♠️ M77
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You have the Delphi V2 harness , (2016+) you need the OEM regulator that uses part number 32800HN9121 – Which is GD250, GV700
Hyosung used GD & ST regulator because they changed the stator unit completely (it is green stator) , older EFi models had black stators with smaller plugs.
Henceforth your GD regulator did fit. I would get the OEM one as it will probably outlive any china-clone (which don’t exist) , china just makes really knockoff ones for older models , they are quite wild (hit & miss in terms of success)
It is probably why I only do true-mosfet Shingden ones like you saw on the shop, fit once and forget about it for years & years (unless your electrics / stator / battery blow it!)
thank you very much for the “bug” in regards to the add-media button , I will fix it!
Just used a test account , it seems to be working fine on my end ?
Do you see this button?
(it is above the white Reply Box)
If yes , then:
Step 1 – Click Add Media Again below:
Then step 2 , click the tab that says “Upload”
Final Step, click “Select Files / Find Files” (it may be a different word depending on PC,Apple, Android etc.)
Then find your pictures (Phone = Gallery / PC = where ever you stored them)
Sorry for any frustration caused , I am actively looking for ways to make image uploads more seemless so there is less hoops to jump through .
If there is bugs (ie. you physically can’t see a specific button eg. “Select Files” or “Add Media” or “Upload ” tab
Take a picture on your phone or screenshot
–> send it to this website -> https://postimages.org/Paste the link to the image here.
Infact as Plan B , you can use PostImages.ORG to upload pictures and select “Hotlink for forums:” , the links will look like this:
[ url=https://post images.org/][ img ]https://i.postimg.cc/G37B2wZD/rt125-test-image.jpg [ /img ][/url ]Just copy and paste and it will turn to this instantly when posting:
Sorry , I edited my reply to say this:
A bit too high 14.9 when idling – Should be 14.0-14.4v – but we can tolerate 14.5-14.6 as normal too.
Hyosung’s limit is 15V so you’re just on the border!
but OEM or Knockoff regulators are just wild = they would jump around from 11.5 to 16V! = 16V is basically time to blow up the battery or cook everything that’s attached to the harness that needs a 12v source.
Check yours again at 5,000 rpm (as per service manual) and tell us ?
I just seen your new reply now, i would check at 5k rpm and advise ?
Find out if voltage changes at the battery side when turning on the lights on/off , since these are 55 watts right out of the gate.
Since you have a brand new stator , the stator unit should be OK otherwise the bike wouldn’t start =A bike won’t start if its the wrong stator due to different pulse timing dots on the flywheel.
Also when the bike is running ===> disconnect the regulator , and disconnect only the “yellow” stator plug.
Measure at 5,000 rpm at the stator itself
Pin 1 – Pin 2 = Volts AC
Pin 1 – Pin 3 = Volts AC
Pin 3 – Pin 2 = Volt ACThis way we can check each yellow wire how much voltage in AC is being output at 5,000 rpm so we can fully rule out a new stator.
Then we progress further in to the harness itself if there is something on the harness or some kind of part attached to the harness that’s causing things to go haywire.
As long as the stator is feeding AC power in to the regulator itself ==> Disconnect the regulator from the harness and measure its 2PIN plug in DC , this should be between 14-15V DC , 13.5V DC would be Hyosung’s absolute acceptable lowest charging rate (less AC power when idling ofcourse)
Keep the yellow plug connected to the regulator , we’re just measuring the regulator’s 2Pin DC output once it takes the stators AC energy from the yellow wires.
I hope i made sense ? If not , let me know!
My bike loves to charge at 14.2V despite having the same kit as you , but it does the job, i would love to have 14.5V , but alas , its 14.2V all day , in any revs and has been that way for a few years now so i’ve yet to change the stator , it’s not bothering anyone. When i turn the lights OFF (removed the bulb!), then i see a big spike at 14.7V and stays there all day long.
