♠️ M77
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Everything seems connected , what seems to be the issue ? although i see the last owner has put a custom white plug going to the rear lights.
You have a 3 plug CDI unit which is good, it is similar to the GT125, so look below
Needing a little help with my current project (+GT125 CDI PIN OUT)
GV250 = Some models have clutch switch but some early models do not use clutch switch , it was up to South Korea.
If you have a side-stand switch ===> Cut the side-stand switch at the side stand leg. Join the wires on the harness to bypass it, use electrical tape to hide this so naked wires are not exposed , then hide it far away from the road , so that water / dirt does not try to cause ingress.
Regards
Idling is controlled by the Idle Speed Control valve and check your TPS values is the same in the service manual too.
Take pictures and post them here showing us what plugs you are looking at , and we shall decipher what connects to what
GV carby will be simpler to wire up but also check GT250 carby manual as it is “similar” (both vtwins, both same carbs, both use twin clocks at the front and a cable driven speedo drive) , just the GV might have its wires different for the switch gears and rear lights etc.
Usually based on the model year , you will find the diagrams in the service manual near the end of the pages , search this site or manualsLIB site also.
I sell them below
https://www.ebay.co.uk/itm/257243814986
They come as SHORT HEIGHT (from carb model) or Tall Cone style = Makes no difference to EFi , if ebay won’t let you ship them (I always enable global shipping) it is up to ebay if they themselves will ship to you as we use PitneyBowes (ebay owned couriers for global orders)
Otherwise, send an email for a custom quote and we will use the UK Postoffice to your local country post likely DeutschePost
ET sensors on the Hyosung may be programmed differently on the ECU compared to other bikes, but it is a good idea to get a spare part.
If the engine is hot , measure the sensor OHMS vs the manual readings to see if it is within spec then inspect the ET plug to the ECU plug, follow its wires to make sure there is no break in circuit or the resistance has gone up (oxidized pins do affect final OHM readings to the ECU)
Once you open the bike up , move the tank out of the way , clean every single connector you find with contact cleaner, the ECU will thank you for it.
Keep the ECU dry , only blow dry (air compressor) the ECU pins itself.
The harness on the bike is OK to have contact cleaner liquids but do not connect anything again until the harness plugs are dried out.
You most likely will be spending time diagnosing the TPS , ISCV (idle speed control) and the whole metal throttle bodies , split the throttle bodies away from the engine and replace the O-rings.
Lastly test the injectors.
I would caution that throttle body has 4 orings (2 in the middle) and 2 at the cylinder heads , these get caked and crumble under heat , causing unstable idles. (unmetered air entering the bike) you would not want any microscopic debris entering the pistons.
The connector will have a small tab inside the gap, so either a finger or small screw driver will free it off. I can’t remember if you have to squeeze out or press the tab inside and pull out, so exercise caution here.
Send us an email , click the at the bottom of the site and it says “Contact” with your address , and we will check for you. if you change tensioners, you will need gaskets too like these
There is 2 sizes too.
While the airbox is apart, split the throttle bodies carefully and inspect the O-rings, there is 4x of them (middle x2) and 2x to the engine cylinder heads
Then when the throttle bodies are apart , use carb cleaner all over them (remove sensors first!)
Least you want to make sure the intake system is pristine so there is no macro air leaks , making the idle Speed controller work too hard or throttle possibly getting sticition (or jammed from dirt)
For sensors, their connectors (wires) and the sensor pins should be cleaned with contact cleaner and dried up for 24hrs at least if its cold out doors. Now use this time to check the pins for oxidization , as too much oxidization can affect how precise the sensors can send signals back to the ECU. A badly corroded pin can easily jump from factory 0.5 ohm to 3 ohms, that’s enough to panic the ECU, it’s just an example.
Remove the ET sensor carefully (Temp Sensor in front cylinder) , the pins will need to be cleaned. If the ECU asks the sensor what temp engine is, and it gets 50 ohms (100 degrees celcius) , it might go haywire when the engine is actually 65 degrees , it was the oxidized pins and connector plug fouling the ECU with incorrect values. (these values are just examples, real figures will be in the service manual)
The service manual will tell you if the sensor is good or not with a meter to test and you use a hot glass with thermometer. If the glass bowl of water says 60 degrees , you need help with someone holding the sensor TIP in to the water (black body must not touch water) , you will probe the 2pins , it should say (example) 2,000 ohms , the manual says 65-70c should be 3,000 ohms etc, you will know if you want to clean the sensor or replace it if it is failing. The ECU does depend on temp sensors.
