A You may have a problem with speedometer, the sensor, or the wiring. To determine which is at fault locate the speedometer's electrical connector block, which is clipped beneath the right hand cylinder head cover. Disconnect it, with the bike in neutral and the ignition ON have someone slowly turn the rear wheel while you measure the voltage between the white wire (+) and the green/black (-) (make certain you're testing the wires on the side of the harness that come from the speed sensor). The voltage should pulse between 0V and 5V. If the voltage is there, replace the speedometer. If it isn't check the white wire for an open or short circuit, and check the green/black for an open. The speed sensor is located beneath the left rear crankcase cover behind the coolant tank. Honda sells a test harness that's used to troubleshoot the sensor but with a little imagination, you can probably jury rig something that'll work although you'll need the shop manual and some Honda specific terminals to do so, and I'm thinking that if you had those you wouldn't need me. You can also use the process of elimination, if the wiring is good between the sensor and the speedometer, but there's no voltage flowing when you spin the wheel it's a safe bet the sensor is kaput.