So personally myself i have an achingly long job over the winter to strip the entire bike down to get to its harness and repair it and give it some nice TLC with ACF50 around its plugs , as to be fair some connectors near the front of the bike have oxidized a little bit (stupid wintry northern freezing wet climate! – I envy Australians)
Believe it or not , in July 2025 , i could not start the bike as the battery was 11V as soon as the key turned on (headlight is permanent ON for later models of the GT series bikes) , and i went under the bike , the headlight wires where burning my hands! – If i disconnect the bulb , she starts flawlessly , but connected them when running made the issue worse, i was flabber gasted – I tested the battery with a YUASA Load Meter (it does a deeper dive to verify battery is OK or not) , it was fine, mind you this was a YUASA battery which brand i trust the most and it was 3yrs old without fail , i swapped regulators again, same issue.
So in the end i replaced the bulb and got a new battery too. As the bulb was killing the battery other than the charging system. I wasted £120 all because of a bulb! – Mind you, this was 6 month old bulb too , so i made sure to get another one that isn’t “defective” / “bad batch” , excuse the quotes. I went back to my old regulator that’s always been good to me, and we are back to 14.2V (not a great number but ugh… old harness needs love eventually) and new battery , starts everytime now.
So i will make a routine to touch my headlight wires every now and then , and i also put a volt meter mod above the dashboard , that’s how i know the voltage is whenever i am with the bike. Great mod. Just tap in to your “side little bulb” inside your headlight and don’t cut the wires. Just copy the plug , make a “male – female” bridge
in the end [side light little bulb]–>female end–> (start of male mini bridge) with wires going to the volt meter–>female end of mini bridge) –> male end of the main bike harness. That way i can disconnect it at will and stays inside the headlight shell away from any water / nature attacks. Knowing Hyosung isnt making any harnesses for GT bikes (discontinued model) , best to preserve it.
I am digressing sorry , hope you had some ideas of checking for unusual power robbing along the harness too.
Do you have a short somewhere ? Ie parts of the harness touching the frame or…… 2 plugs are both 2 pin. One is for stator sensor One is for reg to harness Its easy to mix those two up & the harness gets fried or reversed terminals on the battery. 14.5V is usually the norm but 15V is Hyosungs limit as per manual. Disconnect your lights and see if bulbs affected them? I replaced my 4yr old bulb 3 days ago as the resistance grew so much the wires got too hot! Happy to test your reg again if you want to be extra sure as i did promise warranties provided the bike doesnt cook either the stator or reg & a new AGM battery is used (no lithiums) Confirm stator makes 65v-85v at 5k revs on each yellow wire via AC (service manual pn forum has tutorial) with reg unplugged?
just a follow up question, those 14.5 to 15 volts, are they at 5k rpm or idling? Because mine showed 14.9 when it was idling
A bit too high 14.9 when idling – Should be 14.0-14.4v – but we can tolerate 14.5-14.6 as normal too.
Hyosung’s limit is 15V so you’re just on the border!
but OEM or Knockoff regulators are just wild = they would jump around from 11.5 to 16V! = 16V is basically time to blow up the battery or cook everything that’s attached to the harness that needs a 12v source.
Check yours again at 5,000 rpm (as per service manual) and tell us ?
Congratulations!
This should be a fun off-roader!Start by getting the bike first , have a good look all around. Take some pictures on the day of delivery , post them on this forum so we can see what we’re working with.
Also be ready to give the engine a much needed checkup , they will last long if you take care of them 🙂 – I don’t know where to start until we find out what’s happened to the engine first ? So you may drain oil , remove the stator + clutch covers , see if there is anything suspicious ?
Ie. fried stator , damaged clutch plates , oil pump issue ? etc – Just wild guesses here. Hopefully should be a quick rebuild if it spins & starts well.
Did your harness have a BIG or SMALL connector for the Stator (Stator unit) ? or post a picture.
Can you try to upload an image directly on this forum?
If there is an issue with this site , please take a picture and upload it to the POSTIMG.CC website so i can see the errors preventing you using our image uploader.
