Many causes of 2 stroke engine failures are difficult to pinpoint and can be downright frustrating at times, not to mention potentially dangerous, .. Ignition failure, due to carbon fouling of the spark electrode. is one that I have personnaly experienced. One day, I was flying over the rural parts, when all of a sudden the port engine just up and quit, no sputtering or coughing just instant death, fortunately, I had farm fields below and chose  the best of them, which ended up  having about 2 feet of grass growing on it, a brisk deceleration, but no damage, On the ground I tried to restart but to no avail, I couldn't even get the thing to pop.I had to leave the old girl there since it was gett'in late. The next morning I was out with the tools trying to fiqure out, what the heck was wrong with this damn thing, after checking the obvious ,I remembered something  somebody said long ago, about pieces of carbon breaking loose and jamming between the spark gap causing a dead short ,I figured "what are the chance of that happening" well one very close look at the spark plug confirmed this syndrome ,I got out the feeler gauge and cleared the little briquette from the zone ,re installed the plug and she fired right up.(Since then I have not had any failures due to carbon fouling,oh sure Ive had a few more failures caused by the other 99 things 2 strokes throw at you)
     When you get down to it,  if the2 stroke hadn't been invented for motive power it would be the next best suited to the mass production of carbon . Carbon, that nagging little by-product that results when,  burning the lubricant with the fuel. Oil,due to its extremely low volitility, does not burn very well, even when its mixed with one of the most explosive vapour combination known, Its incomplete combustion products condense on the surfaces of the combustion chamber, are cooked at high heat and pressure and converted to carbon.This basic element builds up to a point where peices will start breaking off ,bouncing around perhaps for a few cycles before being ejected through the exhaust port , Now this set of curcimstances is ripe for murphy's law ,if it can go wrong,it generally will , and eventually through the law of averages one of these chunks(sometimes fibre looking in structure) will just of the right size and shape ,will bounce into the spark gap and get jammed , which then your immediant attention will then be drawn. In most cases restarting will be a futile  and its best to focus your attention to a forced landing. (Thank god for that second engine, eh)

     After experiencing this, I was told about a slick little trick that a local engine shop recommended that was very helpfull, Regs Aircooled Engines did much of the maintence and repair on many of the 2 stroke engines flying here in the 80's early 90's and must have learned alot about the nuances of 2 strokes once propellers were fitted on them .They recommending trimming back the grounding bar that sits just above the electrode, thus preventing any secure place for carbon to roost ,it does not effect performance in the least, it may even increase it ever so slightly due to the more exposed spark, but it is one solution that can definitly help increase reliability,

Check and compare,modified vrs stock This is what we want to accomplish ,the plug on the left could still be cut down a smidgen. .

Place blade of screwdriver between gap and pry up grounding bar Avoid putting  too much pressure on electrode.

Bend up to about 45* ,this gives room for grinding with reduced risk of damaging centre electrode

Grinding down tip till roughly inline with edge of center electrode (or you could use a dremal cut off wheel)

Do final finish up with a fine file.

Tap plug on firm surface to reset gap....and presto