[LAV1000]

Think you are right on the CDI grounding issue.
CDI coils have a low primary resistance, maybe rewire your circuit could work.
Not sure about this never used it.
Also make sure speeduino is driving enough current trough the ignitor, 10-20mA.

That is not a good idea, the internal diode will clamp the fly-back to just above the 12V rail which will massively reduce the spark output. Also as the voltage builds across the coil it will push the gate towards turn-off.

Does this apply to the ignition module only ?

[LAV1000]

Kettlekev,
Does your CDI system needs a battery ?
What type of sensor does it use for timing ?

Why this questions ?
Maybe there is a way to use speeduino ignition output to replace your current CDI timing sensors.

[JHolland]

Think you are right on the CDI grounding issue.
CDI coils have a low primary resistance, maybe rewire your circuit could work.
Not sure about this never used it.
Also make sure speeduino is driving enough current trough the ignitor, 10-20mA.

That is not a good idea, the internal diode will clamp the fly-back to just above the 12V rail which will massively reduce the spark output. Also as the voltage builds across the coil it will push the gate towards turn-off.

Does this apply to the ignition module only ?

I was referring to trying to use the ignition module as a high-side switch, the quote dropped the image. The ignition module must go on the low-side.

[LAV1000]

@JHolland,
Thanks for the clarification.