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gv250

Fuel System Problems and Question about GV250

Hi all,

My girlfriend just picked up a 2007 GV250. We knew when we bought the bike that there was an issue where when you twist the throttle, it dies. It was too good of a deal to pass up on, so we decided to give it a try as her first bike.

When we got it home and started working on it, I figured it would be a fuelling issue, so we took the tank off, and there only appears to be one carburetor. Everything I saw online for these bikes showed that there should be 2 carbs, so I’m wondering if that was a factory thing on some of those bikes, or if someone has swapped this in since. If anyone happens to have any diagrams showing a single carb, that would be much appreciated.

The issue with it running does appear to be fuel related, as I did get it revving slightly by playing with the throttle adjustment on the carb, but it still does sometimes die, and when I do get it running sometimes it won’t idle now. Also when it is sitting not running, there is sometimes fuel leaking out of the intake side of the carburetor.

If anyone has any advice on what to try to make this work properly, I would really appreciate it.

Thank you in advance!

Kevin

GT250 EFI DSpec Stalls at Idle after Warm Up

I own the above mentioned bike bought second hand from the original owner who had purchased it in 2013. When I bought it, it was still under warranty with about 3000km on the clock. It is important to note that this version, the DSpec, has some minor differences in the number of sensors than similar GT250’s of that period. It is a twin cylinder equipped with Delphi electronics. The bike, which is always garaged, worked flawlessly for the first couple of years but after that it had started to loose power erratically after warm up. This was happening after about 15mins of starting from cold. From time to time I was also getting error code 132 intermittently which indicated problems on cylinder one. When the O2 sensor was inspected it was found to be covered in soot. Because of this I had assumed that the problem was limited to around cylinder 1. I replaced the plugs and high voltage cables and also swapped the coils and the O2 sensors around but the problem did not seem to change or move. I also had the injectors cleaned up by an experienced bike mechanic. I was also lucky to find a nearly new ECU which I could purchase at half price, but even this did not improve the situation.

Finally I decided to replace the coils which solved the problem completely.

Unfortunately a few more years down the line I am starting to experience a similar, though not so drastic situation so far with the bike starting perfectly but after warm up it starts missing occasionally at idle and if I stay at idle long enough the engine stalls. I don’t feel any loss in power when I am revved up.

Because of this I am starting to suspect the coils again even though these are no more than 3 years old.

Any ideas?

Regards

Adventures With Rosie

Hi

Well the following nonsense is coming out of something Marcel said last week “You could post a forum journal on the front page, incase we make threaded replies to follow your outings or garage workings”.  I can’t see where or how I do that exactly – hey I’m 62 years old, we didn’t have social media in the seventies, no internet, just great music and lots of fun, so if Marcel wants to move my bloggy blatherings somewhere more appropriate he is very welcome to do so.

So this is Rosie, my 2016 GV250 EFi, that had just 2,785 on the clock when I bought her 17th December last year, and is now showing 3,190 so she’s done 3 times the mileage in the last three months than she did on the previous 3 years.  And you know, I think she rather likes it.

A little more bling

As with any new girlfriend you have to start spending money on presents, so the boring black air filter covers have been replaced with chrome and, more practically, a centre stand has been fitted.  I was pleasantly surprised that the 5 minute job as demonstrated on YouTube (see https://www.youtube.com/watch?v=jzljlX9CyHI ) took just that although my garage floor was a lot more cramped, and very much colder, than lucky old Two Wheel Exploits in Melbourne. With shipping the stand cost about £70* from South Korea, and I’ve seen these on eBay for £115 – £125 so I’m happy with the deal.

I think I’ll probably recoup that cost the first time I do my own oil change, plus I can fill the tank on the level without risking a crotch full of Ethanol.

Next bit of bling was replacements for the missing front fork top covers.  Now it annoyed me that I hadn’t noticed that these were missing when I inspected the bike, the headlamp has been replaced with a unit held on by two clamps attached to the fork tubes.  Now these clamps are either stopping the front forks from working, or are scratching the tubes any time the forks depress, and they are certainly stopping the refitting of the chrome covers.


