For me it's usually at least 134 miles to reserve and occasionally 150 or more if I've been easy on the throttle.
I usually stand my bike upright to fill and fill to the very top. I get 3.6 gallons in if I have just hit reserve. About 35-40 MPG with the Memphis Fats and lowers on. With them removed, and being judicious with the throttle, I can get 48-50 MPG. I have put 4.3 gallons in once and have never quite run out.
I have found my odometer to be well within 1% accuracy, the speedometer does not do so well.