2005 Heritage softail - 88B 5 spd

All last summer I consistantly got 45mpg .... that was in the middle of july...

This year I'm getting 35, is that because I'm riding in 40 F weather ? On the way to work its 40F on the way home its 60 F for the whole tank ....


My bike is fuel injected...

 

Just a guess..... the gas you're buying now has 10% ethanol....
My mileage drops about the same when i have to run that crap.

 

wow really ? a 10mpg drop ? that's insane

 

When the temp drops below 42-deg my fuel mileage drops down to around 31-mpg...When the temp gets above 60-deg the fuel mileage gets to 42+ mpg and that is under the same riding conditions...I get my gas from the same station..Engine/oil temp makes a difference.

 

That's good to hear, I'm hoping I'm in the same situation... having to buy gas every 150 miles can sure sneak up on ya. .

 

I read an SAE article years ago years ago about the internal combustion engine and how efficient it operates at temp...Oil temps between 195-225 in a water cooled engine allow for better fuel economy...With an air-cooled engine it's more abstract because the temps are never consistent.

 

Yep it runs a little ricker in the cooled days and it same like it has a little more horse power too.

 

Yes indeed, that cold dense air adds some "pop" to the exhaust and keeps the combustion chamber cool!

 

I found out last yr (but some won't and don't agree) that when I run gas that has ethanol I dropped 3-5 mpg, did it every time I filled up with it last summer.. from 42-44 usually to 39-40

Also seems to go down 2-4 in weather temps under 60, and the cooler it is the more it drops.. again around 39-40

Add these two together and I could see 8-10mpg less not out of the picture...

 

I hope that's all it is - my '05 Heritage has a carb and gets about 35 mostly, even with warmer weather, new plugs and wires. I have stage 1 with a sportster needle and 48 pilot, SE II's, and k&n cleaner. Oh, and syn in all holes. I'd expect better.