Hello dear community, after a longer service life in the outside under the balcony of 5 years of the Aprilia SR50 with Morini engine (carburetor model) I wanted to make my scooter fit again. The old piston had a screw, then I decided recently to install a 70cc set of Airsal. I installed everything correctly. The scooter had exactly 2.3 bar compression before the cylinder change and after the cylinder change (complete kit). The engine block has never been split. The carburettor was renewed (dellorto 17,5). And the shaft sealing rings Vario-side and Lima-side were renewed. The engine does not generate enough vacuum to suck in mixture. The candle stays dry. If I pull with the mouth on the vacuum hose, then the fuel runs into the carburettor. I already let it run full, but that didn’t work, because the vacuum from the crankshaft housing is simply not enough for the Gemis When I kick then no fuel runs through the petrol hose. I’m really at a loss. I can run it for a few seconds with the start pilot. It rotates for a short time and then the speed increases immensely. So it has to pull out some wrong air somewhere. I hope you can help me. Thank you very much! Greetings MPowerr