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    • #3218
      • Topics: 2
      • Replies: 0
      Jun 24, 2019
      GT125R (2016)

      Hey guys,

      When running my GT125R, it really struggles with acceleration, get’s quite boggy, and really doesn’t accelerate properly. A friend who has seen this has looked at my bike and suggested it looks like the carbs have never been set / adjusted, yet I can’t find any sort of guide to doing this online. Does anyone have any advice at all?

    • #3222
      ♠️ MARCEL
      • Topics: 38
      • Replies: 545
      Jun 24, 2019
      North UK


      The manual says not to tamper with the air mix screws and i agree with the koreans as they tuned it right for 125s ,  tuning it is going to the abyss and extreme as the pilot jet is the perfect size.   Hence pilots dont change either, even 1 step up is just too big. 15s can power 600cc bikes in a row of 4.

      Assuming you have probably read the tutorial on how to swap main jets on the forum,  you can change the mains to 1 size up max that helps with full throttle riding for sure.

      full throttle riding is also dependent on the carb float height,  when the carb is upside down on the table, the floats should be 7mm height & watch the tangs (near fuel valve ports) are not bent.


      so we have fueling sorted, but it will be only as powerful as the sparking system, so while the bike is apart, you or your mech will confirm these figures:

      – HT lead to the frame = 6k ohms max  (coils & ht cap check) high ohms? = replace.
      The coils are one of the major sources of bogging or top gear riding then it starts to wane, common on many hyosungs, we tend to uprate n change the lot.

      – Spark plug =   Clean the IX plug but be warned that RC’s dont like IX or Denso plugs once they start to perform poorly due to RC having weaker sparking system than older gen bikes.
      The RC likes the STOCK CR8E plug (yellow)  or  platinums (silver) just win them over, i wouldn’t go back to stock plugs either

      To comment further on richness etc , heat,  —–  click “add media” on the reply box and show us the spark plugs in the middle.

      The regulator is your last worry,  it will say 14.2v at the battery around 3k revs then its healthy. any single 13.xx reading whatever revs …. then investigate battery or reg itself.

      now if we have electrics sorted, your bike should be zippy from 1st to 5th with good fuel and spark sorted out.

      Fatter lines don’t generally add any torque except we enjoy the 5th gear more as bike feels less starved off (more juice) & less likely to just cut out.  Cold starts are a little better, its hard to ignore overtime.   if the stock lines are 2-4yrs old , change em as book suggest, and the filter isn’t clogged  (clogged fuel delivery parts can bog the bike down)

      Hope that helps , let us know.

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

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