it might be the speed sensor, that has gone, googel it for that make of bike, you can get one on ebay, try find out were it is on your bike, its sometimes next to the oil filter, and when your takeing it off, it will have a O ring seal on it, because it might be built into the bottom of the engin, and oil will spill out when you take it off, so have a can at the ready, and replace the oil. if you have a good manual try see were it is on your bike, i would say your clocks are ok , its just the speed sensor. check that out first,,
k, January 2012