Piaggio Gilearo Runner 50 SP Don’t jump on

Good morning The ca 2 year old scooter Piaggio Gilearo does not start. “Baster” have tried to haircut this scooter, which probably did not work. (piston eater etc.) Now of these hobbyists a new piston, cylinder & cylinder head was mounted. After various start attempts they have given up. Controlled I have : 1. spark plug (new ) 2. spark is there (but very weak ) 3. carburetor; fuel arrives ( was however after 40 x start off off; crankcase half 4th carburetor, gaskets, valve looks all optically good 5th battery is new, and charged 6th When spinning through with Kickstarter Compression is noticeable After drying the candle and starting with Startpilot no success. Maybe someone has any idea what it might be. Greeting, Thomas