I have the 50th anniversary sportster. Mileage - 7k. I used to get 50ish mpg overall. Now I'm down to 32mpg over the last Fall.

The only thing different was last spring I over-filled my oil reservoir and rode for several months before noticing. I drained the oil and refilled properly.

Any suggestions on where to starting looking?

Thanks

 

50th anniversary is a 2007? Carbureted I'm pretty sure? 7,000 miles is pretty low for a 8 year old carburetor. It's probably pretty gummed up in there, and might be time for a rebuild.

 

There are several factors that could contribute to reduced fuel economy. The biggest outside factor is colder weather. On the bike, lack of regular maintenance is the biggest culprit.

Oil Viscosity
Heat makes oil thinner. That reduces the drag on the engine and improves gas mileage. Cold makes oil thicker. That increases drag on the engine and degrades gas mileage.

Tire pressure
In the fall and winter tires lose air pressure due to the colder weather. Under-inflated tires increase rolling resistance and degrade fuel economy.

Air Cleaner Intake
Hot air is not as dense as cold air. Your gas mileage will be better in warmer weather.

Winter Fuel
Most states require gas stations to sell a special reformulated grade of fuel during winter months. This type of gasoline is diluted and will lower your fuel economy by 3+ percent due to its reduced energy content. Gasoline sold in warmer months has a higher energy content which results in better gas mileage.
Article: http://newsroom.aaa.com/2013/06/what...lend-gasoline/

Bike Maintenance
Make sure you are changing filters, sensors and cleaning fuel system components according to the recommended schedule for you bike. Dirty parts can contribute to poor fuel economy.

Electrical Accessories
Often times in colder months riders use heated clothing, grips and other accessories that increase the electrical load. That will put a higher demand on the charging system and create additional drag on the engine which reduces fuel economy.

 

The sportster first came out in 1957 and in 2007 they made a 50th anniversary edition sportster.

Also, starting in 2007 all sportster were fuel injected.

 

The winter blend gas will have an effect, but it shouldn't be that much.

 

What ethanol blend gas are you using?

 

Ethanol will reduce your mileage also. Again, not 18 mpg worth. But, there could be multiple things adding up.


Another thing, every blip of the throttle eats gas. If you recently made modifications that you just have to hear when you're stopped, there goes your gas.

 

Some riders will use a windshield in the winter and not in the summer. That alone could account for a 1-2 mpg decrease in fuel economy.