♠️ M77
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The TDC would be specified in the service manual , but you know by now if the timings were bad, the valves will 100% hit the piston and engine won’t even do 1 single full revulotion at this point, you would see dents in the pistons caused by a valve
If you took the valve heads off , did you notice the valves ? Are they fully sitting inside the head ? If not could we assume maybe “valve seals” need changing or double check the piston rings
They have notches , but Hyosung wants rings to be staggered ie.
====____=====__====
__===Each row is a ring , but the bottom _ dash is a gap, they must be some distance away from each other ,
If you get 10 kg cm2 compression, that’s GOOD! – now test compression again after running on choke for 5 minutes , so we know the compression values when it was hot vs cold to see if it went up or down.
It is part of the internal fuel pump. (Inside the tank)
Not sold on its own because pump + filter are one-unit.
It doesnt need changing unless its so black the gauze cant even suck fuel anymore?
What is the story?
Those are not made anymore but can you show us a picture? I might try to think of a fix.
Click Add Media button as you reply to upload pictures
Yes you can only use a twin plug ecu on a twin harness.
It is a very messy job to mix and match and may fry it altogether
The single plug is just the prototype ecu hyosung used on early batches. So you have a 2017/2018 chassis (no matter if it says 22 plate). ECU supplied on the bike determined its real year.
Twin plug ecu is better. Hyosung isnt making single plugs anymore.
Regards
IAP will look like something like this:
https://www.ebay.co.uk/itm/256727468290
It will physically be on the throttle body, and also there will be a TPS (throttle position sensor) on then, so a bunch of wires in your picture seen to burying themselves deep down your intake pipes, it is suggesting there is other sensors you haven’t seen yet but it is a narrow space down there.
It can be easier to carefully remove the throttle bodies but do not forget where each cable goes so you don’t accident put “rear injector” connector to “front injector cable” etc.
Also if you ever remove those bolts (CAREFULLY!) , it is 100% advised to replace the bolts same size with stainless steel and new rubber-orings!
Take the starter motor off , and check if it spins when manually connected to the battery ? (becareful as the stator motor may spark! when clamping its body)
Also sniff around the bike until you find the area strongest with smells , and try to upload a picture of what you see (green add media button on the forum reply box) or use OneDrive/GDrive and get a public share link for photos or use IMGUR website and get BB codes to paste on to this forum
Put a screwdriver pointy part on to the engine where the noise is , then the handle side on your ear , can you hear the sounds changing as you rev ?
If pistons where hit = it would likely be thudding hard and you will feel it when your hand is on the engine.
If you leave the bike on full choke, does it ride even a little bit ?
And does the smoke stay constant on the exhaut, or does it only puff smoke when you rev fast and let go (throttle blips) ?
Hey,
See the “green add media” button as you write replay on here. Click it and click “upload file” , then navigate to where your picture is stored in your device
Get us a picture of your situation so we can see what’s going on.
If you can’t , use OneDrive/GoogleDrive/DropBox –> upload there and get a “public share link” to that image so we can see it.
Regards
Have you actually removed the fan , and put it on the battery directly to see if it spins ? It could be just the switch which i gave you a forum link above ^ ?
Fans rarely fail but it happens , its almost always the switch needing a replacement before the fan does.
The clearances look good! , the compression should be good when it warms if it is showing 10kg cm2 cold.
The tensioner, if it makes a noise then yes replace it because it seems like you replaced almost all other components inside the motor.
Do you think the cam shaft bearings & crank bearings are OK during your inspections ?
Hey , it’s okay
Here is 2 links.
1 = FUEL HOSES
How to upgrade Fuel Lines & Filter on Hyosung GT125R GT250R (Carb Hose Diagram)
2. = AIR LINES
How to change Vacuum Lines on Hyosung GT125R GT250R & GT Comet (Air Hose Diagram)
Hope this helps ?
The GV250 & GT125R = Both share the same pin out. Yes the 125cc is very common in EU , the baby version of the 250cc Hyosungs!.
Hope this helps below and good luck cleaning those carbs out.
Needing a little help with my current project (+GT125 CDI PIN OUT)
Hyosung has issues with the supply chain globally affecting certain parts being available to distributors but , good job on replacing the thermostat
Next, you will need a FAN SWITCH , see the topic below:
Get a bottle of MOTUL FACTORY LINE RACING COOLANT , it is my most recommended coolant for any Liquid cooled motor.
Download the service manual on this forum , so it will show you how to deal with the temperature issues and how to test your TEMPERATURE Sensor
So remember, 3 things to check:
- FAN Switch (Link above ^ )
- Temperature SENSOR (Measure values using multimeter to make sure it is within OEM spec on service manual)
- Thermostat (again, get water in a bowl at boiling 80c degrees, and see if it pops open) , then put it back inside the engine & check for leaks.
Last thing to check, make sure the WATER PUMP is OK. If the pump is dead, it won’t be able to move coolant around your cylinders to the radiator to cool it.
Water pump is very hard to get these days , so be ready to repair it if necessary but hopefully there is no issue with it.