The reason for asking is to verify if you have a Delphi V1 or V2 harness. So showing us the stator plugs and harness plugs will help me confirm what you have.
You said 2016 GT250R at the start of the post, so you may have 2016-2020 electronics but Hyosung can still use 2014-2015 electronics in other models made in 2016
(eg. 2019 bike at the dealership still has 2014 electronics inside it etc…)
Two Ports ECU = Delphi ECU. This requires a harness with 2-plugs for the Delphi ECU
Delphi Electronics have also changed, so to be safe get parts for 2014+ onwards
2008 – 2012 = Daewoo & Sentec ECU = Not made anymore and very very very difficult to find and fix!
So i would advise to upgrade all electrics to 2014+ model including harness , and you will find these parts on EBAY USA (It’s a big 250cc market)
Coils ?
HT Caps?
Stator Unit?These 3 need each other. If any of them are out of spec , there lies the “cut outs” you’re experiencing if it is electrical.
Try to get access to a cheap pocket meter and follow this topic:
Confirm back here your findings with the hard figures.
While the bike is apart, clean every single connector plug you can find with Contact Cleaner, incase some gold pins have oxidized due to nature , and ONLY (i mean only) use Dielectric Grease called ACF50 , it is #1 to have in every biker’s tool box. Don’t use anything like WD40 as it’s flameable. Just use ACF50 , after cleaning the pins , this helps the connectors maintain a good connection and not oxidize too soon.
Check for sparks again but this time , see if one coil is better than the other or replace the battery (if too old, the cells discharge too quick, you won’t have a good CCA left for it) , if battery is new , use a bike-charger (car chargers will burn the harness and the battery as there is too much current) , if jump starting = remove the battery out of the car and jump start , if the car / truck is running alive while you’re jump starting = you will quickly say goodbye to the GV250 (again, too much current).
Fortunately a GV250 carb is FARRRRRRR easier to get going than any GTR or GV Injected for that matter. I love working on those bikes when customers drop them off to me.
If they are IX plugs , they won’t be good for it. You want either the basic CR8E or LASER platinum plugs (but beware of fake NGK plugs now , it’s so bad there is even a post about it on NGK’s own website.)
If in doubt, get basic CR8E from halfords.After that, verify that both coils are actually sparking the same colour.
If not, go here below:
Rectifier – How to Test Stator , Battery , Regulator – GT125R Carby
Report back to this topic with readings of the stator, coils (without caps) and caps (on their own)
Ensure the airbox is fully secure, sometimes the front carb exposes some of its lip on the front airbox hole, so air leaks mean poor running, it is very very very picky when it comes to making sure the bike idles with a sealed air system.
Get carb cleaner , turn off choke, increase the idle ==> spray the engine rubber inlets. If the revs change for whatever reason, you may have cooked / caked up old o-rings, a fresh set would help restore its vacuum loss
Intake Pipe O-RING (Inlet Boot Seals) x2 – GV125 GT125 RX125 GV250 GT250 Hyosung
Whatever you do, make sure not to stress the rubber pipes as Hyosung isn’t making new ones anymore (they moved on to Gv125-S EFi now)
Double check the jet sizes and tell us ? eg. Front and Rear Pilots should be size 15 (forever) and rear mains should 87.5 & 90 as a baseline but can go up to 90 & 92.5 if you have an upgraded filter.
Like here:[Tutorial] How to swap Carb Main Jets – Hyosung GV & GT 125/250
if the bike has cone-filters , it will never run right until it gets its airbox. Hyosung made sure of it. everyone tried and failed, so airbox is a must. If the air filter is dirty, replace it as there is less air going in to the engine to mix the fuel properly , hence boggy running.
I may have said a lot , but take your time. 1 thing at a time. if you do a lot at once, you won’t know if its making progress or regressing (getting worse).
Wise but last war is crucially to check cylinder compression when it has warmed up but… let’s deal with that LAST.
