Hi,
First of all thanks for your replies! I appreciate your effort to try to help me.

These are the symptoms of the engine,

The engine is very difficlt to start (I use a chicken stick and the last time I tried it, a new glow plug was installed)

The idle usually is ok
On full rpm, once I find the appropriate rich/lean setting, is also ok

Transition from low to high revs is not always perfect.
The main problem of this engine is to start it, and that after a flight or 2, i need to set it again for optimum transition. (I am sure that the screws are not turning by vibrations, because I marked their position before the flight and the screws remained the same)

And what I meant when closing the carb intake, is that I close it with my finger, so I am sure that air is not going in, and still it takes too long to go off.