trha K4 1,ooo blows the k1 out of the water, i have ridin both. the k1 is too heavy of a bike. the k7 and k8 are the lightest by far but the k1 and k4 comparison different as well. plus a k4 with a 180 back tire gives u the most out of performance when tryin to manuvueur going over 145 around a bend or corner.