♠️ M77
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No where that exists on any carb 125 GTR – I’ve fixed too many of them to know this.
Where did it come from ? and what did it connect to ?
What year is even the bike ? (or confirm does it use an older dashboard that has “GREEN LCD” + “BLACK REV RPM GAUGE” ?
The manual is incorrect , our floats in the shop are around 7mm (petrol is full inside carb) and they lift up to 17mm (empty fuel)
So the height from that picture should be 7mm. when the carb floats is facing the sky.
Clean the carbs again, 125cc carbs work on 250, just requires “Size 20 Pilot Jets” and “Size 90 and 925 or 92.5 and 95” main jets.
The starter jet gets very clogged easily, you can’t remove it but you can use air compressor all over the carb where you see any holes. it is very crucial.
We do liquid cleaning , and after carb is dry, we use air compressor to blow everything clean inside the skeleton body
Check for leak or damaged “O-Rings” on Intake Rubber pipes attached to the cylinder heads because they affect everything including vacuum for fuel pump + tap , difficult starting , poor running
This picture , remove the gold seat , and check O-Rings are OK and clean the mesh filter attached on the other side.
Can you drain the oil ? and take off the magneto casing ?
Look behind the flywheel to make sure the flywheel “sprocket” hasn’t lost any teeth too ?
Sorry for the late reply been really busy but yeah the last when i bought it in about November it got new coils, regulator,plugs,plugcaps and a new battery about a week before that then it was sat until January but i saw another forum that said something about it not going past certain rpm and a problem with acceleration and im having that same problem – thank you
Have you considered….,
- Clutch Plates ? OK at lower revs but what if 1 plate is cracked and bike is jerky at acceleration or high speeds or the plates and spring have worn down.
- Stator Unit. I hope not but if its funny, the rest of the bike acts haywire. its part of ignition (not just charging) = multi purpose unit.
- Carb Clean?
- Leaking O-Rings under the intake manifolds
- Loose airbox? (it is very sensetive to that if it is not sitting down tight and properly)
- Air filter (is flowing less air thru as it gets old up)
- Someone in the past put wrong jets, messed around with mixtures in the carb, floats, float seats (they control how much fuel comes at high revs too)
- Someone also probably messed with the slide needles making it lean than OEM or little richer ? (needle = the needles attached to the black carb diphragms)
- Weird as it sounds = Lubricate the gear linkage parts so it shifts easier , and check chain isn’t slacking too much and isn’t too tight when you sit on her
- oil change ? Motul 7100 is great on these hot 125 twins, oh yes they do get hot! n (250 cooler would be like a good present for her tbh before summer hits)
I hope this info helps ?
Thank you again bro. I reseted ecu. It was soo easy. In a 2 seconds, i made on of key 5 times and ecu reseted. Since 3 days i am geting just o2 sensor 1 high voltage, o2 sensor 2 high voltage. Bike is super. Everything is super but f1 light is lighting but there is no problem on driving. Is this f1 ignore important or never mind? And how can i solve this problem?
It means replace the parts soon because if O2 sensors fail, the bike will stop running = FI/F1 warning is telling you the ECU thinks there is a part that is almost going to the grave soon (not in good spec anymore) or part is loose
Also make sure regulator is always 14v (idle) and (5,000 rpm) – If it is 16v , it will fry a lot of parts and the ECU is very sensetive and expensive part to replace than a carby CDI
Hi Marcos, how are you?, I saw your answer to my question in the other topic and came here, well my bike is not having sparks in both cylinders, I’ve changed the spark plugs and coil and I’ve also checked the CDI connection and it’s everything is OK!
Maybe this ….
- Faulty Stator or wrong stator fitted.
- CDI unit faulty
- Wiring harness has a break (wires broken inside somewhere along the harness)
- Side Stand Switch (Bypass it) or check wires are not rusted if it is bypassed
- Clutch Switch Handlebar (don’t bypass it) but replace it. Take old switch out and find another bike at local bike shop , and find a matching switch, it is common part for many bikes, just find the size that fits Hyosung
Hey guys, I’m from Brazil and I have a hyosung 250 and I’m having problems with its CDI, I’m not trying to get a spark in the cylinders, I’ve already changed the CDI, coils, spark plugs and spark plug wires and it’s not resolved, could anyone give me some help??? I already did the same tests mentioned above and got no results.
See my latest reply on this topic below:
If you still get problems => Post a new topic for yourself and tell us everything you did.
Good luck!
Please also look at this topic for the CDI diagram to very the wires are going in the right places.
Hey,
Welcome!
Let’s get to it…
- Which part of the harness is not sparking ? = Front or Rear ? (in otherwords , which engine is not waking up?
- Has the harness shown any signs of rust? => Try contact cleaner ?
Got a meter? = See it stays on 0 ohms (dead wire or a break somewhere) or the numbers go to infinity when on 10000 ohms (mark on meter)
See the rear coil ? = if it has a blue/white strip wire colour ===> Probe there. and go to the cdi plugs => find the same colour to see if the circuit is complete.
Also, go to the stator unit ==> See the “2Pin plug” coming from the stator => Put your meter to 200 ohms and tell us the ohms it says on it.
I feel like we want to be sure the “harness” is actually not broken in some hidden places resulting in loss of spark signals going to the coils to fire them up.
The CDI rarely fails but if it did , then it was likely a chinese clone or the stator & regulator (married together sadly) toasted it up. = followed by a bad battery cells that was annoying the overal electric system that made it go haywire.
I hope you get somewhere , keep us posted.
Open fuel cap.
Use SIPHON to drain fuel in to a veey clean bucket.
