My 07 1200 custom has a 4.8 gallon tank. I put 369 miles on it today but I feelgreat. It goes on reserve when I have 1.8 gallons left - enough to get 90 more miles almost.
1.9 tank? That is the smallest sportster tank I've heard of.Too many fills up for me.I get 140-160 miles on my 3.3 gallon tank.I've only used the reserve once and it was only to get to the gas station.
I have a 3.2 on my 80" chopper, 2 maybe 2.2 usable before reserve, 80 mi normal riding, never ran out reserve because I head for the gas station immediately after switching. I just hate pushing a bike by hand.