You can build your Harley any way you want, but when you’re done, it’s still a Harley. This statement has been made countless times by countless people allegedly wise in the ways of Milwaukee’s famous motorcycles. But Robert Johnson disagrees. In fact, he offers his own alternative conviction: “An engine can’t read what’s written on the valve covers.” That first remark says that the character of a Harley’s powerband doesn’t change, stock or modified: Off the bottom, torque is mighty, but it dwindles away as the revs build. Johnson’s philosophy, however, means that an engine doesn’t have to be stuck…