♠️ M77
Forum Replies Created
-
Posts
-
Is this a brand new bike (zero miles) ?
The mixture looks strange!
Here in UK (it was once part of the EU but i digress) , it is usually Front = 3.0 Full Turns out & Rear 3 and 1/4 full turns out because the rear is hotter)
Also in summer time, it gets VERY hot , so you want the carb “slightly little bit” richer to avoid leaning out.
Yes I am able to turn the rotor both ways
Go behind the Flywheel Drum = See the BIG sprocket with lots of teeth?
Remove your starter motor first.
Can you spin that big sprocket in both directions ?
It could be important, as Simon is likely to suggest your sprag clutch & starter motor need fixing or replacing
This is the sprag clutch that starts your bike (also known as One-Way Starting Assy)
Hello,
Would this one help ? (It’s used but it appears it was barely run in when we stripped the bike down)
https://www.ebay.co.uk/itm/256778857924Aftermarket Pistons = They don’t really exist off the shelf 1-to-1 copy as Hyosung makes the pistons themselves.
Cylinder Valve Heads = Hyosung makes them. as with their 125cc Cylinder Jugs
If not, send us a private email below we shall see how rapid we can acquire a “new front piston” for you.
HF131 is the correct filter for all years (2005 to 2020) – They did not change the oil filers for all carb model 125cc.
Hello, yes.
Open the magneto cover. That is where the flywheel is. When you see it , remove it , that is where you find your sprag clutch like this one (aka. Starting-Motor-Clutch)You could monitor the A/F ratio on the exhaust and also use some kind of heat gun to measure cylinder temperature so you know which one is still cold ? as you said it stalls in 15mins of working ? =
Measure that temp sensor on the front cylinder cold and hot values vs the manual figures.
Removing the flywheel does not require a full dismantle of the engine. Just the flywheel stator cover off, then extract the flywheel out , that’s it. You should be able to see if the sprag system is worn down (since it is 26,000 km , so it could be worth a look!)
I have had a few engines apart a few times, sometimes the pistons will be in different positions. I open the top valve covers to do clearance jobs , so i can either spin by hand to confirm the timings are correct , then i use a starter motor to battery to see if it will crank OK but ofcourse oil will shoot out!
Once the engine is completed and closed up, it did not matter where the piston was, the bike cranks within 2 seconds after the fuel pump stops priming. At some time ago, it took longer than 5 seconds to spin and start but it sounded weary.
So I removed the flywheel, and some some teeth of the sprag-clutch was gone , could this be related ?
Have you ever taken off your flywheel to inspect your starter-clutch system for abnormal wear / damage?
I recently worked on a customer’s 2017 bike GV250, it was a delphi. It was a stressful job! I changed a lot of things despite positive readings on the meter, the harness was clean as it could be , no wire oxidization yet (garage queen) , but i was shocked that in the end I replaced the stator unit & made sure the battery is 100% charged and brand new , voila it started within 2 seconds of the fuel pump priming. I didn’t really investigate too much as if “piston” position had any influence to how the ECU expects the piston to be.
However, everytime i press start (within a milli second) ==>i see sparks on the spark plug which tells me , the ECU had already been ready to fire up the coils as soon as i hold the clutch switch in. The suspicion in my mind right now is that it did not matter if the front was up, and rear was down or rear up and front down position of pistons , it always started in 2 seconds. Longer cranks in my past were a result of the fuel injection system needing a clean or fuel pump was underperforming. I did not keep DELPHi systems for long , but i always had Daewoo & Sentecs bikes to work on. Sometimes my customers ask me to just convert the machines to “carby” (expensive investment but less maintenance in the long run however the DELPHi system is not too bad, and is more “instant response” with throttle which is good)
As i get more information , I will share when i can. I don’t think i’ve heard too many people discuss piston position vs cranking time for ECU. I have to keep in mind both cylinders are connected to the same crank anyway! Everytime the bike is switched off (during a crash, or normal riding to stop or rider activates killswitch, the pistons don’t always return to the same position as they did before , a bike could be switched off mid cycle. )
Have you got any Fi light warnings ? (2008 model, so I assume it is the SENTEC EFi model) (also 2009 is the last year we saw carb models changing to EFi)
If possible, did you follow service manual to get error code from the ECU ?
If this was a carb bike = high revs usually means extra air is coming inside the bike (intake system leak)
As its an EFi model = I understand that ISCV was changed , could there be any chance it is failing again ? Have you tried your old ISCV unit if you did not throw it away by now.
Otherwise, using the service manual (which has the readings) get a meter and test these parts:
- MAP sensor (it will be on the throttle body or airbox as you have an early model EFi likely (that’s if the previous owners didn’t upgrade it to newer injection parts)
- Lambda Sensor ? (Oyxgen sensor in the exhaust) => Suppose the ECU thinks the mixture is off (wrong signals by the oxgen sensor) => injection system raises more revs.
