Primavera/hp 4 flywheel

I’m asking some stupid question, but I’m new with scooters:
I have primavera with full-circle crankshaft, malossi 136, et3 stator and flywheel. The motor hasn’t been tested yet, but the flywheel has been lightened and i have the impression that it will break. What about the hp 4, is it a good alternative? Someone told me that there might be problems with idle?
If I choose the hp 4, where do I have to take the measure of the cone?

Yes,the cone will need to be compatable with the crankshaft.

Personally I don’t like HP4’s,I’d stick with the lightened origional.[;)]