I do not know if it is true or not, but I have heard that speedometers are always optimistic. or reading faster than the actual speed, for both cars and motorcycles. All speedometers that I have ever verified via user-friendly patrolmen shooting radar, bikes and cars, were optimistic. I think that there is some legal connotations there, such as lawsuits against manufacturers for receiving tickets and accident involvement. I have heard that motorcycles, as a general rule of thumb, are very optimistic.
