I have had this problem for quite some time with 3 different engines. Brillelli 50, CRRC 50, and 44cc stihl conversion. 2 different planes, one Yak and one seagull bling. 5 different carbs. One of them has the nipple soldered on the plate and a hose run into the fuse. They run fine on the ground, good transition, good idle, strong top end. When flying and cut it to idle, it will quit after a few seconds. if you try to get it to recover before it quits its like its lean, but richening the low end didnt help. I have tried tuning all of them as per two different threads found here on RCU. I'm sure i'm doing something wrong. I just cant figure it out. I have tried to make both needles richer and leaner. I posted this problem a few years ago and never did get a fix. Please you gurus like PE, Tired old man, Ralph, and Bob help me figure this one out. You guys are top of the food chain for gas engine knowledge. Any ideas would help