I'm on my last effort before selling my YS FZ 120 and I want to make sure I have everything covered. I am having idle problems and have sent the engine back to YS but they say there is not a problem with it. I have checked fuel lines and tank and have not located any leaks. Hoping that the settings they had the engine running with would be a good starting point I did not touch the idle or pressure adjustment. Starting from fully closed on the high speed needle I came two and one half turns out. At full throttle I turned the high speed needle in until 9500 rpm was reached then backed off to about 9350 / 9400 at top end. I came back down to idle and the engine was running high 3000's so I trimmed down to the point shown in attached image and did achieve a 1950/2070 idle. Now after coming from full to idle the engine idles at 1950 /2070 and sounds like its about to die then it slowly creeps back up on rpm in the 2500 /3000 range. It will then drop back down in the 1950/2070 range but will not idle reliably. It stops running sometimes. Can anyone tell me by looking at the attached image if the opening I have set is sufficient or do I need to make adjustments here and then compensate with the idle screw?

Don't worry about the idle screw. Set the transmitter up so the high trim is a fast idle and low trim closes the barrel completely and kills the engine.
Don't try to idle it below about 2300 rpm.
It is too lean on the regulator. Rotate the reg. screw counter clockwise 1/2 turn and let me know what happens.

THE REGULATOR SCREW DOES NOT CHANGE PRESSURE!

Did what you said and after going from high to idle it will almost die then raise back up to 2800 / 3100 range appoximately. It seems to stay there. If I ever cut the throttle in the air in that state it is most likely going to die. So i tried setting the trim higher so that lowest end, where it almost dies is a bit higher. What happens then is when it raises back up the idle is way to high. Turning the regulator screw out 1/2 turn like you said puts it above being flush with the housing. I'm not questioning your setting just letting giving you an idea of where it was when I recieved it back.

It doesn't matter where the regulator screw sits in relation to the housing when you reach the final correct setting. Flush with the casting is just the starting point and it will get adjusted from there. We are at 5000 feet here, and anything set here will be too lean at sea level. from the info you are giving me, it is still too lean.

By the way, what fuel are you running?

Im running Wildcat YS Blend 20/20. So come out another half turn? We are at 180 feet.


Edit:
I have been out 2 full turns total from where I started, using half turns each time and trying quarter turns as well. Same results. Engine idles below 2000 after coming from full throttle and if it don't die it raises back up in the 2500/3000 range. Sometimes it stays at that high rpm and sometimes it might idle back down slowly and then die. I removed my fuel lines and tank and checked for leaks and all is fine there.

Edit:
I'm spent. I have had the engine now for a month and its had more fuel run through it on the gound than it has in the air. The only good thing I can say about this engine is that it might get a Saito 180 in swap.

It is still acting lean, but why not try going the other way. You have nothing to lose.
If all else fails, try another brand of fuel.

Lesson learned. I should have taken notice from others who warned me against it.

Good Flying!