That broken part of the jet well (the missing piece of aluminum) is going to cause you some problems with getting the bike to start and idle properly. You can fab up something as simple as a sheet of brass or stainless steel in a little half-round shape and fix it to the carb body with a good two-part epoxy. Not sure of any brand names to look for in Europe, but Loc-Tite makes a couple of excellent ones. They're typically one white part and one black part you mix in equal proportions. Allow it 48 hours cure time before putting it into service. Let me make another suggestion, though. Loose your headaches with the carb you have and look around e-Bay for a used YZ450 carb from '05-'09. Get as much of the throttle cables, hot start cable, lever, etc. as you can with it. The throttle cables are different, but they fit right into your throttle grip, and the rest of it is basically a bolt-on. The newer carb will run so much better that you'll wish you had done it long ago.