my speedf2 50cc dies down on revs?

my scooter bogs down on revs..
im running a 19.5mm polini carb
size88 jets
stage6 70 kit
tecnigas next-R pipe
5.6g rollers
PM tuning foam filter
could someone please tell me what their clutch springs/rollers/jet set up they have with a similar spec to my scooter?
or maybe just tell me what could be wrong with the scooter, I'm thinking jets but I've tried a lot and the same thing is happening