â™ ï¸ M77
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Hmm in Spain, go find this bottle (this exact bottle) and get 2 of them (yes 2 of them)
https://www.halfords.com/motoring/engine-oils-and-fluids/fuel-and-oil-additives/wynns-formula-gold-petrol-treatment-500ml-166754.htmlDrive with both bottles filled in the tank and also about half a tank of E5 fuel (5% ethanol? here it’s called premium fuel in UK) as the cheap ones (standard fuel) %10+ ethanol is just not good on Hyosungs , although it will run E10 fine but nothing positive for any vehicle using too much ethanol but i am digressing.
Observe her, the idea is to try clean out your entire fuel system critically the pump and the injector. I know myself that when i increase the throttle, the pump gets louder , what if your fuel pump has some kind mini-delay to the throttle response or the injectors are waning ? TPS would be the last thing we check but it is also worth checking to make sure it is in OEM specs with your multi meter as per manual guidance.
If the tank is nearly empty, siphon the fuel out of the tank carefully, and inspect your fuel pump or the fuel strainer being clogged, it gets clogged eventually causing the pump to work harder than it needs to or slightly less pressured fuel going to the injectors.
Least if the 2 bottles get used on the tank, its one less maintenance thing to do knowing you had the bottles try to clean out the fuel parts.
Another tip , spray carb cleaner (be wise! âš ï¸ðŸ”¥) around the intake pipes , so see if there is an air leak (even a tiny bit) , these O-Rings eventually do need replacing to keep things optimal:
Intake Pipe O-RING (Inlet Boot Seals) x2 – GV125 GT125 RX125 GV250 GT250 Hyosung
Also , check your ISCV O-ring on the airbox, like this example below:
GV125s idle speed when hot / ISCV problem (Idle Speed Control)
The cheapest “premium” chinese can you can get that is GOOD (personally the only china can i like) is LEXTEK 350mm exhaust , go to Lextek’s website and get their 350-450mm exhausts (the longer the better)
Man that is a CLEAAAAAAAAANNNNNNNn bike, don’t drop her! Wow.
Good question on lights, personally leave it Halogen , 99% of LED lights are china made and ofcourse they won’t fit as their heads are too bulky for the GTR shells.
Until Osram & Philips the 2 top EU brands of bulb makers invent a road certified LED for bikes, i would stick with halogen. They do make LED for certain cars (ie. Audi R8) but on bikes there is no LED bulbs for them yet. Sometimes the chinese LED’s are “bright and glaring” , you want a light that is brighter but not painful to your oncoming road users
Get Osram Nightbreaker LASER and Philips Xtreme Vision bulbs , these are the peak of the halogen tech.
Hey , upload a photo here as a test , there should be a bright yellow box above the reply box showing a tutorial link for picture uploads.
And show us the exhaust in particular ?
EFI bikes need a balance: sound + performance.
Instead of a very short “straight through†muffler:
Look for a slip-on designed for EFI bikes, tuned to maintain some backpressure while increasing volume.
Some aftermarket mufflers give a nice growl without killing midrange torque.
Avoid removing DB killers entirely. Some aftermarket options include removable baffles for track-only use.In other words , as i have leaned over the years Black Widow Exhausts that are 400mm always gave the best sound and balance or Lextek OP1 350m long cans . EFI bikes need some backpressure—super short slip-ons can make them run lean and lose midrange torque. Keep a DB killer and use an EFI-friendly slip-on: louder sound without killing performance. Those fake akras are just “annoying” loud , but a proper slip on from the likes of Black Widow , 2Brothers USA (rare) , MTC , HAWK in my own experience have been excellent.
I also modified the baffle so that the overal hole size is about the size of a 10p british coin (forgot dimensions) , as an exit-hole too big in the DB killer meant it felt “flat” riding it , but too narrow is not good either. I experimented a lot , though my old previous bike was the Kawasaki ZZR400 , it did not care what exhaust it had (for the most part) as it makes its power much higher up (screaming inline 4!) , the twins on Hyosungs both GTs and GVs i own really prefer the torque at the early revs not to be disturbed , the GV was more frustrating but i am digressing.
