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Strange engine running problem

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  • Strange engine running problem

    My bike normally runs very well from cold start ,through warm up and fully warmed up. It' s got a jet kit, Uni filters,different muffler and pulls strong from low to high speed...
    But lately there's a glitch...The bike starts as usual, ride off and all is normal for a few miles and then the engine devolops a noticable bog off idle. But once past the flat spot all is normal and it idles normally. Full power is great although I don't like to flog the engine till it's fully warmed up. After a few minutes the flat spot disappears completely and runs with no issues....engaging the choke has no effect on the problem. The tank is clean, new petcock, fuel filter , newer quality fuel hoses..and it has the Mikuni vacuum pump conversion . There is a few pops out the exhaust during the problem like it's it's ignition related but no sneezing through the pod filters like a leanout issue..The plugs look good ....
    Any ideas?

  • #2
    When is the last time you cleaned the carbs?

    I know that's basic math.... But they can gum up little by little.

    You could have a slide starting to stick, thus the bog of idle that goes away once they have started moving free.
    Don't spend money and buy, spend time and learn.


    • #3
      try tuning the idle mixture screws following the fsm idle drop procedure. make sure the choke isn't sticking partially on (no slack in cable).
      Last edited by squirrelman; 06-05-2022, 06:39 PM.
      "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.


      • #4
        Thanks for the info....The carbs were cleaned 500 miles ago ...I will go through the ile drop procedure