140L is new this season. Dave, this is the one that quit shortly after take-off on its first flight in my QQ Yak in March that we talked about. You told me it "quit rich". Plane is rebuilt and the 140L has approx 1 gallon of 20/20 between 5 flights plus break in stand time before reinstallation. 18x6 APC, high end in the high 8k range, nearly 9k. OS-F plug. (2) Craptrap filters - on both supply and pressure lines. Regulator screw is set flush with casting. NMP QQ canister style muffler and header. J'tec iso engine mount.

High end is fine, tuned to approx 150 rpm off peak. Makes plenty of beastly power and flies the plane great. However, when sitting at low idle in the 2000-2400 range, it shakes a lot, as if trying to quit. Getting it toward 2800-3000 and it smooths out. Engine loads up with fuel if idling for 20-30 seconds, which is visible when throttling up. Gets rougher when ni-starter is removed. So, it sure sound like it's rich to me. I need to keep the low idle fairly low, or this plane keeps flying!

Airbleed - I started with the factory 1-1/2 turns out on the airbleed, and have leaned it out to 4+ turns out. I've not had a YS needing to be that far off factory settings unless there was a problem. At 4+ turns out, it's improved enough to be flyable, but still shakes and has some tendency to quit when taxi-ing. Tank pressure is excellent, and retains the pressure overnight, so check valve is working.

I pulled the regulator apart, to make sure there was no debris inside. Plunger, poppet valve/spring, diaphragm, passageways all clean and clear. It ran/flew the same afterwards.

Transition is a bit slower than I'm used to on my other YS engines, and idle is rich/rough. Perhaps the regulator just needs to be screwed in a bit?

Thanks, Dave.