Have a 2006 softail heritage. At purchase I had a set of python staggered duals installed along with a race tuner at the dealer. Also had the dealer Dyno the bike. My question is do these upgrrades cause a significant decrease in fuel mileage. The bike currently has 7400 mi on it and I am getting about 37mpg. I purchased in 2007 and have just recently started checking fuel mileage

 

It's such a loaded question........
Highway or City riding.....
Heavy on throttle or easy..
Loaded bike with Windshield or stripped down...

 

Just checked the receipts I had on hand mine or Heritage is getting 40.6 on average. If You want great Milage keep it at around 55-60 Mph. Much above 60 and it starts to really drop off. Think my average Speed would be 65-70 for that average above.

All I have done to my bike is Slip ons and Filter change Plus a remap.

 

Upgrades should increase, not decrease mileage. What would be the sense in doing something that would decrease performance.

It was already asked, but what are your riding habits? What kind of fuel modual did you install? Who had it Dyno'd, you or the dealer? If Dealer, I would take it to an indy on your own, and get it checked out.

 

I lost a few mpg with all my bikes when I did the upgrades. Think about it...you're enriching the fuel so it'll run cooler so more gas is being used.

 

Reading the replies I have received on fuel mileage I believe I have a problem. I am 5 to 6 gal. per mile below what everyone else is getting. I ride easy on the throttle all country road riding.Appalachian H.D. did the dyno work on the bike. Graph showed an 8hp increase out of my 88

 

mine dropped 10% due to the crap gas they sell these days. mods can make it use more gas but it is due to the driver taking off faster is a big usage.

 

I have a 2008 Fatboy. I bought it used and it was stage 1 when I got it (still is). I was only getting about 130 miles out of a tankful. I changed the exhaust and added a fuelpak. I have not had the bike dyno'd, but I can now get about 170 cruising around town, and I can squeeze almost 200 on the highways. I also only use 93 octane.

 

I have an 07 heritage with v&H true duals sert and stage1 and avg around 43mpg.

 

I get between 37 and 40 mpg city and 42-48 mpg interstate.