I had an XYZ 50 that had the blue plastic cased ignition. Even on 2.4 it had a lot of RFI. The surfaces jumped erratically at high throttle. A cheap fix for troubleshooting is to wrap the ignition with a formed tin can(not the aluminum type, but the magnetic type.) and ground it to the motor case somewhere. Swapping a good CDI in is probably an easier troubleshooting attempt, but I just wanted to see if it would work. Of course, the more costly fix is to buy a new ignition.