The needle on my tachometer was bouncing around, so I figured the cable needed greasing. I know, how quaint that my Suzuki uses cables to run the tach and speedo. The tach is run by a cable from the exhaust camshaft. I pulled that out and greased it. The speedo and odometer are run by a cable off some gears on the front axle (shown). The cable is shown pulled out of the housing.
I like using BG products for grease. I use the Special HCF grease for cables on the bike and for packing the bearings on my bicycles:
http://www.bgprod.com/products/greases.html.