The frequentie depent of the engine you gone use.
A Zenoah need high frequentie and a chainsaw low.
I think we need 100x the rotations per second the engine run to load the capacitor(s).
High frequentie giving also trouble, the transformers can be saturate.
I think we must use the flybacktransformer we use now without the feedback wind.
Becourse we make the PIC frequentie, the transformer can't be saturate anymore.
The capacitor must also be changed, two small capacitors are faster loade the 1 big one.