I have been riding dirt bikes since i can remember, and have been looking into street bikes. My friend just bought a 2007 yamaha yzf600r and plans to upgrade to a bigger bike next spring. I have been looking into the kawasaki zzr600, but he offered to sell me his yzf for $4000. I was just wondering if there is a big difference between the bikes or if i would be better off buying the used bike.. There is nothing wrong with the yzf just a little scrape.