Front forks with the offending headlamp brackets

So when it became apparent that the headlamp couldn’t be refitted with these clamps gripping the fork covers rather than the forks an order had to go back to South Korea for a proper headlamp mounting unit, which fits into the lower fork brace.  Oh, and a new headlamp housing to fit on the mounting.  What’s the betting I then need a replacement headlamp lamp unit to fit in the housing that goes on the mounting?
“And the foot bone’s connected to the leg bone.
The leg bone’s connected to the knee bone.
The knee bone’s connected to the thigh bone.
An’ that’s the word of the Lawd.”

Just in case anyone’s thinking “you’re wasting money on bling!  What about brake pads and tyres and…??” rest assured they have all been checked and are perfectly in order for a bike with just 3,000 miles on the clock.

BTW: If anyone knows of a really cool looking and powerful LED headlight unit that fits into the standard GV250 EFi 7.6″ headlamp housing, then I’d be much obliged.

Once these geegaws have been fitted that will probably be it for bling.  For a while.  Although I’d love to fit a lamp rack with a pair of fog lights.  And of course I do need some saddle bags for the gear I have to tote too and from the office.

Meanwhile I’ve been trying out my ‘A’ roads route to Northampton that misses out the M1.  Although hampered by a light spot of rain I had a very enjoyable blast along the A6 today that certainly exceeded 60mph and may have reached the dizzy figure of 70+mph.  Rosie certainly seemed to be enjoying herself.

Why have I called her ‘Rosie‘.  That’s in honour of Bon Scott, Malcolm Young and of course surviving brother Angus, who on the 16th May 1978 blew my ears off with one of the loudest sets I ever heard.  Like I say, we had a pretty good time in the seventies.  For a 250cc bike there’s a ‘Whole Lotta Rosie’, and she’s quite a ride.  Although at 27 stones she’s a bit heavier than the original
“Doin’ all the things
Doin’ all the things you do
Ain’t no fairy story
Ain’t no skin and bones
But you give it all you got
Weighin’ in at nineteen stone”

‘ave a gud ‘un
Zigger Zag

GV250 Chrome Front Fork Covers (Upper)

Hi

Does anyone know whether there were any changes to the Upper Front Fork Covers (Current Part #51881HJ8200) for the GV250 over the years?  I have a 2016 registered GV250 EFi Aquila with missing upper fork covers (only noticed it last night after delivery – Doh!).  There’s a good looking pair from a breaker not far from me noted as from a GV250 Aquila 2001.  Does anyone know if there was a change in the part design over that time?  Admitted, 15 years is a long time frame, but it looks as though there’s no change in this cosmetic feature on all the pictures I can see.

Many thanks
ZZ

 

2003 hyosung gv250 carb model – idles ok but wont go

Hello guys, i have a problem with my 2003 gv250 carb model, its having trouble revving. While stationary it idles well, and can take slow rev ups, however when i pull the throttle quickly the engine turns off. I tried letting it warm up a bit but it made no difference. When i try to move into gear it instantly turns off. The modifications ive made are iridium spark plugs cr8eIX, after i changed the plugs the bike worked well except for a little loss of power for a second at about 7k revs, later i changed to these ht leads (https://hyoriders.club/shop/gt125-gt125r/hyosung-spark-plug-cap-cover-gtr-gt-gv/) which is when the no go problem really became a problem. Has anyone encountered a anything similar? Or can maybe guide on how i can fix this?

[How to Tutorial] How to Change Oil & Oil Filter on Hyosung GV125 GV250 GT GT250R GT125R

Time for an oil change? …One of the crucial things to stay on top of!

This short tutorial shows you how to change your oil with ease on the 125/250 twins (2001-2018) and also the filter!

This applies to: GV125 (01-2018) / GV250 (upto 2018) / GT & GTR 125 (03-2018) including GT250+R.

