Forums 🚥 PIT STOP 🔧 Hyosung Technical Help GT125 stalls at high speeds

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    • #3148
      • Topics: 1
      • Replies: 0
      Aug 18, 2019

      Hello riders,

      My GT125 stalls when I’m driving full throttle in 5th gear, around 95+km/h. When engine braking it has problems with getting up to power when opening the throttle again.
      I’ve already checked for air leakage. but non found. I’ve cleaned the fuel pump changed the fuel filter and checked the tank valve. All looked fine. At this point I have no idea where to look.
      Any suggestions are more then welcome.


    • #3160
      ♠️ MARCEL
      • Topics: 38
      • Replies: 674
      Aug 18, 2019
      North UK


      It sounds famously like the dreaded 60mph (95kmph) bug that happens to faulty coils or clogged carbs.

      Remove your spark plugs and clean them   (50/50 chance they may need replacing if they aint sparking hard anymore)

      Get a meter , put red wire inside HT cap.  Black wire on the frame.  You should read 6,000 ohms max (6k) for the coils .

      Take a look below and learn how to remove carbs off the bike , then you can clean them.
      – Take out the piston slides (black tubes) = clean with a cloth & its carb holes (piston walls)
      (they control main jets)

      – Get a carb cleaner & compressed air can (aerosol air) , and blow the jets clean from particles.

      – Put the carb upside down, make sure the floats are 7mm high (not less , not more, just 7)
      (full throttle fuel control happens here too)


      Let us know if that worked , before attacking other parts of the bike, as these 3 ^ above are usually main culprits  (plug | carb | coils)

      // Meditation doesn't mean you have to sit still....

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