The frame will twist and you will be in A&E before you have a chance to use the full power of the 650, there is a reason the 650 frames are built around the engine in trellis form and the steel is stronger than what Hyosung uses on the 250 frames. So personally i won’t entertain dropping a 650 in that frame to save your body.
Why not buy a spare engine and fit it yourself, it’s not too hard , just requires a lot of time and patience but your hands are free labour.
$1000 is cheap compared to UK standards as an engine alone in the UK is actually hovering around $500-800 USD with sketchy histories by last owners lol. Then couple dollars for labour ofcourse unless doing it alone.
That is good news. Thank you, Marcel. I almost talked myself out of replacing the swingarm but if they come out easy i can reuse them. Hyosung Factory sold me some but did not post them and no refund yet. They are annyoing to communicate with. I transalted my English to Korean so they could fully understand what i think of their lame service. Will never buy from them again. I’ve been waiting and not riden since Winter – it’s almost Summer here.
Gotta becareful now sad to say “most” of these so-called Hyosung parts sites will be quick take cash but no parts or be lucky to wait a year sometimes!- Could be easier to get a used swingarm off ebay and get it powdercoated with much better paint ? Just an idea!
I assume you mean #7 and #8 ? – They just literally slide out , but sometimes may need a little bit of a shake incase it catches the bearing cage lips , these spacer tubes also help the pivot bar roll on the needle bearings easier.
Normally that area is heavily greased including the pivot bar , bearings, and spacers to avoid seizures.
Remove the fuel filter that’s inline to the T-piece and allow the pump itself to use its own strainer attached to it inside the tank. You will be reducing less stress needed to push fuel through , although it’s not a big deal as cars do this anyway but let’s eliminate that first and see if it responds better.
Then replace the spark plugs again , make sure it’s CR8E only (ignore the likes of “IX” tagged plugs as they don’t always like them) – So stick with copper CR8E (Yellow box) or “LASER Platinum” (Silver rainbow box)
Electrics, see this topic:
Rectifier – How to Test Stator , Battery , Regulator – GT125R Carby
Ignore that it’s targeting a 125cc , that’s just its younger sister but instructions are the same.
Report back what your electrical values are ? if we can be extra sure other electrics are okay, then we can move on to other bottlenecks.
Last war could be possibly a dragging clutch or clutch too worn down or cylinder compression or clearances need sorting but this is just a guess, so if you can do:
1. (Fuel) Remove the inline filter and see if fuel delivery is better for it.
2. (Air/Spark) Replace the plugs, ride on new ones. Take a picture and post the new plugs (we shall see if the cylinders are leaning out or not?)
Doesn’t hurt to check if the air filter is clogged up or put a fresh one to make it breath like new again.
3. (Spark/Electric Power) Do the electric tests mentioned above ^ & report back figures.Am sorry to slightly change the thread, but how much does putting a slip-on on affect the bike in terms of hp/torque running needing re-maps mot s or potential engine damage from running lean etc.?
What sort of slipons would cause less issues + not need a re-map?
Ive just got a 2018 gtr650 efi + mite like something a bit louder + lighter but couldnt i just cut/gut or drill some holes easily in the big black stock pipe for starters?
TIA
Lextek , MTC or BlackWidow = make sure the cans are 400mm long (like your OEM one is) and keep the baffle inside (your neighbours will hate you before the bike moans of a missing baffle lol) but it’s a vtwin, it always runs better with baffles in.
BlackWidow gets my vote. UK company and they do make road legal cans , just as Lextek or MTC does too. If not , any can that has a BSAU stamp on it is generally road legal and can’t be disputed at MOT places and engine will be fine.
Messing with your stock muffler on the 650 could be messy but unless you can take the rivets off , remove maybe 10% of what’s inside the can and close it back, it will be more throaty yes.
