♠️ M77
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As far as i know with the OEM korea bars , they tend to spot weld them inside
however , here is an idea (please be creative and becareful) . Get a “Hole Saw” attachment for Steel Cutting , on your drill, then measure the hole inside your handble bar, find a hole saw that fits inside.
Then use the drill attachment. What will happen as it will make a deep circular cut until it consumes the insert. Then it should come out.
This is just an idea, you may feel free to use a better idea than myself 😉
Hello 🙂
I hope you had a nice weekend and you was able to make some free time to make any further diagnosis ?And also it sounds stupid , but i feel like i need to start here first
– can you make the engine hot for 5 mins idling
– plugs out , both of them
– full throttle open
– put a compression tester in front head
– crank the bike for 5seconds , and see how much PSI the engine makes at full throttleThen repeat for rear head , report back here.
Please make sure to use only the “metal part” of the compression tester (it is a straight metal bar with a rubber end that needs pushing down hard)
Don’t use a “Flexi Flexi” hose attachment , so to avoid false readings as flexi hoses bulge anyways
I will not lie , i have seen it a long time ago , they are just copying GV300S , to make a “version 1 vs version 2” so people decide which dress they want for their bike lol.
I like both variants to be honest!
Hi yes you can use GT carbs on your GV
Differences as below:
- Plunger (This is infamously known as “Jet Boost, Jet Streamer” , it squirts a tiny bit of fuel each throttle twist, so that the “heavier” GTR bikes can move forward.
- Overflow pipes are at the top diaphragms
- Floats have a minor design change because of above 2nd point i said.
- These are called Design 2 carbs
- Requires more maintance (has extra holes in the bodies and floats , due to addition of plunger on the side)
GV Aquila & GT Naked (Pre 2010 era GT Naked)
- Uses GV125 Carbs
- GV Carbs are called “Design 1”
- Less parts (ie. no plungers on the side, no needles in the throats)
- Easier to maintain due to aformentioned point above this sentence
- Overflow and Drain pipes are at the float bowls. Can’t be used with GTR carbs for obvious reasons
Hope that helps!
So, is this summary what you want, or would you like me to open a new thread and make a small tutorial when i do a service? … Kind regards, Koen.
I loved the summary , i am sure certain lurkers will appreciate the new information to digest. You never know, you might just save another rider from Belgium facing hell later.
If you did things like , servicing , you can always make “How To Guides” , like this other GV-S member did below
[Tutorial] Hyosung GV300 (Valve clearance check & correction Guide)
Big jobs or tiny jobs , it does not matter too much , as long you helped save someone from expensive garage costs. I know one rider was charged £100 to change a front sprocket! – It was a 14T to 15T 428 , and yet bike is slower because 15T on 428 was too big gears for bike to accelerate on hills. I said 12T , 13T, or 14T on 520 is better.
I will get him to join forum soon so he shares his experiences with the GV-S models
Watch out, a new model of GV-125 is coming again to EU maybe 2024/2025 called GV-125 S “EVO” , do not worry to much, it just a face lift , it will have same engine as 2018-2023 models.
But i hope they do not change swingarms or other parts of the frame like wheels lol , i would not be surprised, but we might see USD forks!
Welcome my fellow man , i am happy to see the bike has left its nest and it is far away in to the sceneries , i like the pictures , makes me a little jealous haha. it has been raining like hell over here lately.
When i see the sun, I will catch up!
Hey , you are more than welcome to share anything you do to the bike, it will help a lot of GV owners as we are slowly getting more EFi 125 members to the forums now.
Ride safe!
Good points by Simon!
Also please make sure the “RUBBER DUST” cover on the front engine head is actually fully sealing the spark plug hole.
If it’s wet , the water from the front tyre flies to the engine heads, then water tries to invade the spark plug hole (where your HT cap hides) -If dust cover is cracked or looks bad, i’d just replace it.
Speaking of wetness, inspect your air filter too. Wet air from the filter or plug holes = spark plugs will bog down and bike get the signal to kill sparks off (hence sudden loss by your bike , forcing you to pull over, risky business in a busy wet day!)