Personally, one of my other twins gets its oil changed every 1,000-1500 miles using Ester oils. Manual suggests longer intervals, but I prefer premium oil (JASO MA2, Ester good) every 1500 miles max. 🏍️

Moving on, let’s prepare the parts & tools first…

Oil – 2x 1L Bottles
(Bike needs 1.5L total)		 Oil Filter & O-Rings
(don’t skip filters!)		 Drain Pan/Bucket
(3L+ capacity)
Torque Wrench
(too crucial, you’ll see why below ⏬)		 Size 15/17mm Socket
(12 sided, NO SPANNER)		 Size 10mm Socket / Driver

Plus these bits also: Pliers | Funnel | Gloves | Clean rags | Measuring jug

1. Undo your filler cap first!

For stock caps, use pliers (anti-clockwise). For custom CNC Caps, use 19/21mm socket.

2. Go under engine & loosen the drain plug

For GTR owners, use a bar extension or remove fairings. ⚠ Be slow to prevent the plug falling into the bucket!

3. About those drain plugs…

Roads are salty; stock plugs can seize. Use a coloured, weather-resistant magnetic plug to avoid issues. Available here.

4. Finished draining? Close the drain-hole!

Clean under the engine, use torque wrench max 15ft lbs. ⛔ DO NOT OVERTIGHTEN THIS BOLT.


5. Go to your oil filter cover next!

Undo the 3 nuts holding the cover. ⚠ Oil WILL fall out; place a rag/pan underneath. Wear gloves. Dispose old filter.


6. Filter Cover Inspection & O-Ring Change (Pt.1)

Clean the cover, check spring, replace big O-ring (dress in oil first ⛔).


7. O-Ring Change (Part2)

Replace the O-ring at the back inside the filter area. ⚠ Use a small hook, don’t force. CHANGE THE OLD O-RING TO A FRESH ONE.

8. Next, your new oil filter goes in!

Ensure the hole of the filter goes inside the engine as shown.

9. Close the filter cover!

Tighten nuts to 6 ft lbs max. 🚦 Ensure the cover O-ring is oiled.

10. Done? Grab your oil (& measuring jug!)

Pour 1.5L (1500ml). Not less, not more 😉 No jug? Use bottle markers.

11. Get your Funnel and pour the oil in…

12. Close the oil filler cap!

Ensure cap and O-ring are clean and undamaged.

🚦 Complete – Idle for 60 seconds & turn off!

Check sight glass, top-up if needed, and ensure drain plug is secure.

Tidy up & Go ride. 🏁

Questions? Fire away in the comments! 🤺

[How to Tutorial] Adjust Carb Slide Needle (Tuning) Hyosung GV250 GV125 GT GT125R GT250R

[Tutorial] How to adjust Carb Slide Needle (Tuning) - Hyosung GV & GT 125/250
How to adjust/tune the carburettor slide needle for improved riding…

⚙ What does this do?

This modification allows the bike to reach better cruising speeds via slide needle adjustments. The throttle slide needle controls main jet fuelling as revs change. This also eliminates flat spots between 4k–7k rpm, common on 125s. For example, if the bike struggles at near full throttle, this mod helps it pull with less twist. Your bike should run better from 1st to 5th gear.

👇 Before we start, this tutorial assumes:

  • You will do this at your own risk and without rushing.
  • You have good spark plugs (e.g., Platinums) or older IX plugs.
  • Your ignition coils & HT caps are sparking well.
  • Your carb has already been upjetted (tap here…).
  • You have a performance filter (K&N, BMC, etc.), or if using a stock cotton one, cut its snorkel.

Tools needed:

  • JIS type screwdriver (+ Philips style)
  • Large & long flat head screwdriver
  • Size 7mm socket (front bolts sometimes hex shaped)
  • Watchmaker flat screwdriver
  • Clean microfibre cloth

1. Go to the right side of your bike

Spend most of your time here. Work on one pot at a time and avoid distractions.