- Engine Temp Sensor at the front cylinder ==> If it thinks its still cold , the ECU revs up to warm it up? Test that sensor.
- AIT sensor = Air intake temperature sensor (sometimes its called pressure sensor as weird as that sounds) it will be sitting on the airbox (if Hyosung put it there)
- EGR unit = It’s a big electronic box that has 2 pipes => going to front and rear engine ==> block the air feed or disconnect it and see if it changes anything (since the lambda sensor will be in the exhaust pipe)
This is my guess as annoyingly Sentec & Daewoo ECU’s can be troublesome to diagnose.
If Simon on this forum doesn’t say it , I will say that strip the harness out of the bike & clean every connector you can find. You’ll be surprised how much a little resistance in the wires can skew readings to the ECU.
Keep us updated!
If it is brand new and its gold tip hasn’t popped off , then keep it inside the grey metal shell (if it came with one) or put it back inside the airbox and see what happens to it?
I don’t expect any issues if its brand new though?
I imagine you have a SENTEC ECU as your post says 2008 (though some countries had a Daewoo ECU a little earlier than 2009) – I really hope the ECU is OK!
Welcome , beautiful babies! As much as you love the 650, don’t give up the 250 yet , as when winter draws nigh , jump down to the 250cc
Riding a 650 in the UK ice isn’t fun during winters, but ofcourse neither is any cc bike on black ice. No idea how cold it gets where you are ? I guess your winters are just a mild 15c temps?
Either way the 250 makes a good backup!Turbo on a GV650 ? Better make sure the swingarm , tyres, brakes can still stop you without slight warping! – Ill be following that journal if you ever make one, not many even dare to try lol.
The top feed of the shell is usually connected to the air box nipple (one of them underneath)
I will have to see about that again when I get my hands on the bike.
I saw this post, what do you think, is it possible to swap the throttle bodies from my EFI model bike with the appropriate carburetor from the older models, would it even fit?
You will change a lot of things: carbs, intake pipe, harness, stator, airbox, dash, many electrics etc – as nothing “efi” is backwards compatible.
It could be the “fuel gauge” unit itself in the display.
From the TANK sensor to the blue connector plug of the harness = That yellow/black line must have a reading to make sure the level signal is still travelling along the harness.
It is possible to repair the fuel gauge unit in the display (tricky , there is no instructions online) but try the wiring first. But as you said , if the wire from the tank to the display plug is all clear ===> then it will be the actual unit itself inside the display that sweeps the fuel level up & down.
normally , when the bike is switched off, it drops down to zero (empty) , then it rises up when the bike is running.
There is another topic somewhere in the forum where a guy mixed up a GT & GV carby fuel sensor to make his GT work.
I can’t remember what you had before because GT250 have 3 displays. Analogue and Digital Carby and third one is Digital EFi (fuel injection model)
Wirings do change.
If the fuel gauge is in LCD glass (Fully digital glass display) = Then it should be ZERO when fuel gauge is disconnected. The fuel level sensor inside the LCD is controlled by a chip behind the Green Dot Matrix LCD glass. Carby ones can be changed easier but Korea stopped making replacement LCD glass many years ago.
You could find a wrecked GT250 in your area with ANALOGUE display and try it. (Some GT Naked bikes want analogue displays with analogue speedo drive under the left fork = carb models) (It’s rare here in UK i find carb model GT250 with digital display unless it is EFI fuel injection)
Good luck & make a new topic though , so the original person doesn’t get notifications of their thread as they haven’t replied. 👍
The top feed of the shell is usually connected to the air box nipple (one of them underneath)
Hopefully on your tests , we don’t have to replace the ECU as its near impossible to acquire one!
Good luck
Hmmm,
If it helps, here is a few spare parts from our ebay
This one is the last one we got and likely may or may not work but i could not test out of the donor bike as engine was removed
https://www.ebay.co.uk/itm/254811047849
If you need just the plate? (Yellow plate goes to the frame, here it is)
https://www.ebay.co.uk/itm/254811047849
On your airbox = you can fit a dead ISCV to block the airbox hole and its 2 nipples under it.
If your frame does not have the welding spot to attach the metal shell , then keep using the airbox for your ISCV unit when the issue is resolved.
The metal shell will just be for testing ?
Good luck!
Can you confirm that if the ISCV actually sits inside the airbox or it has its own clamshel ?
I believe you have a clamshell that hangs on the frame to feed air on the 3 pipes sticking out of it.
I have an idea = Put the ISCV back in place and fit it inside the metal shell or airbox = Does it still “hit” the end of the airbox/clamshell?
If you pull it out again, it should have been keept in place instead of springing forth too far out.
Next tip = It will sound foolish but bare with me….
