The Bogging Gremlin - Hyosung GT125R

[Devoid]

Intro

Frustrating problem which sucks the enjoyment out of riding a bike and make me anxious to get on it from fear of getting a car ram me up the ass.
Had this bike in the past had no issues with it loved it so I brought it again after my KTM was giving my jip. Before this issue my Hyosung felt and rode a lot better than my KTM.

The Gremlin

Problem is my Hyosung GT125R has started to run crap, bogging down when pulling away from standing at a traffic light so much so that I need to rev the bollocks out of it to pull away.
Bogging down also affects the bike intermittently when traveling at speed it will pull back and also start bogging down, I have to drop a gear and again rev the bollocks out of the bike to get the revs back up to accelerate.
On some occasion the bogging is that bad I have to pull over(roll actually, maybe even use my foot to push) then play with the throttle (attempt to rev the bollocks out of it) until the bike wakes up again and can continue for a little bit longer before bogging down again.

Then on some occasions the bike seems to run fine with maybe 1 or 2 bouts of slight bogging.
Below is a brief summary of what I remember the mechanic said he did

Mechanic

Cleaned out carbs, re-jet, replaced spark plug cap and plugs, fuel lines checked, all unnecessary electrical mods i.e. led lights disconnected(for troubleshooting, still disconnected now), electrical cables checked, Vaseline applied to particular areas where risk to weathering exists. Exhaust checked for obstruction, throttle tuned, and manual choke cleaned/tuned, cleaned bike. I think that’s everything he said he tried that was in response to the bogging down. £300 that cost several days of work.
He also replaced regular parts during service i.e. brake pads.

Interlude

A week later the bike has started bogging down again, it ran perfect for the previous week after the service, however the mechanic did say it seems to be working now but I have no idea what was really causing it.

Present day

Issue remains and I’ve got to a point where I with little mechanical knowledge plan to investigate this myself with the help of random internet folk, fecking you tube and many other sources such as forums etc.

Requesting help

If anyone has some suggestions of what could be causing this or where I should look, your assistance would be gratefully received.
Please explain the reasons of your suggestions so I can learn rather than blindly following the help so that I may have some understanding of what is going on, like I said I have little knowledge and a base understanding of the workings but more in-depth troubleshooting may be a little more difficult. I play to “dry dock” the bike to work on it in-between working which sucks as I use the bike to get to work so the wife isn’t going to be happy driving me to work 3 days a week.

Information and materials

I have the usual home tools for a bike owner with the extra bonus tool, an impact wrench which I don’t see the need to use with this issue.

High quality pictures and videos of the bike and its guts can be posted on request to aid in the trouble shooting.
Any questions please ask I will do my best to answer and fill gaps.
If something is suggested that has already been tried I will let you know but just because it’s been tried doesn’t mean it’s been done the way you’re thinking so make it a step by step how too if possible.

Finally

Thank you so much for all who add their input I will endeavor to stay in contact here at regular intervals during the battle, family and work. I will post the final solution once it has been identified for others that may run into this issue.

[Nobby the Bastard]

It could be the coil breaking down but then it wouldn't work well until left off long enough to cool.
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Triumph Sprint ST 1050

[Devoid]

[Nobby the Bastard]

[Devoid]

[Nobby the Bastard]

In that case, as it's not related to speed etc. I suggest the carb valve is sticking.
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Triumph Sprint ST 1050

[Devoid]

[Nobby the Bastard]

[pepperami]

The side-stand switch can become corroded and cause an intermittent fault

I disconnected mine and added a loop, intermittent fault cured .

Might be worth having a look there?
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I am the sum total of my own existence, what went before makes me who I am now!

[Devoid]

[Devoid]

[Nobby the Bastard]

[Riejufixing]

[Nobby the Bastard]

I'm gonna go out on a limb and blame the chain tension.
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Triumph Sprint ST 1050

[Easy-X]

I see no mention of valve clearance check.
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Royal Enfield Continental GT 535, Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[pepperami]

[P.]

What year model is it.

[martin734]

Have you checked all of the vacuum hoses to the carbs? These can sometimes fail and leak. It may also be worth checking the vacuum fuel tap.
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Current bike: ST1100 "Big Red"

[Sister Sledge]

Firstly feel your boobs.
No reason except that I'm a pervert.

Sounds like either coil or fueling issue. The coil is quite cheap and if you can replace that first we can eliminate it.

Fueling: Does anyone have an exploded diagram of the carb please?
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CCM 404 DS

[Nobby the Bastard]

He already said it's been replaced.

Always assuming that he knows what it looks like. The mechanic could have put a different brake lever on for all he knows.
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Triumph Sprint ST 1050

[Teflon-Mike]

Intermittent or randomly occurring problems are always a bast to trace, cos you never know when they are gboing to occur, or if something you have 'fixed', was actually the problem to start with.... that's the nature of the game... good luck.

First bit of normal diagnostics though is a plug-chop. Look in the Heynes manual, usually at the back, and there's usually a photo chart showing what bad spark plugs look like for you you to compare yours too.... when you pull it out and if when you pull it out the problem was happening...

But, to this end, stick a spark-plug spanner in your pocket or in the gap twixt seat and tank... possibly a pair of pliers or a cotton rag too cos spark plugs tend to be hot when removed from a hot engine... and watch your fingers... go ride the bike 'till symptoms occur, haul in the clutch, coast to a halt and pull plug(s) and coimpare to piccies.

IF plugs black and sooty, you are over fueling. Usually implies that the choke is stuck on, and or you are burning oil 'cos valve stame seals or piston rings are worn out.

If white and maybe knobly, tends top mean that the engine's running weak, like it's run out or petrol, indicating that the jets are blosked and or your float needle is sticking in it's guide.... that, at the mo is a top candidate, as it wont always stick...

But this is first resort checking.. and an excuse to just ride around a bit...

Go try, report back on plug colour...
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My Webby'Tef's-tQ, loads of stuff about my bikes, my Land-Rovers, and the stuff I do with them!
Current Bikes:'Honda VF1000F' ;'CB750F2N' ;'CB125TD ( 6 3 of em!)'; 'Montesa Cota 248'. Learner FAQ's:= 'U want to Ride a Motorbike! Where Do U start?'

[stevo123]

My bet is water in the fuel form a leaky filler cap.

[A100man]

[Devoid]