• Topics: 38
  • Replies: 519
Nov 30, 2017
North UK


it is not ideal to work on the carb while it is resting on the manifolds because the rubber is very easy to crack and it is very hard to order new ones since Hyosung stopped making them (discontinued).     Even the engine can be lowered down to have more room to remove the airbox.

I would rather hold the carb very tight with my hands while forcing the airbox out of the bike.  strange design yes it is but thats Korea lol


Carb jetting  = there is a [Tutorial]  already on the forum , check it out.  for GV125 i would use 90 front mains and 92.5 rear mains. Thats more than enough even for summer heat.  you dont want the bike too rich it will start bogging down unless you have powerful electrics , freeflowing leovince pipes.

92.5Front and 95 rear would be extreme but a limit!  thats a 250cc bike jetting!

The pilot jets = never changed. And also never mess with the mixture screws too, it would be the abyss if you do hence its usually discouraged by the OEM maker too.

Standard CR8E or Laser NGK is more than enough.  Hyosungs like the size 8 plugs.  they run weird with others. Denso is not good for hyosungs either.

You are better off by improving the oil cooler system to a 250cc one, ngk laser plug, better ngk caps as they handle heat better, coils,  slightly richer carb.

Also check (Slide Mod) on this forum which helps the bike speed up around 4k-8k revs (mid range tune)


Hope this info helps, lets see how you do 🙂


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

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