The stock cans on all hyos are too heavy! – You could get a tiny acceleration gain (very tiny) but shaving off the weight by switching to”road legal , performance exhausts” , if it helps check ebay UK and find BSAU stamped exhausts (BSAU generally meaning for road use) but just loud enough to get noticed! – In UK , if an exhaust is too loud , the inspectors (MOT Test) will fail the bike if the guy hates it and issues papers to the owner to change it (before he can ride on the road legally again) we have to get our bikes checked every 12 months to make sure the bike is “road worthy” , but exhaust noise is just one of them, though some harleys are very loud and still get away with but i am digressing , its 10pm as i write this haha, i think my brain is going 😔
Hope my un-organized reply helps ?
use the carb version of the GT250 / GV250 manual for engine clearances and its internals
For EFi parts, take a look here:
Also , check the 650 manuals , (some , i mean SOME, efi parts are shared between the 650 and 250) , I uploaded a lot of 650 EFi manuals.
Welcome!
Hope you put enough miles on her this summer and what are you future plans with it?
Share a picture of her if you want!
Like you i was part of the 4 wheel world but i had more better friendships with my 2 wheeler buddies and i feel more free (although i wish England had summer all year long lol)
Sounds like you have regulator issues and stator issues (both have their own independent issues (ie. Reg is probably under/overcharging at low and high revs which affects more sensetive parts like the sensors all over the bike and the ECU or the stator itself has an output that is either too high or too low. So have a look at the topic below and confirm with numbers what state your charging system is ?
Rectifier – How to Test Stator , Battery , Regulator – GT125R Carby
Ignore that it says Gt125R , the principal is the same for GT250.
If you can verify the charging system or fixed the charging system has gone stable now, then go for a longer ride (but carry a spare battery safely incase you need to swap it if heaven forbid you get stranded)
The general idea is to put the bike under some real world load to assess how its performing etc
Thanks,
On my first go, I think the float stuck as it wouldn’t go then gas came out the overflow. Tore it down again then used your suggestion and with some tweeking I have it running reasonably well. I’m letting it sit and will see how it behaves tomorrow.
It’s not a bad idea to go through everything once more , good job!
Mix screws generally on that bike start 1 full turn from seated or 1.5 and see how it behaves?
They produce it on the spot but exact details will be confirmee by the garage
Alternative Option!
If for whatever reason you are not able to use the forum’s own image uploader , then follow the instructions below to upload your images elsewhere so you can link them on to this forum:
At least if you upload to a place like POSTIMAGES.ORG which allows free image uploads, all you need to do is then copy the [BBCODES]
Then write your forum topic like this below:
This is an example post with a picture and the picture is below:
[BBCODE] <— image will actually appear inside this bbcode don’t worryStartright Motorcycles in Leeds sell the restrictor kits or they will fabricate it for you and make it “official” , just tell them we sent you.
If not, it is possible for your local garage to grab the SV650 kits and try to retrofit them to the Hyosung throttle bodies and give it the “garage stamp” if insurance ever asks for it
But generally I have not heard much about it being an issue riding full power the riders did have A2 but were much much older folk who ride sub 400cc bikes for years , so they just went full whack (yes strange enough I did hear about older riders staying on A2 because they find riding beyond 700cc useless for street use)
For you , you can still make yours A2 compliant , if the Hyosung kits are not there from Startright Motorcycles , then its closest cousin would be the SV650 (Well Hyosung Korea did get involved making the engines or its parts in the past for suzuki) so should make life a bit easier to retrofit some kits.
Really its just restricting the throttle output that’s all!
I saw this bike for sale on eBay , i missed out on it but hey you have now become part of an much rarer exclusive club because the GD series was more of a “limited run” globally including its bigger St7 sister, generally Hyosung makes GT & GV models , but now these days they are doing GV models in varying sizes.
Keep the GD bike, it was an official race bike in New Zealand races and i only ever met 1 owner in the UK with the GD250 bike , rode together from Yorkshire to Wales in the same day, to my surprise , it is a nippy bike for its size!
Again take care of it and i really like the graphics on it.
Don’t worry about photos , you did fantastic using the external website to host it , next time just copy the [BB-CODES] and our forum will gladly take those [BB-CODES] and translate themt to full images as i just did for your post!
I am in the process myself of slowly revamping the site so that it will be easier to upload images directly here instead of using external sites.
You haven’t ridden for 20 years , so get out there and ride as much as you while we only have maybe 1-2 good months left of mild weather before its too cold to have fun!
