♠️ M77
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You can go to halfords and get CR8E as that is the OEM plug for every Hyosung sold since 1999 , so always stick with CR8E no matter what.
Also, while there, ask then for a spark plug tool that fits CR8E plug , get more than 1 tool, incase Tool #1 is being awkward in the frame , get Tool #2 that may be shaped different to avoid hitting the frame or ancillaries attached near the engine.
Do that first…
Ride a little bit , come back.
Send us the picture of the FRONT and REAR plugs = We will know they if the HT caps are on the way out (common! hence we only use NGK Race ones that’s NOT plastic as i would NOT use plastic caps, they will crack!) .
Also have a multi meter ready , and we will send pictures on how to test your own coils to get some hard proof to see if the coils are OK based on readings.
You could do way better than your current mechanics at this rate , good luck!
Sounds like you need to drain the oil out entirely (grab fresh one and fresh oil filter)
Next , go to the stator cover , remove it carefully and SLOWLY (the flywheel has a strong magnet) , so it might try to pull the case back in and also there is a “STARTER Motor SPROCKET” idler gear (looks like this)
Then once the cover is off (don’t forget to carefully disconnect stator plugs near the rear shock / regulator area) , put it aside nicely.
Have a BRIGHT torch, check the “Flywheel SPROCKET” (like this one) , spin it ONE direction and check for broken teeth,
Spin the sprocket the OTHER WAY
===> If it moves ==> Sprocket SPRAG CLUTCH is damaged
===> If it DOES NOT MOVE ==> Then the sprag clutch should be one.It should only spin ONE-WAY (sprag clutch looks like this)
if sprag clutch is damaged , DO NOT buy 250cc version. (it will not fit!)You could probably repair your old sprag balls, with this one….
Here is a full diagram of your starting system behind the flywheel…
This is your starter motor below
It sounds like in the video the starter motor is struggling to spin the engine (with or without plugs)
Having a replacement starter motor is not a bad idea 👍
Old Starter motors that spin too slow make it hard to start!
A healthy fuel pump will always make a “whirring” sound as it stays continously on until you switch the bike off. Even as you turn the key on it makes that “whirr” sound.
That’s a lot!
– How about we do this to stop any hydrolocking issues as that would mean a big disaster later!
- Remove the fuel and vacuum line going to the “TAP” on the tank , GET A BUCKET! , if fuel pours out….even a drip drip
Replace the tap! - If not, but when you crank the bike, with throttle closed (don’t touch throttle), fuel is dripping a tiny bit in to fuel filter
Replace the tap - If you are sure the tap is OK, then remove the intake manifolds (the rubber pipes going to engine cylinders)
Replace the O-Rings you see there
(LIKE THIS ONE)
These orings can also a LOT of vacuum loss sometimes, and this is why you have a hard time starting and the taps & pump are not opening properly due to vacuum loss. - If the O-Rings are ok , replace them anyway , and you will be alright for a good long while and use STAINLESS bolts on the intake pipes because it is not fun drilling out stuck rusted cylinder bolts!
- Open the fuel pump (see if anything looks broken inside) (if it says MIKUNI on the back, then it is Genuine) = > If suspicious or unsure, just replace the pump with a NEW one (I would not trust used pumps)
- The bike will start to hate running on the tap, so that’s why Hyosung put a pump on it. It is advised to put it back or get a new one and refit the vacuum lines properly again.
If having a new pump ==> Crank bike for 5 seconds max => You should see fuel SHOOT out of the pump going to the carb … this means TAP & PUMP are OK now…
If its doing “little drop” (*very little drops*) , then go back to my comments above again ^ before reading below….
We need to make sure the fuel system is actually sending fuel properly first… - Open the “OIL FILLER” CAP next to your clutch cover ==> Sniff hard, if you smell FUEL inside ==> drain oil & replace filter!!!
Use motul 7100 oil
If you need a tutorial
Click here - If the oil is fresh and good, you saved a lot of money and possibly broken crank!
- Get fresh CR8E plugs again (yes again) , don’t bother with CR8E-IX (blue box) , they are rubbish on 125cc Hyosung — Keep it stock or use LASER NGK
If both plugs are sparking WHITE-BLUE , the coils are OK
If plug is sparking faint colour => Damaged coil or HT Cap (NGK HT cap is better)
If replacing one coil , replace both (keep the old one as spare!)
