Forums 🚥 PIT STOP 🔧 Hyosung Technical Help Bike suddenly dies in top gear.

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    • #4463
      Trevor
      Member
      • Topics: 6
      • Replies: 14
      Joined:
      Apr 30, 2018
      @bigtrev1969
      Lisburn
      Hiyosung Gv125 aquila
      Points: 275

      Having a problem with my hyosung 125cc gv aquila after driving for 30 mins or so fast.

      When i open the bike out in top gear after driving a good 30 mins it suddenly just dies splutters and stops. After 5 mins it starts back up normal and drives normally again.  Always happens in top gear and at speed then after sitting all fine again.

      Anybody any clues to what this is as its doing my marbles in now. I have replaced everything on this bike from the shop and practically rebuild this bike like new.

      Regards Trevor

    • #4464
      ♠️ MARCEL
      Administrator
      • Topics: 38
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      Apr 30, 2018
      @mf448kxn6
      North UK
      GTR
      Points: 4,203

      Hey Trevor,
      Any form of bog downs / cuts is usually electrical and or fueling –
      You said you replaced almost everything? Usually these are the suspecs to check out:
      – Plugs ? (Still using Laser ones ? if so… clean them if too sooty)
      – Coils ? / (Plus the “black HT caps” ?)  (2 ignition parts here)
      – Stator unit was changed already?
      – Reg rec?  (It will say 14.5v constant if you had the uprated ones, but i have nothing positive to say about the stock hyo ones sadly, we all hate em)
      – Battery? (what size is it and what brand? how old?)
      (some times half of these things above get worse due to heat, some OEM parts were cheap outsourced/built).  Engine itself is good, overengineered thing lol.

      Moving to the fuel side, is the filter usually full ?
      – You can usually check the manual tap doesn’t have a lot of dirt, it has a trap at the base of it.
      – Vacuum pump ?  (and also intake lines + manifolds aint leaking vacuum pressure)
      Because if the pump wasn’t optimal, your carb drinks its own fuel until the pump feeds it  (incase of a slow fuel delivery system to maintain top gear riding)
      – Hate to say it! ==> Carbs taken out for a clean?
      Not just jets but there is fuel valves under the floats that control fuel input, so the little mesh ball can sometimes trap dirt coming from the tank.

      I was aware some bits changed but i have an old brain that sometimes needs reminding lol.

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

    • #4474
      Trevor
      Member
      • Topics: 6
      • Replies: 14
      Joined:
      Apr 30, 2018
      @bigtrev1969
      Lisburn
      Hiyosung Gv125 aquila
      Points: 275

      Hi Marcel,

      Yes m8 i replaced stator, reg rec uprated, plugs, wiring loom, ignition coils plus caps, full service to.

      Now im wondering could it be the battery as thats the only thing hasnt been changed on the bike. Bike runs well until it heated up and i plant it full speed then dies. Sits 5 mins runs perfect again m8.

      I did notice exhaust system was very hot like smoking hot tho i was doing 70mph.

      Cheers for reply Marcel

    • #4500
      ♠️ MARCEL
      Administrator
      • Topics: 38
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      Joined:
      Apr 30, 2018
      @mf448kxn6
      North UK
      GTR
      Points: 4,203

      If you go to the battery with a multi meter,  rev the bike to 2k revs = what voltage does it say?  If you rev the bike at 5,000 revs , what voltage is it again?
      2k Revs & 5K Revs are 2 tests , let us know what it says.

      The battery is on you this time, it could mean time for a change, no size or brand was mentioned , so i will say go for YUASA (legit ones) or VARTA.  Your caddy box is limited by physical dimensions , so a 14BS may be too big to slot in  (that’s what us GTR / GT folk use)
      So you may be limited by a 9BS -11BS type battery.  New is still better than old, either way.

       

      The more I read, the more likely its starvation involved too, & that we need to investigate the fueling side of things as i mentioned in previous reply as a checklist.  Have you done either of those things?.

      A final thing,  pull out your spark plugs.  Tell us if its “light brown,  dark muddy brown,  or jet black , wet black  or glazed white”  === pay attention to the CENTER WHITE TIP of the plug , otherwise you can attach an image if possible…. This is key also.

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

    • #4507
      Trevor
      Member
      • Topics: 6
      • Replies: 14
      Joined:
      Apr 30, 2018
      @bigtrev1969
      Lisburn
      Hiyosung Gv125 aquila
      Points: 275

      Ok will get this done this week m8 as busy with work. Hopefully its solved as bike runs well until this happens

      Regards Trevor

    • #4508
      Trevor
      Member
      • Topics: 6
      • Replies: 14
      Joined:
      Apr 30, 2018
      @bigtrev1969
      Lisburn
      Hiyosung Gv125 aquila
      Points: 275

      Battery seems ok at 2k and 5k

      Reading 14.45 v

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