β οΈ M77
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It could be the coil packs going out and also the HT caps, here is a tutorial to test them (It says 125 but instructions are the same for 250 EFi)
Rectifier – How to Test Stator , Battery , Regulator – GT125R Carby
There is 2 plugs under the engine = One is for Oil Drain (It is surrounded by a triangle plate)
2nd plug is at a 45 degree angle so to speak , is it likely he removed that plug ? and bits fell out ?
There is a Bolt => Washer => Spring => a tip ==== These move along the gearbox cam shaft (It has a camshaft in the gearbox itself) or can we suspect he damaged one of the gearbox forks ?
How comfortable are you splitting down the entire engine and rebuilding back up after sorting out the crank/gearbox area ?
Your video suggest issue came from the “gearbox” stopper bolt being removed under the engine (mistaken for oil drain) thus bike is now in neutral , otherwise take it out , check what’s going on or god forbid the actual forks for the gear-select sprockets inside are damaged (bike lost gears) , but can’t be , because if its lost 1 gear, other gears should still click in to place as you spun the wheel and let in/out the clutch to engage.
I am hoping i made any sense so far?
Starting up = 15-2000 revs
Warm / hot = 15-1800 revsThis is normal. It’s been the case since 2001 for Hyosung GV125 (Carby) & GV125-S EFi to idle at 1500- ish when hot as per manual.
So you’re Okay there π
Hi Marcel
I am having problems uploading pics, theres no upload button on add media (Desktop)
Thanks
Barry
Bare with me , I will try to fix the bug and i will upload a test picture using a dummy test account in to this post. I was in the process of revamping the entire site’s looks , so its easier to navigate on phones, so I think i may have missed something.
I could judge (if i can) if you upload a nice video of the phone near the engine valves so we can hear if the valve chatter sounds OK or not. (try to get away from the exhaust as they are louder than the engine)
Try Motul 7100 oil. Probably the best oil Hyosung bikes can drink and it does help a little bit to calm down the sounds of the moving parts inside the engine (just a little bit!)
Plus your gearbox will love you.Old ducatis are loud generally and have a dry clutch with adds to the ticking noises but it’s normal for it to sound like a “tractor”.
The GV125-S should have a small bit of valve chatter especially with the rocker arms hitting the tappet buckets , a bit of ticking will occur until its a little warmer and oil is fully circulated before riding off.
My new fuel pump is not activating. The relay works as I tried a different one and got the same snapping noise. I checked the fuses. The F1 light will stay on
how do you find the neutral switch to see if itβs bad
How do you clear an F1 code to reset the ECU
it would be easier to start a new topic , then tell us the history of the bike and what problems its having , what you have been doing since then. It starts a new thread so we can follow up with ideas.
In the meantime, download either the 650 EFi or 250 EFi manuals on the forum, it will let you know how to check the condition of the ECU and what wire colours to check if there is a break / short somewhere in the harness.
Iβll keep you updated and post some pics, if I can work out how to post pics (I tried following the instructions, but the options Iβm presented with donβt match what the instructions say β thereβs no βadd mediaβ button, only βinsert/edit mediaβ and when I click that, thereβs no option to upload files).
I will login with a test account and post a random picture in this thread to see if that’s the case, and i will fix the bug if i see it. Sorry about this , I was revamping the site entirely , so something might have cracked but i still presented a backup option to upload to IMGUR (website) and just copy their share “BB_CODES” , those BB-CODES will translate to pictures in this forum automatically as it will pull them from a remote source.
Bare with me as i investigate and good luck with your purchase!
That’s a multi-issue there hmm, lets try to address the pump.
If the ECU senses the bike isn’t good or if the ECU is toast = The pump won’t prime.
The ECU directly controls the pump, so maybe we either have a burst fuel pump relay and fuse
(On some 2018 models = the pump has its own “Relay” and its own “fuse” = So 2 things here just for the pump)Headlights = Relay may be burst ? Without the relay, the lights stay OFF unless bulbs have gone burst at the front, the rear is all LED, so should just light up.
Also LEFT switch gear & Right Switch gear = Directly control the lights too, so if either of them are faulty or have issues with contacts , the lights stay off.
You will want to replace all the fuses (If its 15A , use 15A and some fuses are 20A , 30A etc. So match them accordingly as you would not want a 40A fuse on a 30A slot
You will also want to replace all the relays.As for the pump = Double check the stand, bypass again , verify the same wires at the ECU are complete, so the ECU can sense it. (On carb bikes = If the clutch switch or stand switch are dead, the CDI would cut the sparks off, so principal is the same for EFi models)
Buy a backup ECU just incase, it would make troubleshooting much easier too.