Your plugs will thank you! - If you crank the bike, and plugs are WET from fuel ==> Coils , Cap , Stator , CDI problems
(Sometimes = Clutch switch will stop sparks , replace it here — DONT BYPASS!)
(sometimes “Kickstand Switch” is an ass hole, and it must be cut off from bike, it is very annoying…. Make sure the kickstand plug is “bridged” (bypassed)
Don’t forget to check stand before riding!!!)If kickstand switch is bypassed already , maybe water has got inside that plug and turned to rust, check those wires …. if CDI thinks its “missing” , it will not spark or cut sparks after 1st gear == make sure the wires are good there and water proof it hard from rain and salty wet road!
I can’t stress this part. - If fuse box has rusty fuse, replace it. No questions asked, that’s an easy 2volt loss there! use blue 15A fuse only.
Try all this and let us know of improvements ?
Keep us posted, Simon knows his EFi babies inside and out lol, so follow what he says!
Topic locked as its a duplicate. Ill respond to your other one here
Then i would assume you have faulty coils ?
Swap the front and rear coils ?
If that’s true, it time to get a new coil and probably new spark plug caps (as yes the coils can kill them) – NGK ones are too recommended,
Since these bikes came out of the factory we always get orders for the rear coil and pair of plug caps. The rear coil fails first as they wasn’t put on properly and the ECU can’t always tell you its a coil problem.
Sometimes you may need to also make sure the regulator is doing “14.2-14.5v” MAX & LOWEST , if it falls outside 14v in any revs , you will face more electric issues and possibly a slowly dying ECU as it’s the most voltage sensitive of all.
Do this with a fresh set of CR8E plugs (yellow box) = DO NOT use “CR8E-IX” (Blue Box) as Hyo 125’s don’t like em. Surprisingly yes the Stock plug or LASER NGK plug is way better for the injection 125cc. Carb Models are hit and miss most of the time.
If it has CR9/CR7 etc = bin them straight. CR8E only.
Keep us posted , we will get to the bottom of it 😉
Just hard for me to give a straight answer online without the bike next to me unless its a common issue we’re already familiar with , unless otherwise in the end, all the checking you did , probably will turn out to be a bike just needing a new part or you missed a small simple thing such as corroded plugs (strip it all down and clean every plug you can find) , unlike Carb Models, the EFI system also checks “resistance” to certain sensors. So if the resistance is too low or too high , it is usually caused by an oxidized / rusted plug that needs cleaning out instead of the actual sensor being fault.
Ie. Tank Level Sensor plug says “100 ohms” , it has a yellow wire (the black one is for ground usually) , if i see the same yellow wire at the dashboard connector , it says 150ohms , i think i have an issue along the wires that rose the resistance quite significantly possibly a bad kink or exposed wire rusting or connector at the dash has water invasion (if its not waterproofed) etc…. Assume that an object attached to the engine has high resistance but the ECU is expecting it to be low when it calls it , it will go haywire sometimes when running , as it’s not getting the values it wants. Hence Simon and Myself in this site usually repeat to owners to try to ensure the harness is as pristine as possible before replacing faulty sensors on EFi bikes. Resistance that is too high on Stators will burn regulators , slowly cook everything that’s connected to the harness unless the fuse blows first, the ECU won’t behave the same anymore, but since you have a DELPHi unit (hopefully, not the 2018 MOTO1 ECU) it “may” or “may not” warn you with an error code at the start “Battery Voltage too high” etc…
I digressed a little!
Hey
Check this topic, just incase it is the idle speed controller having a loose/damage o-ring like this guy found out below:Also try the cleaner mentioned in the topic above to clean out the fuel system
Keep us postedTry the Vulcan 800 ones, the worst case is just a bit of metal work to shave some off the metal to slot in to the bike rearset?
In honesty, the Daewoo ECU is problematic , thats why not community investment was made to attempt to mess with it on a large scale , and the only tool that can reliably Read the ECU is “Hyosung Scan Tool”, you could ask local dealer in your country to buy one as Hyosung sells it to Hyosung dealers only. I believe Delphi is a better system overall. As you said, Daewoo is rare , so it is best to leave it alone and improve other parts like using NGK leads for the coils etc and using MOSFET regulators.
