Well, I re-read the 5100 thread and I must have picked up the term "carbon scoring" somewhere else and assumed those 5100 problems were carbon related, so I was wondering how too lean a mixture could cause carbon build-up and scoring. Apparently those scoring problems were from burned piston heads or valves or something like that.
I'm still wondering if I should richen my mixture or not (Husq 440e). It's as it came from the dealer who did run it before giving it to me (although I don't know how thorough he was, since the chain was on backwards when I got it
). I just don't want to overdo it, I guess.