Also your airbox will have a TEMP sensor (Air Temperature) as hotter air has less oxygen, so it will tell the ECU how much fuel goes to the injectors, so the engine doesnt get too rich or too lean. Another “temp sensor or heater element” is the lambda sensor (hot exhaust gases , it will warm it up) but not every modern bike uses this , so we just call it Oxygen Sensor instead, it will sense oxygen in the pipes (too rich or too lean)
All these separate parts affect how well the bike idle, runs , and rides. So do one thing at a time and the manual will help you test each part to see if they are still in spec.
Yes that one was a problem for many bikes and because of that , Hyosung updated them silently. Those tensioners had a high failure rate, so i made that tutorial to warn others indeed.
I think it is because in 2007-2010, those tensioners had bad springs inside (if i remember correctly) but they updated them to use a better spring inside , around after 2012 (circa).
Do i have to synchronize the throttle valves?
I would not touch the butterfly valves if they are still original (nobody touched them before you), as it could be hard to re-balance it if you’re not sure what to do. Normally the factory sets up and discourages anyone from touching them. If in doubt , have a spare back up throttle bodies from a crashed donor bike, just to rule things out.
It is possible the plug for your Idle Speed sensor needs checking and your TPS needs checking (using the service manual)
My suspicions point towards the Idle Speed Control (Sensor Valve) and your TPS unit as this is affecting throttle twist and idling. Riding seems normal (riding doesn’t need idle speed sensor valve that much as bike is moving at full speed)
Spray your intake bodies with carb cleaner to check for leaks , while you cleaned injectors , it would be good to change the O-rings inside the throttle-bodies themselves
Regards
These issues point to a possible of the following:
- Harness needs all connectors check for oxidization of the pins
- Check ECU for oxidization pins (you can use contact cleaner on the harness) but never put liquids at the ECU itself, just blow the ECU pins with compressed air and let it dry fully on the harness before pluging stuff back in.
- Spray carb cleaner on on the throttle bodies to see if there is air leaks , the bodies have little o-rings that may have age-rotted ?
- ISCV (idle speed control) – Common but does affect idling and gear changes (momentary idle for rider to change gears ot twist throttle again)
- TPS Sensor (use service manual to make sure its in spec, its on the forum as 250 EFi manual)
- Fuel Pump is waning (age) or strainer-mesh is clogged in up (triggers Fi when riding) ,
- If the LCD glass panel says 50mph / FI / 20mph / FI 0 / FI / while moving, its 100% to do with the pump and injectors.
- get Wynn’s Formula Gold Petrol (or extreme equivalent) (not RED-EX) , pour the whole bottle in the tank with maybe 3 bars of fuel , rider until its nearly empty , you want these bottles to make their way down the whole fuel system to clean any stubborn accumulated deposits
- Injectors waning (age?)
- Check rtelay for fuel pump and replace it (or if the pump uses a 30A fuse , check it ) == It is up to Hyosung to use a 30A fuse or 20A/40A relays on these bikes for fuel pumps, they updated the harness a lot across all EFi machines.
Welcome to the forum, René! 👋It is great to have another GV125 owner here who loves doing their own maintenance.That “clac-clac” ticking noise at idle is actually a very common quirk on early Hyosung V-twins. When you reset the cam chain tensioner (CCT), you temporarily force it to extend. However, if the noise returns after a short ride, it usually means the tensioner’s internal ratcheting mechanism is slipping or the cam chain itself has stretched slightly past what the spring can self-adjust for. ? So you also may need to check your cam-shaft bearings too ?Regarding part number 12830HR6500: Hyosung famously redesigned their V-twin tensioners multiple times across generations. The older carbureted pre-2009 models often use a completely different shape than the later models.Before ordering anything: It is highly recommended to do a visual match against online parts photosMake sure the tensioner looks the same as yours as GV125 only has 3 tensioner designs so far (Old Gen Big Alien Head, Gen 2 is smaller head but wide big engine hole, and later 2018+ EFi GV125 uses even smaller tensioners.
If unsure , post a picture here.
