♠️ M77
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Hello,
I do work on customer bikes yes in my workshop, besides selling parts.The stock setup is perfect , as any tooth less on the front or tooth more on the rear is kind of 10% better on take off BUT you lose top speed a lot, they dont like screaming at top revs all day.
Better to lose the heavy monstrosity of the stock exhaust for something better. The only aftermarket exhaust i can recommend is the italian Leo Vince. Just search on Google “LEO VINCE HYOSUNG” and you will see it. Looks really good too! but expensive! , i believe it is on Amazon also.
Welcome Jasper!
Good choice on the GV250 being your first bike, depending on your 2009 model (They can either be carb or EFi injected , and also specify which ECU it has)
2001-2010 = Carbs
2008-2009 = Slow Transition to Injection system using SENTEC ECU
2009 = SENTEC ECU or DAEWOO ECU
2009-2014 = DAEWOO ECU
2014 onwards = DELPHI ECUSo Hyosung has made numerous revisions under the hood, but didn’t change the looks too much.
If unsure , just take a picture of the ECU you see on the battery tray or show us what you can see if its not easily accesible (never know what the last owners have been doing to it)
I could probably advise better on the electric department.
Also , some history of the bike on your next reply would be good? Any reciepts of work? What did they do ? What is the mileage? Did they do clearances etc?
Have a look at the Techinical Section of this forum first => Download the 250 Service manual, have a good read through it, as it can explain a lot of things to look out for maintenance wise, this will let you know if the bike is still up to scratch!
Most of all, enjoy it , ride safe as spring is nearly here. The winter has outstayed its welcome!
Rears are special as they have bigger holes and use plates to lock in and lock out as you have seen on yours.
Here is the front one below, same place you got the ET sensor from:
https://www.ebay.co.uk/itm/255956878875We got the ET sensor and is on its way to you, i will throw something random inside as a freebie (some part in our workshop, we don’t need)
the 10 1 7 1 7 1 10 is actually 10 1 7 1 10 1 7 4 somehow I put an extra 71 in there
10 1 7 1 10 1 7 4 = The closest i can decipher is 10 1 1 7 x 2 = Temp Sensor , so probably still refering to the same part , if the Temp Sensor was not working or oxidized contacts , the ECU won’t know the cylinder temps to adjust injection system , could explain why it runs in “limp” mode to discourage higer revs or die quickly forcing the user to investigate. The good part is that the ECU must stay intact , no liquids near the sockets , just a compressed air in to every ECU pin will help reduce resistance (if the Engine said hey the sensor is 80 ohms at 45 Celcius , that signal going down the plug oxdized , ecu plug oxidized , etc , might read as 120 ohms at the ECU side, it will panic and go a little haywire , also the forum should have a service manual for either GT650 or 250 to check the TPS as that would be key too, there is a diagram for it , it could directly affect what the ECU does next
I could not decipher 1 7 4 , but if you work towards overhauling the parts, while the ECU is disconnected, it should report less errors I am hoping!Good question in regards to AC/DC. It will be DC for the GV as anything AC produced by the stator will go to the regulator anyway, though the pulse trigger on the stator goes directly to the CDI, so I expect that a CDI being pre-programmed to read certain timing pulses as the flywheel spins.
I can’t remember but i strongly suspect we may not get a full output of the AC wires as diameter of the 12 pole stator is different to the EFi 18 pole version. This was experienced on the 650cc where the later models required a full flywheel change as the diameters changed by a few mm!
I think you will surprise us as most riders don’t like go in to the abyss like we do haha , they swap the whole thing and be done with it.
Replace the stator to the older 12-pole version
The EFi 18-pole stators never worked on carby flywheels as they use different timing dots. Next get a GV Harness (carb model GV250) and put carbs.
Your next trouble is to get a carb model GV tank + GV vacuum pump + Tank Tap = there is no way to use the Electric EFi pump inside the EFi tank on a carb model.
This should help hopefully.
There is fuel line diagram tutorial on this forum and another tutorial on how to carefully insert the airbox – I have no advise on running Pod-filters and strange chinese-clones or Keihin USA carbs because it will be a frustrating experience for you, you have to be experienced to do this kind of work and i would rather advise on using the OEM carbs and OEM airbox.
strange. it only seems to let me post when it feels like it. I can write a single line, but most times it tells me your reply cannot be created at this time.
It’s a mess! I intend to sort it out in stages, but you seem to reply OK so far !
light it gives me this: 10 5 10 5 10 1 3 1 10 1 7 1 7 1 10 1 7 4 10 1 3 7 10 5 10 10 10 and it repeats.
Hopefully this is correct as i had to try decipher these numbers in block stages, as the bike is reporting multiple faults at once. These are in order of your numbers but i excluded some as i could decipher them correctly, as number 10 was missing for some of them. Notice that the sequence starts with 10 blinks first.
