♠️ M77
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Hyosung uses china springs & china plates on the latest GV125-S EFi (to save costs) , so they are prone to slippage sometimes, if you were to switch to EBC UK springs & EBC plates they definitely help the basket last a bit longer since the GV EFi will probably carry luggage etc (being a cruiser etc) , you want the stronger springs to bite harder , you will notice it more when changing gears with Motul 7100 oil (great Ester oil)
If you ever dare change the exhaust, use the OEM Harley one, as other ones will loose power on the GV-S (Historically, GV Aquilas were always slower than their GT sisters, and using slash cut cans make them worse) , it would make your other upgrades pointless , so best cans so far are “OEM Hyosung” yes the ugly one or the Harley OEM one (it;s stock but slimmer and is almost OK enough not to loose too much backpressure as vtwins start their power in lower revs than screaming i4/i1 bikes.)
See here: https://hyoriders.club/forums/topic/exhaust-suggestion/
@Tom in that topic has posted a youtube link and name of the HD exhaust (HD = harley davidson)Stay away from knock off Temu exhausts lol, china doesnt care
Hi , If you don’t mind , would you be able to let us know what you were saying in English please?
You can read the oil line banjo of the rear cylinder, gives a good enough indicator of the temps if trying to compare with the front. The rear cylinder doesn’t allow much room under the frame.
Or do a custom job to bore the cylinder itself near its internal oil gallery and tap a sensor to it like what Hyosung does to the front cylinder on EFi machines, so you have to be careful here unless you have a spare cylinder to experiment on.Ignore those plugs. thats dealer mode.
Switch on the bike and, let the fuel pump prime. Then flick the killswitch ON/OFF 3 times quickly , (the big red button) and see what error code comes up on the dash ?
Also it may flash a sequence of red Fi light, so count the sequences.
Check the forum now for the service manual (250 EFi) in the “manuals” section of the forum, it will describe in more detail how to get error codes.
You can try replacing the battery cables and see what happens there on, a full harness replacement is usually last resort but they are getting rarer now as there seems to be a few left on ebay based on the ECU the bike has.
Hi, no worries if you owned the bike since 2012, so definitely not a novice at this 🙂 and check ebay now, there is an OEM tap being sold now that mounts to the frame and good luck when you get it.
The UK Hyo scene is more or less run off to FB as doing “forums” seems ancient for some people and they like “instant replies” on facebook! – We have a group called “Hyosung official club” on FB with Barry as my co-admin, he is on this forum too. Most people 10+ yrs ago have moved on , you may find these individuals still on FB if you want to pm them yourself.
GT is dying down in UK as Hyosung has moved on to GV Aquilas now , hence you will find mostly GV owners now in UK
Anyway, get that OEM frame tap on ebay before it goes, some other guy is selling it.
about 50c on a fast 70mph road on a summer day but hovers at 90c in rush hour traffic or less 80c but limit should be about 100c before its cooking itself, this confirms data on the EFi service manual on engine temp sensor ranges (only 250 EFi gets it and is for the ECU only, so you wont see it on the dash)
A fan might be overkill , as you want the radiator to not have objects on it to pass air through the back of the rear engine so it gets some air , however since you’re on a naked bike , it should get more than enough air will ever need and a 250 cooler to help it. A fan might be extra tax on the electrics (albeit a tiny tax)
There is no hard data on the 125cc/250cc from Hyosung but generally air-oil cooled engines will hover around 50c at 70mph road , assuming the sensor is in the cylinder head, anything over 100 isn’t good long term
Have you taken the tank off to inspect the harness for any signs of shorting or wiring burns ?
Was there any chance the old regulator likely popped one of the electrics ?
Horn is triggered by the left switch gear, disconnect it and see.
While it is apart, attempt to download the service manual on this forum , so it gives you instructions on getting an error code from the ecu (red icon will flash in a sequence which tells the error)
Check your neutral switch and clutch switch contacts/plugs = they would stop the bike from starting.
A bike violently loosing power with the horn blaring loud suggests either electric spike or a shorting somewhere but that is new to me also, all my years of dealing with hyosungs (mine and customer ones), this one is strange considering the bike is only 2k miles old. Practically young!
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Starter is grounded to the frame and battery, so the long cable is the positive from the solenoid yes.
Welcome! Hope to see the completed upgrades you will post on the forum 🙂
Not many people do ECU flashes as they are afraid that a false move could mean they can’t get a replacement ECU , however , they try to improve the sparking a little bit , the most improved mods would be something like a 520 chain set and a good clutch upgrade for long summer trips.