Try and see if you can wind down the philips screw maybe 1/4 of the length back inside from your current state
So for example if the the silver thread is sticking out 10mm tall with its locking nut combined, loosen the locking nut , and screw down the thread about 1/4 down and lock it , test again, this will be trial and error, so have good oil supply (4L jug of oil and its a good excuse to let the old oil flush out the engine, the bike always loves fresh oil)
Measure thickness of the fibre plates vs OEM values , get hard numbers.
Put your steel plate on a glass table , if they are bent or warped, replace them. and make sure clutch springs are torqued down to about 5ft lbs max (if you go over this, the bolt will snap!)You want to make sure the whole stack is good before adjusting the push rod center.
Then follow this to adjust the engine arm
[How to Tutorial] Fit or Adjust clutch cable – Hyosung GV125C GT125R GT250 GV250
Let us know if that worked and what helped ?
it sounds like a clutch drag issues caused by previous owners
Hi Marcel, It’s in with the mechanic now and it’s the cam chain, just a bit loose. Says valves are ok and not the source of the tick. Would this be a job for a new CCT? If so can you send me a link to a decent set of automatic tensioners?
Check ebay for those automatic tensioners , I don’t know if i have a cam chain for it but i am not sure. If its on ebay UK, it should be good to go! – Some tensioners are stripped which look mechanically OK and retract fine but i can’t tell you if they rattle or not as the source engines have bottom end issues (otherwise i’d rather sell the complete engines intact normally) – They are cheap enough that he can compare one or the other, otherwise if he says the Auto CCT is fine and not making a sound, then you should be OK , if it does make a sound then yes replace it.
Though , keep an eye on this dark shop as i intend to stock new ones soon (need to buy loads to stock up first as i know they will go quick here and riders abroad)
Get valve clearance numbers = Its a must. Its for your peace of mind too.
Since you’re in the US, have you tried calling WhyGoStock website directly, they have direct contacts to US Hyosung dealers, and they will fetch the part for you.
We don’t see many TE450 in the UK since it was less imported , the US got the most of the quads, so there should also be an ebay / FB advert of a crashed bike you can buy to salvage parts from ?
Regards
Check your TPS using the service manual and don’t forget to to make sure the fuel injectors have been cleaned with an in-tank cleaner such as “Wynns Formula Gold Petrol” or a similar product in your country.
Forum Replies Created
-
Posts
-
Everything seems connected , what seems to be the issue ? although i see the last owner has put a custom white plug going to the rear lights.
You have a 3 plug CDI unit which is good, it is similar to the GT125, so look below
Needing a little help with my current project (+GT125 CDI PIN OUT)
GV250 = Some models have clutch switch but some early models do not use clutch switch , it was up to South Korea.
If you have a side-stand switch ===> Cut the side-stand switch at the side stand leg. Join the wires on the harness to bypass it, use electrical tape to hide this so naked wires are not exposed , then hide it far away from the road , so that water / dirt does not try to cause ingress.
Regards
Idling is controlled by the Idle Speed Control valve and check your TPS values is the same in the service manual too.
Take pictures and post them here showing us what plugs you are looking at , and we shall decipher what connects to what
GV carby will be simpler to wire up but also check GT250 carby manual as it is “similar” (both vtwins, both same carbs, both use twin clocks at the front and a cable driven speedo drive) , just the GV might have its wires different for the switch gears and rear lights etc.
Usually based on the model year , you will find the diagrams in the service manual near the end of the pages , search this site or manualsLIB site also.
I sell them below
https://www.ebay.co.uk/itm/257243814986
They come as SHORT HEIGHT (from carb model) or Tall Cone style = Makes no difference to EFi , if ebay won’t let you ship them (I always enable global shipping) it is up to ebay if they themselves will ship to you as we use PitneyBowes (ebay owned couriers for global orders)
Otherwise, send an email for a custom quote and we will use the UK Postoffice to your local country post likely DeutschePost
ET sensors on the Hyosung may be programmed differently on the ECU compared to other bikes, but it is a good idea to get a spare part.
If the engine is hot , measure the sensor OHMS vs the manual readings to see if it is within spec then inspect the ET plug to the ECU plug, follow its wires to make sure there is no break in circuit or the resistance has gone up (oxidized pins do affect final OHM readings to the ECU)
Once you open the bike up , move the tank out of the way , clean every single connector you find with contact cleaner, the ECU will thank you for it.
Keep the ECU dry , only blow dry (air compressor) the ECU pins itself.
