no matter how many plugs you stick in there, you will still only get ONE spark.. whichever gap is the smallest will be the first to breakdown and conduct. until all gaps are even at which point it is just pure randomness which one will spark.
unless you run separate cdi or have both ends of the coil exposed, so the current has to flow from earth, across one gap, through the coil, then across another gap, back to earth.
the stock standard CDI will not allow this.
an aftermarket CDI with separate coil should, if it has a separate earth wire but probably wont, unless its off one of these new wizz bang car engines that use one coil per two cylinders.
you have also doubled the voltage requirements, so the coil needs heavier insulation, the magneto has to supply extra power that it cant produce...
all in all, rather pointless.
but, if you have a strangely shaped combustion chamber, or really big pistons... then dual sparks do make a difference. the biggest example being aircraft that standardly have two plugs per cylinder, as well as two separate magneto/ignition systems. if one plug fouls up, or a magneto fails...the other one still produces spark. you dont have to try gliding and landing with no engine.
pre-flight check is to start on both magnetos, then switch one off...the engine RPM drops to almost half! and kicks straight back up when both are turned on again.
why? because they cylinders are usually huge... having two flame fronts means the air/fuel charge burns faster, faster burn means faster pressure rise, faster pressure rise is more force on the piston.
another method is to simply use high frequency sparks, multiple sparks on one plug... but the whole concept is rather pointless on tiny little 50mm or less cylinders. and really does require a special coil and circuitry.
