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OPERATION No MA. 142-O :
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f/a<, rarhnrt,//or
Op. MA. 142.0
1
ADJUSTING THE IDLING SPEED
To carry out this adjustment,
the following
is needed
A tachometer
A device
lor checkinq
idling
speed
adjustments
on the carburettor
( or on approved
gas analyser
)
- A CDA 23 checking
oppmotus
or a workshop
test bench
( equipment
mentioned
in the Equipment
and Repair
Materials
list,
or in the Tools
and Equipment
notes
green notes
)
NOTE
: WEBER
Carburettors
ref. No W 54-50,
55-50,
69-50,
74-50
fitted
on 1977 models
onwards
ore fitted
with
a
fool-proof
plug ( white
) on the mixture
screw.
To adjust
the exhaust
emission,
this plug has to be
removed, and
replaced,
after adjustment,
with a a Repair
PI plug ( black
). See Op. MA, 142-000
for removing
and fitting
the plug,
and the necessary
tools.
ADJUSTMENT CONDITIONS
1.
The idling
speed
adjus!ment
must be carried
out on an engine
on which
the rocker
clearances
and the ignition
are correctly
set. with a clean
air filter
and
with the engine in good order.
2. Check that the butterflies
return
fully
to their
stops.
3. 30 not let pnythinq
except
the ignition
and the engine
cooling
fan ( or ions
) impose
any load on the alternator.
4. Run the engine
to bring
the
oil temperature up to 70 to 80' C (
wait for the electric
cooling
fan ( or fans 1 to cut
in 1.
I. M 20/616,
M 22/617,
M 23/623
ENGINES I i< ?I< (5 wi/hr ,111 /or<,,,< co,1, <,r,cr or air ro,,di/io,ii?,g
I
,I '-/
1. Wait for the electric cooling fan ( or fans ) to cut in.
2. Adjust
screw (3)
controlling
the first
choke
butterfly
opening
until
the following
result
is obtained
: an idling
speed of 850 to 900 rpm.
3. Slowly
adjust
mixture
screw ( 2) to obtain
the following
result
1.5 to 2.5 "/ of CO
1
7h~se
authoris<,</
wadings
correspond
to a,,
8.7
% or more of CO2
nmbiot~l
I~mpcuatur~
0i 1 Y to 30" C.
4. Adjust
screws
(3 ) and (2 ) so that both the idling
speed and the quantity
of CO and CO 2 me correct.
Make sure that mixture screw (2) is adjusted last
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