Horizon Hobby Evolution Radial Glow E777 Manuel D'instructions page 9

Engine Tuning
The break-in settings for the carburetor needles are:
High-speed needle:
Tip: For the initial break-in, open the high speed needle to 1-1/2 turns before starting.
Low-speed needle:
Use a tachometer (HAN111 or HAN156) to tune the engine based on RPM.
WARNING: Always adjust the carburetor from behind the propeller. Keep all loose
items away from the propeller at all times. Never reach over or around the propeller.
1. Start the engine.
2. Move the throttle stick up until the engine is running at approximately 2,000 rpm.
3. If you are using separate exhaust pipes, use a temperature gun to make sure hot exhaust
is exiting all engine cylinders. If using a collector ring, make sure that each cylinder is of
a similar temperature to the others, indicating that it is running.
4. Move the throttle stick up to full (open) throttle.
If the engine runs rough or if some cylinders are not operating, the fuel mixture is too rich.
Lower the rpm to approximately to 2000 and lean the high speed needle valve by 1/8 of a turn.
5. Repeat Step 4 until the engine is running reliably at full (open) throttle. Proceed with the
break-in process described above.
High-Speed Needle Tuning
Once the engine is running reliably at full (open) throttle:
1. Lean the high-speed needle 1–2 clicks at a time.
2. Wait 2–3 seconds for the engine to respond. Radial engines do not respond immediately
to tuning changes.
a. If there is an increase in RPM: Lean the high-speed needle an additional 2 clicks 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: Richen the high-speed needle 4 clicks 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. Richen the high-speed needle until the RPM lowers approximately 10% of the maximum
RPM (Example: If the maximum is 6,500 RPM, richen the high-speed needle until the RPM
drops to 5,900 RPM). Richening the high-speed needle allows the RPM to increase when
the airplane is flying. Further adjustments can be made after flying the engine to fine-tune
this needle position. This is a safe place to start to avoid overheating and an engine
flame-out.
Low-Speed Needle Adjustment
Low-speed needle adjustment controls the fuel/air mixture at idle and the quality
of the transition between idle and wide open throttle.
Tip: The use of an on-board glow driver will hide the effects of a poor low-speed needle
setting. When you are tuning the low-speed needle, turn the on-board glow driver off and
on to check the engine RPM response at idle.
2 1/2 turns open
2 turns open
EN
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