The harness on the bike is OK to have contact cleaner liquids but do not connect anything again until the harness plugs are dried out.
You most likely will be spending time diagnosing the TPS , ISCV (idle speed control) and the whole metal throttle bodies , split the throttle bodies away from the engine and replace the O-rings.
Lastly test the injectors.
I would caution that throttle body has 4 orings (2 in the middle) and 2 at the cylinder heads , these get caked and crumble under heat , causing unstable idles. (unmetered air entering the bike) you would not want any microscopic debris entering the pistons.
The connector will have a small tab inside the gap, so either a finger or small screw driver will free it off. I can’t remember if you have to squeeze out or press the tab inside and pull out, so exercise caution here.
Send us an email , click the at the bottom of the site and it says “Contact” with your address , and we will check for you. if you change tensioners, you will need gaskets too like these
There is 2 sizes too.
While the airbox is apart, split the throttle bodies carefully and inspect the O-rings, there is 4x of them (middle x2) and 2x to the engine cylinder heads
Then when the throttle bodies are apart , use carb cleaner all over them (remove sensors first!)
Least you want to make sure the intake system is pristine so there is no macro air leaks , making the idle Speed controller work too hard or throttle possibly getting sticition (or jammed from dirt)
For sensors, their connectors (wires) and the sensor pins should be cleaned with contact cleaner and dried up for 24hrs at least if its cold out doors. Now use this time to check the pins for oxidization , as too much oxidization can affect how precise the sensors can send signals back to the ECU. A badly corroded pin can easily jump from factory 0.5 ohm to 3 ohms, that’s enough to panic the ECU, it’s just an example.
Remove the ET sensor carefully (Temp Sensor in front cylinder) , the pins will need to be cleaned. If the ECU asks the sensor what temp engine is, and it gets 50 ohms (100 degrees celcius) , it might go haywire when the engine is actually 65 degrees , it was the oxidized pins and connector plug fouling the ECU with incorrect values. (these values are just examples, real figures will be in the service manual)
The service manual will tell you if the sensor is good or not with a meter to test and you use a hot glass with thermometer. If the glass bowl of water says 60 degrees , you need help with someone holding the sensor TIP in to the water (black body must not touch water) , you will probe the 2pins , it should say (example) 2,000 ohms , the manual says 65-70c should be 3,000 ohms etc, you will know if you want to clean the sensor or replace it if it is failing. The ECU does depend on temp sensors.
Also your airbox will have a TEMP sensor (Air Temperature) as hotter air has less oxygen, so it will tell the ECU how much fuel goes to the injectors, so the engine doesnt get too rich or too lean. Another “temp sensor or heater element” is the lambda sensor (hot exhaust gases , it will warm it up) but not every modern bike uses this , so we just call it Oxygen Sensor instead, it will sense oxygen in the pipes (too rich or too lean)
All these separate parts affect how well the bike idle, runs , and rides. So do one thing at a time and the manual will help you test each part to see if they are still in spec.
Yes that one was a problem for many bikes and because of that , Hyosung updated them silently. Those tensioners had a high failure rate, so i made that tutorial to warn others indeed.
I think it is because in 2007-2010, those tensioners had bad springs inside (if i remember correctly) but they updated them to use a better spring inside , around after 2012 (circa).
Do i have to synchronize the throttle valves?
I would not touch the butterfly valves if they are still original (nobody touched them before you), as it could be hard to re-balance it if you’re not sure what to do. Normally the factory sets up and discourages anyone from touching them. If in doubt , have a spare back up throttle bodies from a crashed donor bike, just to rule things out.
It is possible the plug for your Idle Speed sensor needs checking and your TPS needs checking (using the service manual)
My suspicions point towards the Idle Speed Control (Sensor Valve) and your TPS unit as this is affecting throttle twist and idling. Riding seems normal (riding doesn’t need idle speed sensor valve that much as bike is moving at full speed)
Spray your intake bodies with carb cleaner to check for leaks , while you cleaned injectors , it would be good to change the O-rings inside the throttle-bodies themselves
Regards
These issues point to a possible of the following:
- Harness needs all connectors check for oxidization of the pins
- Check ECU for oxidization pins (you can use contact cleaner on the harness) but never put liquids at the ECU itself, just blow the ECU pins with compressed air and let it dry fully on the harness before pluging stuff back in.
- Spray carb cleaner on on the throttle bodies to see if there is air leaks , the bodies have little o-rings that may have age-rotted ?