Keep us updated!
Hi Maciek. Your REAR CamChain TENSIONER is not the right part. Your Front tensioner is the correct part. It’s 27.1 mm in diameter, from memory. Try a wrecker or new aftermarket part to see if that eases the noise. The manual says to TURN THE MOTOR 10 times, at least, before measuring VALVE CLEARANCES. Pop the right shims in both cylinders and it will sound & run better. I didn’t read all your post – is your rear cam chain ruined for sure? It may not be idk. When you lay your cams on the head, place the cam that’s furthest away from the tensioner, on first. After i lay the 2nd cam down, under the chain, i press my finder in the TENSIONER HOLE to apply the pressure to the cam chain, so i can see how it will look when the tensioner is installed). Then i release the pressure & rotate this cam until its in the right spot. Bike will run with the cams out a bit but it sounds bad & the bike doesn’t like it. I use NGK CR8E spark plugs & testing CR7E from memory.
I noticed that too, but it happens in UK too. Owners mix cylinders (eg. Front engine use 2016 cylinder with updated tensioner and rear cylinder use 2003 cylinder that uses Generation 1 tensioner)
Hello, I’ve recently bought a GT650R and I need a new wiring harness. I’ve spoken to Marcel about it and he said that I have a discontinued ECU. It has a mitsubishi logo on it. If anyone can help me make or find a harness, that would be amazing!
Follow chris’s other thread here, see how he laid out his harness
If i see the harness , i will tell you about it but in the mean time Chris is correct to suggest repairing it will be easier route / quickest but don’t rush anything you have one good shot not to fry that ECU. Everyone is after it and drives its scarcity up even more.
Hyosung moved on to Delphi electronics since 2013-2015 (US/Singapore) , if you repair your harness well , stay on that Japanese mitsubishi ECU instead.
Hi Leo,
Sorry i didn’t see this one.
Yes 1x Gasket (if you need 2 , then add 2 of them)
RegardsIt is discontinued, so it isn’t made anymore , GT Naked cables are in stock but do not fit well because they are too long , you will end up using a lot of spacers under the switch gear to make up for the slack.
Download the 250 EFi service manual onthe forum , then go to where it says error codes = Yours is C18 , it will tell you how to diagnose it the sensor
C18 = Intake air pressure sensor (Engine 2) (Likely the sensor on the throttle body for the rear engine)
No didn’t work
Check the GT650R EFi manuals on the forum, it will show pictures how to do it better than i could explain on text.
Forum Replies Created
-
Posts
-
The TDC would be specified in the service manual , but you know by now if the timings were bad, the valves will 100% hit the piston and engine won’t even do 1 single full revulotion at this point, you would see dents in the pistons caused by a valve
If you took the valve heads off , did you notice the valves ? Are they fully sitting inside the head ? If not could we assume maybe “valve seals” need changing or double check the piston rings
They have notches , but Hyosung wants rings to be staggered ie.
====____=====__====
__===Each row is a ring , but the bottom _ dash is a gap, they must be some distance away from each other ,
If you get 10 kg cm2 compression, that’s GOOD! – now test compression again after running on choke for 5 minutes , so we know the compression values when it was hot vs cold to see if it went up or down.
It is part of the internal fuel pump. (Inside the tank)
Not sold on its own because pump + filter are one-unit.
It doesnt need changing unless its so black the gauze cant even suck fuel anymore?
What is the story?
Those are not made anymore but can you show us a picture? I might try to think of a fix.
Click Add Media button as you reply to upload pictures
Yes you can only use a twin plug ecu on a twin harness.
It is a very messy job to mix and match and may fry it altogether
The single plug is just the prototype ecu hyosung used on early batches. So you have a 2017/2018 chassis (no matter if it says 22 plate). ECU supplied on the bike determined its real year.
Twin plug ecu is better. Hyosung isnt making single plugs anymore.
Regards
IAP will look like something like this:
https://www.ebay.co.uk/itm/256727468290
It will physically be on the throttle body, and also there will be a TPS (throttle position sensor) on then, so a bunch of wires in your picture seen to burying themselves deep down your intake pipes, it is suggesting there is other sensors you haven’t seen yet but it is a narrow space down there.
It can be easier to carefully remove the throttle bodies but do not forget where each cable goes so you don’t accident put “rear injector” connector to “front injector cable” etc.
Also if you ever remove those bolts (CAREFULLY!) , it is 100% advised to replace the bolts same size with stainless steel and new rubber-orings!
Take the starter motor off , and check if it spins when manually connected to the battery ? (becareful as the stator motor may spark! when clamping its body)
Also sniff around the bike until you find the area strongest with smells , and try to upload a picture of what you see (green add media button on the forum reply box) or use OneDrive/GDrive and get a public share link for photos or use IMGUR website and get BB codes to paste on to this forum
Put a screwdriver pointy part on to the engine where the noise is , then the handle side on your ear , can you hear the sounds changing as you rev ?
