet adjustme nt sh ou ld first be done when the engi ne is cold. Proceed as follows:
Close both jets and open the adj ust ing screw af the main jet and th e adjusting s cr ew
of the i dli ng jet a gain to the val ues given in the carb urettor char t (see technical d ata ).
Turn the idli ng adjustment screw so far back that it is no l onger in co ntad wi th t he
bu tt erfly valve lever; then turn the screw in again about one who le turn , so that the
butterfly valve is slightly open .
Now star t the e ngine and a ll ow it to warm up (open the choke as soon as the engi ne
starts up).
Final
adjust m ent: see section "Tes t-running the eng ine ".
Maintenance of the carbureHor
At certain intervals every carbu r ettor must be disassembled, cl eaned and overhauled.
A ll ex terior dirt sh ou ld be cl eaned off with gaso line before disamssemb ly . The holes,
ducts, passages
and jets must not be cleaned wi th hard objects (e . g. wire or drill), but
should only be rinsed wi th gasoline and clea ned wit h compressed air (remove dia-
phragms before blo w in g t hrough). Befor e assembly, check that all car burettor com-
ponents (especially jet sea ts and diaphragms) are in proper work ing order.
Checking and cleaning th e fuel fi lt er in good ti me helps to achieve satisfactory
functionin g of th e carburettor and l onger eng ine service lif e.
Special maintenance instructions
1. If pump failure occurs, always check (before removing the pump diaph r ag m) the
impulse pipeli ne for l eakage and blockage.
2. Wh en fitting th e in let cont r ol l ever and the compression s pr i ng (see illust ra tion),
take care th at both ends of the spring are be dded in the spri ng seat s.
3. The compression s pring must
not be stretched, as the spring
pressure is accura t ely adjuste d
to the carburettor.
4. The inle t contro l le ver is cor -
rectly inser ted when it is at the
s am e level as th e bottom of
the diaphragm chamber (see
arrow on illustration) .
5. The
inlet needle s hould close
just
when the inlet contro l lever
is flu sh wit h the bottom of the
chamber. If not , th e lever
should be adjusted by bending
it a little (on the inle t needle
side).
6.
Wh en assembling th e carbu-
re tto r, make s ur e that main Fig. 27
diaphragm, gasket and casting
of the housing ar e car ef ully in-
serted
in to the east -on cente-
ring pins; si milarly, the gasket ,
fuel diaphrag m and fu el pump
body are adjusted by means of
the same kind of centering
pins.
The gaskets at both dia-
phragms are in eac h case
posi ti oned on that si de of th e
diaph r agm which faces t he
carburettor housing.
F" &S t.. J(L151
21