Took a ride today with 6 bikes... 1 sporster, 2 softails , 1 road king , and a electra glide. We went 290'ish miles . they all were at that reading +/- 1 mile of each other. ME on the other hand was at 274.3 .. What could cause this ? Fuelpac maybe ? Oooh sorry , 2010 1200c . Please, any advice ?

 

Larger tire in front. Odometer miscalibrated.

 

Yea, are you running something other than the stock REAR tire?
Speedo's on a Sporty haven't been driven off the front wheel for ( 15+ ?) years.

 

No everything is stock...... That's why I am thinking computer.. Maybe fuelpac ???