Hello, I'm new to the forum and really need some help. Last week I was driving my big bear and everything was working as it should, at the end of the day I shut it off and the starter would not restart the bike, I checked the battery and it was dead. There was good power coming from the stator and the battery was good so I ordered a voltage regulator. New regulator came in and it was charging but letting through to much voltage so it was returned and I got a different regulator from a different company. Now with the regulator plugged in the bike would idle but if you hit the gas it would backfire and stutter and if you let off it would return to idle normally, if I run the bike without the new regulator it runs like the day it came from factory. I plugged in my first regulator that started this problem to check voltage again and now the bike has weak spark and will not start with a booster pack or the pull start.
Any help would be appreciated as I drove the bike no issue with the regulator out with no issues until I started trying to put in the new regulators. Thank you.

 

My guess would be either "power coil" that supplies power to the CDI, or trigger coil shorted onto the main stator coils, either on the stator, or could be just the wires from the power coil or trigger coil shorted onto them.