Do a google search for a 'speedo healer', a plug-in electronic module to correct the factory error in the speedo which also lets you swap from kph to mph. About $110, way cheaper than a GPS and WAY cheaper than a new speedo. They also sell a version that will display what gear you are in, should you miss the high gear indicator they used to put on japanese bikes. I used to put in a lot of them- takes about 10 minutes, and the sportbike guys love them because you can calibrate it to remove the speedo error when you swap sprockets or tire size.