Test the stator using this topic and verify , confirm the readings?
Rectifier – How to Test Stator , Battery , Regulator – GT125R Carby
ECU won’t tell if the coils are dead or not, so use that same link to check your coils and confirm their readings? = if the pump primes back to life but there is no sparks , the ECU may get shot , we don’t know if they got water damaged , as you said you found places of mud and water ingress on the electrics.
While you can, disconnect everything on the bike, and try to test every sensor with a meter ? = Tedious process but helps narrow everything down.
Browse this forum and get the latest service manual , they have picture tutorials on how to test each sensor.
Since the sensors are out of the bike, this is a good time to remove the harness and clean every connector with Contact Cleaner. All Hyosung 650 ECU’s for whatever reason are more sensitive to resistance changes in the wires (oxidization etc…) unlike carb models. Hence Hyosung Korea tried to replace most plugs with waterproof japanese connectors. but it still can’t hurt to double check.
Hope this helps and keep us posted!
It will be at the top of the headlight , remove the dashboard 1st.
If the bike looks good , generally the GV650 is a solid bike.
Every owner would be wise to:
– upgrade the stator and regulator to a mosfet one (like what you saw on the shop)
– upgrade the caliper pistons to stainless versions and braided brake lines from Goodridge UK.Use motul factory line coolannt.
Look for any burnt plugs near the regulator to see if previous owner put a knock-off aliexpress regulator on it?
Go for a little test ride again and take note of the clutch , if there isn’t any rattle or slips , then the clutch should be OK. They love Motul oils, so as per Hyosung service manual it is advised to use “premium oil” , cheap oils are not worth the engine rebuilds later even if it’s an actual distant cousin of the SV650 (Hyosung made both SV and Hyo650 engines, as they did make engine parts for Suzuki since the 80s before they split up as Hyosung did have an R&D plant in Japan. ) so quality of the bike is dependent on how well the owner looked after it .
Tyres = check for any side wall cracks , then you know if the owner was using OEM tyres or not , at that mileage you said, it likely still has very old rubber tyres on it. So expect to put fresh ones in for a peace of mind, blowouts are not fun.
You also have the comfort of downloading the manuals on this site which will help you look for every small thing during service time.
Lastly , check the forks are in good condition or if they need new seals. If you ever have to change seals, put fork gaiters in to protect them from road pittings as they use GTR forks)
Hi Iβm wondering what I can do about my broken pivot bearing on the link, i canβt find a replacement link for the life of me, thank you, and incase i got names wrong, itβs the bearing that the bottom of the rear shock bolts into
I personally am studying this item so i can stock them them before 2026 , Hyosung Korea stopped making them as they moved on to the newer bikes they are making (EFi 125 now)
If not, take your Y-Bone unit and go to a local bearing shop, they should be able to make up a one-off bearing kit to fit in there.
Hey , if possible, upload a video to youtube and mark it as “unlisted” (means no one will find it on youtube)
Simply just paste the link here:
Make sure the phone or camera is away from the exhaust or too much wind , so we can hear you revving up and letting it idle for a couple of seconds.
While you do that, go to the engine with your ear and a screwdriver, poke the Tensioner with the pointy end of the screwdriver , then your ear on the other end , see if both tensioners make the same noises ? Or if you hear any chain slapping.
Also do the noises change if you pull the clutch IN (pull cable) and clutch OUT (let go)
The idea is to pin point exact noises where are most loudest and it would be the area to work on.
Yes clearances both cylinders:
Intakes = 0.08 (margin 0.01 = 0.07 to 0.09 is OK)
Exhaust = 0.11 (margin 0.01 for any feeler gauge inaccuracies as above)It would be alarming if it was both 0.03 as no that’s way too tight of a clearance and would disappear when it’s hot. Just a bad day waiting to happen.
Do they sound like this ?
https://www.youtube.com/watch?v=GAWKHBycWvQYes it’s a silly youtube video, but imagine that same ra-tat-tat-tat faster and more metalic higher pitched sounding, then i suspect either clearances or cam tensioner or chains , but if you’re wise enough to remember howw everything was installed, and record yourself ==> Remove the cams and check their bearings and cam-sprockets for any teeth damage.
Welcome Barry π
Hope to see the changes you make to it , you made a good choice compared to the Virago, although Virago is still a good classic.
