PARMA-TECHNIK MIKRON III A - 7.6 Carburetter

22
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MIKRON III A
MAINTENANCE
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Appearance of spark plugs removed from a warmed up engine
provides the following information:
light brown to whitish - spark plugs and engine
adjustment OK
velvet black - big spark plug electrode gap
- fuel mixture too rich
- air quantity inadequate £or
combustion
- engine not reaching the
required operating temperature
oily shining - intermittent spark plug ope-
ration
- too much oil in the combustion
chamber
- cylinder or piston rings worn
pearly pattern - low spark plug temperature
rating
- loose spark plug
- fuel mixture too lean
- engine valves leaking
7.6. Carburetter
The JIKOV 40 SOP L is a motor car carburetter modified
for aviation use. It is equipped by a choke for cold
engine starting. The choke replaces injecting fuel into
inlet manifold. An acceleration pump provides for richer
fuel mixture if the throttle is opened quickly. It is not
allowed to change carburetter adjustment elements.
Noz_zles and jets may be cleaned, preferably by means :::>f
compressed air.
Due to engine wear and changes of the operating condi-
tions idle speed of the engine is changing in course of
its operation. Then the idle speed requires adjustment.
Idle speed is adjusted on warm-engine after the ignition
magnetos were adjusted, as well as valve clearance and
fuel level. Observe the following procedure:
- adjust idle speed approximately 650 'rpm by means of the
throttle stop adjustment screw
- turn the idle speed fuel mixture richness adjustment
screw to reach maximum engine speed for the given
setting of the throttle
- decrease the idle speed by approximately 50 rpm
changing the throttle stop adjustment screw settting
- adjust the idle speed fuel mixture richness adjustme.nt
screw for maximum engine speed
- repeat the procedure·· t~ll the engine idle speed is
570 rpm
- turn the . fuel mixture richness adjustment screw
clockwise and anticlockwise to find its positions where
the engine speed is starting to decrease. Set the fuel
mixture richness adjustment screw to approximately ~he
middle of the adjustment range thus found
check the engine acceleration for continuouHly
following the throttle setting
Issued 5/92