2. Unscrew the 1st diaphragm cover

Remove the 4 bolts holding the diaphragm cover.

⚠ Disconnect throttle cable!


3. Remove the spring & diaphragm

Gently remove piston slide & spring.

4. Inspect & clean parts carefully

Use Wynns Carb Cleaner for all parts including diaphragm cover. This prevents sticking between revs/gears & scoring internal carb walls.

5. Unscrew plastic plug holding needle

Use long flat blade screwdriver, gentle ⚠.


6. Remember the order of re-fitting

Keep the image in mind when refitting small parts.

7. Remove the E-Ring (Circlip) slowly

Use a small watchmaker screwdriver. ⚠ Handle gently.


8A. Needle grooves

  • Pointy end of needle faces down
  • Push down black spacer slightly
  • Put E-Ring in 3rd groove
  • Push black spacer back against E-Ring


8B. Another view

Ensure E-Ring is in 3rd notch with black spacer pushed back. (Lowest groove, pointy end down. Factory usually 2nd or top near flat end.)

9A. Check throttle slide hole

9B. Grab needle & follow image

9C. Slot needle & mini-spring

⚠ Review step #6 and 9A/B

10. Check needle for free movement

10B. Coat throttle slide ring with oil

Prevents leaks & particle trapping.


11. Refit slide, spring & cover
  • Reconnect throttle cable
  • Ensure 4 screws are finger tight
  • Finished? Move to next cover.

12. Repeat on rear carb

13. Final check 🏁

  • Airbox clamps tight
  • Slide cover bolts finger tight (x8)
  • Throttle & choke cables checked
  • Air lines secure (prevent vacuum leaks)

Done!

Straightforward process. If unsure, comment. Otherwise, go ride! 🏁

FAQ / Troubleshooting 🎳
  • Bike runs worse after mod? Check covers & airbox for leaks.
  • No air leaks but still worse? Inspect spark plugs; ensure better sparking than stock.
  • New plugs but still worse? Check HT Cap & ignition coils. HT Cap removed ≈ 6kΩ; Coil ≤6kΩ to frame.
  • HT cap/coils high resistance? Replace both; stock ignition parts can’t be repaired.
  • Changed coils/HT caps but still worse? Ensure main & pilot jets are clean. Tap here to remove carbs.
  • Can this be done on stock 125cc? Mod will slightly enrich mid-range; jetting & better electrics improve results.

💡 Tips:

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!

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.

FI light on! GV250

HELP!

The FI light on my GV250 Comes on as usual with the ignition, but stays on even when the engine is running.

The EFi manual talks about a “Flash Code” but the lamp is just “On” no flashing!

Is there an on board diagnosis socket anywhere?

Any ideas how to reset the ECU?

Any help or suggestions welcome.

David.

[How to Tutorial] Change Vacuum Lines on Hyosung GT125R GT250R & GT Comet (Air Hose Diagram)

Hyosung vacuum line setup

Changing the vacuum lines on carburetor 125/250 vTwins should be fairly easy. All you need is 15–30 mins of your time. Let’s start with the basics.

  • Hyosung advises that if your factory lines are 2–4 years old, discard them regardless.
  • Old pipes can rot internally, especially cheap Chinese rubber ones.
  • Larger, colder air pipes can improve the vacuum system, but use strong clips!
  • Strong clips are essential to prevent air leaks.
  • This tutorial applies to all carb-operated 125/250 GT & GTR Twins (including GV125)

Let’s go now… strip your fairings (GTR owners)

(Naked bikes can skip this step)
hyosung gt125r air vacuum line gt250 gv125

Diagram of how the “AIR LINE” system should be connected:

Study the diagram images below first before moving on.

hyosung gt125r air vacuum line gt250 gv125
hyosung gt125r air vacuum line gt250 gv125
hyosung gt125r air vacuum line gt250 gv125

