im pretty sure the pista was made by ADLY which is a far eastern scooter and quad manufacturer.regarding the running of it its a fuelling problem or a reed valve or crankseal problem i would say,most likeley to be a blocked main jet though as you say it idles ok saying that a busted reed petal will do that too so check both.i take it the fuel tank has fresh fuel in it if not totally empty it and fill it back up with fresh fuel.
adam bike doctor(of milton keynes motorcycle centre)
January 2011