Piaggio NRG with Polini Evo 3 Problem

Hello guys i am new here , i have a big problem with my piaggio nrc mc3 (AC) , i bought all necessary parts for this project
-Polini EVO 3
-RMS Racing crankshaft
-Top Performance woodruff key
-Yasuni C20
-Carb 24MM pwk ( main jet 120)
-Malossi cluch ( MHR Spring 10kRpm)
-Malossi reed
-Malossi multivar 7,2g
-Athena racing pink spring
My problem is when I accelerate he stuck at 8kRPM for 3 seconds and then it raising very high rpm 12kRPM and barely moving only with 3 roller (15g) , I tried with (20g) 4 roller but it stuck at 8kRPM , what can I do , please help me !!
PS: I'll buy blue contra spring from malossi and 6 roller 3,6g malossi .