♠️ M77
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Not that I know of , unless i need to re-read every service manual Hyosung has made carb 650’s , but you can quickly on Youtube & Look at how they balance carbs on the older Suzuki TL1000S & Honda VTR1000F, as some DIYer’s tend to get their hands stuck in (“sometimes” a little better than mechanics at the garage but… use caution).
These two bikes while bigger in CC both still use similar size twin carbs as the Hyosung does (around 35mm-50mm ish bores) , then you will get some carb balancing kits , run your bike until you find the sweet spot it likes.If changing anything, always take pictures or write stuff down, this can help you go back to whatever the default settings were in the carb incase the bike runs worse.
I’m getting power from the ecu to the injector but it’s still not firing it seems like it’s not getting the negative power pulsing
If possible try this: if you could get brand new injectors or spare working injectors from a donor bike seller locally , if the new injectors won’t fire, then it is back to the ECU and the harness to see why it won’t fire the injector.
Usually i wait until the fuel pump is primed then play with the kill switch button 3 times or if the pump doesn’t prime i give the dash a few seconds to sweep up and down, then try again.
Also while at it, double check continuity from the clutch switch down to the ecu connectors and same for the side stand , so you want to be sure the ECU can sense the bypass (thinking the switches are still there, then it will allow you to shift gears)
Turn on the keys , don’t start it , but flick the red kill switch button 3 times and wait for a red light to flash in a sequence.
If it does , count the sequence (ie. 4 blinks , pause , 3 blinks , pause 1 blink) = that would be like code 4.3.1 for example, and we can trace this to the service manual to see what the issues.On a carb version = It would be easy, either thee clutch switch/neutral switch/stand switch cut sparks off as soon as its put in 1st gear. Stand switch usually number 1 culprit , so much so that sometimes a bypass isn’t enough, we have to make sure the wires have not rotted inside badly to the point they don’t contact each other anymore.
Just my thoughts!
Do the tests of checking the harness from injector plug to the ecu i mentioned earlier and i linked a nice pdf above too
Do you get an error code ? or even a flashing red light
Eg. it will blink in a sequence = 5 blinks, pause , 3 blinks , pause 2 blinks and repeats. = code is 5.3.2 for example then we can find out what it is.
Injectors not firing would either be no connection to the injector from the harness to the ecu, so follow the wires and make sure there is no break in them or verify with a meter , test the injector plug to the ecu connector to be sure the circuit isn’t missing (broken)
Also, have a quick read on this one, it may be for a GT but it gives some more information on the EFI system that may be relevant to your situation:
It is very crucial to make sure the connectors are very clean , use a contact cleaner and fully dry as the ECU does not like wet liquids near its connectors, so dry the connector before re-plugging it.
Also let us know if the fuel pump actually turns on (makes noise) when the key is ON etc.
if red light won’t flash on the dash when key is on. Flick the red kill switch button 3 times max and wait.
Keep us posted.
Funily enough, my bike doesn’t have any tps even though it’s and EFI, one less thing to check, I guess. I did find a loose airbox tube to the intake, which I have tightened correctly, and I took the time to change sparkplugs too. The issue seems to have improved, but I don’t know if it’s a placebo or not. Did have the chance to spray brake cleaner to check for leaks since I didn’t have any, but will probably do that, and if I find anythin,g I will check it and if not I will just assume this is the normal harshness o the bike
You’re on the right track! 🙂
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?
Would you be comfortable taking the SV motor + electrics + harness ? (Work involved⚠️) then putting it in the frame?
I have not used an SV650 cdi but i suspect the two engines will not have the same cam shaft timings as each other. Or that the cdi expects a hyosung cdi
I suspect if SV worked Hyosung would not need to make their own as they did help make the SV on some parts but to Suzuki’s own requirements
Those sprockets are well overdue! They are starting to look like hooks. Wow. You definitely used them hard 😉
Yes a full replacement is advised but this time email us for an X Ring option as I have not added it to the site yet.
Also as per Hyosung manuals. Replace clutch plates every 4-6k miles otherwise your clutch will start to affect your gearbox but this is just advise as I dont know when your clutch was replaced.
Dang that red looks sweet!
Indeed it does!
Hey,
I would drop down to 13T , 14T is too heavy for it. I almost never use 14T when i do 520 conversions. As you have 428 , i do not know what tooth count of rear sprocket to comment further, this could contribute to speed issues. 67MPH is usually the factory speed but here in UK National speed is 70mph and that is even dangerous for some riders as cars normally drive to 80mph + all day long, hence the need for a longer gear rear sprocket but also quicker small front sprocket , so you have to experiment with ratios that suit you.
