• Topics: 38
  • Replies: 447
Nov 30, 2017
North UK


Carbs hence i left it as last haha. There is some discussion about this too on the FB group too.

The service manual actually forbids workshops or dealers from tinkering the air mix screw.

Hyosung never revealed how to mess the air screws simply because it would be the abyss to get it right again!

(Lots of plug chopping & re tuning)

If the carb was lean all he had to do was increase main jet 1 size up.

90 n 92.5  so bike is less lean more rich without messing the air screw.

Stock is 87.5 n 90

Dark brown is good!   Should be lighter brown all round , suggests to me that you may need more air (filter upgrade due?)

More fuel = more air to mix 👍.

If you search *carb* at the top ,there is a tutorial on jet swapping which mentions more detail on sizes and why we dont need to change *Pilot Jets*

Just *Main Jets* usually only upgraded thats all.

Sooty exhaust may indicate a weak sparking behavior from magneto/cdi?   –  or else you need more air  or  the jets are too big   (or air/fuel screw ratio off?)

Your mech owes you to fix the carb since he tinkered with it so it must give us a good result?

A little soot is a ok but caution ofcourse how much soot is there.  Too much aint good  (hint = bike spits raw fuel on cold warm up)

If the carbs are cleaned thats brilliant  but did the mechanic clean the CV sliders (the black tubes)  they are the mother of the carbs , defo must be zero signs of particles then they slide & retract nicely

(Slider behavior -> Up n down based on your revs => they release JET needle up n down attached to it)

Usually touching carb sliders.  Push up by hand and you will see them retract very fast  & same pace , no delay or getting stuck =  thats a hint of health there.


So battery works.  No dimms.  Seems to hold well.👍

Did you strip down the bike plastics? And then look at every nook n cranny near the intake system n carbs to really be sure its leak free.

Whatever bolt is on carb n engine must be *tight* =  hot engine can make things flex like rubber boots  (like taking a gulp of air) the clamps must be tight so it doesnt leak out even a small hint of air.


Last not least,  confirm with yourself that all exhaust bolts are tight.  We loose power on a leaky exhaust system too.

So to put in short, we are checking  intake system , exhaust system for leaks.   Re investigate the carbs , jets , air filter and including the black CV sliders in carb bounce nicely (critical)


Keep us updated ,   we can do all we can to help the bike 👍


Good luck 🔧

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

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