MPG correction...
 

After changing the sprocket on my bike.. the mileage reads about 5% low.. is there a way to add this so that my mpg will be right? thanks..

No, there's no way to compensate for a faulty odometer—sorry about that. It's not trivial to build and kind of an outlier. I'm afraid you'll have to do the math each time you add a fuel-up, or export your fuel-ups and do the math in something like Excel.

https://www.healtech-electronics.com/

Click speedohealer on the left.