♠️ M77
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they look ok dont get me wrong but im worried if i ever dropped it there would still be damage may have to do lots of measuring up, plan on trying to wheelie it at some point anyway just cause i can lol
Please please don’t wheelie it! , you WILL regret it. Even the SV650’s don’t like wheelies either.
A DRZ400 SM? yeah sure go ahead!
It may sound silly, but can you get carb cleaner ?
And do this outdoors due to vapors! ==> Spray the intake system in different spots to see if revs change
If idle takes long to return to normal after a high rev = air leak or ISCV unit possibly (but another air-related sensor may be involved that’s on the throttle body such as TPS)
If if you quick twist throttle and it dies = Injectors (clogged or underperforming (wanning) ) or else the fuel pump is wanning? or else again intake system (throttle body and its ancillaries attached there)
Air filter should be clean if its a young mileage bike (if under 10,000 miles , air filter should be fine unless there is some unexplained damage to it)
Let me know if the above ^ even helped make slight changes (then we are getting somewhere)
If possible, remove harness => clean every single connector you can find (resistance or voltage loss can happen along the lines to make certain sensors on the bike perform less than optimal , in thus the ECU may not always overcompensate for this)
Also , test your stator (importat) and your regulator (way too important, probably the #1 electric device every one discards for a better one)
Battery should be new (where possible), as it’s 2025 , give her a fresh one and make sure it’s a genuine YUASA one (USA brand) , not too keen on other brands (chinese crappy cells)
That’s a fair point there! – Not seen such pre-made cages you speak of, so it looks like a custom job if you’re not keen on the simplistic R&G Crash Mushrooms they sell.
For what reason would it need one ? It seems the fairings already shield the engine (not perfect but still plastic!)
Also R&G UK already make large crash protectors that go through the fairing incase the bike drops on its side.
There isn’t an “off the shelf” pre-made cradle / engine guard for the GT125R
As its a security issue, and being a public forum. I locked this topic to continue this privately.
Send me an email below , and I will discuss what we can do for you (unless your dealer or insurance company can help you?)
Thank you, Marcel. It’s only been a few hours, don’t apologise. Order was made today around 2pm gmt to Bradford, BD4
Thanks again!Bare with me for 3 days (By wednesday i should be shipping it) because I need to order again the special rear sprocket (There is only 1 company abroad that makes it for us so far), a customer took our last stock we had on the shelf today funny enough. So I will need more sprockets!
Hold tight, any “tracking alerts” will be sent to your email.
Hello,
No need to cut the chain, we will do it for you.
Hyosung went from 140 links to 138 to 136 , so it meant some “early” models had slightly longer chain adjusters on the swingarm.
Your 22 plate will be fine! Email us if you have other sales enquiries, it will be quicker since it concerns the shop parts.
Sorry for the delayed reply. Long day!
Sounds stupid but is there any way at all you can get the bike warmed up for 5 mins hot
remove both plugs out
Put a compression tester in front engine , crank full throttle for 5 seconds.
Do the same for rear engine.
Can you tell us the compression figures.
I feel like it is very important to start there 1st before i would advise anything else for that matter.
Similar issues last week , a client of mine said he needed a new engine which we helped him get despite me cleaning his carb & tuning it twice. His rear engine had low compression!
I hope it is not your issue but it is usually overlooked , she’s a big girl!
Regards
Is this a brand new bike (zero miles) ?
The mixture looks strange!
Here in UK (it was once part of the EU but i digress) , it is usually Front = 3.0 Full Turns out & Rear 3 and 1/4 full turns out because the rear is hotter)
Also in summer time, it gets VERY hot , so you want the carb “slightly little bit” richer to avoid leaning out.
Yes I am able to turn the rotor both ways
Go behind the Flywheel Drum = See the BIG sprocket with lots of teeth?
Remove your starter motor first.
Can you spin that big sprocket in both directions ?
