i confess ive always been an eyeball gapper after experiences with lil particles of carbon getting in an annoying place.... 1-2mm
the cdi is not weak. they are intended to produce spark at rates of up to 20,000rpm for single cylinder use... far superior to any induction coil/points system. very hot and intense sparks of a fixed length and strength.
maybe in these engines they are POS(in my opinion, yes)...but...
at high RPM, whilst the charge time is less, the charging ENERGY is MORE due to increased speed of the magnets passing the coil. the basic laws of electromagnetics. left hand or right hand rule? iunno
Voltage AND Current are proportional to the RATE at which a WIRE "cuts" a LINE of MAGNETIC FORCE.
the spark is still just as long, and strong, irrespective of speed....within limits. (module circuitry mostly)
its ironic that cdi is not good for extremely low speed engines! the magnets dont pass the coil fast enough to generate the voltage required...
you can improve spark energy by using stronger magnets (more lines of force) or more turns on the coil (more wires to cut lines of magnetic force) but then...the cdi module has a regulator built in! so.... you replace the module
the module contains things like a capacitor and fancy bits of silicon to do the hard work, including spark advance!
then the upper limit is still restricted to less than 40kv. high voltage starts thinking
everythings nice n conductive....