- ISCV (idle speed control) – Common but does affect idling and gear changes (momentary idle for rider to change gears ot twist throttle again)
- TPS Sensor (use service manual to make sure its in spec, its on the forum as 250 EFi manual)
- Fuel Pump is waning (age) or strainer-mesh is clogged in up (triggers Fi when riding) ,
- If the LCD glass panel says 50mph / FI / 20mph / FI 0 / FI / while moving, its 100% to do with the pump and injectors.
- get Wynn’s Formula Gold Petrol (or extreme equivalent) (not RED-EX) , pour the whole bottle in the tank with maybe 3 bars of fuel , rider until its nearly empty , you want these bottles to make their way down the whole fuel system to clean any stubborn accumulated deposits
- Injectors waning (age?)
- Check rtelay for fuel pump and replace it (or if the pump uses a 30A fuse , check it ) == It is up to Hyosung to use a 30A fuse or 20A/40A relays on these bikes for fuel pumps, they updated the harness a lot across all EFi machines.
Welcome to the forum, René! 👋It is great to have another GV125 owner here who loves doing their own maintenance.That “clac-clac” ticking noise at idle is actually a very common quirk on early Hyosung V-twins. When you reset the cam chain tensioner (CCT), you temporarily force it to extend. However, if the noise returns after a short ride, it usually means the tensioner’s internal ratcheting mechanism is slipping or the cam chain itself has stretched slightly past what the spring can self-adjust for. ? So you also may need to check your cam-shaft bearings too ?Regarding part number 12830HR6500: Hyosung famously redesigned their V-twin tensioners multiple times across generations. The older carbureted pre-2009 models often use a completely different shape than the later models.Before ordering anything: It is highly recommended to do a visual match against online parts photosMake sure the tensioner looks the same as yours as GV125 only has 3 tensioner designs so far (Old Gen Big Alien Head, Gen 2 is smaller head but wide big engine hole, and later 2018+ EFi GV125 uses even smaller tensioners.
If unsure , post a picture here.
Try and see if you can wind down the philips screw maybe 1/4 of the length back inside from your current state
So for example if the the silver thread is sticking out 10mm tall with its locking nut combined, loosen the locking nut , and screw down the thread about 1/4 down and lock it , test again, this will be trial and error, so have good oil supply (4L jug of oil and its a good excuse to let the old oil flush out the engine, the bike always loves fresh oil)
Measure thickness of the fibre plates vs OEM values , get hard numbers.
Put your steel plate on a glass table , if they are bent or warped, replace them. and make sure clutch springs are torqued down to about 5ft lbs max (if you go over this, the bolt will snap!)You want to make sure the whole stack is good before adjusting the push rod center.
Then follow this to adjust the engine arm
[How to Tutorial] Fit or Adjust clutch cable – Hyosung GV125C GT125R GT250 GV250
Let us know if that worked and what helped ?
it sounds like a clutch drag issues caused by previous owners
Hi Marcel, It’s in with the mechanic now and it’s the cam chain, just a bit loose. Says valves are ok and not the source of the tick. Would this be a job for a new CCT? If so can you send me a link to a decent set of automatic tensioners?
Check ebay for those automatic tensioners , I don’t know if i have a cam chain for it but i am not sure. If its on ebay UK, it should be good to go! – Some tensioners are stripped which look mechanically OK and retract fine but i can’t tell you if they rattle or not as the source engines have bottom end issues (otherwise i’d rather sell the complete engines intact normally) – They are cheap enough that he can compare one or the other, otherwise if he says the Auto CCT is fine and not making a sound, then you should be OK , if it does make a sound then yes replace it.
Though , keep an eye on this dark shop as i intend to stock new ones soon (need to buy loads to stock up first as i know they will go quick here and riders abroad)
Get valve clearance numbers = Its a must. Its for your peace of mind too.
Since you’re in the US, have you tried calling WhyGoStock website directly, they have direct contacts to US Hyosung dealers, and they will fetch the part for you.
We don’t see many TE450 in the UK since it was less imported , the US got the most of the quads, so there should also be an ebay / FB advert of a crashed bike you can buy to salvage parts from ?
Regards
Check your TPS using the service manual and don’t forget to to make sure the fuel injectors have been cleaned with an in-tank cleaner such as “Wynns Formula Gold Petrol” or a similar product in your country.