Well then IF YOU DID NOT CHANGE ANYTHING and it was running and then QUITE then one of the following went bad. 1. plug 2. Boot Cap 3. COil wire 4. COIL 5. CDI 6. Pick up COil 7. Stator feeding the CDI (cause no battery) 8. Ground motor to frame 9. Killswitch is grounding out the CDI.
The stator does a few things: 1. Feeds the CDI IF it is a AC CDI. 2. Feeds the Regulator/Rectifier which in turn charges your battery and some lights.
So yes it could be bad.
But you need to find out which kind of stator you have? If you have a PICK UP COIL that sends a signal to the CDI to fire you need to test that and see if it registers .25 -2.5 VAC if so it is good if less than .25VAC the pick up coil is bad.
And i test that by using the blue/yellow that runs from the stator to cdi? I was also told to test the cdi.. I i leave the stator wire and the ignition coil wire in the cdi and connect the positive of the batt charger To the cdi positive and and the negative To the cdi negative