Clutch Plates = Some minor HP loss happens if springs are heat fatigued & plates are too worn down ? = Less HP transfered to back wheel, so it is possible that it may contribute to your vmax issue.
Intake System = Connect the carbs to the airbox first ====> then tighten nicely.
Now your carbs and airbox are fully sealed up.
This means you have one big piece (carb+airbox) going down to the intake pipes connecting the engine.
Be VERY cautious as it is getting harder & harder everyday to get good condition rubber parts and they are very delicate things.
Is it possible to take a picture of the manual and upload it here ? And also show us your footpeg area to see what they mean by that.
In the past , i basically used universal pannier kits (was cheaper) but were hard shells which I needed and also got a universal rack kit that mounts to the sides of the grab rails along the rear pillion area. I just had to get creative and swear a lot to make things fit! This was on a bigger older GV (carb ) , personally I have not fitted one to a GV125-S, however Hyosung did not change any structural parts for the footrests since 2018-2025
The major change in 2024/2025 is their new model called GV-125X (X) , totally looks different. S-models will remain S-models without much change visually to be fair
The worst is that you could end up getting a metal plate fabricated to get around fitting the boxes or return it but i would also email or contact Shad themselves.
They are an OK company (quality wise), personally I use their Click-Lock tank bag systems, but as for customer support I can’t comment as i never had to bother them about any issues i had personally with their products.
Keep us posted!
Can you also upload a picture of the front sprocket and rear sprocket please? so we can see the close up of their teeth , then I will have better advise if it wise to replace just the chain or not.
general consensus is that a chain should be replaced with the sprocket , but because it is a 125 running on a 520 sprocket, you “may not” need a rear sprocket yet but the front sprocket is more critical as it wears down much much faster.
Also report how many miles you have done and what chain lube do you use ? how often do you lube it ?
Sometimes not lubing the chain after it rains , makes it wear out a lot faster , it’s just how mother nature is vs naked moving parts.
If you do a LOT of miles every day, I could do you an X-Ring chain next time but we can discuss that privately via email.
For now, just show us here what your sprocket teeth look like and report back “miles , lube product , how often etc.”
Try to tap in a socket in to the bolt and nut on both sides , get the impact socket, and use a breaker bar instead ?
Those frame bolts will turn to cheese , so be ready to replace them, it sounds like it was rusted in ? (owner not expecting to remove the engine but rode through mud & salt so much that anything not stainless gets seized in terms of bolts. Copper grease advised when refitting critical stuff!
Attack them tactfully as they round off easily but i took out the worst ones with breaker bar + a black impact socket
Not myself personally but I don’t have any further comments without more pictures of your situation to advise further.
Sounds like you just need to copy the old parts & old harness layout over to the new stuff etc , but yes sometimes Hyosung adds extra stuff on later models without notice.
probably means Fi light was flashing ? You may be getting a sequence flash ie,
Fi light blinks in a sequence = 5 blinks , pause , 6 blinks , pause , 7 blinks (it repeats itself)
567 code = could mean EFi system thinks battery is too low to power everything on it especially the pump too. (code 567 is just an example)
If its not that, go to the 650 manuals section of this forum and download the service manual that matches your bike (Daewoo Korea ECU or Mitsubishi Japan i am guessing based on 2010) , the manual will show you how to read the flashing sequence.
The dash could say “Fi / 0 / Fi / 0 ” but also test your stator using this guide below and tell us the ohms
(ignore that it says 125cc, the principal is the same)Rectifier – How to Test Stator , Battery , Regulator – GT125R Carby
get ohm readings for the coils that spark your plugs and HT caps too , tell us
if you have extra time, drain oil nicely ==> Remove the stator cover slowly as not to rip the gasket that may get stuck to the engine crank, and see if the stator is burnt out.
if in doubt, upload some pictures here.
Upload a picture of your spark plugs on the forum so we can see what is happening if you can.
Sometimes black smoke means you’re too rich or there is air starvation on the bike.
Personally i have not used it and would never use it, there has been a lot of people complaining about its “scammy” behavior and if you do get lucky, some parts are missing etc. So use caution.
If not, buy a wrecked engine in your country or a wrecked hyosung bike and take its engine.
