Out of gas

[F900rstormie]

Happy to report the f900R gives ample warning to the rider as it's about to shut off from fuel starvation. I deliberately tested this and it started cutting out while cruising at 75mph and the bike started slowing, I was able to downshift to 5th and continue maintaining 60mph for another half mile before it was no longer to maintain that. Downshift again and proceeded to maintain 45 mph on the shoulder of the freeway with hazards on, so on and so fourth the bike finally completely died around 20mph and I coasted in neutral.

 So from the time of first sputter to rolling to a stop I managed to travel an additional 3.1 miles! Kinda pointless I know but I hope this info is of good use to someone out there.

[gogs01]

Does the bike have a fuel pump and, if so, is it in the fuel tank ?
I believe that some BMWs have this arrangement and running them dry can lead to the pump motor burning out.
Before I test the miles I can get from a full tank, I need to be sure that an empty tank doesn't risk having to replace the pump.   

[rcb78]

The manual says to not run it after the light comes on any longer than needed, I think it's a safe bet the pump is in the tank.

[F900rstormie]

The small fuel tank is my only real gripe about the bike, I feel better knowing my bike that much better after doing this in case of the unexpected. I will accept the potential increase in wear on the pump in the name of "science" .

[rcb78]

Doing it once won't hurt anything, just not a good idea to run it low when there's no need.

[F900rstormie]

Completely agree!

[Ayonbaner]

The light apparently comes on at 3.5 litres of fuel in tank with some calculation of most recent mileage but curious if it says 76 kms left, how much of that is really reliable to get to a gas station? Some say it’s as low as 20-30 kms.

[rcb78]

I think it really depends on how aggressively you ride.  I read the review by Motorcyclist Magazine (online) and they claimed to have only gotten 33mpg while I'm averaging closer to 50mpg (US).  If I refuel when the warning light comes on it's rare that it takes more than 3 gallons to refill, that tells me that there is close to 1.25 gallons left (4.3 gallons total), and at 50mpg, that's just over 60 miles left.  So doing the math, I have close to 90km left when my light comes on.  When I ride aggressively my mileage drops to about 40mpg, so even then I'm looking at close to 50 miles or 80km left when the light comes on.

[Ayonbaner]

The math makes perfect sense...guess the calculation is based on fuel volume left in reserve and the mileage based on the driving style in the last XX kms (on my X3; i believe it uses the last 10 odd KMS to compute...assuming similar logic on the bikes) and keeping style similar to the last 10 kms, you would still clock 50 mpg for 1.25 G to get 62 odd miles or 90 odd KMS. Question really is does this hold up in similar driving conditions?

[GiaxLV900]

Not helping the conversation (but neither trolling), my advice is to not bet your life on expected milage projected by the bike (or car) when running on empty. It could a good guesstimate, but won’t spend too much time in reverse engineering the logic behind.
When the fuel indicator is on, hold your breath direct to the nearest refuel station ASAP.
Anyway trying to understand how BMW’s engineers had design the fuel indicator’s heuristics is interesting, but ours would remain only educated guesses.