Here is an EU company who does OK for exhausts (personally i used them on a non-hyosung branded bike, and it was OK as long as the baffle was inside, that was 20yrs ago lol) so who knows if they improved their tech ?
https://ixil.com/en/16-hyosungAlso despite them making slip-ons for Hyosung , but no news yet on GV125-S , so your best option is to browse their page and look for a long & narrow can that’s about 400mm (long the better!) but don’t go under 350mm and should be as wide as your original one , because if its too wide (not a bad thing) you will need the bracket to extend it away from the swingarm + a 75 or 60 degree custom link pipe to connect back to your exhaust pipes. (then another link pipe, so it makes an S shape to keep the sleek look of the bike ie. [can___/—-engine]
The _ and / and — are just a simpler way i can visualize what i mean )Scorpion might be OK, there is other EU exhaust makers (usually the EU is more strict with exhausts being road legal for some countries due to Euro 4-6 laws , here in UK it’s not really a big deal unless the baffle is missing then it will fail for “exhaust too loud” unless it is designed to be loud by OEM (ie. really old harleys)
I would suggest OEM 2025 factory harley cans but they weigh too much and you loose power (adding extra weight to the bike it doesn’t need) , so you want to stay light and nimble until extra weight is reserved for a pillion or luggage use.
There is no public info on that request but where it got sheered off , measure the where it would normally be, Hyosung used different size strips on the magneto rotor but there will be a mark showing you where it was and how long /wide it is. Thickness estimated to be about as thick as a credit card (just off my head!) i have no personally measured it.
Get an EFi flywheel rotor for the Hyosung 250 and use that to measure the thickness , it will be similar to the old one. Obviously don’t use the flywheel as it’s for EFi model models.
Hope that helps!
When the lights go dimm, it means 3 things
- I know its tested but i highly bet the battery drops volts and amps as fast as you press “start” , because it’s asking to spin the starter, supply power to cdi and coils etc to spark 10,000 volts pulses to the plugs to fire up.
- Solenoid could be gone yes
- Starter Motor has gone weak (thus causing extra battery drain) – Replace it or open it to inspect starter motor bushes but drain bike oil first before removing starter motor.
Also when lights go dimm, does the dashboard go dimm too? do you hear a click ? buzzing like flies? or thud-thud ?
hello my bike is currently doing everything as you explained at the bottom, i installed a new starter motor and it started a few times but once after i forgot to put the kick stand up and now it wont start at all it’ll crank for only so long then go dim and buzz then make clicking noises and shut off it’ll turn back on if i keep holding it but it just drains alot what can i do ?
Best to make a new topic , so we can isolate your specific issues.
Quick answer = Battery, Charging System (Stator & Reg) , Poor Sparks . More of that in your own new thread and try to report back if you followed my replies to this topic also so i can avoid repeating things like if the battery is brand new and what brand it is etc.
If you see the metal unthreaded part , it should be stopping the exhaust arm from moving too far away from the spiral thread (and not touching the intake arms). In the older models , we still had to remove the cam shafts. In fact hyosung has made 2 versions of the engine one that uses a screw-top to adjust and yours is classic shim style
Like this one https://hyoriders.club/forums/topic/tutorial-hyosung-gv300-valve-clearance-check-correction-guide/
I will double check later if there is another way to get to the shims without taking apart the cams away , i envy some newer engines that have a newer screw top , makes life so much easier.
This one is would do better that the one you mentioned and road legal too , i focused on cans that are least 400mm long https://www.lextekproducts.com/part/SA1
Confirm with your local fabricator to make you a short link pipe to join it to your narrower downpipes
Blackwidow remain as my personal #1 brand
https://www.blackwidowexhausts.co.uk/black-widow-silencers-239-c.asp?_=&f-SILENCERLENGTH=f-400mm&minprice=104.99&maxprice=194.99Hope that helps.
Does the shim come out if the engine can be spin until the rocker arm is at its highest point ? (This is just checking if the arm is not bent or anything)
If not , show me a video (upload to youtube => mark as “unlisted” , so it’s only found on this forum , get the share link) or a picture upload here.
If the engine you say sounds fine when it is running with no issues , i suspect there should be nothing stuck.
