as an engine warms up it fattens up slightly and the fatter the mixture the less likely it should be to detonate. it shouldnt change it as far as richer or leaner when you change your ridding style unless for instance one type of ridding keeps you on the main jet most of the time and it is the correct size while another style of riding keeps you mostly on the needle or pilot jet and they are a little rich. then the same bike would give you a good color plug after one style of riding and a rich colored plug after the other style of riding you do. It sounds like mostly a jetting issue to me. and tight woods and trails is more typically pilot jet and needle position type ridding unless your crazy or just good. you were asking about detonation is it or does it show sighns of detonation?