I think this was it. Yesterday I pulled the plugs and cleaned them and the boots of dielectric grease and checked the gap ... all good, nothing chipped or cracked on the plugs, no carbon tracing, boots and wires inspected for cracks, all ok. I did notice that the boot on the rear cyl center position had slipped too far down the plug and I could just barely see some shiny metal (the socket that fits on the tip of the plug) while looking down at the top of the boot where the wire enters ... suspect #1 for some kind of spark leak. When I reinstalled I put a very sparing amount of dielectric grease on the porcelain part of each plug and sparing amount of anti seize on the threads ... reassembled and made sure the rear center boot was not pushed down so far that I could see metal anymore.

Bottom line is on my test ride I could not replicate the problem. More mileage will tell the tale but I think that may have been it, some kind of spark leak from the boot being too far pushed down.

Moral of the story - be sparing with the dielectric grease, just on the white part and make sure the boots are installed correctly.

 

Dielectric grease on the porcelain does nothing but waste money.
It's purpose is to shop water and moisture from compromising and electrical connection.
But if this works for you, who am I to argue?

 

All I know is the bike runs like it should now so yes, it worked for me

 

I only apply dielectric grease to the boots, not the ceramic on the plugs. Never had an issue.

 

yeah, never was designed or intended to lube the emblems

 

The purpose of dielectric grease is to prevent electrical connections from corrosion, moisture and dirt. Place a tiny dab on the head of the spark plug. It literally does absolutely nothing to apply it to the ceramic insulator.