Evolution EVOE10GX Mode D'emploi page 13

Low-Speed Needle Adjustment
If you have properly set the idle need, the
low-speed setting should be within 1/16th of
a turn from perfect. Remember we are talking
about minute amounts of fuel going through
the carburetor, any adjustments you now
make to the idle needle should be very, very
small.
Take into consideration the length in service
(e.g. break-in time) and the size of propeller
you are using. In the beginning using a small-
er propeller, early in the break-in process, you
will not be able to achieve an idle much below
2800 rpm. The larger the propeller, the lower
your idle rpm will be, and the more broken in
your engine is will allow a lower idle rpm (13 x
6 should be about 22–2300 rpm).
Your engine will idle at low-speed needle set-
tings from far to0 rich to far too lean without
any damage so the quality of the idle is not
a good indicator of the proper low-speed
needle settings. The transition from idle to full
throttle will be used to determine the position
of the low-speed needle.
1. With engine started and warmed up, open
the throttle fully then reduce to idle and
note the rpm. Listen to the engine.
2. Let the engine idle for ten seconds and
then rapidly advance the throttle to full
open. One of three things will occur:
a. The engine responds instantaneously.
Your low speed needle is set perfectly.
Now use your throttle trim to achieve the
lowest reliable idle.
b. The engine slowly accelerates to full
throttle. This indicates the low speed
needle is set two rich and that fuel is
building up in the crankcase. Shut the
engine off and lean (clockwise turn)
the low speed idle screw by an amount
equal to the thickness of the screwdriver
blade you are using to make the adjust-
ment. Restart the engine and repeat
steps 1 and 2.
c. The engine stutters or stops on it way to
full throttle. This indicates the low speed
needle is set too lean. With the engine
off, richen (counter-clockwise turn) the
low speed idle screw by an amount
equal to the thickness of the screwdriver
blade you are using to make the adjust-
ment. Restart the engine and repeat step
1 & 2.
3. Once you have achieved the instantaneous
throttle transition your low-speed needle is
set perfectly. Now go back and recheck your
high-speed needle valve setting. There is
some interaction between the two needles
so you might need to do this process (HS
and LS needle setting) a couple of times.
Patience here will reward you with an easy
to use engine. Don't try to do this too
quickly.
4. Once you have achieved the instantaneous
throttle transition your low speed needle
is set perfectly and you should never have
to touch it again regardless of the propeller
you try to use.
EN
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