engine cutting out

[shooter]

Got my first bike a few weeks ago, a hyosung GT125R.

I am having problems with it cutting out at low revs/idle. This seems to happen mostly when it's warmish (starts after i've been riding about 10 minutes). If I'm approaching a junction for example, and I pull in the clutch and free wheel for a moment while changing down, the engine will cut out.

A mechanic told me it needs jetting because it has a race can on it, and that's the reason it doesn't run very well. But he wanted £400 to jet it. But a friend of mine I spoke to doesn't think this would cause the engine to cut out repeatedly.

Does anyone have any ideas of what could be wrong and how I might fix it? Or do you think it really does need jetting? I don't have £400 to spend and it's not really safe riding it in its current state.

[skatefreak]

Hey,
I would say the first port of call would be the idle needle. On the carb there will be a screw that will ajust the mixture at idle (and if the mechanic was going to charge you £400 for that then what a c*nt).

Jetting requires dropping the carb and getting the float bowl off, changing them, trying and seeing if it helps.

A set of jets shouldnt cost to much but it will take a while to go through them.

I would have thought someone on here would know what jets to try first.

Again, if its stalling at idle, i would have thought it would be the idle mixture (4 stroke right?), this can be twiddled with a screwdriver, just start up the bike, move it 1/8'th and see how it effects the idle.

Best regards

-Jvr

[Scotsman37]

Have you checked the fuel mix?

Try turning the knob left to increase the revs to the required amount as according to your manual, and hopefully that will stop it dying as the mixture maybe incorrect? Other possibility you may have partially clogged jets which maybe preventing it to idle properly!

When you bought the bike did the seller mention if it had been resting on it's side stand over the winter, then if so then the bowls on the right side of the carbs may have allowed crap in the carbs to dry up to eventually clog up the jets!

You could remove the carbs and use a can of compressed air i.e. from maplins electronics or some other store, and a compressed can of carb cleaner, but if it's still subborn and still won't budge the crap then something like an 'E' string electric guitar wire will suffice to break through crap clogging the idle/jets.

Once the carbs unit has been removed for inspection

Don't remove the head of the carbs but only the bowls itself because it's a freakin' nightmare trying to put the top part together again. Stick with the bowls as that's where your problem will be found to fix!

You may need an impact driver to turn stubborn screws, if need be!

Here's link to view a copy of the workshop manual just in case you don't have one

https://www.scribd.com/doc/16066620/Hyosung-GT125-GT250-Workshop-Manual