What carburetor does a piaggio NRG MC3 54 Reg Have Whats The Model?

I need a new carburetor for my piaggio nrg MC3 54 reg because i think its broke because it seems sometimes when im driving that it will suddenly slow down when i rev the throttle after slowing down to quick it ive had the bike to bits and seems to be like its gasping for fuel but its got a full tank ive cleaned it all out and changed the belt and the rollers