I have a 2003 Fatboy with a carburetor. I have Rinehart pipes and rejetted to larger jets. Stock air cleaner. At home in Nashville TN I usually get about 45 mpg. While in Sturgis I was getting 36mpg. The only thing I can think caused this was altitude. Nashville is 600 ft above sea level and Sturgis is 3500. Now back home I'm getting 45 again. Is this altitude or difference in gas? I posted this here since it's not Softail specific and thought I'd get more views.

 

Think you answered your own question.....altitude

 

Altitude, and/or crappy gas. I've seen it on 3 different bikes.

 

Has to be the gas mix, I always get better fuel mileage with altitude, carbed 111.

 

The wind is also a big factor in mileage, and it was windy this year. It was windy in the hills, and if you rode out/back, it was particularly windy along I-90.

 

I got 10-15% less with the corn gas.

 

I ran non ethanol gas out there in my 02 carbed Softail Standard and I couldn't tell any difference other than price.

 

Altitude--thinner air at altitude=richer mixture. Hence, more gas used.

 

Somebody was stealing your gas.

 

Try running regular gas when you're at high altitude and carbed bike. You'll get better mileage, and it won't ping.