So the dark ones were the problem? Good find on the VR plug.meanwhile there have been developments.
the different color of the spark plugs was due to an electrical problem.
for a few weeks the bike was no longer running well, as if it were running on 3 and a half cylinders.
it was the voltage regulator connector that was blown.
I have now set the idle screw to 3 turns and the popping problem has improved, but not completely resolved.
p.s. i don't speak a word of english, i use google translate. if I post inappropriate terms, take it out on him.