CARBURETTER
ADJUSTMENTS
(2) If the engine speed immediately decreases , the mixture strength of the
front carburetter is too weak.
(3)
If
the engine speed momentarily increases very slightly, the mixture
strength of the front carburetter is correct.
Repeat the operation at the rear carburetter, and after adjustment re-check
the front carb uretter, since
both
carburetters are interdependent.
When the mixture is correct the exhaust n te should be regular
and
even.
If it is irregular, with a splashy type of mi 'fire
and
colourless exhaust, the
mixture is too weak.
If
there is a regular or rhythmical type of misfire in the
exhaust beat, together with a blackish exhaust, then the mixture is
too
rich.
Throttle linkage
Each throttle is operated by a lever and pin, with the pin working in a forked
lever attached to the throttle spindle. A clearance exists between the pin and
fork
which must be maintained when the throttle is closed
and
the engine idling to
prevent any load from the accelerator linkage being transferred to the
thr
ottle
butterfly
and
spindle.
To set this clearance, with the thrott Ieshaft levers free on the throttle shaft
put
a ·012 in. (·305 mm.) feeler between the throttle shaft stop at the
top
and
the
carburetter heat shield. Move the throttle shaft lever downwards until the lever
pin rests lightly on the lower arm of the fork in the carburetter throttle lever.
Tighten the clamp bolt of the throttle shaft lever at this position. When
both
carburetters have been dealt with, remove the feeler. The pins on the throttle
shaft should then have clearance
in
the forks.
Reconnect the choke cable, ensuring
that
the jet heads
return
against the
lower face of the jet adjusting nuts when the choke control is pushed fully in.
Pull out the mixture control knob on the dash panel to its maximum extent
without moving the carburetter jets
-about
tin.
(16
mm.)-and
adjust the
fast-idle cam screws to give an engine speed of
about
1,000
r.p.m,
when hot.
36
PERIODI
CAL
MA
IN
TENANCE
37
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