VACUUM LINE #1 = CONNECT THE REAR FUEL PUMP FIRST

Got your lines ready? On the LEFT side of your bike, grab a hose for the fuel pump and follow the diagram below:

hyosung gt125r air vacuum line gt250 gv125
hyosung gt125r air vacuum line gt250 gv125
hyosung gt125r air vacuum line gt250 gv125

VACUUM LINE #2 = CONNECT YOUR FUEL TANK TAP

  • Once the rear fuel pump is connected from the left side, move to the RIGHT side of your bike.
  • Grab a second vacuum pipe and follow the diagrams below:

hyosung gt125r air vacuum line gt250 gv125
hyosung gt125r air vacuum line gt250 gv125
hyosung gt125r air vacuum line gt250 gv125

That’s it – Vacuum setup is done! 🚦

If you have an AIS device (Fake emissions/EGR), see below:

  • Refer to the cartoon diagram of the “EGR DELETE” mod.
  • Remove or block anything feeding it.
  • Example image below shows setup. Personally, it’s a useless device.
  • If you want it connected, replace “blocked” with “connected”.

EGR delete vacuum line

Alright, we are done. Go test ride! 🏁

test ride hyosung

I hope this quick tutorial was easy to follow. If you get stuck or need help, just comment on this post! This also applies to GV owners since they use the same rear pump.

[How to Tutorial] How to Swap Upgrade Carb Main Jets Hyosung GT GT125R GV250 GV125 GT250R

Hyosung Carb 250 125 GT GV Pilot Jets Main Jet

How to Swap Carb Main Jets on Hyosung 125/250cc V-Twins

Carb Main Jets are one of the most common upgrades on these 125/250 carby twins. This tutorial will show you how to swap carb main jets the easy way. #SwapNGo!

Important: If your bike is under warranty, check with your dealer before doing this. Doing this may void warranty on new bikes.

Anyway, let’s cut to the chase!

0. Tools Required:
  • Large Mole Grips (& small one too)
  • Philips (+) Star screwdriver – Regular Length
  • Philips (+) Star screwdriver – Stubby Length
  • Small amount of cooking oil
  • Hex Bits (& screwdriver Bit) (if you have stainless bolts on the carbs)
  • 10 or 12mm Spanner or Socket Tool
  • Flat-Head (-) screwdriver
1. Remove Side Panels & Fairings

Unscrew the bolts holding the side-panels, then take off your fairings.

Owners of Naked Bikes: Skip to #2.

Tip for GTR Owners: Place a rug under the bike. When fairings drop as one piece (left/right side panels + middle engine fairing), carefully push one side under the bike to remove safely.

2. Remove the Fuel Tank
  • Unscrew #10 (fuel tank bolt) and lift tank slightly to see fuel pipes
  • Disconnect the fuel pipe safely (marked in red circle in pictures)
  • Disconnect the small vacuum-air hose attached to the tap
  • Remove the tank from the frame. Watch out for small rubber parts that may fall out

Hyosung Tank Removal

3. Loosen Airbox Clamps

On the left side under the airbox, use a stubby screwdriver to unscrew the 2 clamps on each carb.

Loosen Airbox Clamps

4. Remove Airbox

Take airbox off and put aside. Remember the 2 bolts holding it to the frame!

Remove Airbox

5. Exposed Bike View

Bike Exposed View

6. Loosen Rubber Intake Clamps

Unscrew the clamps holding the carburetors down.

Loosen Intake Clamps

7. Lift Carbs Slightly

Leave cables & pipes connected. Fuel will be drained next.

Lift Carbs Slightly

8. Drain Fuel Safely
Do this in a ventilated area or outdoors! Fuel vapors are flammable.
  • Unscrew 2 bolts halfway (marked in red)
  • Catch dripping fuel in a bowl

Drain Fuel

9. Remove Idle Screw Adjuster

Unscrew the steel bolt holding the idle screw (left side of engine).

Idle Screw Adjuster

10. Remove Float Bowls

Remove 8 screws holding float bowls. Some may be tight; use force carefully.

