♠️ M77
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its a 09 Mitsubishi ecu with the 2 hole TPS, I assume the one in the shop will do?
If it looks the same as the shop one , then yes it will fit it because later EFi models changed to a smaller ones , and then again in their later 2020+ GV650 models (Since the GT650 tends to get GV650 parts sometimes shoved in by the factory)
Well it’s going to be a fuel injection one I assume, with the stator burned out the rectifier is almost certainly toast until that side is sorted it’s going to be a nightmare, if the voltage isn’t correct then the ECU will just play up.
Auto correct stator isn’t burnt and reg looks ok it just won’t spark at all
Hyosung regulators have always (even the chinese £10 clones) been smoking the bikes or causing all sorts of cvharging issues.
An ECU is not cheap or possible to acquire right now, it doesn’t take much to fry it as Simon said.
If you intend to keep her for long, this will be the most important – numero uno – investment on the electric side of things.
[Regulator Upgrade Part – GV125S ]
Test your stator as simon says and report back the readings.
Use this as a guide (ignore that it says GT125, the instructions apply to all Hyosungs as they still use 3-Phase stators):
Rectifier – How to Test Stator , Battery , Regulator – GT125R Carby
Simon knows enough , go with what he says if i don’t reply. 👍
Welcome Fella ⭐⭐⭐⭐⭐
Go right ahead & fire away 🙂
Also share pictures of your ride if you want so we can see what you got up to 👍
Camshaft tensioners – I’ve checked them, they are moving smoothly, and the spring it’s pushing these pistons quite hard. 
Plugs – they are looking good? They are afer my first valve clearance and done on it approx 20km, 10km test drive, and next 10km to my garage. I’m thinking they are not oily, but I’m guessing they will need replaceing… They are NGK IRIDIUM CR8EIX, replace them with LASER IRIDIUM? I will redo clearance, but if I’m in such a position with the bare bones of my bike I’m thinking to replace the camshaft chain right away. Marcel I will write to you an email for a quotation.If you’re sure the tensioners are good, then no problem. Usually if i hear them making noises , i replace them immediately.
Laser or normal CR8E is better. I don’t think Hyosung bikes like “iX Iridium” plugs very much , despite them being overhyped. If my bike is good and well taken care off, i can survive 2-3 years with the same Laser Plugs. This is far cheaper than replacing plugs every few months / few thousand miles, it gets expensive
It is like getting a K&N Filter , you don’t need to replace stock filter all the time anymore , expensive is K&N to buy now but it makes long term financial sense.
Hi! I did it just like you said and it bumped up to 11 kg/cm2 on both cylinders. I just have to open them and see inside and look for scratches or the state of the rings right? If it is just the rings, where would I find them? Hyosung doesn’t have anything for this bikes here in Spain.
It is easier to find used pistons and cylinders on ebay. Some sellers and myself regularly list them there because Hyosung Korea is not making parts for any bike before 2019
So they only make parts for current models now (Gv125-S EFi 2020+ , GV300, GV250DR , GV650PC now)
However , I am still busy studying and researching different rings , until i can find one that will fit GT125 , then i will list them on the shop but for now, our best hope is used parts. Lets hope it is just cylinder or head-gasket leaks.
Hmmm! Good question, auxilary canisters dripping with fuel is easy for carb bikes but alas with EFI we need the physical tank pressure and also the pump can’t run dry whatsoever as it kills it.
How about this….. .”USE EXTREME CAUTION” and wisdom please….. but with that , lets:
- Go find a good spot in the garage, and see if you can get hook in the ceiling beam? a strong one!!!
- Get a cargo net x 6 , yes 6 cargo nets
- Put the tank onthe cargo nets x3 (3 nets at the bottom)
- Then use them with someone next to you to hook each end of the net with some kind of towing rope on ceiling
- Repeat again with 3 cargo nets, it sounds crazy but you want to avoid any situation or pump shakes causing the tank to fall down as that’s an instant fire hazard.#
but again …use extreme caution and wisdom!