If you have OEM caps, replace them with NGK ones , that’s the only major electrical complaint people have in the UK , sometimes the stock caps ruin the coils next. And invest in a good regulator! That’s pretty much it.
You could at your own pace upgrade the tyres too, so its less suicidal when riding in the rain, i was never a fan of the stock Tyres Hyosung used in the past. #
I believe once you go 520, you won’t go back to the tiny chain 🙂
Vacuum should not be blanked , the tap will need it and the fuel pump is actually needed too. The 125cc uses a DF52 Mikuni Pump that was made for the Hyosung family , so the GV650 actually uses the same pump, it has a flow rate of about 80ltrs per hour, no way the 125cc will maximize the fuel pump , infact it is needed to help it sustain speeds at the top gear as it works on vacuum pulses from the inlets.
Check your inlet O-RINGS , usually we check the O-Rings under the inlets before replacing anything else.
China inlets = Chinesium , it won’t beat the OEM quality but it will get you on the road asap until we find the super rare originals!
Check your oil filler cap, sniff inside hard, if you smell fuel , it sounds like fuel tap is “wide open” after engine is switched off , would suggest future problems with piston rings or hydrolocking too – The tap may have a burst diaphragm
Just some of my thoughts , hope any of what i said made sense to you ?
Regards
This is fantastic news! – Who could have thought ? but you could see why 99% of Hyosung owners go strictly NGK caps immediately as the factory caps were made by a company called “Golden” in china, they always caused random issues there and there, so it wasn’t worth the anxiety. Nice move on the coils too, Tourmax is OK, japanese parts, it should mate well with the RR.
For now, leave her at 25amps as as safe buffer. Service the bike , and take it for a short spin not too far from home and come back. While the bike is still hot, measure any resistance of the new parts and other sensors, to see if they are within the safe margins ? If yes, then we should assume to go for another longer ride and see how it actually feels (power , throttle , idling at traffic, fan temps (if the fan spins etc) ) now you get some real world data for yourself to make a better judgement.
If you feel anxious, carry a spare jump pack to start the bike and limp slowly back home but heaven forbid , as you said it’s idled for 30mins without a hitch.
Another thing, find out if the amperage changes when the 55w headlight is ON or OFF , and watch for any RR wires getting hot.
I have no correct answer yet in regards to the Fi light , despite the bulb working when manually triggered , i must assume it being OFF is a good thing , find out during your longer rides if it ever blinks whatsoever ?
If you come back and say there is zero issues during the test runs , then you must be ready to go! (Hopefully)
A GV250 can start with a 9BS (factory size) as it is smaller than GT250 battery tray , you can start with 9AH, the GT250R has the luxury to use a much bigger factory size of 14BS since there is more inside the battery, you have a better chance of starting on a 14BS than 9BS , just simply it has more capacity & CCA. a CBR Honda can run on a 9BS battery , 9BS is common on many bigger japanese bikes of varying styles and different electronics.
IF you can’t find 14BS , try 12BS which is a nice middle ground anyway.
I can’t answer the starting questions to be 100% true as I don’t have the bike with me to do a deeper analysis , so i can only suggest likely cuplrits and reply to the error codes given by your ECU. However, if the ECU is saying the Lambda sensors need looking, it is a good idea before they fail mid ride.
If you go that far, you can see if the starter motor is tired (prematurely worn out?) and check your engine flywheel SPRAG CLUTCH , it should not be slipping but it won’t hurt to check. This allows you to also see the SPRAG SPROCKET teeth too (2 items to look at there)
Car = Turned Off yes, you can jump start the bike. but i would not depend on a car battery for a complete judgement, we might miss something else, we need to know the bike can run on its own battery first, it should not ever require more than double its original size.
NGK caps is what we all use , we dont have much faith in OEM caps , suzuki gets the same trouble with their caps sometimes, so NGK wins.
Also replace the coils if they haven’t already . Fresh CR8E again as they foul easy.
Stator unit , probably be your last item (it directly , i mean directly affects starting and general running etc.) – If its haywire at any point, the ECU will shut off or get grumpy to start. Probably flag an error code “no signal for pick up coil” etc eventually but if the stator is good, leave it alone for now.