It could be important, as Simon is likely to suggest your sprag clutch & starter motor need fixing or replacing
This is the sprag clutch that starts your bike (also known as One-Way Starting Assy)
Hello,
Would this one help ? (It’s used but it appears it was barely run in when we stripped the bike down)
https://www.ebay.co.uk/itm/256778857924Aftermarket Pistons = They don’t really exist off the shelf 1-to-1 copy as Hyosung makes the pistons themselves.
Cylinder Valve Heads = Hyosung makes them. as with their 125cc Cylinder Jugs
If not, send us a private email below we shall see how rapid we can acquire a “new front piston” for you.
HF131 is the correct filter for all years (2005 to 2020) – They did not change the oil filers for all carb model 125cc.
Hello, yes.
Open the magneto cover. That is where the flywheel is. When you see it , remove it , that is where you find your sprag clutch like this one (aka. Starting-Motor-Clutch)You could monitor the A/F ratio on the exhaust and also use some kind of heat gun to measure cylinder temperature so you know which one is still cold ? as you said it stalls in 15mins of working ? =
Measure that temp sensor on the front cylinder cold and hot values vs the manual figures.
Removing the flywheel does not require a full dismantle of the engine. Just the flywheel stator cover off, then extract the flywheel out , that’s it. You should be able to see if the sprag system is worn down (since it is 26,000 km , so it could be worth a look!)
I have had a few engines apart a few times, sometimes the pistons will be in different positions. I open the top valve covers to do clearance jobs , so i can either spin by hand to confirm the timings are correct , then i use a starter motor to battery to see if it will crank OK but ofcourse oil will shoot out!
Once the engine is completed and closed up, it did not matter where the piston was, the bike cranks within 2 seconds after the fuel pump stops priming. At some time ago, it took longer than 5 seconds to spin and start but it sounded weary.
So I removed the flywheel, and some some teeth of the sprag-clutch was gone , could this be related ?
Have you ever taken off your flywheel to inspect your starter-clutch system for abnormal wear / damage?
I recently worked on a customer’s 2017 bike GV250, it was a delphi. It was a stressful job! I changed a lot of things despite positive readings on the meter, the harness was clean as it could be , no wire oxidization yet (garage queen) , but i was shocked that in the end I replaced the stator unit & made sure the battery is 100% charged and brand new , voila it started within 2 seconds of the fuel pump priming. I didn’t really investigate too much as if “piston” position had any influence to how the ECU expects the piston to be.
However, everytime i press start (within a milli second) ==>i see sparks on the spark plug which tells me , the ECU had already been ready to fire up the coils as soon as i hold the clutch switch in. The suspicion in my mind right now is that it did not matter if the front was up, and rear was down or rear up and front down position of pistons , it always started in 2 seconds. Longer cranks in my past were a result of the fuel injection system needing a clean or fuel pump was underperforming. I did not keep DELPHi systems for long , but i always had Daewoo & Sentecs bikes to work on. Sometimes my customers ask me to just convert the machines to “carby” (expensive investment but less maintenance in the long run however the DELPHi system is not too bad, and is more “instant response” with throttle which is good)
As i get more information , I will share when i can. I don’t think i’ve heard too many people discuss piston position vs cranking time for ECU. I have to keep in mind both cylinders are connected to the same crank anyway! Everytime the bike is switched off (during a crash, or normal riding to stop or rider activates killswitch, the pistons don’t always return to the same position as they did before , a bike could be switched off mid cycle. )
Have you got any Fi light warnings ? (2008 model, so I assume it is the SENTEC EFi model) (also 2009 is the last year we saw carb models changing to EFi)
If possible, did you follow service manual to get error code from the ECU ?
If this was a carb bike = high revs usually means extra air is coming inside the bike (intake system leak)
As its an EFi model = I understand that ISCV was changed , could there be any chance it is failing again ? Have you tried your old ISCV unit if you did not throw it away by now.
