Forums 🚥 PiT STOP 🔧 Hyosung Technical Help Gt125 little jump on throttle

Viewing 8 reply threads
  • Author
    Posts
    • #13303
      Alex
      Member
      • Topics: 4
      • Replies: 12
      @aleek
      Mexborough (South Yorkshire)
      GT125

      So, recently I bought this bike and engine was dead so I decided to find another engine and did it

      replaced engines and installed new one with 14k miles on it which was running fine on other bike and compession was absolutely fine

      But I came to problem where’s bike jumping on throttle about 6-7k rpm

      it doesn’t matter cold or warm it just how it is

      im sure it’s carbs so your suggestions

      what could it be?

      one more time, as soon as I drop throttle off from 8-9k and give it throttle back at 6-7k it jumps like no power for second an then it catches

      im assuming it’s air leaking or carbs not tuned right

    • #13305
      Alex
      Member
      • Topics: 4
      • Replies: 12
      @aleek
      Mexborough (South Yorkshire)
      GT125

      Also just noticed another post about upgrading jets, if it could be a problem with this jumping on throttle

      I got black widow straight piped exhaust and ktm air filter which also give more air

      can it be jumping like that because of them two? And does it means I need to upgrade jets?

      and if it’s possible what can I do temporary until I will get jets as I use bike daily to work and back

    • #13310
      ♠️ MARCEL
      Admin
      • Topics: 45
      • Replies: 1,892
      @mf448kxn6
      North UK
      GTR

      KTM air filter ? Can you show us ? = I am suspicious on this area now.

      Have you tried this mod below?

      [Tutorial] How to adjust Carb Slide Needle (Tuning) – Hyosung GV & GT 125/250

      Exhaust = keep the baffle inside. It will help with backpressure a little bit as vtwins need it to get goin on the lower revs, so it should smooth things out a little bit ,  otherwise a missing baffle makes her loud but throttle feels too harsh.  (it looses the crispy feel)

       

      Jets = It could be why the last engine died ?    , I would upjet the bike , here is a tutorial below

      [Tutorial] How to swap Carb Main Jets – Hyosung GV & GT 125/250

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

    • #13312
      Alex
      Member
      • Topics: 4
      • Replies: 12
      @aleek
      Mexborough (South Yorkshire)
      GT125

      Oh sorry my autocorrect messed that up

      k&n air filter

      yeah I ordered baffle should arrive tomorrow

      also jets and carb rebuild kit so as soon as arrives I’ll do all of the mentioned

      one more thing I’ve noticed, if I’m doing cold start, it want me to turn the throttle 3-4 times so it can start (without choke)

      Keeps idling fine on warm, but cold a bit hard so giving it a bit of throttle

      aaaand, I know I shouldn’t do it but I did screwed in air fuel mix screws about 1 turn in and magic happened it’s not jumping on warm anymore but does on cold

       

      last engine front piston and rings absolutely gone, I’ve opened it and was really surprised as it was just 9k miles

      going to keep last engine for parts in case I need it

      I will update you after my manipulations with jets and slide needle

    • #13318
      ♠️ MARCEL
      Admin
      • Topics: 45
      • Replies: 1,892
      @mf448kxn6
      North UK
      GTR

      Okay fella,  don’t touch it anymore and i would get fresh CR8E plugs from halfords , and take pictures of the plugs after a long run , just to make sure you are not leaning out! – Messing with mixtures would send you in to an abyss!

      Defo avoid “IX-Blue Box” iridium plugs,  they don’t like em.   Stock CR8E  or  LASER is best for them  (LASER is actually NGK’s preferred plug & is OEM to some Suzuki bikes)

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

    • #13327
      Alex
      Member
      • Topics: 4
      • Replies: 12
      @aleek
      Mexborough (South Yorkshire)
      GT125

      I got my old carb (looking better than new one) for ultrasonic cleaning today, and ordered new jets from jetsplus two days ago (not sure if coming and if it’s not scam as ordered with Royal Mail 24 and it’s been two days already)

      as soon as jets will arrive, I will get it replaced on my old carb with carb rebuild kit I ordered here

      hope all of this helps

      (also I remember that air fuel mixture screws on them old carbs was 2.5 on front and 3 on rear, should I do the same when will get all ready?)

      nice to have 2 engines (got every spare I need and can get them for cleaning while riding on main one 😅)

      so yes, will get spark plugs as soon as all gonna be ready

    • #13329
      ♠️ MARCEL
      Admin
      • Topics: 45
      • Replies: 1,892
      @mf448kxn6
      North UK
      GTR

      If the jets don’t come,  just message us and we will order directly from EBC ourselves.

      2.5 turns each pot and leave it there forever  (regardless of mods)  3 turns  (ish) is OEM.

      The slide needle mod has better effect than messing with mixtures.

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

    • #13372
      Alex
      Member
      • Topics: 4
      • Replies: 12
      @aleek
      Mexborough (South Yorkshire)
      GT125

      DONE!!!

      Ultrasonic cleaning, and slide needle mod has helped me

      still will put jets if they will come eventually, but yes it runs now like a new bike

      total spent on bike from buying 1600~
      and now it’s in the best condition with new michelin tyres on (from previous owner who was a twat)

      black widow exhaust (same from previous owner)

      spare engine with blown front cylinder (oh yes)

      and spare carb (dirty)

      could sell spare parts if someone needs it (just give me a message here)

    • #13378
      ♠️ MARCEL
      Admin
      • Topics: 45
      • Replies: 1,892
      @mf448kxn6
      North UK
      GTR

      Well done! ⭐⭐⭐⭐⭐

      And yes send us an email below with your prices, then we will ask a client of ours if they are interested or not as he has a project he wants to build late summer

      Contact

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

Viewing 8 reply threads
  • You must be logged in to reply to this topic.