Stops accelerating

Hey guys, I have a piaggio fly 50 2stroke scooter. It had some problems and i fixed them but i cant fix this one. When I reach high RPMs my scooter just stops accelerating and for a few seconds it like cool-downs or something. I changed the carbureator but the problem isnt gone guys im begging you for help its very important to me i’d be very thankful!! Pls🙏