Forums π¦ RIDERS LOUNGE π General Chat Fuel tap for GT125 Comet
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iyGT3k.
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Mar 31, 2026 at 10:46 PM #22188Bike Model = : GT125
Getting my bike back on the road, got a plan for the existing one but I haven’t got round to sorting it.
Sadly the last time I tried to get one from Richard Hyosung even he couldn’t get one….. π
Unless one of you legends know exactly where to fit the vaccum pipe to from a gt250 tank?
It’s currently setup with that jammed open and blanked off with a shitty fuel tap on.
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Apr 1, 2026 at 9:58 AM #22201
Is it a 2003 silver frame where it uses a “frame mounted” tapΒ and the fuel tank itself has 2 holes coming out of it to feed the tap thats on the frame ?
or a newerΒ black 2005+ frame where the tank itself has its own tapΒ (no need for frame)
Feel free to upload an image of your setup now if you want to clarify ?
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Apr 1, 2026 at 2:14 PM #22205
It’s not an 03, it’s an 06 I believe 06 was the last year of that tap. Richard (who had direct sourcing with Hyosung) couldn’t get hold of it and was waiting on them coming in but obviously went bust at some point. I think the tap coming out the tank is an 07 upwards thing previously they had 2 outlets that aren’t able to be removed in any sort of way.
It’s a blue comet with a black frame, it mounts on the frame with the reserve poking out the top, the main supply is fed on the side however mine here has fallen apart it seems to be a friction fit? but I can’t for the life of me stop it leaking – I have an idea but I have to wait to get the bike back.
I’ll get pics when my bikes back, vacuum feed for the mikuni gt250 vacuum tap is blanked and forced open with a universal tap on it for now I currently only have one outlet to it (main fuel line).
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Apr 1, 2026 at 2:19 PM #22206
Is it a 2003 silver frame where it uses a βframe mountedβ 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 ?
Bikes a blue 06 with black frame, I think the fuel tap changed 07 upwards on the comets to mount to the tank. This tap has the reserve out the top with the fuel supply on the side and it’s broken apart it seems friction fit? but anyway I have a plan but I’m not sure if it will work.
When I get my bike back I’ll take pictures, the mikuni vacuum tap has been blanked off and forced open to a universal fuel tap.
I don’t think I’ll be able to find one of these sadly
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Apr 8, 2026 at 10:06 PM #22245
~My previous tank was the old old comet one, no mikuni vacuum tap just 2 outlets (one main fuel and the other serve) and vent/overflow whatever yano…
My bike is absolutely DRINKING fuel right now, high idle (I suspect my inlet boots are done) has anyone tried the china ones?
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Apr 8, 2026 at 11:05 PM #22247

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Apr 9, 2026 at 8:29 PM #22249
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
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Apr 9, 2026 at 9:41 PM #22250
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 wonβt 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 βwide openβ after engine is switched off , would suggest future problems with piston rings or hydrolocking too β The tap may have a burst diaphragm Just some of my thoughts , hope any of what i said made sense to you ? Regards
As mentioned the way it’s set up IF I removed the blank from the vacuum pipe the fuel would not exit to the fuel line as there’s nowhere to plug the pipe into on my bike lol, the “vacuum tap” is forced open to a universal tap to turn off/on which is why I asked if any of you knew where it connects to from the tank.
^Just to further touch on this, mine does not have the vacuum to the tank as default, it wasn’t there to begin with as it had the manual tap mounted to the frame….. Obviously I know this is not ideal however how it’s set up now is as close to the original tank as I could get it in the moment (and really overall? without knowing where the vacuum pipe connects to). It being blanked off isn’t an issue since I control on/off with a universal tap so the vacuum right now is not needed at all. It’s set up as it should/can be right now when comparing it to the original tank).
Yeah the originals are as rare as the petcock I can’t find thus I have no option (all of us are in the same boat ey π― ).
The fuel tap is DEFINATLEY NOTΒ wide open, my bike is surging when idling to around 3 to 4k and no adjustment on the idle screw will fix this, it does sometimes temporarily however it starts again on my next stop more often than not (I’m pretty sure it’s a vacuum leak).
I know the fuel tap isΒ definitely off when I switch it off, I sometimes would forget the tap previously and the fuel would sit on one or both pistons and hyrodlock and I havent experienced this with my current set up at all. I’ve persisted through fuel leaks to get to this point at the tap however I have fixed this by ordering a bigger tap as the fittings on the ones I ordered clearly weren’t the mm they said they were.
