Carb MPG

Question I have a 2005 Softail deluxe. I purchased it used in 05 and have always had concerns about the fuel mileage. It has a Mikuni carb. had straight pipes on it when I bought it. Has Rush full system long style with 1.50 baffles. gets around 30 miles per gallon. Never has been much better than that. I contacted Mukini and they said fuel mileage should be the same as stock carb research I have done says I should get between 40 and 50 miles per gallon. Any insight on carb mpg on a Harley ? Gilbert

Via Email

Answer Gilbert, Your gas miliage will be affected by your exhaust system and by your air cleaner. To be sure you are getting optimal mpg you should:
Verify what size jets were installed in your Mikuni Carb. If your motor is stock and your only modification is the exhaust, (and air cleaner), your slow jet should be no bigger than a 25. Your main jet should probably be no larger than a 165. After verifying your jet sizes, you need to set your carb. You can find Mikuni instructions on their web site.
After dialing in the correct settings for your carb, be sure you start with a clean air cleaner element and a new set of spark plugs.
You should also be running 92 or 93 octane. Remember the only way to achieve stock gas miliage, is by running a completely stock bike. Thanks for your question.

Related Videos:
Carburetor Rebuild

Have more questions? Check out the Tags here and our Q&A index page to find some answers here.

  • (will not be published)

2 Responses to “Carb MPG”
  1. Kim Kelley
    Kim Kelley

    I just replaced the Magneti-Marelli on a 2001 stock road king with an S&S E shorty. Only upgrade is a V&H exhaust system and a chip. Over 70 miles an hour the previous MPG progressively got to a 20 MPG range. Ran great, just crappy gas mileage. Switched over this spring, and just topped off to 30 MPG range. What jets you suggest on S&S?

    • Customer Service
      Customer Service

      Dear Kim,

      Thank you for your patience. In response to your question-

      We would suggest starting with a .0295 & .072
      If it seems like you are turning the mixture screw out too far when dialing in, move up to .031 & .074

      We’d love to have you be a part of our community. We are convinced you will enjoy the benefits of becoming a member and having access to the best instructional how to videos and professional tips. We would like to offer you a special promotion for your first-year membership.

      Fix My Hog