1. If you have a metal shell , put the ISCV inside it and screw it in so the O-Ring doesn’t leak air.
2. BIG pipe going to airbox ==> clean that area (hygiene!)
3. 2 pipes sticking out at the bottom ==> your other hand expose its palm to them.4. blow air with your own mouth (unless you have a very LOW volume air compressor machine , attach pipe to it)
Can you feel air coming out on both bottom 2 metal holes ?(these holes feed the intake pipes anyway)
Turn the KEY ON
Keep blowing
Do you feel the air getting more restricted ?
If you turn the key OFF
Is the air completely blocked (you can’t blow no more)
Turn key on , it should retract backwards ? to the OFF state in the picture while key is on (I can’t confirm yet if the ECU can sense if its gone too far out and must retract it back a little bit but it may engage once the MAF sensor tells the ECU how much air is flowing in the throttle bodies while in stand still to maintain 1800 rpm revs, it’s a little trickier to study Sentec/Daewoo ECU’s than it is DELPHI units)
This is a weird test I am suggesting but you want to confirm , the same behaviour is happening to the NEW and OLD ISCV units ? Always make sure battery is charged though because that fuel pump draws a LOT of power and we don’t want to stress the pump too much also. It’s more expensive than the ISCV unit.
Tap ? = Disconnect the tank and does fuel still pour out ?
Pump ? = Disconnect the pump from the carb => does fuel still shoot out ?It could be trying to burst the floats open and this possible chance the bike will be hydrolocked (fuel inside the oil & piston walls) , so make sure the above are good first , before progressing further. (Don’t bypass the pump no matter who tells you)
There is an ancient trick of using a “clear hose” attached to the float bowls , and seeing if the fuel level inside the hose is heigher than the carb markings , and if so, then you have float issues (float valve jammed , float valve o-rings leaking fuel past , floats bent too high or too low , or may simply need a new float valve replaced as part of rebuild kit. but it will test your patience but you want to be sure the carb is faultless.
You can do this while carb is on the bench and feed it auxilary fuel hanging from the ceiling , just to test before fitting it all back to the bike.
No fuel should overflow unless the bike fell on its side. If the bike fell, then yes the fuel should overflow out to protect the engine cylinders.
Let us know how that goes , i hope i made sense!
Welcome fellow rider!
I will tell you what , I myself have dropped my hyosung within 6 months owning it , only to realize how HEAVY it is and it managed to survive the trip home painfully! – I can feel your pain! This was almost 10 years ago for me though haha.
If the bike is with you, don’t worry about it. Little by little , let’s get going and see if we can resurrect it from its hibernation.
I believe if you have the time, to dig deep around the forum, you will find some topics between the 250cc and the 650cc members , you will get tid bits of information to help with your quest. If not, post a topic anything on a specific issue if you like , add pictures . If you want to do videos, simply upload them to DropBox/OneDrive/GoogleDrive and just get a “public share link” so we can play it on here.
If on youtube , upload the video as “unlisted” , so that it is only found on this forum (not on youtube search)
Be safe out there!
Thanks for the info, ill make a new mod regulator upgrade soon , already got the terminals , send us an email if you want to try (&you being a test rider)
Video uploaded to vimeo (upload there if you can or Google Drive / OneDrive /DropBox other video upload service because we can’t play Apple videos on certain older android devices)
I saw the video, it looks like its slow to rev up as it may be too cold. Now after 5-10 minutes hot, are both cylinders hot ? and is it riding better?
keep the original airbox & don’t fit the aftermarket one , it looks like its idling under 2,000 rpm (which is the default) , that’s a good sign.
Next step.
idling = what is the voltage ?
At 5,000 rpm = what is the voltage ?
At 8,000 rpm = what is the voltage ?Regulator test, so i need all 3 figures above ^ before i comment further.
Looks aftermarket , interesting! – It should be bigger and all black but for some reason the bolts are both there, so it could be an earlier type before Hyosung updated it (Yes, they are known to fail since 2001!)
Follow the plugs and check the connectors.
Also measure the bolt holes apart ie…. (0)_____40cm____(0)
I might do some upgrade version that makes sure it stays “14.5v” constant (no flactuations or droping to 13.5v) , although earlier carb models lived on 13.5V as they had way less electronics , but because you have fuel injection model with a lot of sensors , best to ensure it is 14.v in any revs
If it ever spikes above 14.8v while running = don’t ride it. That would be battery or regulator or stator on the way out (both worth together, so ie. a bad reg slowly kills the stator unit inside the flywheel crank)
Good luck though, it seems as though with the snow all over UK, put her indoors & work on it slowly.
That’s no good, too much rust = easy voltage drop (even a little) , we’ve been there. (or even a sensor somewhere else , having its resistance affected (ohms too low or too high on the wire, the ECU will trip)
Go under the bike and find your regulator rectifier, get pictures of it and also the connectors on your harness.
You have a long job but i am sure it will be worth it, you want “nothing electrical” to have rust , even down to the red battery wires etc.
Hyosung tried but remember UK rains too much!