I fear that we may possibly have to clean the ECU connectors hard , then dry it off , but the ECU only having a dry clean (air blast only) and try to see if we can use the service manual to trigger a blinking red FI light. It’s that Fi blinking confirms the communication to the ECU and it will tell us the code by either telling us the number on the dash or doing a series of sequence blinks (most likely)
Can you also try to trick the ECU to throw an error code to see why it is not sending sparks ?
Or although the stator shows good readings but could we have an internal fault with the pulse sensor of the stator unit , in such that it can’t tell the ECU’s how fast the drum is spinning, thefore the ECU can’t send the pulses to the Sparking Coils to light up the spark plugs
The ECU should be alive , as only the ECU triggers the pump to prime => which should mean its ready to go? but you have power to the coils which is strange , i would also see if changing the HT caps & HT wires makes any difference incase of an internal fault with the HT wire or HT cap itself.
The last thing to do is a long process of stripping the harness and using a meter to very every “end to end” connection is verified and there is no lost readings in any of the wires you probe to test (incase of a short somewhere along the harness or a broken internal wire that is not visible but the meter would say zero (ie. Fuel Gauge Connector to Dash board – the yellow wire is dead , so explains why the fuel gauge is not telling what fuel level is in the tank etc or the pins have oxidized too much, so need some rescue)
Today I finally received the brake lever I ordered and it is a correct fit for the old one. I did have to force the mounting bolt as the hole in the new lever was slightly out of position. I also put a bit of white grease on the bolt and lever to allow it to operate smoothly.
If someone needs one of these levers, search the part number listed earlier and a couple of sources pop up. I used Hyosung Parts. The shipped quickly. The long delay before I got it was due to Canada Customs processing time.
Thanks for the update , it should help future owners who may get these rarer primas
keep yours alive & have fun now!
Do you mean the “idle sprocket” that connects the starter motor and the flywheel drum ?
(Here we call them “idler gear”) but correct me if i am wrong?
Hey, the link below:
Wiring Tables – GT650 / GT650R EFi ECU Pinout / Wiring Diagram & Speedometer
It may say GT650 , but considering you have a 2010 model as he does, the GV650 does share most of its similarities with the GT650, so use that link to look in to the wiring diagram Chris has made in the other post and let us know if it helped ?
Have you also stripped the harness down to find out where this mystery black wire goes ? Without pictures i am not able to verify what it does as Hyosung uses a lot of black wires in different places even as much as a horn! A solid black wire “could” be the fuel pump (as you said it is on a relay?) but again we can’t confirm until we trace it apart
There should be power going to the coils to spark? (Assuming the bike spins when pressing “start”) , also does the fuel pump prime nicely at all ?
I won’t lie , I have NOT dared myself to take apart a daewoo ECU plug as you said the harness or ECU can’t be ordered anymore , however, i was religious to use the “air duster” or compressed air” on the ECU itself (no liquids!) and also the harness plug
The harness = I used contact cleaner on every socket found on the bike, then compressed dry air on the smaller sensors such as injectors , lambda etc ,
The harness is the only thing that got soaked wet with contact cleaner but i let it dry overnight indoors to be absolutely sure (winters can get very damp outside here in UK, so best to do stuff in a dry area that’s warm) , you’re about to enter Spring season? So i will just assume outdoors are OK for you over there!
Dear Marcel
So I inspected the exhaust pipe and it seems there is a crack before where it appears to be joining the other one before going to muffler. I think I have to remove the exhaust system complete from the engine to take it in for welding.
That would be a good idea as the noises will be leaking through the cracks
Do you have a video of this ? (upload to youtube / onedrive / googledrive and post link here) so we can see what is happening.
And have you done tests to the coils and tells us :
1. Primary and Secondary resistance of the coils
2. Swap the coils , see if the front coil works on the rear better?
3. Do you have NGK caps ? (Sometimes stock caps will cause sparking issues) or just use another standard Hyosung cap again or SV650 ignition cap and try again.Hi will the new hyosung st900 be coming to UK awesome
Do you have a link to a hyosung article showing this ?
ST7 was discontinued a while back but the GV650 lives on and gets a 2025 update with ABS and LED tail lights etc for the EU and Asia markets but no news on UK yet
I am curious about this ST900 you speak of! :-O
oh , make sure both plugs are out of the engine and do it full throttle for a few seconds fully charged, then you get some compression readings.
Also throw a little bit (tiny bit) of oil in the cylinders , and do a 2nd compression test again. Does it go up when the oil is added? (piston rings vs scored cylinders)
