Horizon Hobby Evolution 152GX, User Manual

Page: 10 / 16

10
Having started the engine, leave it running for about 5 minutes at a higher idle speed. Then run it for about 20 minutes, while changing
revolutions from idle to 1/2–3/4 of the range and shortly holding each position—gradually prolonging the holding periods. After 10 minutes
of operation, open the throttle to maximum for a period of about one minute. At this point, stop the engine and let it cool down. Then restart it
and check the adjustment. If everything is all right, you can make your first flight. During the first few flights, do not overload the engine and
do not let it run at high revolutions for long periods of time (very important during hot weather). Use up all the fuel that was mixed with the oil
that is included with your engine. From then on, fuel and oil should be mixed in the proportion 40:1.
First, start and warm the engine for 30 to 45 seconds before attempting to adjust the carburetor. In order to confirm that your engine is
properly adjusted you should follow the procedure below.
1) Move the throttle from idle to 2/3 of the full throttle position quickly (fast acceleration). Then repeat three times – if the engine accelerates
smoothly, go to step 3 below. If acceleration is not smooth, go on to step 2.
2) Faulty acceleration and a tendency to quit is usually attributable to a poor fuel mixture in the medium rpm range. Stop the engine and
recheck the fuel feed (the fuel line must not be pinched or broken). Restart the engine and test acceleration again. If the problem persists,
adjust the carburetor. Open the low speed needle by 1/8 turn and retest. If acceleration is smooth, open the needle by another 1/8 turn—this
should be done because the needle was previously set too lean; if atmospheric conditions have changed recently you may have to readjust
the needle. If the engine continues to not accelerate properly, open the low speed needle by 10 minutes. If the engine’s operation does not
improve, shut it off and check the basic setting, restart the engine and test the acceleration. If the engine runs correctly, go to step 3. If
it continues to not accelerate properly, open the low speed needle by another 10 minutes. If acceleration is faulty, the defect is likely to lie
somewhere other than an incorrect adjustment.
3) If the engine accelerates correctly, according to the above test, set it at idle speed and accelerate to full speed. Repeat twice more. If the
engine functions correctly, go to step 4. If it cuts out, open the low speed needle by another 1/8 turn.
4) If the engine reacts correctly, set it at full speed. If revolutions do not drop, the engine has been adjusted successfully. If revolutions seem
to drop, open the high-speed needle by approximately 5 to 10 minutes.
Caution! The engine must be stopped while you adjust the carburetor in order to prevent injury by the propeller.
Starting the Engine
Continued
Carburetor Adjustment