Forums 🚥 PIT STOP 🔧 Hyosung Technical Help [Tutorial] How to swap Carb Main Jets – Hyosung GV & GT 125/250 Reply To: [Tutorial] How to swap Carb Main Jets – Hyosung GV & GT 125/250

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  • Replies: 461
Nov 30, 2017
North UK


Very good information over here!

I have a question.. how many turns, after all this mods, do you have at the pilot/air screws??

big thanks

Good question, but according to the manuals (which i agree with), is that the C/O (air fuel mix screws are usually pre-tuned at factory and must never be touch, hence they hide the gold screws with a rubber bung.

The reason for that is also the front and rear engine don’t spark at the sametime, jetting is lager on one carb , then front etc.. so “usually” with these carbs on a 125-250cc type of bike would be about 2.75 – 3.5 turns out – more or less depending on jetting on carb too.

The biggest hint = plugs will be coffee brown , that means stop there & the bike is all set.

However, most mechs don’t always know this and i can’t be surprised when ignore the service manual warnings haha.

Anyways, to put it short. The stock carbs don’t need that kind of tune. Only thing to do is uprate the jets (more fuel) = then add more air (better air filter) then its a happier bike.

“Pilot Jets” don’t need replacing as they as good as they get on the 125 twins, only “extreme” tuning would require air fuel tuning or pilot jet swapping.

Only Main Jets is what most of us all do with a K&N Filter – for a “plug n play” simple weekend!

// Meditation doesn't mean you have to sit still....

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