Hyosung GT 125 R 2007 - Advice Urgently Required.

[Immoans]

So I recently purchased this Hyosung GT 125 R 2007,

The previous owner suggested I replaced the spark plugs and Oil as it had been sat for a while with little use,

Anyway I drove the bike approx 400 miles before doing so and the bike was absolutely fine, no issues what's so ever, so 2 weeks ago I got the plugs changed to Iridium Plugs, then I started to encounter an issue where I was driving along around 70-80MPH and the bike would start to lose power and slow right down, sometimes to 10MPH whilst being on a very busy A road.

It did not happen that much but enough to be a problem, so the following weekend my friend checked the carb and it was fine, so I changed the oil to this stuff: Petronas Syntium 800 EU 10W-40 Oil 5L

On the day that I changed the oil I was driving home 45 miles and half way the bike decided to slow down to 0 MPH again but this time it decided it would not go past 20MPH and has not since then.

Any idea's please? I really need my bike working so I can get to work and to see my daughter who is back in my home town.

[UnknownStuntm...]

Ok, so put the old plug back in and see how that goes? What's the numbers on the original plug and the one you swapped it with?

[Immoans]

Not too sure mate as I think we threw them away.
but we tried swapping the plugs around but did not make any difference.

[UnknownStuntm...]

Well, IMHO, if you change something and it DOESN'T work, change it back. Do not change anything else.

Having a bike that worked for 400 miles, changing the plugs, noticing a problem, then changing a carb, would seem to be 'a bit dippy'.

Check the plug is the right one for the engine. If the book doesn't say Iridum, don't put one in, no matter what the spotty fella at Halfords tells you.

Check to see if problem goes away. If not, put the original carb back on.

[Immoans]

The carb has not been changed, my friend just checked it to make sure it had no crap inside of it.

[UnknownStuntm...]

[Immoans]

Nope none mate.

[tom_e]

Check you're getting a spark and the fuel is flowing and go from there.

[Immoans]

The bike starts with no issues,

I will however mention that when trying the sparks plugs in both the heads, both spark plugs started on the front head but would not start only on the rear head.

??

[Wull]

I bought a GT125R brand new in 2007 for when I passed my cbt. Worst bike ever, heap of shite. Not much help but some rags doused in petrol, a match and blow the fucker up is the best advice I can give. Mind you shite doesn't burn.
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"Scooters are for men who want to ride motorcycles but prefer to feel the wind on their vaginas"

[Immoans]

Problem was bud, I got ran off the road on my CBR and it was wrecked, and I needed a new reliable bike, a mechanic told me they are reliable so I bought it for £700, I needed something reliable to get to work (25 miles away) and to see my daughter who is sick in hospital (50 miles away)

and now the thing won't go above 20/25mph =\

[wots]

I've said this, from personal experience with a carb'd fireblade, carbs and iridium plugs do not mix. My fireblade lasted about 20 miles before going back to the WELL USED plugs and running much better.

A well respected friend disagrees with the above, but I'm going on my experience.

They work great in modern FI bikes, don't seem to like carb'd bikes. Get some standard plugs in there ASAP and go from there.
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Currently: Yamaha DT 125 LC2,Repsol Fireblade, and Bumblebee MSX 125

[Immoans]

Ok mate I'll get him to do that for me.

Do you know if it's normal for the rear head not to start without the front ? but the front starts without the rear.

Thanks

[Rogerborg]

I have no idea what you're saying about front and rear "heads".

Don't even think of touching the carb yet.

Is it running on both cylinders? Run it as hard as it'll go, then check (carefully) if both exhaust are hot.

Get the plugs out, see what colour the tips are, and if either is wet with unburnt fuel.

The HT caps melt when they get hot, take a look at them when you get the plugs out, and check for continuity (£5 multimeter, don't just guess).

It's probably not relevant, but that oil you put in it is way too techno, and it may cause clutch slip (i.e. it revs but doesn't accelerate). The cheapest 10W40 from Tesco will be fine in that engine.

Aside, the 2006 one that I worked on ("been standing for a bit, just needs a good run") was a complete dog and a money pit. While you're looking at yours, check that the swinging arm isn't rotting out in the centre.
____________________
Biking is 1/20th as dangerous as horse riding.
GONE: HN125-8, LF-250B, GPz 305, GPZ 500S, Burgman 400 // RIDING: F650GS (800 twin), Royal Enfield Bullet Electra 500 AVL, Ninja 250R because racebike

[Immoans]

I'm not quite sure, I'll get him to check that.

He did mention he thought one of the head's was not working if that's what your referring too.

but before we changed the plugs I had no issues with the bike whatsoever.

[Rogerborg]

On the bright side, it's possible that you just have a loose plug cap after changing the plugs. But it's not something that can be diagnosed from those symptoms, you will have to get in there and test the continuity and spark on each plug.
____________________
Biking is 1/20th as dangerous as horse riding.
GONE: HN125-8, LF-250B, GPz 305, GPZ 500S, Burgman 400 // RIDING: F650GS (800 twin), Royal Enfield Bullet Electra 500 AVL, Ninja 250R because racebike

[tom_e]

Do the revs continue to rise even when it hits the brick wall at 20mph?

[Rogerborg]

[tom_e]

[andyscooter]

where did the plugs come from not an ebay copy is it
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gilera runner vxr200 (chavped)
if its spelt wrong its my fat fingers and daft auto correct on my tablet

[kgm]

Just as an aside - that looks like a car oil you used. Don't use car oil - it often contains additives that can cause clutch slip on a bike, as most bikes have 'wet' clutches unlike a car. If you are going to use car oil get a really basic one. This is probably not the cause of the problem - unless the clutch is slipping as described above.

I agree that iridium plugs are not necessary on such a bike. Get the correct plugs as dictated by the manual and swap them back. Get the plugs from somewhere reputable also.

[Nobby the Bastard]

[tom_e]

[Nobby the Bastard]

[pepperami]