10 5 10 5 [Idle Speed Control Sensor Faulty] if its 10-5-10-5-10-5-5 this exact blinking sequence , explains the idling issues and running issues, it is the unit that has 3 pipes sucking the airbox and feeding the injector bodies filtered air (kinda needed to for injectors when throttle is shut)
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10 1 3 1 (O2 Lambda Sensors Front not-user repairable, try to clean them to see what happens unless its a dead dodo)
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10 1 7 1 7 1 10 Engine Temp Sensor Unit (inside the front cylinder next to throttle body or just very bad contacts – extremely sensetive part due to oxidization of pins – ====================
10 1 3 7 [Rear Exhaust Lambda Sensor]
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10 5 10 10 10 [Speed Sensor Faulty = its on your fork leg at the front left of the wheel, could need a strip down and proper clean up or replace it if beyond repair and it repeats.
Hopefully this helps!
Youtube video was handy!
Welcome to the club!
Bare with me to deal with the look of the site , it wont change much on the forum but i will try to make it a bit more simplified than it is now. Your post was edited for you it was a good call!
If you start going through everything properly , then you can start a topic for separate issues as it could be used as future reference for other owners who may have done the same auction deal you did in your country. Hyosung 250cc motorcycles have gone through various revisions, so while it looks the same OUTSIDE , the core engine, electrics have seen many changes as Hyosung was using different sensors, different ECU’s to try manage faults that owners reported until they settled with a Second variation of a Delphi system going forward (250 had carbs, EFi-Sentec, EFi-Daewoo, EFi-Delphi (1st generation) , EFI-Delphi (2nd generation that had a revision of its the harness , stator system etc, ) – You can see why having individual topics could be easier to narrow things down each time (ie. one talks about the pump and the other talks about fairings etc) , or if it helps you, you can make a singular journal style topic where everything falls in to one mega thread.
When i saw Green, i had to look twice as i thought i saw a Ninja 250! – It’s a Hyosung, pretty odd colour on a Hyosung bike. Will you keep that colour? or sleeper black?
Welcome to the club once again, I see that you have now busted through the Registration Gates by yourself, so whatever you did, don’t change haha.
10,000 RPM is a safe limit , but because you are running in the engine, you want to stay around 8k until its about 600 miles run in, so take your time. The benefit is that your have a way stronger chain set as you physically found out, he wont be going back to 428s
The customers who made rave reviews on their bikes had stock exhausts you saw in pictures of the shop OR they used Original Harley Exhaust as quoted above ^ = The GV125 since 2001 (carb model) and currently EFi models (2019+ onwards) still hate random exhausts , so its a matter of trial and error to ensure the right exhaust is not losing “lower bottom torque”
Top speed doesn’t matter if you’re under 50mph , it is the “torque” that matters for quick city sprints or going up hill , the exhaust plays a huge part in it. Some people on facebook will tell you (it is a 125 , who cares) are clearly people you do not want them to service your motor next time.
125s my experience repairing them for customers always preferred a proper exhaust (expensive ones) + a baffle that is about the size of a 10p coin.
if ANY exhaust is as LONG (length) as the OEM Hyosung stock and has about a 10p hole size to exit gas = This seems to be a sweet spot. Europeans are using Harley Exhausts stripped from real harleys (a real harley exhaust will make itself known that it is not a knockoff version you see in china)
The name of the harley exhaust to try is in this thread
Remember, it is a new iron maiden, run her in first and watch the revs gradually settle once he is in top gear. After 600 miles, we should have a service again, then it should behave like everyone else on this shop said , “accelerates quicker off the line , but each gear feels longer ” – This is the balance you want to break out of the 75-80+ mph barrier , Factory speed is 60-65 max at max 12k revs!
Feel free to experiment back on a standard exhaust , as you’re going back to the factory setup with a faster chain thats all. Don’t pay too much attention at top speed, you want to find out does it “pull harder” on stock exhaust or this loud one ? Test the torque first, more speed will come from the bottom low end torque (how much pull it has in gears 1-3 = less struggle to get to top gear.) , don’t be afraid to go between 8k revs and 10k revs
It is OK to rev to 10k rpm in gears 1-3 to build momentum for the bike, then top gear will cruise in lower revs like 8K (kinda pointless to ride at 4-5k revs , its a heavy girl!)
Would be good to add a baffle to it as any 125cc doesn’t like riding without a baffle , then again you will get hard evidence when you take it to a Dyno Shop and they will tell you how much HP was lost using that can vs keeping a standard can vs using a harley factory can (has to be a factory can , not some aftermarket harley can)
Most we know so far on this forum is this thread
Will you not keep her? She looks stunning! Do like the aggressive brawny MOTO3 vibes it gives out , think its the best looking sports bike hyosung has done and such a damn shame it was shortlived as its bigger sister GT650R was more preferred by most riders and the GT250R funny enough due to them having vtwin motor instead of the GD’s unique single piston 250 motor block. Its definitely faster than a GT250R by a small margin if both bikes are factory untouched (no mods)
As they say, “look after it and it will continue to serve you” , get busy , Spring season right around the corner now 🙂
Check the fuel pump connector even gets a 12v signal, just the fuel pump harness ?
If the pig-tail is dead, remove it, then measure the “main bike harness” itself before it connects to the “sub harness” of the fuel pump. Want to make sure all the wires from the pump down to the ECU is not broken ?
