I own a 2004 XB12 R and ride almost every day so I will tell you the Low Fuel Light-Orange ONLY comes on when I have used more than 2.5 gallons of fuel. Sometimes it will come on when I accelerate really hard on a low fuel tank then when I get to a light and the Bike settles with no movement it goes out so I know that By looking at my Trip meter I know if I am close and try to get gas soon only because the gas helps keep the fuel pump cooler. To change the the bulb it isn't to hard but you need to remove the Instrument panel which has 3 nuts and the 1 wire harness plug you need to remove along with the front turn signals and front fairing. There are 10 screws holding the 2 haves of the Instrument dash together. When you separate them be careful not to touch the needle's for the tac or speedometer. There is no part replacement for for anything inside except the Bulbs which are locked in by a 1\4 turn to the right with a small screwdriver. To undo turn to the left..
You always have your trip meter to look at once in a while if you cant fix it.