Remove Float Bowls

11. Use Mole Grips if Needed

Bite bolt heads carefully if screws are stuck, then remove completely.

Use Mole Grips

12. Swap Main Jets

Install upgraded jets: one size up front & rear, depending on model.

Swap Main Jets

Stock Carb Jet Info:

  • GT125 / GT125R & RC = 87.5 Front, 90 Rear
  • GT250 / GT250R = 92.5 Front, 95 Rear
  • GV125 Aquila = 87.5 Front & Rear
  • GV250 Aquila = 90 Front, 87.5 Rear

Pilot jets remain stock: 125cc = 15, 250cc = 20

13. Install Upgraded Jets

GT125/125R = 90 Front, 92.5 Rear
GT250/250R = 95 Front, 97.5 Rear
Aquila 125/250 = One size up each

Install Upgraded Jets

14. Double-Check Jets

Ensure brass jets are snug but not over-tightened. Clean tiny holes with carb cleaner.

Double-Check Jets

15. Oil the Gaskets

Use small amount of cooking or motor oil on your fingers to coat gaskets.

Oil Gaskets

16. Reassemble Bike

Reverse steps #12 → #1. Double-check all screws & clamps.

17. Final Outcome

Final Result
Final Result 2

18. Reinstall Fuel Tank & Pipes

Check all clamps, throttle, choke line, fuel drain cable, and idle screw.

Reinstall Fuel Tank

19. Start Bike

If it doesn’t start immediately, use choke, twist throttle a few times, crank 5-7 seconds. Use Bradex Easy Start if necessary.

20. Troubleshooting
  • Fuel may take a few seconds to reach carbs
  • Use choke lever fully if needed
  • Crank while twisting throttle 5-7 seconds
  • Let idle for few mins to burn off excess fuel
21. Done! 🏁

You should be ready to ride. If you have questions or feedback, reply below!

[How to Tutorial] Clutch Plates Upgrade Replacement for Hyosung GT GV125 GT250R GT125R GV250

Learn how to change Hyosung GV/GT 125 & 250 Clutch Plates on the GV125 / 250 Engines (GT/GV)

💥 NOTE! – SOAK YOUR CLUTCH PLATES IN OIL FOR 24HRS BEFORE DOING THIS! 💥

🛠 Tools Needed

Size 8-10 “O-Spanner” Stubby Flat Screwdriver Allen Keys (if needed)
Oil Drain Pan Size 15/17/19 Sockets Pliers or MoleGrips
Rags Time Patience

Optional 19mm socket/spanner for CNC Magnetic Oil Filler Cap

🎁 Parts Replaced

Clutch Plates (fibre) Clutch Bearing Steel Clutch Discs
Oil (1.5L) JASO MA2 Grade Oil Filter & O-Rings

💪 Skill Level = Anyone can do it, but if unsure, speak to a mechanic. (Follow this guide at your own risk)

HYOSUNG GV 125 250 CLUTCH PLATES uk hysoung FORUM OWNERS CLUB

⚠ Symptoms / Troubleshooting Hints

Always replace your clutch plates when you notice the following:

  • Every 5000-6000 miles. Regardless (just like brake pads have a wear limit!)
  • When you find yourself adjusting the clutch cable frequently.
  • When gears feel notchy or hard to shift.
  • When the bike slips during gear changes.
  • Does your clutch basket “knock” during idle?
  • Does the bike “rumble” when holding the clutch lever in?
  • Acceleration is slower than before.
  • Clutch seems to “slip” on hard acceleration.

🔧 Let’s fix it….

Technical Inspection (What to look for inside)

HYOSUNG GV 125 250 CLUTCH PLATES uk hysoung FORUM OWNERS CLUB

  • Clutch Plate Thickness Limit = 2.6mm (New ones range from 3-4mm)
  • Clutch Spring Free Length Limit = 36.2mm (Normal range 3.8 to 4.6mm)
  • Deep grooves on the clutch basket? Time to replace entirely, or file gently if minimal wear.
  • Silver clutch metal discs (separators) – 1mm distortion limit.
  • Loud rattling sounds? Your clutch plates may be cracked and must be replaced immediately to avoid blocking oil passages.
  • Clutch basket center nut must remain tight with its washer intact.

