Unless they've changed it back again, I'm fairly sure they can run 250 2ts in WMX. It is (perhaps Was now?), the only Pro AMA MX class where equality is allowed. Why no one seemed to take advantage of this, goodness only knows. It's a lot easier (cheaper) to mellow the power of the 250 2t, if you need /want to, than to get competitive (say, against Ashley Fioleks Team Honda CRF250R) power from a 250F. All it takes on an SX KTM is jetting and changing PV springs, and the pre-load on it.
They've been able to fit the 4ts back end in the 2ts for years now - the first I knew of it when I read of the set up for Doug Dubachs YZ250 in the Glen Helen 2t race. MXA noted that again in their recent YZ250 test. Why Yamaha doesn't do this, is very strange. It would save money by further amortising the costs of those components. It also save 1 to 2.5lbs, from what I recall. Doing that, and updating the plastics (please, leave the back bone frame, no twin beam frame, please), might just make up for charging so damned much for a bike that has barely changed since 05, other than the price.
