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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?

    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.


      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, 07:39 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.


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