🚦 Let’s begin!!!

HYOSUNG GV 125 250 CLUTCH PLATES uk hysoung FORUM OWNERS CLUB

Park your bike, get your tools out, and start with the drain pan to drain oil first…

HYOSUNG GV 125 250 CLUTCH PLATES uk hysoung FORUM OWNERS CLUB

  1. Use either 15mm, 17mm, or 19mm socket to drain the oil:
    • A. Clean the oil drain plug.
    • B. Drain all the oil completely.
    • C. Refit the plug.
    • D. Tighten to a maximum of 15 ft.lbs (20 N.M) – torque wrench recommended. If unavailable, tighten until it feels snug.
🔥 BE WARNED! – THIS IS THE “DRAIN” PLUG (DO NOT UNDO ANYTHING ELSE UNDER THE BIKE)

Drain plug warning

Ready? Get the new clutch plates and discs out…

New clutch plates ready

Remove the engine cover bolts in the blue circles. Remember where each bolt goes! Some bolts vary in size. 🔥 Be warned: leftover oil will spill out!

Oil filter warning

When you reach the oil filter rod, carefully remove it:

  1. Put two nuts on top of each other.
  2. Undo the second nut (the top one acts as a stopper).
  3. Continue unscrewing until the rod comes out entirely.

⚠ Note: Mole grips can be used with caution but may scratch the rod.

O-Rings warning

Don’t lose the O-Rings! There are 2: one for the cap, one inside the oil filter hole. Always replace O-rings & filter during oil or clutch work.

Clutch cover removal

Use a stubby screwdriver to gently loosen the clutch cover, working from the bottom and then top near the oil cooler pipes. Carefully remove the cover.

Gasket warning

🔥 NOTE: The gasket must be replaced with a new one. Old gaskets may tear.

Remove clutch bolts

Remove clutch bolts from top down gradually (25% each), then fully remove. This protects the clutch springs.

Inspect clutch hub

  • Remove the front clutch hub facia plate and inspect underlying parts.

Diagram

Inspect parts #10, #16, #17, #13 on the diagram.

Remove plates

Remove clutch plates one by one, remembering the order: First and last plates are always fibre. Steel discs go in between.

Plate order diagram

Fit back parts in this order: #13 → 17 → 16 → 9 → 10

Tightening sequence

Re-tighten clutch bolts: Start top 25%, then bottom left & right 25%, then remaining bolts to full torque. Max torque for clutch bolts = 5 ft.lbs (finger tight!).

Final steps

  • Max torque for clutch engine cover bolts: 5.5 ft.lbs (aluminium)
  • Use fresh oil, O-rings, filter, and gasket
  • Record this event in a log or back of owner’s manual to track mileage and service history

👍 Recommendation: Use high-quality 10W40 or 10W50 JASO MA2 ester oil. Avoid low-quality brands; Motul & Silkolene are best.

🏍 Ride Safe! Any questions? Leave a comment below!

[Download] GV125 & GV250 Aquila / Mirage – Service Manuals & Hyosung Owners Books

Hyosung GV125 & GV250 Aquila (Mirage) Resources

The Hyosung GV125 and GV250 Aquila (also known as the Mirage in Korea) are the backbone of the Hyosung cruiser lineup. As the first 125cc V-twin cruiser to hit the global market, these bikes have earned a massive following. Below, you will find the essential PDF owners’ books and workshop data to keep these classic cruisers on the road.

Cruiser Specifications & Engine Data

The GV series shares its 75° V-twin DOHC engine architecture with the GT125/250 sportbikes, meaning many internal components and torque settings are identical. However, the GV features a unique cruiser chassis, longer wheelbase, and classic aesthetics.

