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Bike coughing when throttle opened

Discussion in 'Technical and Troubleshooting Torque' started by gbren, Mar 23, 2011.

  1. Hi All,

    I am new to bikes and have recently purchased a hyosung gt250r. I got it from a friend quite cheaps as he has gone overseas and no longer needed it but am having an issue with it.

    When i open up the throttle more than roughly a quarter to halway the bike coughs and drops rev's and struggles to continue accelerating, I back off and ease back onto the throttle to get it to go but even then it still coughs. It happens through all gears but appears to only happen when I first start riding it for about 5-10 minutes after which time it runs fine.

    Before I take it in to a mechanic I was hoping to get some opinions so I can haev a look myself as I love to get my hands dirty and want to learn more about the bike.

    All help much appreciated :)


  2. First problem to check, your head in buying a Hyo .. lol (overseas hey?) lol
    Sorry, mate ... cant resist.!
    Basically sounds like you either have a fuel flow prob or could also be something as simple as fouled plugs! And judging that it starts to run fine after it warms up, I would suggest to check them first.
  3. Do you warm the bike up before you ride it?
  4. Haha thats alright mate, its something for me to learn on and build my confidence before heading up to some real machines :)

    I'll have a look at the plubs tonight, I got my hands on a manual so time to get my hands dirty :D

    I always let it idle for 5ish minutes before I jump on but even then it still coughs, it seems to settle down after its been going for about 5 minutes....
  5. Sounds like it just takes a while to warm up honestly...

    Give the carbs a clean anyway, good place to start & find out how things work.
  6. Thanks for the opinions guys, I think it'll be good to get an understanding of the bike anyways so I will check the plugs and give the carbs a clean :)

    I'll be hanging around here from now on :)
  7. (y) Good to hear.
  8. If it's your first time in an engine, be careful cleaning carbs, they are rather important and have lots of annoying little parts that can jump out.

    Plus there is a 100% chance that you will strip a screw head disassembling them, so be careful there.

    Just pull them off the bike, take them to a table or something, lay out a nice big rag (like an old sheet or towel) and go slow and lay out all the parts as they come out spray carb cleaner through all the holes you can see (you WILL get it in your eyes and it hurts like a b!tch) and spray and wipe down all the surfaces, making sure you get the crud out of the bowls...as you have 2 carbs you will end up with 2 piles, try not to mix the parts between carbs.

    If the floats are metal be careful not to bend them, changing the float height effects the fuel/air mixture.

  9. Going overseas to escape from the shame of owning a hyo. Smart friend.

    Couldn't help it.
  10. One other thing - Hyo's also suffer from Vaccum lock!
    To check, when it does it again, stop and release the fuel cap and see if it helps.
  11. Always thought the reason Hyos ran so badly was because they sucked too much...