Speedo displaying the wrong speed?

ever since my battery died onetime last summer my speedometer has read way higher than i am going. when i am going 25 it will say im going 65 and when im going 65 it will say 175 or whatever it maxes out at. my best guess is that its the speed sensor and hopefully not the speedometer itself since im flat broke. hopefully somebody can confirm my thoughts before i go tearing the wrong things off my bike.

Use the search function. I don't have an answer for you but I know several people have been through this before. Is it possible its showing kph?