Motorcycle cables are connected to the throttle and the clutch. They require routine maintenance just like every other machine, and if they are forgotten, they will eventually wear down, decreasing the efficiency of the vehicle until they eventually fail, maybe at the most inopportune time. This will give you a long walk, a difficult push home, and a potentially expensive repair bill.
It is important to know what kind of cables you have before you continue with the rest of these steps and your maintenance. It is also important to do some research into the kind of lubricants you prefer. Some like to use motor oil, though it is messy and can pick up roadside dirt. A mix of powdered graphite and WD-40 also works well for a lot of motorcycles or simply ask for a recommendation at your local motorcycle shop for getting the best lubricant for your particular motorcycle's cables. You should never use chain lubricant on a cable.
Step 1 - Check Type
Check your owner's or the shop's manual for what type of cable you have. This will tell you if they need lubricant or not. There are actually two types. The first and oldest are made up of multiple wires and a steel style cable. This is the kind that must be lubricated. The other is a more recent and more technologically advanced type. These kind are lined with Teflon, and it could actually damage the cable if you lubricate it.
Step 2 - Remove Cable
Unhook the cable from the lever or throttle drum at the handlebar end. Make sure you pay attention to how you unhook them so that you know exactly how to hook them up again once you have finished.
Step 3 - Set Up
Cut a 45-degree angle in the corner of the plastic sandwich bag. Then, stick the end of the cable into the hole and fill the bag with the lubricant of choice. Tape it to the outside of the cable housing with the cable hanging out of it. This can also be done without the baggie if your lubricant has a needle nose that you can place into the cable. Examples of these types are Dri-Lube and Bike-Aid.
Step 4 - Waiting to Finish
Wait for the lubricant to run down the inner cable. You will know it is done when it is leaking lube on the other end. After you have waited a few minutes, remove the bag, wipe everything down, then hook the cables back into their original position.
It is important to perform basic maintenance on your cables at least twice a year. This way, you will not have to worry about them breaking or detaching from your throttle or clutch on their own.