main jet size

Collapse
X
Collapse
 
  • Page of 1
  • Time
  • Show
Clear All
new posts
Previous template Next
  • yotaman423
    #1

    main jet size

    ok so vance and hines reccomends going form a 115 stock jet to a 120 jet after installing there exhaust on my 80 GS850. my question is i already have a aftermarket mystery exhaust on my bike. everything is stock except for exhaust. bike bogs at 70mph if i increase the size will it fix this problem?
    Tags: None
    • Nessism
      Forum LongTimer
      GSResource Superstar
      Past Site Supporter
      Super Site Supporter
      • Mar 2006
      • 35790
      • Torrance, CA
      #2
      Does the bike have pods?
      Ed

      To measure is to know.

      Mikuni O-ring Kits For Sale...https://www.thegsresources.com/_foru...ts#post1703182

      Top Newbie Mistakes thread...http://www.thegsresources.com/_forum...d.php?t=171846

      Carb rebuild tutorial...https://gsarchive.bwringer.com/mtsac...d_Tutorial.pdf

      KZ750E Rebuild Thread...http://www.thegsresources.com/_forum...0-Resurrection

        Comment

        • yotaman423
          #3
          no. stock airbox and filter sealed with weather stripping

            Comment

            • Steve
              GS Whisperer
              • Jun 2005
              • 35925
              • southwest oHIo
              #4
              Originally posted by yotaman423
              ok so vance and hines reccomends going form a 115 stock jet to a 120 jet after installing there exhaust on my 80 GS850. my question is i already have a aftermarket mystery exhaust on my bike. everything is stock except for exhaust. bike bogs at 70mph if i increase the size will it fix this problem?
              Might help to try 122.5, or you could also shim the needles to help with the mid-range.

              My son's 850 has what I am told is a Jardine header and a stock airbox. 120 mains work well with that pipe, but the V&H might flow a bit better, requiring larger jets.

              .
              sigpic
              mine: 2000 Honda GoldWing GL1500SE and 1980 GS850G'K' "Junior"
              hers: 1982 GS850GL - "Angel" and 1969 Suzuki T250 Scrambler
              #1 son: 1986 Yamaha Venture Royale 1300 and 1982 GS650GL "Rat Bagger"
              #2 son: 1980 GS1000G
              Family Portrait
              Siblings and Spouses
              Mom's first ride
              Want a copy of my valve adjust spreadsheet for your 2-valve per cylinder engine? Send me an e-mail request (not a PM)
              (Click on my username in the upper-left corner for e-mail info.)

                Comment

                • earlfor
                  Forum LongTimer
                  Charter Member
                  GSResource Superstar
                  Past Site Supporter
                  • May 2002
                  • 42413
                  • off grid cabin 1/24/26 7pm
                  #5
                  Originally posted by yotaman423
                  ok so vance and hines reccomends going form a 115 stock jet to a 120 jet after installing there exhaust on my 80 GS850. my question is i already have a aftermarket mystery exhaust on my bike. everything is stock except for exhaust. bike bogs at 70mph if i increase the size will it fix this problem?
                  Before doing any rejet guessing, I would first do a vacuum carb synch.
                  If they carbs are out of synch badly, the engine will bog or die at certain throttle openings. You can not jet a bike to run well if the carburetors are all drawing different vacuum levels. Once the sych is correct, I would run the bike up to 70 to see if it still bogs.

                  Earl
                  Komorebi-The light filtering through the trees.

                  I would rather sit on a pumpkin and have it all to myself than be crowded on a velvet cushion. H.D.T.

                    Comment

                    • yotaman423
                      #6
                      sycnc. already but i will check again

                        Comment

                        • Guest
                          #7
                          Even running lean with the 115s you should still het redline though I don't recommend it.
                          I would try a larger main and shimming the needle but if it still bogs I'd check ignition.

                            Comment

                            • yotaman423
                              #8
                              thanks will check when the weather breaks. i think my problem was a in-line filter restricting fuel. need more test rides

                                Comment

                                Previous template Next
                                Working...