Fwiw, I have a pair of .46AX's in a twin, and I've set a few for newbies. When new (or after removing the needle), most OSes seem to do well with 2.5 turns out. That almost always gets you rich, but not so rich that the engine won't stay running. Just a datapoint. My .46AXes, on a side mount, with APC 11x7 props, OS #8 plugs and Omega 15% fuel, at about 300ft above sea level, I set them at 2 turns to start with if I have to remove the needle or something (like taking off the cowls for maintenance).

The exact needle position will depend on fuel, air pressure, humidity, prop, and so on.

Personally, I'm not a fan of running an ABC/ABN/ABL engine really rich for any amount of time. Running the piston/liner fit really cold just wears them overly fast, and you don't get as much power as you otherwise might (though for a first engine, loosing some top end RPM is probably not a big deal). You don't want to run lean either, since that results in too much heat in the conrod ends, and can destroy the engine if the conrod seizes and breaks.

So, I like to mount a slightly smaller prop (I used a 10x6 on my .46AX). A smaller prop means less load on the engine and less strain on the conrod.

Then run the engine so that it's just breaking in to a clean two-stroke whine. No idleing, it's start engine, go to full throttle, set needle (slow lean until clean two-stroke noise is heard), count to 10, kill engine.

After the needle is set, I don't touch it for a few runs, just let the engine cool down, then run it again for about 20 seconds. Then 30 seconds. After that, I'll do some of the RPM cycling in a longer run, using the needle only. Lean it out to almost peak, then back it off, then lean it out, then back it off, but never into that "blubbering" 4-stroking rich setting.

Now, for engines with rings, it's totally differnet. You need to run them really rich for a while, keeping everything nice and cool and well lubricated.

Oh, and fwiw, Evolution engines aren't broken in at the factory, just test run. You can tell they aren't broken in because the idle mixture will often change quite a bit over the first few tanks of fuel, and all the parts work together. You often have to lean out the idle a bit, sometimes you have to remove the limiter to get the low end lean enough (I took the limiter off my Evo .46, and off of several students' engines to get them to transition with out sputtering).