No announcement yet.

Struggling to get this hawk's carbs to behave.

  • Time
  • Show
Clear All
new posts

  • Struggling to get this hawk's carbs to behave.

    Hey guys, i'm trying to get this hawk that sat up going again, and i've got an annoying issue. The bike runs fine if I ride it fairly sedately, but if I start riding it hard, it starts feeling like it's out of gas.. eg, when I go to roll back on throttle, say after the apex of a corner, it falls on it's face until the throttle is opened up a good bit, like when you're running out of gas and need to switch to reserve. It'll do it after running WOT as well... WOT -> shut throttle -> roll on, it doesn't pick back up until like half throttle.idles fine, revs out fine while riding, at least at first. snapping the throttle open at idle, it doesn't hesitate, revs nicely.

    bike has a delkevic can and stock airbox, oem filter.. the carbs have been cleaned, the diaphragms are in great shape and seated properly, running stock jets (138f 132r 42 pilots), stock needles, floats @ ~9mm, mixture screws at 2 turns--the settings the bike had before it sat. Sync is also good... new electric fuel pump (I haven't measured it's flow, but it takes about the same amount of time to fill empty bowls as the other hawk's does), clean fuel filter. the tank vent is clear. carb vents are clear... plugs are good, and the bike has good spark and a good battery. I've also tried riding it with the fuel pump relay connection jumped with a wire in place of the relay to eliminate it as an issue. it's got fresh non ethanol gas. bike has something like 28k on it.

    seriously, i'm at a loss, any suggestions?

  • #2
    Sounds like its happening on the needle. Sounds lean. Id check for air leaks first, then work on jetting, maybe space up the needle.
    Don't spend money and buy, spend time and learn.


    • #3
      it's odd because before it sat up, it ran pretty well.. the intake boots aren't in amazing condition, but there's no change in RPMs when I spray ether around them. Checked when it was warm, with gas coming in from an aux tank.


      • #4
        have you checked/cleaned the small filters just above the float needle seats ?
        "It's only getting worse."

        MY rides: '97 VFR750, '90 Red Hawk, '88 Blue/Black Hawk, '86 RWB VFR700 (3), '86 Yamaha Radian, '90 VTR250, '89 VTR250 (2), '73 CB125, '66 Yamaha YL-1

        Sold: '86 FJ1200, '92 ZX-7, '90 Radian, '73 CB750, '89 all-white Hawk, '88 blue Hawk, '86 FZ600, '86 Yam Fazer 700 , '89 VTR250, '87 VFR700F2, '86 VFR700F.


        • #5
          Tank screen, petcock, or like Squirrel says, float valve filters.
          J.D. Hord
          Keeper of Engine Nomenclature, 9th Order