โ ๏ธ M77
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Hyosung has likely moved on to newer production pistons, so they don’t really make the old type anymore. Hence it is good to get a piston + matching cylinder. Even their Japan GV250DRA 2026 uses 57mm pistons now
If you don’t see it on this forum, check manualsLIB website it has the biggest database of manuals for most bikes. New cylinders will fit your 2001 , just get pistons with it or check ebay for used pistons & cylinders
The float part number is the digital version that is used on the 650cc but the extra wire is overkill , likely for (warning) , these are very rare , as Hyosung is using 2 pins since 2004, their newest GV125-S EFi model 125cc is 2 pins and is using a float arm. (much better) than the rare stick version you see in pics.
You should be able to find a gasket for the fuel sender on ebay incase you go back to the 2 pin version, I suspect the last owners got desparate and used the old old 650 3pin version.
All EFi 250/650 use the float arm that moves up & down with 2 pins. For some people, they use the ODO Trip Meter to count the miles before filling up again if the fuel gauge isn’t working. Hell some older suzuki bikes did not have a fuel gauge. So it was a luxury thing for Hyosung since their GA Cruise 2 125cc days & made sure other future models always have it. Bikes without it i know and owned in the flesh was the supermotos/enduros (RT125/RX125)
I suppose with your 3pin version being rare as it is, you wont worry about a float breaking off , as its all digitized (and yes some GT650 still used analogue style clocks before the LCD era after 2005+) , you just have to figure out wiring on retrofitting some gauge you have either a suzuki one or aftermarket gauge, and expect to read OHMS for each wire and study yourself how much fuel is in tank and what ohms it is, and see if that registers on the whichever dash you’re using. I have not seen these fuel gauge values in the manuals yet. Aftermarket Senders ? = Custom work for yourself , I don’t really use them as my bikes still use their OEM clocks , i prefer the OEM senders, (despite them being optimistic at times) , i do a lot of motorway distance trips. Not every stop has E5 , so will need to travel further to fill up sometimes.
Would you be able to record this inside the garage (so that there is no wind noise) and point to it (ie, your finger is showing where the loudest sound is) . Upload it to GoogleDrive/DropBox etc , get a public share link to post on this forum, i could try to suspect what it is
Hyosung only uses 2 wires for every fuel sensor they make (any model) , its always a grey-black wire and yellow-black wire (or just yellow ish) for fuel level. Not clued up on bandit clocks there, so you have to check Gixxer forums for clock wiring diagrams , that includes the speed sensor.
125/250 do not use oil level lights or temp gauge , it’s turned off the chip and no wires for it in the harness or even ports for it on the engine.
Only 250 EFi gets Temp Sensor in front head strictly tells the ECU (not the rider) so you will never know what temp the engine is, you have to go custom route there yourself.
650cc hyos are the ones who get user-displayed temp sensor as there is fan & switches around the radiator and thermostat. No oil level indicator , just manually checking the sight glass instead.
Would i be correct to say it sounds like an Ak47 in slow motion and where is the sound most loudest ? which exact part of the engine ? – Seems to be idling eneven, so also check your spark plugs incase one cylinder isnt burning properly
If the engine is cold, start it and put your hand on it and see if you feel anything that suggests something is banging against the walls ?
I am not able to decipher the video properly but my guess so far would be either clutch basket or top end
or one cylinder isn’t burning properly (causing uneven running?) – I haven’t even addressed the carbs yet (it will be the last thing unless plugs are pure white clean = no fuel in that cylinder)
Worst case scenario is that i really , really hope it is just a time to do valve clearances (if they were too loose , you would also get that Ak47 sound but usually happens at higher revs)
Have a look at this topic below in regards to intake pipes, it could be worth repairing it.
It is very difficult to get one as the RT125 versions don’t fit (which is a more recent bike than the XRX), so you have to preserve yours as much as you can and you can comment on the topic above ^ and hopefully he replies with extra times.
