i have the same system.. i think. i looked through my manual for you, it says nothing about AC or DC. and when i went to buy a coil i had no choice also. it just had my bike model and the coil for it.
i would think with no battery its AC. i have a cadet 100 with a 6v system and no battery and this is the coil i use. AC
https://www.domiracer.com/comersus/s...Product=123895
i re-read the description, it says for a whole bunch of bikes listed and "for bikes that dont have a battery"