I haven't had the nerve to test it out and couldn't find anything in the owners manual.
I've got a Sportster 1200 Custom.
Once that little light comes on how much gas is left???

 

When the light comes on, fill up. Subtract the amount you buy from the total your tank holds. That's how much is there when the light comes on.

Later!

 

If I get gas right when that light comes on I'm only able to pump in 2.8 gallons. That's on my '08 1200C. One time I went about 190 miles, really worried there until I spotted a BP station. I pumped in 4.3 gallons, now how close is that to running out. LOL

 

OK sorry I found it

 

Where did you find that??? I need the 883 version haha

 

I have an Iron, and mine tends to have about a gallon or so left when the light comes on as well.

 

Y'all have lights!? Mine just starts to die to tell me to turn the petcock to reserve

 

https://www.harley-davidson.com/cont...rs-manual.html

Under Specifications

 

This is a frequent subject around HDF. Although there may be around a gallon left when the light comes on, that is not something to be relied on. Best to check your own bike, which also takes into account your own riding style. The owners manual tells you what your tank capacity is, so as Bob points out in post #2, if you fill up as soon as the light comes on, you know what fuel you have left, hence how far you can ride next time. The 'reserve' is there to be used, it simply requires each of us to do some simple preparation to establish how far we can safely ride while the light is on. It's not any different to riding an old carb bike with a reserve tap.

 

With my 3.3 gallon tank it came on with a gallon left. Now that I switched to a 4.5 gallon tank it now comes on at the same point except now I have 2 gallons left