Plastics = They have always been orange mainly , the UK loves that colour! – I don’t , its too bright for me, but i will tolerate RED or BLUE but black stealth is better with a red frame!
Graphics = Hyosung won’t do it anymore and it was rare , so you may need to go custom here.
Welcome to the club!
Could you possibly be able to record this ? and upload it to Google Drive , then get a public share link , post the link here to view it.
But do check the clutch basket , rattling is something spinning, so I hope it is just a thrust bearing for the clutch or 1 clutch plate that has worn down too far and it has cracked (Happens actually) then its just clutch overhaul job.
Tensioners Cam = I am not sure what to say just yet until you get it running fully or check the flywheel area to see if the sprag clutch is making noise there ? or a rattling worn out starter motor ?
Just have to find the source of the noise as far as you can.
The bike wont like running cone filters , you will be in hell for sure.
Though you can make a metal box , fabricated , then cut 3 holes (2 for the carbs and use GT125R airbox rubbers) and cut other hole for tube custom flexi hose to connect to the air-filter box on the side of thebox Thats what some people do now. Costly but least with a custom metalbox, you never have to worry about the plastic airbox ever again.
Besides hyosung isn’t making new ones anymore. They moved on to EFi GV125 Bobber models now.
Using a multi meter, check the same wire colours from this thread below
Needing a little help with my current project (+GT125 CDI PIN OUT)
And verify the coil wires are not broken towards the CDI or fray, otherwise the meter would say “eg. Blue/White Tracer wire for rear” no signal since its broken somewhere along the harness or it will tell you the circuit is complete (no breaks in the line) , then we should check the clutch Switch (Dont bypass it as fake neutrals can happen , rare but does happen) but you want the CDI plug to know it can sense it at the front handlebar lever switch , then also check sidestand (bypass it hard) , if it is bypassed sidestand, remove it and check the sidestand bypass wires did not get rottten (it makes it very hard to start the bike!)
These 2 I just mentioned do cut sparks off if the CDI can’t sense it.
Worst case scenario is that you may need to remove the harness and fully examine it , then check the coils using the link below:
Rectifier – How to Test Stator , Battery , Regulator – GT125R Carby
Check their resistance and report back the figures. Check your HT caps too. Then test again for sparks , see if they are bright blue or just very dull yellow sparks. (Becareful though as you don’t want to spark anywhere near fuel! – So just be wise)
Hopefully we are not looking to replace the CDI as the last resort or the bike has the wrong stator fitted. (Stator = No sparks will happen unless the CDi reads the stator’s pickup coil first)
RC & OIder R models use different flywheels, previous owners may have tried to put the wrong stator and bike wont start , it is just an idea, you will see for yourself if it is correct. RC stators rarely need replacing unless they got cooked by a crappy OEM Reg Rec
The fuel pump making a whirring sound is a good thing while running, it must keep running until you switch off the bike as the injectors need fast pressure fuel for injectors compared to slow fed carbs. A slight delay would cut out the bike.
The black wire , looks like a fire hazard, that’s the plug which gets power from the rectifier yes , don’t cut it, but make a very tight bandage around it using a very good electric safe black tape, so it doesnt touch anything else naked. Good excuse also to check all your other wires.
Regulator = I highly advise sending that regulator in the bin. It is the #1 most dangerous thing on the bike, as if it ever goes funny, it will smoke everything. No long term hyo owner keeps its , hence we always stress to use a trusted MOSFET Japan version , a real one.
Like this example here:
Upgrade Regulator Rectifier & Stator Magneto – Hyosung GV250 GT250 [EFi DELPHi 2011-2015]
BEFORE changing the regulator, please check your stator’s output , or show this link below to your mechanic:
Rectifier – How to Test Stator , Battery , Regulator – GT125R Carby
Hopefully the stator is OK and all you need is just a regulator upgrade. probably the most imporant electric upgrades will be “Regulator (Mosfet) , avoid many million fakes out there” + NGK HT Leads (OEM ones are rubbish) + New OEM coils (Old ones be kept in garage for emergencies) , these three along should be enough for a long road trip this summer.