The stator has 2 plugs . 1 is for charging (3 yellow wires) , does not affect starting unless fried (thus frying the battery and regulator etc if its shorting out)
other one is a 2pin plug = this is what the ECU wants from the moment you press start and general running all day. It can’t live without it.Ignition Coils = ECU won’t know if the coil is failing , so it wont warn you , go and measure the coils for their primary and resistance OHMS as mentioned in service manual and report back.
O2 sensors are needed for ECU timing & fueling.
Your battery should be 12.8V when the key is out of the bike (turned off) , then a drop of 11v while crank may be tolerated but dropping below 9v will 100% trip the ECU to say “battery voltage too low”
Get another starter motor cable = Yes a starter motor cable for Hyosung specifically, connect it to the battery NEGATIVE and then connect the other part to the frame (unpainted part) = This starter cable is thicker, and can be used as extra ground for the bike. Do not connect it to starter motor! or anything postive. I really hope i made sense!
I assume those codes are flashing sequences of the red Fi light, = They all point to the oxygen sensors (exhaust lambda sensors ) (high Voltage & low voltage errors) , so they may be going haywire tripping up the ECU. You will need to replace them and make sure the ECU plugs and ECU pins are very clean too (no liquids , just compressed air only)
Get YUASA YTX 14BS or VARTA 14BS (german brand) = That’s all I use and ever recommend for EFi machines , i can’t comment on other cheap brands as i don’t like them and they have always let me down eventually. Though any battery will crank a carb motor as it has far less electronics to power up , go figure!
Is it a 2003 silver frame where it uses a “frame mounted” tap and the fuel tank itself has 2 holes coming out of it to feed the tap thats on the frame ?
or a newer black 2005+ frame where the tank itself has its own tap (no need for frame)
Feel free to upload an image of your setup now if you want to clarify ?
Great to hear! – Topic now marked as resolved, incase anyone comes across this.
Did you get a can of carb cleaner and spray the airbox outlets that swallow the carb and also spray the intake pipes attached to engine cylinder heads for any revs changing ?
Possibly a loss of vacuum under the engine intake pipes where the O-rings are (there is o-rings that sometimes need changing) , tedious process as its awkward to remove the airbox but fortunately forum has 2x tutorials to make this a whole lot easier. Check the Air Lines thats feeding the pump for cracks ?
Large fuel lines would just hold more volume inside which is what you want , then more fuel is readily available as soon as the floats open inside the carb.
Did at any point the carb got opened to change jets ? Micro dust particles have entered the carb before closing up? or is there a chance the floats got bent even if it’s just 1mm off (see this link below to check float height as it directly affects how much fuel the carbs have before it shuts off , too much adjustment will simply leak out of the overflow or drown the engine – be cautious. or look at possibly jammed floats not opening fully?)
Otherwise , clutch switch and sidestand switch (even if bypassed would have corroded wires inside the harness, strip back and see.) – I would NOT bypass a clutch switch though especially on EFi models.
Just quoting this , as those will cut sparks off too. You did not say “Cuts out when going in to 1st gear ?” ?? I could not understand your previous phrase “Bike shuts off when put into her intermittently”
So i will assume its electrical and needs stripping down to investigate either way and contact cleaner will definitely help if some pins or wires have oxidized bad causing a signal loss
You mean it cuts out as soon as its in gear ?
If its EFi , have you downloaded the service manual on this forum to get a flashing sequence eg. the red Fi light will blink with pauses
10 blinks, 3 blinks , 3 blinks , 7 blinks = It repeats , this is Stator Sensor Coil for example. The ECU should let you know why it didn’t want to carry on , it should report itself on the dashboard once you turn the key on, dont start it. Flick the kill switch 2-3 times quickly and wait for the ECU to flash red codes on the dash.
Report back , if you struggle to understand the sequences , record it on your phone and upload the video to GoogleDrive/DropBox etc , and get a public share link, post it here and we shall see.
Otherwise , clutch switch and sidestand switch (even if bypassed would have corroded wires inside the harness, strip back and see.) – I would NOT bypass a clutch switch though especially on EFi models.
Hyosung sold Gv250 models with carbs until 2011 in some parts of the world, Hyosung introduced EFi models in 2008 with a SENTEC ECU (ultra rare now) and sold them until 2009 , then 2009 was the start of 2nd generation EFi which had Daewoo ECU until 2012 (then it is now Delphi ECU present day)
So being a 2009 of yours , I don’t know what’s under your hood (carbs? EFi? – Though EFi manual is at the forum to get error codes , if its carb model then it has way less electronics to diagnose)