Run to halfords and get 8-10mm braided hose and fuel clips and come back home , connect the pump to the throttle bodies and tighten#
the tank must be high enough / low enough that you can still use electric plug to connect it without pulling the harness!
now you can actually test what’s going on under the hood with the tank that’s hanging above the frame
I hope this makes any sense ?
I think you could try a local car garage and ask them who does local stickers , and show up with the bike so they can take measurements and print it for you , they may copy the hyosung logo from the internet though!
If not, there seems to be a few ebay sellers already making “pre-made” stickers for the bike, you could ask them do some custom writing if you like.
Compression test done (with a flex tubem didn’t have the metal type near me)
Front Cilynder: 90 PSI (6,4 kg/cm2)
Rear Cilynder: 91 PSI (6,5 kg/cm2)
Check valve clearence and everything checks okay in both cilynders (done it previously to warming up the engine)
What does that mean?
Do it 1 more time again, and this time try:
- Pour a little tiny oil inside front and rear intake pipes for the carb, so that oil goes in the cylinders , then see if compression is improved ?
(piston rings or possible slight damage to cylinder walls of the piston cylinder) - Try to get it done with a “metal pole” as it is far more accurate , flexi-hoses have always given me mixed results (sometimes good, sometimes bad) , so i always try to use a metal pole.
I can’t edit the previous post, so I’m writing another one.
I have done my homework properly and know that valve lash affects piston compression.
I have checked them and they are:
FRONT – 6,73kg/cm2
REAR – 7,65kg/cm2
It should be 8kg cm2 minimum, so i suspect you have gone over the “safe limit” , as per service manual but the bike is still operational.
Next time you do this ===> Pour a tiny bit of oil inside the RUBBER intake pipes , so that oil will go inside the cylinders
Then see if the compression improves?this will help determine if we have to look at piston rings or a possibly scratched cylinder (A cylinder is easier to replace)#
Keep in mind also, if you or previous owner ever removed the cylinders or changed cylinders (they did, i can see you have mixed size cam tensioners) , then it is possible some compression loss is due to bad gaskets ? It is just a thought . Very common on cars , but you are lucky that if a gasket has problem, your engine is not burning blue smoke (water radiator coolant has mixed with oil!) – Your GT125 only uses oil, so the worst is burning oil (plugs will be oily and very sooty) and loosing compression overtime. It is advised to check ebay for a cheap piston and cheap cylinder as emergency back up. Korea is not making any more cylinders for carby 125cc bikes , so they only make parts for Fuel Injected GV125 now (it wont fit GT)
Also it will be advised 100% to buy spare cam tensioners , it looks like we cannot trust the ones you have. So buy a backup on ebay that’s cheap.
Also don’t forget to get tensioner gaskets! (I have loads), if you re-use tensioner gasket, you will burst oil there, the chains spin a lot of oil!
Also, if you ever get time, remove clutch cover ===> look at the rear cam chain crank, hopefully the right side of the crank does not have damaged teeth causing chains to dance and skip around and knock#
The left side is tricky as you will need to remove the flywheel and magneto, then look at the crank teeth there too
If you go this far, you might aswell replace the cam chains
Another chance with the gap on valve;
Front
0,03 (IN) 0,12
0,24 (EX) 0,26
Rear
0,11 (IN) 0,11
0,25 (EX) 0,16
I’m crying right now…
Front intake is too tight. Try to aim for 0.13-0.15 as perfect mark.
Rear = It will need re-doing as both EX & IN are on the tight side , if the engine gets hot, you will get problems and possibly cylinder head damage as hot heat reduces the clearances even more, so it is like we are “chocking” the bike’s neck and it can’t breath like it used to.
I’ve uploaded them here for you. Just click the “Add media” button when reply, so it uploads directly to the site. Google Drive is a good backup! (⭐)
That regulator is very big! :-O , where did you even mount it ?
I hate doing Forks , so good luck , as sometimes it is a stressful job doing USD forks, when your forks are apart , get “FORK GAITERS” to protect the chrome & seals from bursting!
10W fork oil is good. 15W is too stiff , factory is 5w but its too bouncy!
This may sound stupid, but i trust you already did that but can you tell us what compression is on each cylinder?
