Hello Lads, Ladies.
Many is the word written on single fire and wasted spark ( redundant spark ), for the most part wasted spark is a working solution to an engineering or production feasible issue. Some systems run triple wasted like the Rita et al for the Triumph triples. Did work out where sparks occurred on that configuration, in the induction cycle was occurring. For some motor configurations the wasted spark causes abnormal vibrations.
Not so much on the 180 ( and 120/240 motors ), lot of bother to make a single fire ignition for the Laverda triple, though i did one design without cam position sensing. Red correctly said, it is the cam position that needs to qualify the actual crank position on a compression stroke ignition point.
Coil on plug technique was more to do with reducing Radio Interference, and more so, unwanted interference finding its way into the engine management computer control systems, via the sensor wires located in the engine bay. Plus it looks elegant from an engineering/visual point of view i suppose. Others may disagree.
What wasted spark does bring about is the added demand on an ignition system to produce twice as many sparks for a given rpm. At 8Krpm a wasted spark ignition is producing rates at 16Krpm. This means coil magnetic saturation time becomes critical, which brings about the concept of extended dwell systems to overcome this time critical issue. This then leads to significant increase in power demands on the ignition and charging systems. Included is the prospect of over heating the ignition coils with near constant connection of ignition coil to the battery or system volts. This is an issue for constant or total loss systems like on race bikes. Racing lads have found solutions for this and their approach is very valid, given races are short duration. For usual prolonged road riding it is an issue of course.
As for "wearing out" a coil, doubt it will be a concern for the riders 57 and over.... coil will out live us... grin.
**** BTW some spark plug cross reference books, recommend ( correctly so for factory bosch ignition ), to reduce the plug electrode gap on the outer cylinders for the 180 engine. With modern ignition systems this in no longer required, standard gaps as found on new plugs out of the packaging box, is good to go on IIS.
HTH John.
Get's rid of the wasted spark which can cause issues in high tune 4 strokes. Also allows individual tuning of advances on each bank of plugs, potentially many benefits, including longer spark duration and lower temperatures.
