First off, you need load on your engine. You should really mount it in your heli, or at least mount a propeller on it - that size engine would probably take a 10/6, but still the best is to mount it in your heli. Perhaps you did this already?
The first thing that is critical with all ABC engine is proper heat cycling when breaking in as you know from the instructions. With no load and if you didn't have a propeller installed for air cooling or have the engine in the heli for fan cooling - I am thinking you might have done considerable damage to your engine already. If you had a cooling source and load no problems. There are many ABC break in procedures - I am now a full believer in breaking in an ABC engine just on the slight side of rich, not super rich as has been the long standing normal procedure. Run them for 5 min at varying throttles and then let the engine cool right down - increasing the run times and the high speed throttle durations during the break in procedure and slowly leaning it out. The whole idea is to get proper heat cycling to expand and contract the piston and cylinder for a 100% perfect running fit. If you are running rich and cold, this will not happen to the same extent. Since using this hotter needle method in my nitro cars, my ABC engines have huge compression and last for years.
I personally feel, a ringed engine in a heli is a better long term choice, but that is just my own opinion from 20 years of flying.
Once you get the break in sorted out, you will want your heli to run just a bit on the rich side and set your idle needle mixture screw so when you pinch your fuel line closed at idle speed, the engine will continue to run and then speed up and die in about 4-5 seconds from when you pinched off the fuel line.
These are good base settings, but things like fuel used, altitude at your location, and specific bird set-up will alter these settings. If you have an air bleed screw in your carb (forgive me, I am not 100 % familiar with the Irvine 39 ABC heli engine) you can further improve the carb settings. The air bleed is used to set your idle, your idle mixture is used to set your mid range, and your needle valve to set your high end. This (3-setting) carb adjustment method is ideal for nitro helis because you no longer have to have your idle mixture set super rich to compensate for lean mid range.
Hope that Helps,
H.H.
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