Announcement

Collapse
No announcement yet.

need some carb tunning advice

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    need some carb tunning advice

    Ok so I need some thoughts on carb tunning.

    What we have is a 1978 GS750 with K&N pod filters and a Kirker 4-1 system.

    The carbs are stock Mikuni VM series carbs. Rebuilt them with new o rings and gaskets.

    The stats
    Floats set at 25.5 mm
    Main Jet 107.5
    Jet Needle clip set in middle ring (was at top)
    Pilot fuel screw 2 turns out
    Pilot air screw 1.5 turns out

    The issue, bike has a mid range flat spot. Off idle it takes off like a rocket, hits about 5k and brick wall, rap it WoT and off it goes again. So I am thinking of raising the needle 1 more clip.

    Thoughts?

    #2
    Forgot, can I remove the needles in the bike without removing the throttle shaft?

    Comment


      #3
      My thought is

      Your main jet's too small (should be more like 115)

      The fuel screw should be about 1 turn out

      How big is your pilot jet?

      Wouldn't hurt to raise the needle a notch, that's what controls the midrange
      1978 GS 1000 (since new)
      1979 GS 1000 (The Fridge, superbike replica project)
      1978 GS 1000 (parts)
      1981 GS 850 (anyone want a project?)
      1981 GPZ 550 (backroad screamer)
      1970 450 Mk IIID (THUMP!)
      2007 DRz 400S
      1999 ATK 490ES
      1994 DR 350SES

      Comment


        #4
        Originally posted by Big T View Post
        My thought is

        Your main jet's too small (should be more like 115)

        The fuel screw should be about 1 turn out

        How big is your pilot jet?

        Wouldn't hurt to raise the needle a notch, that's what controls the midrange
        pilot jet is stock, which BB says is a 15. I don't recall seeing a number on it.

        Comment

        Working...
        X