Forums 🚥 PiT STOP 🔧 Hyosung Technical Help [How to Tutorial] How to Remove & Re-Install the GV125 Carby | GV250 AirBox (Alternative Guide)
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♠️ M77.
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Jul 6, 2022 at 10:23 PM #8020
Note: This is a rough copy tutorial. Removing and re-installing the airbox is a global frustration!
For Carby GV125 & GV250 Carby Models only.
In my experience, this is the best method I’ve used. (I will update this tutorial with pictures later)
- Assume you have already removed the “right-hand side air filter cover” and “left-hand coil covers”.
- Remove the metal mounting brackets for the side covers.
- Grab M6 x 20mm Stainless Steel Allen Key Bolts or M6 x 16mm (check your old bolts for carb rubber pipe inlets).
- —Take a 5 min break—
- Disconnect the choke cable and accelerator cables from the carb.
- —Put them safely to the side for now—
- Locate the front intake pipe (aka inlet, carb rubber pipe).
- Unscrew it from the engine cylinder head.
- —Pause—
- Unscrew the metal clamp holding the inlet rubber pipe to the carb mouth; leave it loose.
- —Pause—
- Remove the screws from the rubber pipe coming from the cylinder head.
- SLOWLY AND GENTLY: Slide the front intake pipe left and right so it comes out of the carb, then move it away from the engine.
- Voila! The front intake pipe is removed from under the carbs.
- Repeat the same process for the rear intake pipe.
- Slide out the rear intake pipe carefully—these are rare parts!
Now you can safely unscrew the big bolt holding the airbox to the frame and remove it easily with the carb still attached 🙂
How to fit it all back together? Do everything in reverse order 😉
For any confusion, issues, or new tricks, please comment on this topic—it may help others too!
🤍 Tips:
A. Replace the O-rings every time you remove manifolds to prevent air leaks. Always work in a clean environment as intake holes are exposed. We sell the O-rings in the shop!
B. For less stress, use stainless steel socket cap (Allen key head) bolts with a good CRV Allen key and tighten properly. Form A M6 stainless steel washers are recommended. In the UK, these are widely available at car shops including Halfords.
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Dec 18, 2022 at 12:58 PM #9252
I got them off OK, but it’s a bugger to get back on! What do you use to hold the O rings in place whilst trying to ease the intake pipes back on? I’ve never seen such an awkward job in all my motorcycling years – and I’m 76!! And of course you need to position the carb clamps so that they can be re-tightened. Hope someone can give me advice before I tear what hair I’ve got left out!!
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Dec 18, 2022 at 5:17 PM #9254
What do you use to hold the O rings in place whilst trying to ease the intake pipes back on?
Hey, this is how Korea does things and i am very convinced they put the engine and carb together in to the chassis during production but im sure they have other ways too, until i find more tricks , i will expose it!
Anyways, the manifold orings …..
- Clean the intake pipe grooves well
- Get something similar to PUTOLINE RACE GREASE
- Dress the orings in that grease (no silicone / no instant sealants / no RTV markers)
- Put the oring inside the manifold circle groove
- Find a glass table or table that is very straight.
- Place manifold (oring facing down) on table
- Hold the manifold and press down hard (but be gentle?) so that the o-ring firmly sits inside the groove.
- Hold the pressure for maybe 30 seconds.
Next
Lift the manifold, the oring should now be firmly inside , it should not fall out anymore.
Again, get a little bit of grease, apply a very small coat on the engine cylinder heads where the manifold is going to sit. Just make sure the area is clean.
Take extreme care not to let dust, or debris inside the valves as they are directly exposed in the intake holes of the engine.
Get a very short allen key, and m6 socket cap bolt ready, as soon as you fit a manifold nicely between the carb and cylinder heads = screw in 1x bolt all the way down , while your other hand is holding the carb+airbox combination. It is tricky but you will practise this and it will be easier next time you service the bike.
in my experience (no matter how good i get at this) it will always take me 1hr to put everything back to gether nicely before i start it!
first time i tried years ago , it took me 4hrs and a lot of swearing and an almost damaged intake pipe.
You will be forgiven if it takes you time, it’s okay to be patient 🙂 = After all the real enemy is the frame spar in the middle of the chassis but i guess it was the best way they can design the chassis and cram in everything it needs to function well .
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Dec 24, 2022 at 1:42 PM #9275
Thanks Marcel. I eventually got it all back together again, checked fuel to carbs, and sparking nicely, and …….no start! Not even a cough! Looks like I’ll have to take them off and start the whole process again. Very despondent. Any more advice before I do. Won’t start again now until after Christmas!
Have a good hol!
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Dec 24, 2022 at 8:08 PM #9276
Hey,
well done on putting her back together! –
I hope this is true below:- Both jets were clean (pilots)
- Starting jet is clean (the tall one inside the carb that can’t be removed)
- Main Jets are clean
- Every part in the carb was meticulously put together.
- Fuel pipes are connected and fuel tank tap is working
When you crank the bike, you will see the fuel drip inside the clear fuel filter as a hint the engine is now pulling fuel out of the tank
This also means the fuel pump is working and connected well.
Now, this should be a very easy process to start it (I hope!)
- Remove the “Air filter” on the RIGHT SIDE of the bike (That small baby air box that hangs on the right side of the bike)
Open it. - Get this product in your local car shop or bike shop, (or something similar to it)

- One you get it…
- Put your bike in neutral (make sure of it by checking the rear wheel spins free, as rarely but sometimes fake neutrals happen)
- Put your carb in FULL choke mode
Since you have 2 hands ofcourse,
- 1 hand twists the throttle & thumb presses start (twist throttle on and off as fast as you can)
- Hand #2 will be spraying “crazy” amounts of easy start in to the air abox hole (since you removed the filter)
Trust me, if your bike is sparking good, it will INSTANTLY start and scream to 4K revs.
- Now leave it on choke for 5mins screaming.
- Then slowly turn the choke off and watch the “IDLE SCREW” adjuster on the left side of the bike to make sure bike idles at 1500 rpm
The fuel should be E5 only please. No E10 fuel. (if i haven’t mentioned it elsewhere on the forum)
Once the bike is okay , get this bottle below (DO NOT BUY ANYTHING ELSE) … It must be precisely this one as i swear by it,

- Now, if you have HALF a tank of fuel. Do not add more fuel.
- Pour the WHOLE bottle of the Formula Gold above
Go for a short ride but dont be far from home yet, just go around the neighbourhood. See how it feels before venturing out far.
Now the reason for 1/2 tank + full bottle of formula gold, is more like an agressive mixture thats going to make its way down to the ;
- Tap (collect debris)
- Fuel filter (dump debris there)
- Travel to fuel pump , collect debris in the lines..
- to the carb
- Full Throttle will have the main jets & throttle slides fully open to dump any micro debris out of the exhaust while riding the bike.
If all is well, the fuel will go to low level after many miles of riding and the bike should be fully awake at this point 🙂
Oh yes before i forget, put the air filter back nicely once the bike starts from easy start.
Also use Formula gold once every 3-6 months to keep the carbs optimal and fuel system generally clean.
Fresh fuel lines and fresh filter helps a lot.
hope this digest of information helps 🙂
Have a good winter break!
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