Im assuming you want a 400 motor instead of a 250. Restricted riders have always had the dream to throw a 400cc into there 250 frame for as long as time itself, the frame & motors are visibly different shapes, the 400 rear mounts on through the frame where as the 250 mounts are forward from the frame and further in. Not saying it cant be done but some engineering work will be needed & then theres the driveshaft clearance with the frame etc. Ive heard gsxr 400s go straight into a gsxr 250 frame and rvf400s into cbr 250s but never heard of a zxr being done
