I upgraded my front sprocket to a 14 tooth. What do I need to get the spedo back to normal??

 

A speedo-healer, google it or check out ebay.

 

http://www.speedohealer.com/

There's a formula to get it calibrated correctly.They are well worth it. But a pain to install, you are probably going to need an extra set of hands to help out. Makes it easier. The sensor is under the gas tank, infront of the rear shock. Good luck.