Ok Dag des nouvelles pout ton probleme vopila la photo c,est le gouverneur, il a pour mission de donner plus de torq quand le moteur en a besoin ex: si tu tombes dans un gros banc de neige alors le moteur va rouler plus vite pour pas qu'il etouffe si celui si est mal ajusté ben ton moteur va etouffé dans ton cas c,est ce qui se passe. Pour ajuster un gouverneur Briggs voici un texte anglais pour la procedure
In order to adjust a governer you must first know how it works and weather or not it need adjusting.
When you put the engine under load the governor should advance the throttle perhaps to full depending upon the extent of the load. The governor is two flyweights that move out due to centrifugal force and pushes against a spring that is connected to the throttle linkage. You should ,for sure, see the throttle linkage move by the governor when going between no load and full load. That might be hard to see directly on some engines. If there is no movement it could be that the flyweights are stuck or the little thimble is frozen on the shaft it rides on. Before you start the engine the throttle linkage should be holding the CARB at full throttle and when the engine starts the governor will close off most of that throttle to run the engine at a reasonable no load speed by the centrifugal force acting against a spring on the throttle linkage. When you advance the throttle manually you are only changing the tension of that spring which the governor pushes against. If the governor ISN'T working for some reason you could expect a radical change in speed between no load and full load. If the engine is running at a reasonable speed at no load and the governor is stuck you could expect the engine to bog down and almost quit when a load is applied because the governor can't advance the throttle to maintain constant speed in the face of the increasing load. So let us know if you still think that your govoner is the culprit and needs adjusting.
Si je ne l'ai pas, c'est que je n'en ai pas besoin!