Horizon Hobby LOSR1900 Manuel D'instructions page 24

PRE-CARBURETION
Correct carburetion of a car model engine requires patience
and engine knowledge. Continuous
incremental adjustments contribute to your experience and
ability. Internal combustion engines are indeed difficult to
tune; if you have persistent problems or don't feel confident,
don't hesitate and ask your retailer for hints and suggestions.
CAUTION: adjust only one needle at a
time; tune
incremental adjustments. As you get closer
to optimal performance, use 1/12 of a turn
for incremental adjustments of the needles.
Start and get the engine warm. Keeping the model stationary
and secured, follow this procedure to adjust the needles:
To adjust the top end needle: fully open the throttle.
•
The engine should reach 80% power and stabilize. If
the engine RPM rise too much, close the throttle and
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trials and small
the engine with small
open the top end needle
the procedure till you achieve the best result. On the
other hand, if the engine is flooded and makes a
deep-toned roar (like a four-stroke engine), close
the top end needle turn at a time until a good
result is achieved.
To adjust the idle: open and release the throttle. If
•
the engine stalls, tighten the idle screw until the
idling is stable. On the other hand, if the idling is too
high, loosen the idle screw until you reach a
constant idling.
To adjust the bottom end: fully open the throttle
•
and release it quickly. If the engine idles for 2-3
seconds and then the RPM further decrease, the low
end is too rich. Close the low end needle in small
increments until the idling lasts for about 10-20
seconds. If the engine idles for 2-3 seconds and
then the RPM suddenly rise, the low end is too lean:
open the bottom end needle in small increments
until the desired result above is achieved.
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turn at a time; repeat