I'm all city driving where I hardly ever get out of 3rd gear. Light comes on ~70-72 miles per full tank. I can barely squeeze 2 gallons on fill up when I fill up immediately.

Are you sure you're putting in 93 octane? I just noticed your sig. Is your bike tuned?

 

I've seen several mileage posts pop up in the Sportster section and it seems that generally speaking most people get 40 - 50 mpg when driving city/highway. I think I've seen mid 40s as the most common.

I can understand that city driving with the frequent stop and go definitely hurt gas mileage but 25 mpg seems way too low even with your crazy hills unless you're going uphill all the time and never coming back down...but even then, I'd think it's a stretch.

In Sept I went on a group ride mostly doing twisties and I ran the hell out of my bike for the first time. I used low gears and rarely got to 3rd and 4th and was constantly hitting 60 mph in 2nd gear. I thought the high RPMs would kill my gas mileage but even when running the engine pretty hard, I was getting 47 mpg when I filled up.

I noticed that you have an after-market A/C but if you haven't had your ECM remapped, that could be the cause for your low gas mileage. If you haven't, you might want to invest in a remap, which I'd think would significantly increase your mileage.

 

you can't find 93 in SF, only 91, but I wouldn't thing that would make that big a difference. Should i use an octane booster? I have the stage 1 download, that is an ECM remap, right? would a remap just be doing the same thing again?

 

I believe the HD Stage 1 download is a generic remap for SE Muffler and A/C so you should be good to go there. I'm not sure about the different octane gas but I wouldn't think it would kill your gas mileage that significantly?

How are you calculating gas mileage? I use the Trip A setting as a fuel gauge and for about 3 months I would write the number of miles in Trip A before refueling and then write down the gallons pumped to fill up the gas tank.

Take Trip A miles / gallons to fill up and you should get a very accurate mpg reading. Do this over and over again for a couple of months and you get a very good average.

Perhaps you have better mileage than you think and you're just calculating incorrectly? Just a thought.

If that's not it, I have no idea why your mileage is so low...

 

IMO You need a good Mechanic to look It over..
I got a 2008 1200R worst city mpg is 33 Mpg,,
If I was to get less than that I'd be scared I was burning up the motor sitting at lights.
Combind city hiway is always 38-42,,best hiway at steady 75mph is 47,,
Best at 65 mph Is 49 mpg

I'm about 225 In gear and the Bike Is almost stock,,
stock pipes,,stock breather,,
Only Mod Is the X14ieD fuel enricher which did not lower my MPG at all

 

Could be your jetting is off?

I got 70 coming down the mountain!!! Yes it was on, but lots of coasting due to the slope...

 

I'm not going to speak to your mileage v. mine or anyone else's, as that's getting beaten to death. To answer the question you actually asked, yes, that's pretty close to right. The fuel pump takes up about 1/4 of a gallon, and the pickup doesn't get right to the bottom of the tank, so there's another quart-ish. Together, there's going to be about 1/2 gallon "remaining" in the tank's nominal capacity when the bike sputters and dies. In actuality, there's only a quart or less remaining when it dies, but either way, you'll get less than three gallons in it after that.

 

I run 150 miles a day, between 65-75mph. I average 46-48mpg, all stock 2008 "C" with Rush slip-ons. Idiot light comes on at 135-140miles, I can go 200-220 miles per 4.5gal tank.

 

I run about 90 miles before my light comes on and I generally get 2.5 gal per fill-up at around the 100 mile mark. I am averaging about 47MPG mixed city/highway driving.

 

Idiot light came on once, I was at 130 miles,,,,put 2.8 gallons In my 4.5 tank,,
It was windy as hell.
Same type of ride on a calm day,,Idiot light came on at 146 miles,,
put 3.3 In the tank,,
Another ride,,Idiot light came on at 110 miles held 3.0 gallons,,,
I guess I was doggin it,,,,,

SO as best I can tell My Idiot light comes on between 2.8 and 3.3 gallons burned.
Give er take a .2 for not filling Exactly to the mm of the same height in the tank..
and or a hot day versus a cold day.
I pretty much just stop an fill near 130 ish and fugetaboutit.

I did see about a 3 mpg jump after throwing my Air filter In the dishwasher,,,

When's the last time ya cleaned and regaped the plugs????

Tip, try a bigger gap for ***** n giggles,,bout .045 or .050,,,even .060

when ya go for power or any throttle up are ya up In the power band ??

Pullin *** from low on the tach even tho It feels good Is a fuel dumper,,,

Even when I'm showin off or zippin round I get tons of haul *** with very little throttle,,10-15-20-25% twist.