I've got a nice '99 YZ400F. Ty Davis IMS tank, WR flywheel & stator, kickstand, headlight, spark arrestor. It's setup pretty nice for enduro type riding and I can street legalize it with a quick tire change and a tail/brake light, although I haven't gone through that process yet. So, I'm looking to upgrade this year to a new, lighter 450 for mx & enduro racing. Question is, should I keep the 400 for my trail riding and dinking around, or once I get a new bike, will I never ride the 400 again. I can get maybe $1800-2000 out of the 400, and that would be nice to be able to apply to a newer 450, although it's not totally necessary that I sell it for the money. Anyone that's kept their older bikes, do you ever ride them?