I've got a Sirio .12 5-port (older version) in my G4 and it flames out continuously at the exact same spot on the track. It's at the end of a 270 degree left sweeper at the instant I let off the throttle to make a right hairpin at the end of the left sweeper. Dies almost every time. No other place on the track does it do this, right hand sweeper, hairpins, chicanes, etc..... At the other end of the track there's a right hand sweeper followed by a hairpin and it has never flamed out there.
The engine has a Nova carb on it because my Sirio carb had the air leak problem but it never missed a beat when switching carbs and I run at about 230 degrees on Wildcat 20%.
I'm stumped and it's about to friggin' drive me crazy!