I've owned my '06 YZ450 for about 6 weeks and have about 20 hours on it of fairly hard track use. My suspension has made it clear that it needs to be serviced soon and it made me start wondering about other more major service. Since I live in Mexico now it would be best if I can plan it out and have the work done on one of my trips back to the States as opposed to waiting until something major happens and I'm forced to make an unexpected trip or be without a bike. At approximately what hour intervals does major engine work come into play and what all does that entail? I hear bottom end and top end but what does that mean in terms of service? I hear guys talk about how expensive 4 strokes are to maintain but I have no idea what that means.....$500, $1000, $2,000 per year? I ride mostly SX with some fast trail riding thrown in on occasions. I don't want to jump the guy on major maintenance but I don't want to push it either so I'd like to know what's the longest I can safely go? Or do I ride hard all year and then get a new bike when I come back each summer? A year old '06 goes for as much down here as what I can buy a new '07 for so one option is to bring a new bike down each year. Thanks!