If pistons where hit = it would likely be thudding hard and you will feel it when your hand is on the engine.
If you leave the bike on full choke, does it ride even a little bit ?
And does the smoke stay constant on the exhaut, or does it only puff smoke when you rev fast and let go (throttle blips) ?
Hey,
See the “green add media” button as you write replay on here. Click it and click “upload file” , then navigate to where your picture is stored in your device
Get us a picture of your situation so we can see what’s going on.
If you can’t , use OneDrive/GoogleDrive/DropBox –> upload there and get a “public share link” to that image so we can see it.
Regards
Have you actually removed the fan , and put it on the battery directly to see if it spins ? It could be just the switch which i gave you a forum link above ^ ?
Fans rarely fail but it happens , its almost always the switch needing a replacement before the fan does.
The clearances look good! , the compression should be good when it warms if it is showing 10kg cm2 cold.
The tensioner, if it makes a noise then yes replace it because it seems like you replaced almost all other components inside the motor.
Do you think the cam shaft bearings & crank bearings are OK during your inspections ?
Hey , it’s okay
Here is 2 links.
1 = FUEL HOSES
How to upgrade Fuel Lines & Filter on Hyosung GT125R GT250R (Carb Hose Diagram)
2. = AIR LINES
How to change Vacuum Lines on Hyosung GT125R GT250R & GT Comet (Air Hose Diagram)
Hope this helps ?
The GV250 & GT125R = Both share the same pin out. Yes the 125cc is very common in EU , the baby version of the 250cc Hyosungs!.
Hope this helps below and good luck cleaning those carbs out.
Needing a little help with my current project (+GT125 CDI PIN OUT)
Hyosung has issues with the supply chain globally affecting certain parts being available to distributors but , good job on replacing the thermostat
Next, you will need a FAN SWITCH , see the topic below:
Get a bottle of MOTUL FACTORY LINE RACING COOLANT , it is my most recommended coolant for any Liquid cooled motor.
Download the service manual on this forum , so it will show you how to deal with the temperature issues and how to test your TEMPERATURE Sensor
So remember, 3 things to check:
- FAN Switch (Link above ^ )
- Temperature SENSOR (Measure values using multimeter to make sure it is within OEM spec on service manual)
- Thermostat (again, get water in a bowl at boiling 80c degrees, and see if it pops open) , then put it back inside the engine & check for leaks.
Last thing to check, make sure the WATER PUMP is OK. If the pump is dead, it won’t be able to move coolant around your cylinders to the radiator to cool it.
Water pump is very hard to get these days , so be ready to repair it if necessary but hopefully there is no issue with it.
Keep us updated!
Hi Maciek. Your REAR CamChain TENSIONER is not the right part. Your Front tensioner is the correct part. It’s 27.1 mm in diameter, from memory. Try a wrecker or new aftermarket part to see if that eases the noise. The manual says to TURN THE MOTOR 10 times, at least, before measuring VALVE CLEARANCES. Pop the right shims in both cylinders and it will sound & run better. I didn’t read all your post – is your rear cam chain ruined for sure? It may not be idk. When you lay your cams on the head, place the cam that’s furthest away from the tensioner, on first. After i lay the 2nd cam down, under the chain, i press my finder in the TENSIONER HOLE to apply the pressure to the cam chain, so i can see how it will look when the tensioner is installed). Then i release the pressure & rotate this cam until its in the right spot. Bike will run with the cams out a bit but it sounds bad & the bike doesn’t like it. I use NGK CR8E spark plugs & testing CR7E from memory.
I noticed that too, but it happens in UK too. Owners mix cylinders (eg. Front engine use 2016 cylinder with updated tensioner and rear cylinder use 2003 cylinder that uses Generation 1 tensioner)
Hello, I’ve recently bought a GT650R and I need a new wiring harness. I’ve spoken to Marcel about it and he said that I have a discontinued ECU. It has a mitsubishi logo on it. If anyone can help me make or find a harness, that would be amazing!
Follow chris’s other thread here, see how he laid out his harness
If i see the harness , i will tell you about it but in the mean time Chris is correct to suggest repairing it will be easier route / quickest but don’t rush anything you have one good shot not to fry that ECU. Everyone is after it and drives its scarcity up even more.
Hyosung moved on to Delphi electronics since 2013-2015 (US/Singapore) , if you repair your harness well , stay on that Japanese mitsubishi ECU instead.
Hi Leo,
Sorry i didn’t see this one.
Yes 1x Gasket (if you need 2 , then add 2 of them)
RegardsIt is discontinued, so it isn’t made anymore , GT Naked cables are in stock but do not fit well because they are too long , you will end up using a lot of spacers under the switch gear to make up for the slack.
Download the 250 EFi service manual onthe forum , then go to where it says error codes = Yours is C18 , it will tell you how to diagnose it the sensor
C18 = Intake air pressure sensor (Engine 2) (Likely the sensor on the throttle body for the rear engine)
No didn’t work
Check the GT650R EFi manuals on the forum, it will show pictures how to do it better than i could explain on text.