After full fuelling problem at Piaggio Skipper 125 ( 2-stroke engine ) !!

Hello scooter friends, have a small or bigger problem with my Piaggio Skipper Roller 125 ( 2 clock motor ). Whenever I have filled the scooter and put it there, it presses me or runs after a certain time gasoline on my rear wheel. I just can’t find where the petrol comes from. However, if the tank is only 1/2 or 1/4 full nothing happens at all. I have already checked all hose terminals and connections and also followed up. But it did not bring any success. . Can someone tell me where the petrol comes from ?? Or is this only the case with the currently high temperatures ?? Who has had this before ?? Please write me everything you know. Thank you in advance. Many greetings from Regensburg Klein_Kare Karl-Heinz Klein