  • GV125 Carb: 124.5cc V-Twin, DOHC 8-Valve, Mikuni Carburettors.
  • GV250 Carb/EFI: 249cc V-Twin, 28hp (EFI versions) or 26hp (Carby).
  • Drive: 5-Speed gearbox with chain final drive.
  • Maintenance: Shared engine parts with the GT series Comet/GTR.

For more details, check our GV125 Carb Wiki or the GV250 (Carb/EFI) Gallery.


⬇ OWNER’S MANUAL – GV250 (Carby / 125cc compatible)

⬇ OWNER’S MANUAL – GV125 [First Gen 1998-2001]

⬇ OWNER’S MANUAL – GV125C [2002 Model Only]

Pro Tip: If you are looking for the GV250 EFI Service Manual, please head over to our GT/GV EFI Manual Topic. For troubleshooting assistance, post in the Parts Help section!

[How to Tutorial] [Bike Mod] GV250 GV125 GV125C Rear Luggage Rack Mod Upgrade

Hyosung GV250 & GV125C Custom Rear Luggage Rack Upgrade

Finding a high-quality, durable rear luggage rack for the Hyosung GV250 Aquila or GV125C can be a challenge. While factory options are often scarce or expensive, many riders opt for a custom DIY approach to increase their bike’s carrying capacity. Whether you are planning a long-distance touring trip or just need a secure spot for your daily commute gear, a solid rack is an essential cruiser upgrade.

This tutorial demonstrates how a few well-chosen pieces of metal and standard garage tools can be used to fabricate a professional-grade luggage solution. By following this guide, you can create a custom mount that integrates perfectly with the existing lines of the GV-series frame, providing a stable platform for top boxes, tail bags, or strapped-down panniers.

Benefits of a Custom Fabricated Luggage Rack

Building your own rack allows for specific customisation that “universal” aftermarket kits often lack. You can ensure the weight distribution is centered over the rear axle and choose materials that offer the best balance between weight and structural integrity. For those who enjoy metalwork, this project is a rewarding way to improve the utility of your 125cc or 250cc Hyosung v-twin.

Note: We would like to give a huge shout-out to the original author of this tutorial for sharing their engineering expertise with the HyoRiders community. Please follow the instructions carefully to ensure your rack is safe for road use. Download the comprehensive PDF book below.

Safety Disclaimer: Regularly inspect your mounting bolts for vibrations and wear, especially after long rides with heavy loads.

[How to Tutorial] [Bike Mod] GV250 GV125 GV125C H-D Aftermarket Pillion Backrest

Custom Hyosung GV250 & GV125C: Harley-Davidson Pillion Backrest Mod

Are you looking to improve the passenger comfort on your Hyosung GV250 Aquila or GV125C? One of the most popular styling and comfort upgrades for these cruisers is the addition of a sissy bar or pillion backrest. While official Hyosung accessories can be hard to source, this DIY tutorial explores how to adapt Harley-Davidson aftermarket parts to fit the GV-series frame.

This specific modification focuses on using just two main brackets. For the fabricators and CNC hobbyists in our community, this is an excellent opportunity to create custom metal sheets that bridge the gap between the Hyosung fender rails and standard H-D backrest mounting points. By using high-quality steel or alloy, you can achieve a “factory look” for a fraction of the price of OEM parts.

Why use Harley-Davidson aftermarket parts?

The aftermarket support for Harley models is vast, offering various heights, pad styles, and finishes (chrome or matte black). By following this guide, Hyosung riders can tap into that market to give their 125cc or 250cc cruiser a unique, custom look while ensuring their passenger feels secure during longer rides. Whether you are building a “bobber” style or a full touring rig, this mod is a great starting point.

Disclaimer: This tutorial was contributed by a community member. HyoRiders does not take responsibility for any structural modifications made to your motorcycle. Always ensure your bolts are torqued correctly and use thread-locker where necessary. Download the full technical PDF guide below for step-by-step instructions.

Note: If you have successfully completed this mod, please share your photos in the main forum gallery to help other riders with their builds!