Hello first the history. I bought a Aprilia SR 50 Bj. 2000 very cheaply with air-cooled, lying Minarelli engine. The scooter had a piston eater. The reason was that the needle bearing has disassembled and a part of it has eaten between the piston and cylinder. It was then tried so often to start that the starter freewheel also broke. What I noticed later. I have now installed a different cylinder, piston and bearing. the engine started. It also started very normal for a short time. After 20 sec (more or less) it went out again, and now I can’t get it started. Zündfunke is there. What surprises me, that it doesn’t light with starter spray. I had already thought of a defective CDI. I changed the one for a new one, still the same. I also made ASS new. The only thing that isn’t new is the carburetor and the ignition coil. But even if the carburetor was defective, then I have to But get it with starter spray at least for a short time. But apart from a few false ignitions nothing moves. Has possibly any idea what I could still do. The scooter still gets me done Achja, I even looked again (with Endoscope) the piston is properly installed (arrow down)