High-Speed Needle Tuning; Low-Speed Needle Adjustment; Low-Speed Needle Tuning - Zenoah ZENEP20 Mode D'emploi

hIGh-SPEEd NEEdLE TUNING

Once the engine is running reliably at full (open) throttle:
1. Turn the high-speed needle clockwise 1/16 of a turn at a time.
2. Wait 2–3 seconds for the engine to respond.
a. If there is an increase in RPM: Turn the high-speed needle clockwise an additional 1/16 turn and wait
for the engine to respond to the tuning change. If there is no increase in RPM after the change, turn the
high-speed needle back to its previous position.
b. If there is a decrease in RPM: Turn the high-speed needle counterclockwise 1/8 turn and wait for the
engine RPM to stabilize.
3. Repeat Step 2 until you determine the maximum RPM with the fuel and propeller you selected.
4. Enrich the high-end fuel mixture by turning the high-speed needle counterclockwise until the RPM is
200–300 RPM below maximum. This will allow the engine to achieve proper fuel mixture during flight.

LOW-SPEEd NEEdLE AdjUSTMENT

The low-speed needle adjustment controls the fuel/air mixture at idle and the quality of the transition
between idle and wide open throttle.

LOW-SPEEd NEEdLE TUNING

1. Adjust the high-speed needle for the current conditions.
2. Allow the engine to idle for 10–15 seconds. Rapidly advance the throttle from idle to full open.
If the engine transitions with no hesitation, the low-speed needle is adjusted perfectly.
If the engine slowly responds to throttle change and gradually reaches peak RPM, the low-end fuel
mixture is too rich. Turn the low-speed needle clockwise 1/16 turn to lean out the low-end fuel mixture and
test again.
If the engine stops running, the low-end fuel mixture is too lean. Enrich the low-end fuel mixture by turning
the low-speed needle counterclockwise 1/16 turn and test again.
3. When the low-speed needle adjustment is correct, check the high-speed needle setting again.
4. When you are satisfied with the needle settings, you should not need to adjust the mixture needles again.
The best indication that your engine is tuned properly is the color of the spark plug when you remove it from
the cylinder. A nice, dry, tan color is an indicator that the fuel mixture is correct and burning well. Wet plugs
or carbon deposits generally indicate that the engine is running too rich. If the spark plug has a white or gray
appearance, you are running your engine too lean.
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