Compare the Yamaha XT 660 R - [2006] vs Kawasaki S3 400 SS MKII - [1974]. Find out which motorbike is the fastest, most powerful, lightest or has the biggest engine in our top trumps style comparison page. Find out which bike has the highest top speed or is the fastest accelerating, is it the Yamaha XT 660 R or the Kawasaki S3 400 SS MKII. We'll leave it up to you to decide which is your favourite. These 2 bikes have been carefully filtered and paired together according to their similarly performing technical specifications.