2005 KX450F

So far what Kawasaki has released is that the new machine's 449 cm3 DOHC 4-valve engine is housed in a semi-double cradle frame with a unique tapered box-section backbone tube. The photo's reveat that's an aluminum, non-perimeter frame - both the 450 and the 250 2-stroke will return to a "traditional" backbone style frame. A close look at the engine shows a mount that was clearly built for a perimeter frame, so it looks like Kawasaki did test that combination.