Didn't look at the specs but with that small tank 1.6 liter (I think) I don't think your gonna be trailriding that thing at all.....
Well we all know how popular the Japanese bikes are, so IMS/Clarke will have a tank out for the 2010 very soon.
The 10 YZ450 has such a complex tank design, I wouldnt be surprised if no one makes a tank for it, much like the new Husabergs.
It's a tiny tank and it's hinged so it swings up to allow access to the forward mounted Air Filter.... I Think IMS/Clarke have their work cut out for them...