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Topic Tag

air hose

How to change Vacuum Lines on Hyosung GT125R GT250R & GT Comet (Air Hose Diagram)

Changing the vacuum Lines on carburetor 125/250 vTwins, should be fairly easy. All you need is 15-30 mins of your time, let’s start with the basics first.

  • Hyosung says if your “standard” factory lines are 2-4yrs old.   Discard them regardless. 
  • Old pipes can also rot inside , especially those chinese ones with trashy rubber
  • Larger colder air pipes can help improve the vacuum system but get strong clips!
  • Strong clips are very essential to avoid all possible air leaks.
  • This tutorial applies to all carb operated 125/250  GT & GTR Twins  (includes GV125 too)

Let’s go now…  Strip your fairings down  (GTR owners)   
(if you have a naked bike,  go to next step)
hyosung gt125r air vacuum line gt250 gv125

 

Below is a diagram of how the “AIR LINE” system should be connected.
 Study (look at) the diagram images below first  , before moving on to the next step….
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hyosung gt125r air vacuum line gt250 gv125 hyosung gt125r air vacuum line gt250 gv125

 

 

 VACUUM LINE #1  = CONNECT  THE REAR FUEL PUMP  FIRST
Got your lines ready?   
On the LEFT side of your bike Grab a hose for the fuel pump & follow the next diagram pictures below:

hyosung gt125r air vacuum line gt250 gv125 hyosung gt125r air vacuum line gt250 gv125 hyosung gt125r air vacuum line gt250 gv125

 

  VACUUM LINE #2  = CONNECT YOUR FUEL TANK TAP
* Once your rear fuel pump  is connect from the left side.
* Now, move on the the RIGHT SIDE of your bike
* Grab a second vacuum pipe and follow the next diagram images below:

hyosung gt125r air vacuum line gt250 gv125
hyosung gt125r air vacuum line gt250 gv125

 

That’s It – Vacuum Setup is done! 🚦
However, if you have an AIS Device (Fake emissions/EGR) then read below!


*Remember above ^ , there is a cartoon diagram of the infamous “EGR DELETE” mod, right ?
*Remove it or block anything that feeds it.
*This image is another example for you.
* Personally, it’s a useless device. 
* But, if you want it connected -> replace “blocked” with “connected”
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    Alright, we are done.   Go test ride! 🏁  

 

I hope this fast toturial was easy to follow,  however if you get stuck or need help. Just comment on this post!  This tutorial should also help GV owners since they use the same rear pump anyway.