Nutball
TreeHouser
Supposedly the dealer can plug it into his computer and tell you the hours and maybe even the number of rope pulls.
I'd go with a 7 or 8 to keep it on the cool side, especially if you get the 500 modified. I run #8 plugs, which can be a bit slow to warm up, but are definitely needed when run hard.On the topic of spark plugs and 500i’s. What ngk plugs are recommended for what saws? I see there is a bpmr5a-bpmr7a (if my memory serves me correctly). I have stihl saws from a 201t,251,261,261c,440, 460x2, 500ix3, 661. Where should I use certain plugs?