Can anyone tell me the size of the bolt for the passenger peg mounts on a sportster 2014?

 

3/8 alan key, and the torx is under a T30 for the throttle side, the clutch side is going to be a T45 i believe, just get a torx bit set that has different sizes up to a T47 so youll have them all...or are you asking bolt lengths?

 

If you want to know what size the screws are they are:

"#3214, SCREW 3/8-16 X 1-1/4 socket hd., thread-cutting"

For future reference you can often get that sort of info on line here.