100% change the oil yes as you will have oil that’s fuel damaged , so if it keeps circulating , you may kill some small critical parts as it runs and find the oil will vanish quickly too (burning away rapid)
Carbs =
Disconnect the fuel tank and get a bucket, if fuel is dripping out of the tap away from the bike, then replace that fuel tap , as it will flood your bike or jam your floats in the carb overnight. And you may find the engine hydrolocked.Confirm float height is OK inside the carb , take a look below and look for my reply inside that topic which confirms the float height of the carb
Clean the spark plugs , but they may be fouled anyway (lost their potency to spark properly next time) so grab some fresh CR8E plugs. (Have 4 of them, so the other next 2 will be your backup, saves you running back & forth to shops)
Once the bike has its own drained, replace the oil filter = 1000% don’t skip this part & leave the spark plugs out, let the engine evaporate away but make sure the area where the bike is safe to do so as fuel vapors will be in the air incase a friend or relative in your garage decides to light a cigar next to the bike! π₯π¬
Cranking too much time would mean the carbs send fuel to the pistons but the engine needs to spark the fuel, so it can make sure as to why the engine got flooded, happens in cars too.
Test your coils and stator , use the topic below (Ignore that it says GT125R , it shares the same coils as its GT250R sister)
Rectifier – How to Test Stator , Battery , Regulator – GT125R Carby
Keep us posted & good luck . Hope my replies made sense
Howdy!
Looks like you got a nice land rocket , we hope to see its revival on the forum too π
Judging by your pictures:
1. The black ones going to the 3-way unit called the Fuel Pump = It will need some clamps / jubilee clips just to avoid fuel leaks, as hoses may swell a little bit under heat.I will annotate each image you posted below:
2x Black Holes under the tank == Get a 1 meter hose and put it there , this hose goes to the rear tyre , suspension linkage= This is “overflow / breather” , it looks missing. And if you overspill or bike falls (God forbid, that overflow hose could drain the fuel away to the rear tyre , instead of it dripping all over a hot engine and if the coils were arc’ing , that’s an explosion waiting to happen.
Fuel Tap = Small Nipple is for the vacuum and the big port is for fuel towards the fuel filter yes. Make sure to clamp/jubilee clip that port too.
Yes you’re correct that goes to the tank’s fuel tap.
Yes those thin lines are basically vacuum feeds coming from the rubber intake neck boots at the engine cylinders where carbs swallow themselves into.
Also you will 100% need a new fuel filter there, so replace it while it’s apart:
Look at the hole again, if its blanked by the factory, then no need to worry about it. Otherwise it is either Vacuum Feed or “Overflow to the Ground/Road”
This cut hose that looks pointy at the end is mostly likely the “over-flow to the road” , if bike falls on its side or the floats get jammed open, extra fuel will gushing out to the road to save pistons being flooded. Also acts as breather when needed.
Arrow β¬οΈ Left black hose , this is “incoming filtered fuel” (so the tank and fuel filter send fuel down this hose as Entry to the pump)
Grey Spring Coil Pipe = > “π ΏοΈ” mark on the vacuum pump means “pulse” , aka vacuum as the pump works in a pulsating fashion. So make sure that spring coiled hose is getting vacuum from the engine’s rubber intake neck boots or make anoter T-junction to join the rest of the vacuum lines on the bike.
Arrow β‘οΈ == right black hose ==> Fuel pumped out towards the carb. This is the fuel that’s leaving the pump going to the carbs.
The pump has also 2 more arrows facing down to the road, ignore them as they have been factory blanked off.
Hope this helps!
take some time to think about it , hunt down a spare engine for a quicker swap ? , you will still get more and quicker for a complete running bike. Plus you gt to learn a lot, so it’s not all waste as your next bike will be an easier fix as you learned what to do and what to look so next seller doesn’t try to sell you a lemon again.
Keep it as a slow rebuild , by Spring time , you will have a totally mint bike that can fetch Β£1.5+ K sold, running, fresh MOT. Parts will go but you will have half a bike that’s sitting there as your hardest things to shift are wheels, frame, forks etc, as they are common to find them now
1 brown valve in he picture looks like it has been through some hell judging by the edges of it.
A valve head change or valves alone + seals could be a safe call to change up. The valves are very hard to press down with your fingers , so amazon a cheap tool that allows you to compress or extract valves so you can see the full state of them and the seals (compression loss? or tiny bit of oil burning possible)
Pistons & The Cylinders, you would end up needing to remove the pistons and the cylinder walls now to judge their condition with your eyes
, if they all look good, grab a spare piston and use its rings to see if compression improves.
Remove the piston slowly! = So you can see which position each ring was, they have a notch on them and mark them. So next time you fit a piston, you can remember how they were.
Like this one:
The wires could be rotting further along the harness of the “stand switch” ?
And cobra is correct to mention the Tip-Over Sensor (Roll-Over sensor) , it can get funny sometimes , I would NOT bypass it but check on your country’s eBay page if you have to replace it but hopefully not.
