The trigger coil is the small coil above the source coil. Its placement and lower voltage output is about the only thing to do with timing.
The source coil send high voltage and stores it in a cap, typically 1uf to 1.5uf. The trigger coil activates an SCR thyristor which let's the cap dump its stored power into the ignition coil.
The time it takes to store the power in the 1uf cap can determine top end ignition timing. There's another cap that helps determine the lower rpm timing.
Most ac-cdi's will probably interchange.
In the case of the tecate,you could use the source coil as a trigger coil. The downfall is it's harder to control the voltage. The source coil on some machines can push 300+ volts. The trigger will push 5-12 volts.
Based on this theory, I should be able to use a yt175, or a blaster cdi.
I just wanna go fast. If your not first, your last!!
Reproducing the Tecate CDI. Contact me if you need one. I'm most accessible on FaceBook. You can find me on the 1984-1987 Kawasaki Tecate KXT250 Group.