Hi Does anyone have a sevice manual for this model
I haven’t uploaded it yet , as i need to make a new GV125-S Section that has sticky topics of manuals in various languages , and make new links, plus i have to read them all . I’ve had 2 bad books (very bad english, missing pictures, inaccurate info, looks like it was rushed)
However, check your PM please i will send a temporary one.
If it has been 20 years. the rubber and mechanisms inside the Mikuni vacuum pump would be bad due to old age, just nature of rubbers.
I would replace the vacuum pump.
Since it is a GV – No fuel should come out of the “TANK” when tap is set to “OFF” mode. If it did, the pump will slowly drip fuel to the carbs , then eventually as you suspect, the floats will get jammed , then bike won’t start due to fuel inside cylinders (hydrolocking) , also, it might damage the crank and snap a rod or bearing failure.
I’ve seen intake rubbers go bad and they are extremely difficult to acquire nowdays.
This is assuming your bike has a “vacuum” pump – Not the “ProtoType Electric” one Hyosung was using on 1999-2004 era GV’s (They are rubbish) , Mikuni Vacuum pump would be better and it doesn’t need electrics.
Hyosung still makes 75 deg engines for 250cc for Japan only now (so far) aka GV250DR
All future 125cc vtwins are the same as the bobber 125 that has come out in 2019 , EFI and Liquid cooled.
300cc is the global replacement for 250cc , it is still 8 valves , but 125cc is 6 valves (strange) but i think they did it for cost cutting , ease of maintenance because 125cc is very popular in EU and UK , than the big sisters and I can see why have 1 central rocking arm (primitive tech) is easier than have 2 cam shafts with bearings on each cylinder like our old 125cc
I think our old 125cc was better but over-engineered!
The main reason for K&N is due to the fact 125 owners put exhausts that flow more air out, thus leaning out the bike, without upgrading the jets together and its a lifetime item than replacing the oem catridge every 5k (if you near the salty seas n sandy air or desert) though Korea says replace 125 catridges around 12k mark but K&N is foreever.
The K&N also
- Requires rejetting (more air in = more fuel in) – You will get a very minor boost on top gear, very minor. It will not increase speed on a 125
- Because the OEM catridges have a snorkel , K&N doesn’t , you will find you will hear more of your intake roarings with K&N (deeper sound)
- K&N is lifetime, if not mentioned before. Re-oil every 20k miles or so
Though as Simon says, the OEM catridges are also used in a 650cc, so they have more than enough CFM for the 125cc without crazy modding it.
However, you will get more gains by following the slide mod for your carb in thr TUTORIAL section, it costs £0 😉
ok understands everything. I have a few more questions. this is my first motorbike. I have a hard time getting into neutral. it very rarely happens Is it normal for the fuel cap to suck in? front valve cover . does it have a lot of pressure inside? when I unscrewed one screw. it took a long time for the air to come out . Is it normal ? The lid gasket was glued on with silicone. today I cleaned it and gave new gaskets and screws
- Use good quality oil like “Motul 7100” , it is very recommended. Change oil filter too.
- Check “foot rest” for wonky / loose linkages , as it makes it hard to shift
- This sounds crazy but check your rear wheel chain slack, chain too loose or tight will make it hard to shift also.
Valve Cover is sealed to keep compression inside the engine , yes 🙂 but no air must leak. Also check no oil is leaking.
Fuel Cap “hisses” sound like a snake because of pressure during heavy usage of bike or summer heat , it is the fuel cap that will make sure the bike doesn’t “lock up” fuel system or cause running problems. We call this “Fuel Cap is venting to atmosphere” , thats why sometimes a little smeal of fuel from the cap is normal , just make sure the cap looks okay and not damaged.
Hey as you are in the US, try to make a phone to WhyGoStock company , as they are a US dealer , they should have something or KR America (Real Hyosung USA) which WGS gets their stock from sometimes
The 125cc models defintely do , but for GV650 i would say most models now just drink the whole tank down to zero but you would basically keep an eye on the fuel gauge bar as it can be optimistic!
