electric starter problems…

Hey everyone, I hear this is the place to come for Honda discussions. Ive got an ’84 atc 125m. It was starting fine till after one winter, the starter solenoid would just buzz, so I thought it was shot so I replaced it. Well the new solenoid is doing the same thing. So I’m wondering what exactly does the CDI box igniter do? And the 12 volt regulator/rectifier? The battery is well charged and it starts if I pull start it. I’m just trying to figure this out, any thing helps, Thanks, Ryan.