Well; test in last weekend resulted negative: Glow plug was not he problem since I tried a OS.8 and a K&B with bar and sudden stop continued... But: I realised the the head of cilinder was too hot, so: Do I have to think that the problem is a small propeller? I can ensure that I was not running lean (nice smoke!!!).
Another sympthom: I calibrated the engine perfectly on high and low; when came the moment of testing "nose up" the high working regime was nicely sustained; when I lowed the trottle (keeping the nose up atitude) and tried to accelerate again sudden stop showed up!!!!! Do I Have to think that the muffler (bisson pitts) does ot pressures the tank properly?
Thanks again
Guille