OPERATION No MA. 142-O :
Adj,,s/iaji 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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