Rather than spending money unnecessarily on having a mechanic switch out old and frayed speedometer cables, you can accomplish this task on your own. To save even more money, you can locate used cables from junkyards. Installing speedometer cables is a task any novice can accomplish.
Preparation and Inspection
Especially if you purchase used wires, double check that the speedometer cables you purchased are the correct cables for your motorcycle. You can verify this with the manual for your motorcycle. Also make sure that the cable has no apparent damage to its exterior, which may mean it is no longer functioning. Finally, ensure that you have the appropriate connectors and threading tools. Before actually wiring the speedometer cables, confirm that all of the adjusters are in a "closed" position.
The Actual Wiring
First and foremost, take a direct route from the "control" connections and the "actuator" connections: ensure that the speedometer cable does not hang or get tangled with the caliper forks that compress near the speedometer cable. Make sure there is enough play in the speedometer cables so they do not "lock up" when you move the handlebars from one side to the other. Aftermarket front wheel drive calipers have a tendency to pinch or tangle the speedometer cable. Once you have connected the speedometer cables, you should lightly grease them and check them every so often to ensure that there is no damage on them.
Things to Remember
The speedometer cable should be tucked away, but make sure they don't touch any hot surfaces when wiring them. Some speedometer cables are made from stainless steel and are "braided." If you can avoid these types of cables, you should, but if you cannot, make sure to tuck them away from painted surfaces. Braided steel has a tendency to scratch and chip painted surfaces.
You should also create a regular maintenance schedule that includes cleaning and re-greasing the speedometer cables. Also keep an eye out for a worn housing (the plastic surrounding the wire itself), or any bending or kinking in the cable. If you find any, you may need to make adjustments because the calipers are pinching the speedometer cable.