piaggio nrg max rpm/ rev problem

[jamesrs250]

my mate has bought a nrg non runner which i have go running.
i assume it is restricted because it has a standard exhaust and very quiet.
when the bike is on the stand and i rev it full throttle it will rev up to 8,000 rpm then drop down to 6,000

is that normal ?

and also i can hold the bike back and rev it and the bike will not have enough power to pull me forward,,which would probably be the belt or clutch slipping ?

cheers james