Luizinho,


From the molted color of the cylinder head, your engine appears to have been run a bit too hot, although this is no cause for immediate concern.

It is definitely the new engine, with the new carburettor. This means the starting setting is 2 mm from the nut.
Adjustments are done in single clicks; not in 1/4, or 1/8 turns. The adjustments for this needle are very fine and 1 'click' out from the ideal setting, could mean a dead-stick landing, or worse, for a low flying 3-D model.

The header that you have appears to be the medium length variety.
You should extend the distance between the header and the silencer to 15-25 mm, for the 12.25x3.75 prop.
And also turn the silencer around itself, to minimize the bend in the silicone coupler.