â™ ï¸ M77
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Take a quick look at this topic below, as i did post some clearance values:
Also , report back to this thread when you spin your engine 10x , then recheck clearance, it might change 0.05mm to 0.07mm , although let the bike cool down overnight and do it on a cold morning as heat does affect the clearances.
If the markings inside the engine look like pen-markers like the green one, that’s what Hyosung did during production, as long as nothing looks broken.
Looks like I’m going to have to split the case, drum will not rotate freely so most like something binding on it.
Before splitting the case up, spin the flywheel to see if the clutch drum rotates too ?
If you were spinning the wheel in neutral, the pistons would stay still meaning the crank doesn’t , but obviously if its in gear , it stops you rotating the wheel freely by hand
Nice purchase and welcome:
We could start with the basics:
– Tyres = Michelin or Bridgestones are best (if you could depend your life on the road, go for michelins) but obviously be very very careful in icy conditions as even cars can slide too.
– Oil Change (doesn’t matter what the last owner did) , do a fresh oil change and filter, she will thank you.
Tutorial here:[Tutorial] How to Change Oil & Filter on Hyosung GV + GT125/250 +R
– Check Battery and Regulator is charging well, a bad charging system could leave you stranded in the cold, here is a topic on how to test your electrics:
Rectifier – How to Test Stator , Battery , Regulator – GT125R Carby
Find every bolt on the bike that’s holding the fairings and replace them with stainless steel. Aluminium is no good. This makes maintenance easy next time.
Cold & Dirty season is here soon, so get ACF50 = Remove “every single connector” on the bike, and add a single “tear drop” of ACF50 in every connector on the bike, it will thank you a lot. Do not USE WD40 as it will go in flames . Just strictly ACF50
Remove your wheels and grease the axles and check bearings are good.
If you remove your Steering Yokes = Grease their bearings.
If you remove your calipers , give them a good soak of brake cleaner and a small toothbrush to clean inside the pistons. then use COPPER Grease behind the pads and copper grease on the “sliding pins for pads” . Brakes are just too important.
If possible, if you see black hoses for brakes , change them to new ones and bleed brakes again (Hyosung service manual says that any brake lines older than 4yrs need replacing)
if you see “GREY” fuel pipes under the tank , replace them all and go to your local auto shop for a fuel filter and maybe 4 meters of fuel pipe so you can also do your vacuum lines, extra pipes can be use for the tank’s overflow if its not there etc.
Tutorials here:
How to change Vacuum Lines on Hyosung GT125R GT250R & GT Comet (Air Hose Diagram)
How to upgrade Fuel Lines & Filter on Hyosung GT125R GT250R (Carb Hose Diagram)
Hope this helps , let me know if I missed something you wanted to hear?
It sounds like your harness may be the one that’s shorting somewhere along the cable or a part is frayed bad causing it to cause instant shorts.
You will have to end up going through a painful process of stripping the harness down , checking every wire and then rew-wrapping the harness after you find or fix any faults you may discover. We don’t know if other parts on the bike are fried ?
Sounds like the fuse is doing its job bursting before it cooks anything attached to the harness ie. dashboard , coils, engine black box, speed sensor etc, they use 12v as soon as key turns on.
The engine black box is the most difficult to replace, so leave it disconnected. Even the starter motor relay has permanent 12v even if your keys are OFF, only the CDI + right switch handle triggers it to go and spin the starter motor , the 12V signal to the regulator is always live even if bike is OFF, regulator won’t do anything until the stator sends AC power to it and then it converts it to DC to charge the battery. Retrograding from the harness itself is rare but happens.
I would say i prefer that noise than an eerie too quiet of a motor, as that silence kills so to speak but if the rattling sounds increase with revs in tandem , it suggests:
– one of the shims is too thin (clearances too wide between the cam lobe and bucket)As the lobe presses down, and lets go ==> if the gap is too much, the bucket’s valve spring shoots it back up until meets the lobe again (almost like instantenous metalic fist bumping, if i can even describe that correctly!)
Cam Tensioner (as the hottest cylinder than the front) , this could be likely as the chain races up and down , the tensioner’s ratchet may be juddering or causing a chain rattle slightly but , you did not mention if the tensioners have changed their sounds from either front or rear or if they both sound identical ? So i will leave that for you to judge with a screwdriver on it and other side of the screwdriver on your ear.
– debris along the cam bucket and inside the shim itself, affecting final clearance figures or that the engine needs to be spun by hand a few more times ice cold to verify clearances before starting it.
Hope this helps!
Ps. Am hoping its somethin simple like u say cos am assuming a new ecu or fuel pump arent cheap?
But if it comes down to it, just a quick one can a faulty fuel pump be fixed or rebuilt easily at all?
If the pump is faulty , it won’t make a sound or it will be very muffled. A pump that’s working will make a loud whirring noise then it stops (primed and ready) by the time the dash sweeps up it’s RPM counter then back down to 0rpm.
OEM ECU will be costly yes , but knock-offs do exist on china’s Aliexpress, they are hit & miss.
This sucks , IMGUR is blocked in the UK now, so we will no longer recommend it.
https://help.imgur.com/hc/en-us/articles/41592665292443-Imgur-access-in-the-United-KingdomShall we try Flickr (Yahoo’s image host) or even make a folder in your DropBox/OneDrive/Google Drive and call it “Hyo pics” or something, upload a picture there and get the public share link to show here.
Sorry for the run-around, I am also behind on other tasks (was fixing multiple customer bikes & shipping them back) as I had a very long week but I will make sure to look out for your replies.
The site’s own image uploader will be fixed and we no longer will need to use external sites or drive-boxes (hopefully!)
Take a look under the tank (becareful as the fuel pump “port” is very fragile when disconnecting it) , then take the tank off. Look for connectors coming from the sprocket area and clean them then contact cleaner (wait to dry) then try again ?
Glad to hear the actual gearbox is still working!
No problem, take your time.
DELPHi is Hyosung’s better ECU and Delphi is used on many bikes besides Hyosung. In the past they did use Mitsubishi Japan ECU’s but because Mitsubishi is not making them anymore, there was a rough period around 2009 to 2014 where they used a Korean made ECU called Daewoo, most failures come from that particular ECU.
Ring my trade partner (oldest hyo dealer in UK) and ask them for the ECU as they may still have it on their shelf , it’s a small shop so expect a busy line but they do help when you are connected to them hopefully. They are called Startright Motorcycles (if i can ‘t get the ECU or they can’t , then i doubt anyone else in the UK supply chain will have a brand new one , leaving us to resort to dark-corners of trusting mr. unknown to buy a 2nd hand ECU on places like ebay etc but let’s hope the ECU of yours is still intact before it needs replacing.
Relays = eBay (there is a few used ones by various sellers there i am sure) , if not i can supply new ones (japanese ones).
Fuses = Either the tray will use Mini-Blade or Blade Fuses = Halfords / Any Local car shop.
When you get back, show us some pictures of your electrics so i can quote you back on this:
Am hoping its pretty simple like u say, mines a 2018 and i had to swap a big square main fuse over from 2 connectors at the back on LHS, could it be those is one the fuel pump fuse too (thats now been swapped/taken out?)
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 🙂
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 it’s 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.
I’ll keep you updated and post some pics, if I can work out how to post pics (I tried following the instructions, but the options I’m presented with don’t match what the instructions say – there’s no “add media†button, only “insert/edit media†and when I click that, there’s 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)