As for Error codes, unplug battery for 24hrs and reconnect, then see if new errors come up and tell us the sequences of the flashing red icon.
is it possible to upload a picture to this forum , we need to see the harness near the battery and also the dashboard, this will tell us if its an RC model or older R model, if the last owners have been making a botch job toit or not.
Hyosung doesn’t make new looms for GT anymore, so we have to preserve what you have.
Blue-wire ends up at the CDI (Rear Coil) and Yellow-Black wire is at the CDI for front coil (which is shared with stator and dashboard for rpm signals)
Here is a CDI pin out too (See reply from @Cobra2)
Needing a little help with my current project (+GT125 CDI PIN OUT)
I would check the tilt sensor, he may have had the bike on paddock stands but you struggle with it on its kickstand ? (Hence tilt ) , but the tilt sensor is there to cut things off when it suspects the bike has fallen down , but it could be faulty or has been bypassed and the wires may be frayed ? Do check your kickstand sensor too.
Fuel pump = Honestly, it really does happen. A dodgy pump has happened to my customer bike , it would start, sometimes not, sometimes yes , but maybe not for a week and voila next week its all good, was annoyed because i did not want to try aftermarket pumps just yet as he wanted to keep it original.
If your pump is suspicious, it will definitely stop starting the bike, try to get a new pump and test again just to be sure.
Also when the pump is disconnected, check the ECU is sending 12V to the fuel pump for 4 seconds or less (This is the time ECU lets the pump prime and shuts it off until you start the bike, then it switches the pump back on immediately)
If there is power to the fuel pump connector everytime you switch the key on, then we should look at the actual pump suspiciously.
ECU will not send any power to the pump if the A)Kick Stand Switch, B)Clutch Switch , C)Neutral Sensor , D) Stator Pickup Sensor have gone haywire in any fashion.
Hope this helps, although i was all over the place but do 1 thing at a time , so it is easier for you to troubleshoot further.
Good luck!
Check the yellow wire from behind the dash itself, it’s yellow with a black line on it, follow it all way down to your harness , then same wire appears at the front coil , likely harness issue.
Clean the carbs , check your jets , and you probably need to check engine compression to make sure its good.
Your just have older style carb, use the 125cc as it is updated. It has jet pump on the side. It is not critical , but helps a little bit on throttle that is all.
Coils = Same for all GT/GV carby models for 125 and 250cc. You will be fine. Otherwise, take 250 electrics and put it in 125 if you’re worried and keep the old 125parts for spare.
Service manual will tell you more on electrics if you want to check coil & stator resistance etc.
For a 2015 Delphi, you said 10-5-10-5-10 or 1-7-1.
I must assume 10-5-10-5-10 = ISC Error (Idle Speed Control Valve issues or errors or not detected etc)
1-7-1 is not found , the closest i can see is 10-1-1-7 = ET Sensor (Temp Sensor in the engine front cylinder) (Malfunction / Low Voltage) , it also says possible ECU malfunction or wiring harness.
The service manual will dive deeper in to the codes i mentioned as there should be a diagram on how to check with a meter too.
RO Sensor = The wires will be hidden in the harness if previous owner has cut it off ? = It is always by the battery area where the tank sits on, always, see where the 2 bolts of the tank screw in to? It is directly under there , very well tucked in and almost hard to access but it is there , it is also before the solenoid ball , then the battery box appears, right there in the center of the bike is where the RO sensor usually sits. Sometimes i get a hard time removing it myself to swap for another one.
98 is too much fuel, it will end up washing down your piston walls. 97.5 is max but it will be fine in 92.5 and 95 (factory setup) , so 98+ is overkill.
