Removed both exhaust pipes today. Noticed that amount and "kind" of soot in cylinder exhaust holes is very different:
Front cylinder whole is white-ish and does not mark my finger:
Rear cylinder whole however has a lot of carbon-black soot. I can easily scrap a lot of it with my fingernail:
Is this something to worry about?
Front cylinder whole is white-ish and does not mark my finger:

Rear cylinder whole however has a lot of carbon-black soot. I can easily scrap a lot of it with my fingernail:

Is this something to worry about?