scooter hesitates on full throttle from stop but then picks up perfect

i have a runner 50 carb version. my old dellorto 17.5 carb was shit so i got a new motoforce one. i have a yasuni r on stock cylinder with a prox piston. 62 main jet, modded air box,polini high speed vario,5.3g rollers,malossi white contra spring,malossi 1000rpm clutch springs,malossi belt,. the ped hesitates to rev from idle, and on full throttle it needs its time to pick up but then it accelerates really well. it reaches almost 11k rpm. i had this problem since day one and it doesnt seem to go away. i was thinking downjetting one or two sizes as upjetting bogs the bike. i installed carbon malossi reed petals and theres no big difference. any idea? maybe pilot jet?