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.
 The Kawasaki makes a departure...  The Kawasaki makes a departure from the previous two 450s and the rest of the KX clan with a non-perimeter aluminum frame. |  Check out the huge weld job...  Check out the huge weld job at the headstay. |  It's real! Tetsuy Mizoguchi...  It's real! Tetsuy Mizoguchi demonstrates the KX450F's roost throwing abilities. |
 The slim profile and well...  The slim profile and well tucked in are evident in this angle. | | |