Your tunning method sounds wrong to me.

If the engine overheats, it will tell you dropping the power, and behaving bad. There are some engines that may run hot and aren't overheated, and boil water instantly.... Listening to the engine, it will tell you if it is doing good or not!! temperature is affected by many factors and in plane engine is in general meaningless...

If your engines doesn't transitions well in an air bleed carb, that's why you have an air bleed screw...you find the max rpms with the high speed needle, then a couple of clicks back to drop rpms about 300rpms to compensate for a lean run in the air.... on idle, if it tries to die when you throttle up, then screw in the air bleed because it is lean, if it sputters and throw much smoke, then you have to unscrew the air bleed screw... you'll find a compromise there.

The mid range should not be set adjusting the high speed needle, the high speed needle is for setting the peak rpms!!


Saludos,

Jorge