A little bit of fuel will come out from hoses because it is normal they are always wet inside on a running machine.
So use cloths to hide electrics and be ready to wipe old drips of fuel if it spills in to a part
Make sure battery is removed from the bike
Not that ugly , but you know it is faster than most old slow harleys – I am biased but i could never see myself riding a harley haha but harley is one of the most popular cruisers in the world these days.
Welcome to the club!!
should I change the needle jets on the carburetors? Because in the manual, I see that for the 250 and 125 they are different.
See this link (click here for tutorial) , and if you want new needles (click here for shop link)
Also you should use 250cc slides (click here to see 250cc slides) , because 250cc slides were different from 125ccThe spark plugs now are new CR8E, I’ve ridden 150 km today, I’ll take them out and upload a photo. This might take a bit because I’m a bit busy this week.
No rush! Just take it easy with her 😉
If the float needles aren’t working, the fuel filter should lower the level when the bike is off, right? It doesn’t. Last week, I removed the airbox and the carburetors to change the spark plugs, and the intake manifolds weren’t wet with gasoline. The fuel filter only empties if I accelerate to the maximum. Do you then see it’s alright how I’ve connected the vacuum lines?
Okay, if you ride next time, go 5-10 miles at lower revs (steady cruising) = Look at your filter again and let us know if its half-full (50% or more IS OK)
We are justing making sure there is no internal carb leaks in the float seats (because float seats have O-Rings too) = slow leak in to engine sometimes.Should I also change the main air jets to the 250 ones?
Not really, it should be fine but keep the carb cleaned as there is lots of holes inside.
This video is 100% explain how our carbs work, because it is a CV carb.
To go from EFi to Carb 650 = All electronics from the donor bike will be needed front to back. And its airbox , its throttle cables , whatever was on the carby motor
Engine = Possible stator & flywheel change. Depends on age of donor bike and age of your motor
Before we do that, have you considered that what you are saying so far will mean it’s just the pump and its relay that needs replacing ?
Or you can take the pump out and see if its clogged ?
Fuel Lines = Usually don’t need changing just yet but they are special as they have “blue tabs” you can squeeze to release them off the pump
Then you can lift the tank off , do things slowly , very slowly = They tried to make it easier for us using hoses that have blue tabs (quick release)
Cleaning the injectors is a good idea why not! – Again, its a slow process to remove 1 part by 1 , so you can memorize where everything went , since EFI has more electronic sensors than a carby motor would.
Could be these in order….
- Solenoid Relay (common)
- Battery too old (Cells have aged , so won’t hold juice , hence the rapid drop from 12v to 9v when pressing start) = The dash almost dims out completely too.
- Battery may be new (if bought in 2024) but charging system is wanning , so next morning battery is not fully charged up to crank faster – 14v idling and 14v @5k revs ===> If less , replace regulator. Don’t buy china ones , they always (yes, always) burn the terminals or go on fire. Stator = Should be 80v @5k revs at every 3 yellow wire (eg. 70v, 70v, 70v) => Service manuals in this forum show how to test it.
- Starter Motor unit.
- ==> Hope not => Open your stator cover after you drain oil first = Look behind to see if your Flywheel Sprocket is missing any teeth. – or – starter “clutch bearing” is phasing out. => could be time for a new one.
cheers for that , had a good blast yesterday but this morning it would barely crank , mot thursday , not looking forward to that
Fingers crossed it could just be #1
Thank you bro but i saw on youtube ms 309, ms 309 pro obd2 we can scan Hyosung gv 250 ecu. And just elmm327 again i saw it perfectly scan with gv 250. But i dont know gv 250 s ecu 4 pin socket diagram. If i would, i would connectöto elm 327 with manually. Do someone know 4 pins diagram for elm 327?
Did you ask the Youtube person who uploaded the video ? if they did any software hacks/tricks to do it ?
As here in UK , Garages use the official Hyosung Scan tool
Here is a diagram to make it easier for you, tell me the numbers and send me an email, i will see what i can do for you
Check your float height , after every ride on my carb bike = the big filter is usually full. Or your float needles are jamming causing some internal engine slow leak of fuel in to cylinders = Your manifolds will be “wet” inside as a hint.
Also open “OIL FILLER CAP” ( on the clutch cover) and sniff inside hard. ==> If you smell fuel => change oil before riding again.
Can you also clean your spark plugs , go for a short ride => wait to cool down => Take pictures of spark plugs so we can see the mixture ?
Simon also has the EFi 250 motor, he knows if the fuel system is too rich or too lean,. Pictures of spark plugs will help
OR
It could be electrical! (Coils? Stator unit?) (Since stator is also part of ignition system = high revs , more pulses to cdi , cdi talks to coils to spark the plugs. , dashboard tells you how much RPM engine is doing
Could be these in order….
- Solenoid Relay (common)
- Battery too old (Cells have aged , so won’t hold juice , hence the rapid drop from 12v to 9v when pressing start) = The dash almost dims out completely too.
- Battery may be new (if bought in 2024) but charging system is wanning , so next morning battery is not fully charged up to crank faster
– 14v idling and 14v @5k revs ===> If less , replace regulator. Don’t buy china ones , they always (yes, always) burn the terminals or go on fire.
Stator = Should be 80v @5k revs at every 3 yellow wire (eg. 70v, 70v, 70v) => Service manuals in this forum show how to test it. - Starter Motor unit.
- ==> Hope not => Open your stator cover after you drain oil first = Look behind to see if your Flywheel Sprocket is missing any teeth.
– or – starter “clutch bearing” is phasing out. => could be time for a new one.
