I think I agree with KM basically - I usually looking for a gas station right around 90 miles or so, give or take a few depending on wind, etc. I only put 2.5 gals in mine each time, as I don't like to run it completely full. But I pretty consistently get 100+ miles out of that.
I had a bad experience with the bike I had before my VN750 though where I ran out of gas and flipped it to reserve - only to find out there WAS NO reserve fuel! Apparently, the little pipe that sticks up from the bottom of the tank on that bike to separate out the "reserve" had fallen off, and I had run through all the gas I had - yikes! The good news? I was in town, only about 1/2 mile away from a gas station. The bad news? It was here in Phoenix, in the summer time, and I was (as I always am) in full gear.
So yeahhhhh.... I start looking before I get "too close" now - right around 90-100 miles like KM said : )
Ride safe all.
7800 orig mi when purchased Jan 2011
Turned 11,000 mi Nov 2011
Taillight relocation kit
Chad's highway peg mounts
Otherwise, all stock
"But it's a dry heat - like the inside of an oven"