As you follow the service manual , i won’t need to explain how to do it but if you get stuck , just reply here again.
Also, when the noise comes from engine –> Get a screw driver and poke the tensioner –> put your ear on the other end of the screwdriver — > ask someone to rev the bike a little bit, so see if you hear any abnormal/weird tensioner noises and cam chain slapping hard ?
Did also check each camshaft is correct ? and checked cam-shaft bearings are OK? – Sometimes previous owner puts a “Rear EX” camshaft in to Front Cylinder and problems start
Check compression as mentioned before and let us know the results.
Compression test?
Bike needs to be warmed up 1st => then get both spark plugs out ==> crank the bike for 5 seconds ==> get compression readings and let us know ?
I can see the ECU plug has gone funny, so try to clean it with contact cleaner but NO LIQUIDS on the ECU itself. It would be miraculous if you found a brand daewoo ECU again. Daewoo for 650 & 250 have historically been sensetive ECU’s and most difficult to acquire.
While its apart, you would also want to go over the harness like a fine tooth comb.
Regards
If it fits , why not but…. if its too long, you will bent it eventually , also the swingarm has a very narrow space to work with , so if the springs are fat, it will hit the swingarm 100%
As found out by another member on a GT650R , was having suspension issues because someone else fitted a 250R shock! – So he got a 650R shock for his 650 and all was better and solved
Also you may run in to the issue that the “Y” bone under the swingarm will 100% hit the frame if the shock is too long and it may not slot the bolt (too long/too far out)
You will be wise to measure your old shock first (bolt hole to bolt hole) and dimensions of the fittings etc to try make sure you get another 1-to-1 copy (or close to it) , also hyosung is a nearly 200 wet kg bike (especially the GTR) , you want the shock to handle it.
I have spent days dredging the dark corners of the interwebs and found nothing but cloned websites of cloned websites. I was concerned about the stainless piston rebuild kit as there is a warning sign next to the GV650. Something about it only working on the silver and not the black calipers. I have the black rear calipers on my 2008 GV650 efi
Yes because Hyosung even changed the rear calipers of the GT650 sister to a “dual opposing” piston caliper and it doesn’t say “TCTC” anymore.
So if in doubt, attach a picture here of the calipers or just email me regarding the brake lines we discussed privately.
But i did had to add warnings for 650cc , they did change calipers all round even the front later on.
As you have a 2008, we should be OK!
2010 EFi – I assume Daewoo ECU but does it have a /_\ triangle logo on it? Then it could be mitsubishi.
Are you able to click “Add Media” on your next reply and attach a picture of the ECU? I could pull up some instructions on how to get error codes from the ECU based on the ECU
(If picture uploads are an issue with your device, tell me if its Android or iPhone , what error message it says if forum fails to grab the image off your phone or tablet etc)Check resistance primary and secondary of the coils? what values are they?
Also check HT Cap isnt cracked or damage but be suspicious of them not sending sparks , it does happen and we usually switch to NGK caps. If coil actually gets power to them, then sparks must come out.
Check Stator Pickup coil resistance and their plugs (or check stator isn’t fried inside but drain oil 1st)
You want to be sure every connector on the bike is thoroughly cleaned and all contacts work , so there is no dead signal on the wire that the ECU is waiting to recieve or send down the line. (Damaged internal/ Shorting wire?)
let us know!
I can’t get an image or link it won’t allow me, the electric start won’t work now either
What was the error message ? I want to fix it as some one else seems to upload pictures OK. So i’m not sure what to look for unless i know what error it says on your end or what it is doing.
If not, upload a picture to “www.imgur.com” and copy the “BB-CODE” and paste it here.
I’m going to overhaul this site this year, believe me so its more fluid to use.
Electrics = explain more?
Answered your other topic. Email me if still needing me otherwise i gave you alternative bikes you could try and also caliper , consider SS pistons sold here, they will get to you faster.
I have GT master cylinders for the shop in stock, they will fit the GV650 but the “clevis” may need adjusting , so i’m 90% sure on fitment.
If not, i can still get you OEM stuff.