Unrelated My front left-foot peg broke and I need a replacement. I see a tonne of “Universal” footpegs on eBay. Could you point me in the right direction? I don’t care about keeping it OEM, so long as it is decent quality at a decent price
im not sure 100% but look at “Vulcan 800” foot pegs, they may “just about” fit but again this is the closest bike i can think of
or try Vulcan 800 footboards (footboards are way more comfy than pegs i wont lie lol)
Winter Time (under 15 *C temps in the air) , basically cold days = 10w40 is fine. I would get Silkolene Pro 4 or Comp 4
Actually find any oil that has ESTER (that’s usually Silkolene Pro 4 or Comp 4) or (Motul 7100 , 300V)
Fully synth is best.
10w30 is too thin, it will break down faster than a 10w40 would.
Personally i prefer to use Motul 7100 at 10w50 or 10w60 all year round even on hot summers. It’s “probably” the best oil for the hyo twins. (Though the manual says use “more expensive oil if you can” to extend engine life)
Why 10w50 (50/60 means it can break down less than a 40 grade)
“10w” only , don’t get 5w , 15w, 20w ==== 10w is the perfect spot. 5w is like water. 20w is like sludge, too thick. Stay on 10w(40/50/60)
Silkolene Super 4 = Use this only if you can’t get the better ones (Comp 4 / Pro 4)
Hope that helps
Usually Hyosung sells direct to dealer or trader if the bike is still in warranty, so your mechanic could have had some “idea” as to how long it will take for them to get it.
Contact us here , we might try to rapidly get one for you , please confirm in the email it is a “SEAL” as we can’t return parts to the factory if it was incorrectly ordered (ie your mechanic gave false info).
oooooh i see!
– Take your time, get your friend to take a nice clear picture of it again without zooming with his finger or screwdriver pointing at it.
I hope a rock didn’t try to pop the casing!
That’s a lot happening there!
Can you put the battery in (make sure its charged) , then i know it sounds stupid , but remove all connectors and parts from the bike, and clean their connectors (plugs) , as even a small resistance or corrosion issue makes even a 2 volt drop somewhere. I had to deal with the bike not starting 2 days ago, i cleaned the bulb connectors as lights come on right away and also the fuse needed changed (the 15A one) , it might not be your issue but damn, the EFI bikes definitely like the connectors to be free of rust or oxidization issues, it makes it easier on the ECU too
Try that again and see if the bike responds better?
Also , disconnect the “starter solenoid 2pin mini plug” to stop the starter spinning, when putting the battery in.
If the bike cranks without you pressing “start” , then replace that solenoid.
Remove the relay that powers the headlights (so the front lights are off) ==> check battery is 13.5V idling , put the relay back in while running, if the volts drop to 12.x ish , replace battery or checkj lighting circuit.
I mention lights often as they already draw power as soon as the bike turns on! The fuel pump is the most power hungry,if it sounds funny , consider taking it out and be sure the “strainer” isnt clogged up or the pump unit itself needing a change,
Sometimes idling issues can point to the pump or injectors, if not , download the service manual on this site that matches your bike and get an error code displayed and tell us what it is.
Keep us posted!
Okay , the holes I see inside the rubber intake pipes are air flow to the outside pipes that connect your vacuum system for the fuel pump
If you have an EGR , you can delete it to reduce the amount of air pipes there. I can link you to a tutorial if you havent found it on this site.
If you need diagrams for fuel pipes and vacuum i can link you to them
Thanks for the video
If missed something else , take a screen shot and circle the area that needs attention.
Go on youtube => upload it as “UNLISTED” (hidden on youtube searches) => copy the share link in to here.
Of if you are on Android > Upload to Google Drive => Set video to “Public” and share the link here
If you have Hotmail (Live/MSN) => Do the same as google ^ but on OneDrive
Instagram allows sharing stories feel free to upload there.
I should program the site once again to be able to accept big files , probably in 2025 when i do a minor facelift to the forum.
Can he take a video or pics so he can send you then paste it here ?
Hey glad you sorted that out, be sure to remove it and apply “contact” cleaner on it and make sure the “plug” is out of sight so that the front tyre doesnt chuck so much water at it.
Then use grease on the actual kickstand & it’s attached switch down there so that it doesn’t seize up since it moves all the time (stand down, stand up, stand down, etc…)
- Remove the fuel and vacuum line going to the “TAP” on the tank , GET A BUCKET! , if fuel pours out….even a drip drip