If the pump had a pink wire , i would trace it all the back to the ECU which i assume it should still be the same colour (Hyosung does change wire colors halfway down the harness! so verify with service manual book that has a wiring diagram at the last pages)
Remove the throttle cables and choke cables
Can you rev the bike manually by hand ? and does the RPM needle come down FAST or SLOW or just hang about for a bit then slides down ? etc…
If not sure ===> Go to youtube , upload a video and select it as “UNLISTED” so no one finds it on youtube , then copy the SHARE LINK paste it here.
Dont set it to “private”
This lets us see what is happening, don’t be afraid if its a 3 minute video (10 second videos suck as they dont help make a proper judgement)
Remember = High revs on CV carbs usually means illegal air is still entering or carb is “hunting” for fuel (carb internal issues) or exterior parts (moving cables or choke assembly rail on the carb jammed etc) are still activating the carb to allow more air than usual.
Put mixtures back to 3 Turns out FRONT and 3 + 1/4 Turn out rear, this sets the baseline.
Jetting Tutorial = Click Here
SLIDE needle tutorial = Click Here
Did you change the Intake O-Rings ? They are a big deal than you think, click here
Airbox missing? = Carbs will behave rough, make sure airbox is on and is fully swallowing the front carb as it can peak out.
Get a fresh set of CR8E plugs from halfords . Buy a pack of 4 (2 for test ride) and 2 for emergency
Come back , upload pictures of your plugs on this forum , we gotta see inside the plug and the threads, this will tell us the mixture from idle all the way to 3-4th gear riding down your street.
I said a lot, but please, take your time. 1 thing at a time, so you can see its mood change gradually till you find the culprit.
Grab some vernier calipers and measure the cork plates thickness , do you think they could have been worn down ? Factory plates tend to wear down a bit sooner than OEM
Usually a full clutch EBC kit solves the issue as you get new plates and new metal discs , least this way, you put your faith in a UK brand like EBC to do well for a bit longer.
It does get hole, so its not alarming to see plates and metal discs go dark , but if its all black then yes i would be very worried and the oil being ultra black needed a change!
So time for a new set of clutch springs, plates and the lot?
Also consider MOTUL 7100 oil (it really is a good oil for hot twins) , i trust it more than any other brand for all my various bikes. keep an eye on your engine temps too, if the coolant is 2yrs old or cheap one used by dealer , get yourself MOTUL FACTORY LINE coolant. Best coolant i trust too. Castrol junk products don’t hold a candle to Motul.
Replace the oil filter again, so that old bits dont circulate back in to the bike spoiling up the new oil.
At 5,000 miles , Hyosung says “Inspect or change” clutch at 4,000 miles, so you were right to have a look.
While it is apart, have a good look at the clutch basket and gently shake it to see if you feel any wobble ? and also spin the INSIDE basket to feel for any “grinding” , it should be smooth.
Hope this helps!
Quoting your previous post
”Bike Model = : GD/EXIV/ 250rHi! New to the group after buying/selling hundred of bikes over the years a Hyosung has eventually ended up on my lift.
2017 GD250R/EXIV 250r only 400 miles has not been started in about a year.
First thing I replaced on it was the battery. It cranks slow. Have tested and tried a handful of known good batteries so it is 100% not a battery issue.
have checked nothing else, I will start with frame/engine grounds, starter solenoid and then starter.
any input from other owners? I just want to acknowledge how cool it is this seems to be an active forum. Almost all bike groups have moved to Facebook at this point and I don’t think it’s for the better.”
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Have you considered removing the flywheel to check the condition of the sprag clutch ?
But looks like you fixed it though , gotta love electrics! – Apply some ACF50 and clean wires, incase of oxidization after all the years , did the owner ever ride through a bad storm ?
Daewoo pumps run at a different pressure rating, did you swap the internals of your OLD pump in to the new plastic shell of the new pump ?
And retry? Also if possible , check if there is a 12v pulse coming from the pump wires when you turn the bike on ? (this is what turns the pump on to prime, so its a wire / signal check)
As you had the bike apart, you want to use only dry air , and blow the connectors clean for every plug you find on the bike. I would not even think twice to put liquids near the ecu ,as you said, you would have to go in hell to even find another Daewoo ECU again, so i too hope it is not that either.
Check this out
Your will see it by your cylinder heads towards the radiator unless it got relocated by previous owners.
Also browse this forum again in the Technical section, and where it says MANUALS, get the 650 version for a service manual, it will go in to detail about troubleshooting temperature issues of the bike or to diagnose the cooling system , it can also show you readings you should get from your meter when testing cooling sensors such as THERMO FAN SWITCH, Radiator Sensor (aka Temp Sensor) , Engine Temp Sensor – And see if you can report back your findings.
They don’t want to touch the bikes? That’s silly, but little do they know Hyosung was partly responsible for Suzuki’s early days as they made parts for them and helped make the SV650 distant cousin!
You will do a better job than them, you got this!
If you struggle, just add photos in your next comments!