Otherwise, using the service manual (which has the readings) get a meter and test these parts:
- MAP sensor (it will be on the throttle body or airbox as you have an early model EFi likely (that’s if the previous owners didn’t upgrade it to newer injection parts)
- Lambda Sensor ? (Oyxgen sensor in the exhaust) => Suppose the ECU thinks the mixture is off (wrong signals by the oxgen sensor) => injection system raises more revs.
- Engine Temp Sensor at the front cylinder ==> If it thinks its still cold , the ECU revs up to warm it up? Test that sensor.
- AIT sensor = Air intake temperature sensor (sometimes its called pressure sensor as weird as that sounds) it will be sitting on the airbox (if Hyosung put it there)
- EGR unit = It’s a big electronic box that has 2 pipes => going to front and rear engine ==> block the air feed or disconnect it and see if it changes anything (since the lambda sensor will be in the exhaust pipe)
This is my guess as annoyingly Sentec & Daewoo ECU’s can be troublesome to diagnose.
If Simon on this forum doesn’t say it , I will say that strip the harness out of the bike & clean every connector you can find. You’ll be surprised how much a little resistance in the wires can skew readings to the ECU.
Keep us updated!
If it is brand new and its gold tip hasn’t popped off , then keep it inside the grey metal shell (if it came with one) or put it back inside the airbox and see what happens to it?
I don’t expect any issues if its brand new though?
I imagine you have a SENTEC ECU as your post says 2008 (though some countries had a Daewoo ECU a little earlier than 2009) – I really hope the ECU is OK!
Welcome , beautiful babies! As much as you love the 650, don’t give up the 250 yet , as when winter draws nigh , jump down to the 250cc
Riding a 650 in the UK ice isn’t fun during winters, but ofcourse neither is any cc bike on black ice. No idea how cold it gets where you are ? I guess your winters are just a mild 15c temps?
Either way the 250 makes a good backup!Turbo on a GV650 ? Better make sure the swingarm , tyres, brakes can still stop you without slight warping! – Ill be following that journal if you ever make one, not many even dare to try lol.
The top feed of the shell is usually connected to the air box nipple (one of them underneath)
I will have to see about that again when I get my hands on the bike.
I saw this post, what do you think, is it possible to swap the throttle bodies from my EFI model bike with the appropriate carburetor from the older models, would it even fit?
You will change a lot of things: carbs, intake pipe, harness, stator, airbox, dash, many electrics etc – as nothing “efi” is backwards compatible.
It could be the “fuel gauge” unit itself in the display.
From the TANK sensor to the blue connector plug of the harness = That yellow/black line must have a reading to make sure the level signal is still travelling along the harness.
It is possible to repair the fuel gauge unit in the display (tricky , there is no instructions online) but try the wiring first. But as you said , if the wire from the tank to the display plug is all clear ===> then it will be the actual unit itself inside the display that sweeps the fuel level up & down.
normally , when the bike is switched off, it drops down to zero (empty) , then it rises up when the bike is running.
There is another topic somewhere in the forum where a guy mixed up a GT & GV carby fuel sensor to make his GT work.
I can’t remember what you had before because GT250 have 3 displays. Analogue and Digital Carby and third one is Digital EFi (fuel injection model)
Wirings do change.
If the fuel gauge is in LCD glass (Fully digital glass display) = Then it should be ZERO when fuel gauge is disconnected. The fuel level sensor inside the LCD is controlled by a chip behind the Green Dot Matrix LCD glass. Carby ones can be changed easier but Korea stopped making replacement LCD glass many years ago.
You could find a wrecked GT250 in your area with ANALOGUE display and try it. (Some GT Naked bikes want analogue displays with analogue speedo drive under the left fork = carb models) (It’s rare here in UK i find carb model GT250 with digital display unless it is EFI fuel injection)
Good luck & make a new topic though , so the original person doesn’t get notifications of their thread as they haven’t replied. 👍
