The speedometer cable continually flexes as it rotates, wherever the cable bends. For this reason, after a number of years and miles, it will eventually break. When this happens, your speedometer will read zero, no matter what speed you are travelling. Replacing it is quite simple, and only takes a few minutes!
Replacement speedometer cables can be found everywhere - online vendors such as Goldwing Cycle Parts sell them for around $15. This is a part that is subjected to continuous wear, so you really do want a new one, not a used one from a breaker bike.
1. Remove the set screw on the speedometer hub. This screw locks the cable into the hub.
2. On the back of the speedometer itself, you'll find this knurled fitting. Unscrew it from the back of the speedometer.
3. Remove the screw holding the speedometer cable and front left brake line to the fender. Careful - there is a tiny, easily lost nut on the back side that this screw screws into! Pull the speedometer cable free from the fitting. Observe the routing of the speedometer cable through the fairing, then pull the old cable out of the motorcycle.
4. The new cable has a triangular shape to the inner cable at the speedometer end of the cable.
5. Before installing the cable, it should be lubricated. The absolute best lubricant to use is graphite. It sprays in with a solvent carrier. This carrier quickly evaporates, leaving a dry coat of graphite behind, which is an excellent dry lubricant. Caution - this lubricant sprays on - and permanently marks - like black spray paint, so be careful where it drips!
6. Insert the tube from the graphite lubricant into the top of the cable, and very gently spray the lubricant into the cable.
7. When the lubricant starts dripping out the bottom of the cable (onto a strategically placed shop towel, as in this picture), the cable is lubricated. Turn the inside of the cable a few times to make sure it is equally distributed, and let it sit for a few minutes to dry.
8. Thread the cable back into place through the fairing. Make sure it goes through the wire stay, which holds it away from the brake hardware.
9. Gently insert the cable into the speedometer, and tighten in place.
10. Insert the hub end of the cable into the hub. If it doesn't go in all the way gently, pull it out, rotate the inside slightly, then reinsert. Tighten the set screw.
11. Refasten the speedometer cable and brake line into the fender stay, and tighten the screw.
