โ ๏ธ M77
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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.
95 + 97.5 Mains.
20 + 20 Pilots
And that’s it. Dont worry about other carb parts.If using a sports filter, make sure its a K&N or BMC etc, as Hyosungs do not like “pod filters”, they will refuse to run correctly with no OEM airbox.
Share a markeplace link for it, then hopefully someone can message you about the advert through there as PM’s on the forum are temporarily removed. It’s a shame you have to let it go, you can always keep it and convert it to another EFi system (find parts hopefully eBay USA as that is the biggest 650 market)
The tip Over Sensor is directly where the battery is , that yellow bar where your fuel tank sits on, unless it got bypassed.
Is there a chance of stripping the bike again and looking for any burn marks along the harness ? also where cables bend at the steering head + under the seat, look for fraying / chaffing ?
Check the sprocket cover and see if magneto cables have any fray or chaffing ?
If the Right Hand Switch Gear works (all buttons) , you wont need a meter on there, but make sure its black connector under the airbox is clean from any rust , debris etc that might disturb the signals , as the ECU does use the Kill Switch to communicate error codes to the dash when user flicks it 3 times fast before starting.
Since you can get a contact cleaner and air spray, spare a day where you can clean every single socket you can find on the bike and let it dry overnight.
โ ๏ธ Don’t spray contact cleaner on the ECU! – Only dry air allowed.
You can clean the ECU plugs though, it will help with reducing some resistance from pin oxidization, so cleaner signals can pass through. Just make sure its been 24hrs before connecting all your sensors back, so it is fully dried out. it is still spring season, so air is still a bit damp to ride away immediately.
12.5V is OK but 12.8V is a charged battery
Running Idle = 13.5-14.5v max
5,000 revs = 14.5V maxAny higher , bin the regulator but becareful with TEMU style regulators , they will smoke the bike in minutes , just look at the last post here
Bike wonโt fire cold but it fires once working = GT250R 2012
Use 250 jets pilots and mains, because of bigger pistons, or it will be lean and burn a hole in the piston.
Don’t worry about the vacuum pump, all 125 / 250 are using 650cc pump – Hyosung uses a 650cc pump on their 125/250 motors. So if a GV650 can use the vacuum pump, your 250 will never max it out.
Good luck!
If I convert to vacuum, can I use the intake hoses from the 125? With the carburetor setup from the 250?
Yes you can.
Hey you mentioned, sometimes it has starting issues when on kickstand, is it bypassed ? and if yes , remove the bypass to check if the wires had internal corrosion, it happens sometimes with these new Gen RC machines.
Also check your tilt-sensor or replace it ? if your mechanic can use a tilt sensor from another bike, it is also called RO Sensor (Roll Over), bike maybe thinks you fell down ? so it shuts off sparks & starting, it can happen, I am not sure it is a good idea to bypass it (heaven forbid the bike falls in the garden and it is still running!)
If its an EFi 250cc , you need the full donor bike (EFi Tank, All electronics, Exhaust because it has lambda sensors , EFi airbox, EFi dash)
This is assuming you are using an EFi 250.
Otherwise if it is a carb model, upgrade your 125cc jets to 250cc one and keep using the 125 vacuum pump (that electric pump in picture is worthless = too many problems that’s why Hyosung used vacuum pump on all carb models after this)
