Have an 06 CRF 250. I bought it new, broke it in, and then adjusted the valves. I have put about ten hours on it since then, and have changed the oil and filter at about every 3 hours. I just barely had to adjust both intake and exhaust valves again. I'm great with lots of maintanence and adjusting valves, but after two adjustments I reckon my next go is to replace the valves and springs. If this is the case, am I going to be replacing valves every 20 hours or so? I am able to trade the bike for an 07 YZF250. I am considering it for the fact that YZFs have a solid rep with their heads. SHould I or shouldn't I?