Another question related to this ... the manual isn't too clear on how the reserve/fuel indicator works. I understand that there's a 3.5L/0.92 gal reserve in the 18L/4.76 gal tank.

When I get to the four flashing bars and I fuel up, it only takes about 14.5-15L of fuel.

So, is it once you get all four bars flashing that you're on your reserve?

There's naturally going to be some discrepancy between the exact gallon/liter numbers. There will still be gas in the tank if the level has dropped to starving point and the bike doesn't run anymore. That's why you see the manuals use the word "approximately" a lot.

Reserve starts when the indicator comes on. Blinking and disappearing indicators are a sort of count down of the reserve level. Either way, it's highly recommended to gas up as soon as possible after the indicator comes on. Or even better, use one of your trip gauges to tell how many miles you've gone since your last fill up, so you have a good idea of when you'll need gas again without the indicator.

Does anyone's indicator stay on all the time or it only comes on when you just turn your key. Or when you are running low on fuel. I only see my indicator when I turn my key. Either than that I'm just using my trip or milage to know my fuel. Even when I'm running low it still doesn't come on and let me know that my fuel is low. This weekend end I ran out of fuel and it still didn't come on.

Your fuel sensor is not working properly then. Maybe it failed, maybe it is disconnected. Do some investigating and see what you can come up with. The gauge will flash on when you turn the bike on (everything on your gauges flashes on when you turn the key), then the reserve gauge will stay off until you hit reserve levels. If you ran the tank dry without seeing it, something is wrong.