I’ve owned this bike since 2012 I’m not new to any of this hah, are baz and sim not around anymore? Are you still in touch with James (BD – cillit banged an engine if you remember)?
Anyway yeah it does make sense but I think you may have skimmed over what I originally put.
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Apr 9, 2026 at 9:43 PM #22251
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 wonβt 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 βwide openβ after engine is switched off , would suggest future problems with piston rings or hydrolocking too β The tap may have a burst diaphragm Just some of my thoughts , hope any of what i said made sense to you ? Regards
As mentioned the way itβs set up IF I removed the blank from the vacuum pipe the fuel would not exit to the fuel line as thereβs nowhere to plug the pipe into on my bike lol, the βvacuum tapβ is forced openΒ to a universal tap to turn off/on which is why I asked if any of you knew where it connects to from the tank.
^Just to further touch on this, mine <does not have the vacuum to the tank as default, it wasnβt there to begin with as it had the manual tap mounted to the frameβ¦.. Obviously I know this is not ideal however how itβs set up now is as close to the original tank as I could get it in the moment (and really overall? without knowing where the vacuum pipe connects to). It being blanked off isnβt an issue since I control on/off with a universal tap so the vacuum right now is not needed at all. Itβs set up as it should/can be right now when comparing it to the original tank).
Yeah the originals are as rare as the petcock I canβt find thus I have no option (all of us are in the same boat ey π― ).
The fuel tap is DEFINATLEY NOTΒ wide open, my bike is surging when idling to around 3 to 4k and no adjustment on the idle screw will fix this, it does sometimes temporarily however it starts again on my next stop more often than not (Iβm pretty sure itβs a vacuum leak).
I know the fuel tap is definitely off when I switch it off, I sometimes would forget the tap previously and the fuel would sit on one or both pistons and hyrodlock and I havent experienced this with my current set up at all. Iβve persisted through fuel leaks to get to this point at the tap however I have fixed this by ordering a bigger tap as the fittings on the ones I ordered clearly werenβt the mm they said they were.
Iβve owned this bike since 2012 Iβm not new to any of this hah, are baz and sim not around anymore? Are you still in touch with James (BD β cillit banged an engine if you remember)?
Anyway yeah it does make sense but I think you may have skimmed over what I originally put.
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Apr 9, 2026 at 10:04 PM #22252
Would be cool if any of you ukhyo lads are around still but I doubt it π hmu if you are.
Also Paul if you are around here and you use the garage at Odsal PLEASE MESSAGE ME! Name your price.
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Apr 12, 2026 at 12:15 PM #22268
Hi, no worries if you owned the bike since 2012, so definitely not a novice at this π 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.
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Apr 12, 2026 at 6:39 PM #22274
Nah mate, thankfully I had lots of spares so I got it back on the road pretty sharpish – I have the inlets coming from the CHINA hopefully they’ll be reet.
I honestly don’t think it’s worth buying that tap… I’ve had it watched for a bit and it just looks as bad as my old one tbh.
With this being a 250 tank it has no reserve anyway (caught me out!) I did have another issue where the filler cap just wasn’t a nice fit (but it was the original, I think the bike it came off was an 05) I’ll get round to lining the tank at some point….I have an old one on there and it seems to run just a little bit better (found another fuel leak today that’s all sorted).
I’m not quite sure what’s going on with my old tank, I believe there’s a vacuum pipe going to the pump so I don’t think that’s my issue but my rubber inlets are really really bad so I guess it’s that and the seals.
Just to note: I think the tank it had on before was from an 03, the colour was way off and it’s not down to fading (it’s the lighter blue hyosung did not the dark that the rest of my bike is) and it has the classic numbers written in yellow under the bottom so I think at some point it came from a breaker before I got it.
If anyone is in need of anything please hmu, I may have what you need π
Hyosung Paul – If you ever see this please for the love of god make me a pair, I’ll pay whatever it costs (well, within reason haha).
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Apr 12, 2026 at 7:38 PM #22275
Found the one you were on about, got it and ill just blank off the reserve, I thought you meant that absolutely shagged one haha!
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Apr 13, 2026 at 12:52 AM #22292
How come I can’t post in the pic forums? I have no images enabled and it errors with:
- Error: forum ID is missing.
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