2 bars left usually means “Fill up now!” , as i have learned the hard way haha
Welcome Andrew,
You made the right choice with the GV650- Looks good, and it is a cruiser but a bit sporty
- Vtwin , but can sling shot away at full throttle if you want to!
- Big girl
- Heavy as you said, but keeps you planted on the road
- Comfy position to ride.
I have to say i haven’t been to Isle of wight , but i am all the way up north of england. However you being at the southern most of UK, you should have better sunny temps than the cold north , enjoy it while you can and the sea scenery!
Hello . I checked spark plugs. they all give the same spark. it’s not the spark’s fault.for the rear cylinder to start working. must choke to max . and I have a question if when we give choke . throttle is closed or very slightly open ? . and unfortunately . when I can make it work on both cylinders. I twist air mixture screw . nothing happens .
Now it makes sense , it sounds you definitely need the carbs removed
- Have them ultrasonic cleaned first (as it has many holes inside)
- Check to make sure pilots are size 15 each
- Set mixture to 2.5 full turns out, (Never ever touch this screw again, no matter the issues), this is close to Korea set up of 2.5 front / 2.75 rear
- Main Jets should be 87.5 front and 90 rear if bike is completely stock or 90 front or 92.5 if it has any exhaust mods (any)
- Set the slide need to rich mode
- Make sure float height is 7mm.
If in doubt, replace floats and also replace the gold float seats and float needle on the bike from a rebuild kit. It will thank you for it.
For carb jetting , slide mode , see tutorials in the “TutoriaL” section of this forum 🙂
Do not worry , keep the original carbs, nothing on the market beats genuine mikunis. And they have more than enough power for a 500cc those carbs even a small GS Suzuki 250E bike.
Right, let’s narrow this down bit by bit.
How good is the sparking ? what happens if you change front and rear coils ?
Fitted fresh CR8E plugs ? (it is to rule out plug faults too)
Keep HT caps in mind , the oem HT caps are always sketchy.And what jets (pilots and mains are inside the carb?)
I am more than happy that you managed to get rid of the taxing device. Sorry, it is what is it, electric taxati0n the bike doesn’t need
But hey, check out “KIES” Heated Apparel and get their gloves & power bank which you can wear in your pocket even while walking around, great bits of kit and plus you charge at home. No need to hack around the bike anymore and you’re all set for winter
As per simon 🙂
If you have a Side-Stand switch , please cut it , throw it high to space.
Then the wires that near the harness , join them (bypass trick) , then the bike will always think the stand switch is connected. It will then have no reason to cut out.
Sometimes the vibrations during rides will trip the switch (useless junk switch) , will tell the bike to cut sparks off as if you put a stand down while riding!
Hyosung calls this “ignition interlocking” system that involves stand switch and clutch switch and the kill switch + key ignition. Before sparks come to life.
Don’t forget to waterproof everything you do with good quality tape. (Exposed wires can be a fire hazard or rain will rust things up)
Hi again. As per your advice measured the compression it’s 12bar on each cilinder. Took of carburetor took it apart and cleaned everything. Put it back together now it starts but won’t rev up. Dies as soon as any throttle applied. Checked for vacuum leaks with brake cleaner all seems good. New spark plugs. Upgraded fuel filter from your site. Hoses not bent fuel coming through. Fuel pump has pressure when pipe removed shoot petrol out. Complete lost at this stage.
Applying revs and bike conks out and dies usually (always) means:
- Pilot Jets and Main Jets are clogged again (the holes are almost microscopic)
- See tutorial section of this site and follow every carb tuning guide to help the bike if you can.
- Fuel has gone stale
- E10 ? (if yes, drain it all and put E5 back in)
- Slides (diaphragms) for carb are jammed or sticky
- Carb needs complete disassembly , and put in an ultrasonic bath (it has many & many holes inside) it will love you for it. Trust me on that.
- Carb Floats are bent => revs applied => pilots can’t reach to draw more fuel and bike conks out & dies
Put it this way, as you allow more air in, it should smoothly rev up or we have fuel woes again and likely electric woes (entire sparking system including stator)
But electrics will be the last war
12bar ? is that on hot and as per my instructions ? How sure was the mechanic or you watched him ?
