Forums 🚥 PIT STOP 🔧 Hyosung Technical Help 1/4 throttle running issue help

  • This topic has 4 replies, 3 voices, and was last updated 1 year ago by Pete.
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    • #2300
      Pete
      Member
      • Topics: 3
      • Replies: 6
      Joined:
      Jul 6, 2018
      @sebringmaster
      Location:
      Scotland
      Riding:
      GT125P
      Points: 79

      Hi guys.

      I’m looking for help with my 2016 comet that I’m quickly running out of patience with.

      Ever since I bought it (2nd hand) it’s had an issue with 1/4 throttle bog/hesitation, this happens when slowing down and getting back on the throttle for say a corner, also straight line speed, again slowing down for say a junction and back on the throttle, quarter throttle doesn’t do a lot although you can hear it trying, hopefully this gives enough info into the issue.

       

      What I’ve done so hoping you lot can come up with something I haven’t.

      2016 model carb

      Full Black widow ss system

      New plugs

      Timing and valves perfect

      Marcel coils

      Compression 90psi per cylinder (seems crap but dunno what it’s meant to be)

      Uprated main jets

      Next size up pilot

      Checked inlet manifold seals and for cracks, all good

      Carbs synced using tool and showed being off however once adjusted it idled a little high, took carbs back off and found not to be synced so bench synced them by eye, this itself points to a vaccum issue possibly.

       

      Hopefully someone can think of something I haven’t  thanks again

    • #2314
      Ashley
      Member
      • Topics: 0
      • Replies: 1
      Joined:
      Jul 6, 2018
      @young2252
      Location:
      Manchester
      Riding:
      GT125R
      Points: 14

      Only thing I can see this being is the same issue that happened to mine. It’s called a Falt spot where the bike bogs down at 5-6k RPM / way to work around this is CDI unit under the seat to cut the green & blue wire & then use some electric tape to secure it. It was a video I seen on YouTube that helped mine. Hasn’t bogged down since! Hope this helps

    • #2318
      ♠️ MARCEL
      Administrator
      • Topics: 38
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      Joined:
      Jul 6, 2018
      @mf448kxn6
      Location:
      North UK
      Riding:
      GTR
      Points: 3,153

      way to work around this is CDI unit under the seat to cut the green & blue wire & then use some electric tape to secure it.

      It works on “GT250-M815″ stamped CDI’s only, and it’s minimal.
      Changing the coils will do better on throttle response than a small cdi cheat which helped old 250s to please eurotree huggers (emissions maybe?)
      The effect on 125cc means the stock coil gets a little push up in 3-6k rpm (which is the area the bike tends to take off from lights)
      M795 or GT”125-M815” are already full power as far as I’ve experienced them on my donors.
      Some report placebo effect , like the SV650 coils are the same as the old 650 lol.

      The original poster may not need to worry about the cdi as there aren’t restricted like an ECU is .

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

    • #2319
      ♠️ MARCEL
      Administrator
      • Topics: 38
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      Joined:
      Jul 6, 2018
      @mf448kxn6
      Location:
      North UK
      Riding:
      GTR
      Points: 3,153

      Hopefully someone can think of something I haven’t thanks again

      Hey,

      The pilots are too big. Size 15 front and rear is plenty. (You said you up-jetted, this assumed to be higher than stock. You did not say what size.)

      Pilots control IDLE & slow running. Your problem could be this too.

      Air mixture screws must not be tampered with by any garage (They are idiots if they did) as the service manual discourages air screw messing , and for good reason.

      Main Jets should be 90 & 92.5 = Unless the bike is doing 90-100mph, it won’t need size 95 which is 250cc

      Some of the information below is copied from other topics which I replied into. (other topics have pictures & much deeper replies, so have a browse too.)

      🔧 Hyosung Technical Help

      ====================================
      Start your bike. Rev to 4k rpm. Your battery “must” say 14.5v at the meter , otherwise change the regulator. All electrics depend on how healthy the regulator and stator is.
      Anything 13.xx is not good. So bare minimum is 14.5 up to 15v as specified in manuals.
      This is your charging system (& sparking juice)

      Big sparks come from better electric supply.
      ======================================
      Speaking of sparks. Remove your spark plugs. If they are “RICH BLACK” (Your jets were too big or the diaphragm slide needle may be on the rich setting, if the garage touched this)

      , a healthy bike will show “DARK BROWN” plugs. No sign of ash blacks anywhere.

      ==============================
      Before you start the bike again, grab a multi meter. Switch to 20K OHMS (20,000), then follow this…
      1. Red wire of your meter INSIDE the HT CAP
      2. Black wire of your meter on the FRAME (NO PAINT) (Find a shiny area!)
      3.—>Your meter must say UNDER 7k ohms max!

      Hyosung says your ignition coils must be 5 – 6.2k ohms max. If its higher, you found your sparking / bogging issues. This is way too common, I digress! – I’d ditch the stock coils at all costs & the bike will be a lot happier (AND less annoyed spark plugs).
      Kawasaki units win.
      ======================================

      Lastly, Grab yourself some “Platinum Laser” racing plugs. No other plug beats this , period.
      You WILL have a better throttle with such instant plugs.

      The stock plugs foul up too easily & hence the peformance of your bike wanes quickly.

      Lasers last 2yrs / 50k whichever comes first, if your fueling system is nice and good too.

      Sorry I took ages to reply, let us know how you get on. Good luck!

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

    • #2320
      Pete
      Member
      • Topics: 3
      • Replies: 6
      Joined:
      Jul 6, 2018
      @sebringmaster
      Location:
      Scotland
      Riding:
      GT125P
      Points: 79

      Thanks for the replies all,

      My bad yes I changed the pilots to 17.5 as it feels like not enough fueling at 1/4 throttle so thought I’d give it a try (no change)

      Mains are 92.5 front, 95 rear

      Needle moved up or down I can’t remember to richen up the mid range

      I did piss about with the air/fuel screws to try and determine if they would help however it didn’t work but originally they were both 1.5 turns out each (made a note just in case)

      Your absolutely correct with the plugs as the bike is running rich now

      I’ve done everything on your helpful list as this has been an issue for a while.

      I’ll take everything back to stock and start from scratch.

      The only thing is this problem has been since I picked up the bike and all carb setting were untouched and standard, nothing I’ve done has made any difference, no better or worse which baffles me.

      I’ll pick up some new plugs anyway and report back soon, at least I can have the carbs off in 5 minutes as I’ve done it that many times  😡 lol.

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