Mine will do 75 pretty easily. The problem is that I get that knock at that speed. And when idling. Y'all have told me that this is the timing chain slapping around and normal. Being conservative with machines to make them last longer (read: cheap) I'm looking to go with a 15 / something combo that will get the rpm's down to where the bike purrs along. Currently, thats at 60 to 65 with the stock tires. My 2 cents.