Forums 🚥 PIT STOP 🔧 Hyosung Technical Help Identifying Jet needle for my 2005 comet 250

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    • #3984
      Alastair Pereira
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      Mar 18, 2020
      @alastair
      Bangalore india
      Hyosung comet 250 2005
      Points: 51

      Need help to identify which jet needle is for the front cylinder and which one for the rear, the one one on the left is more tapered and sharp compared to the one on the right … Some how got these mixed up after cleaning the carbs however the bike starts up and runs good … But I feel the engine is getting too hot … Kindly advice … Thanks In advance

    • #3987
      ♠️ MARCEL
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      @mf448kxn6
      North UK
      GTR
      Points: 4,200

      Slimmer to the rear since it allows extra fuel to cool the rear motor. I shall confirm this next time i dig thru’ some archives , but generally the rear gets a little more fuel hence larger main jet as standard than the front.

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

    • #3990
      Alastair Pereira
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      Mar 18, 2020
      @alastair
      Bangalore india
      Hyosung comet 250 2005
      Points: 51

      Thanks alot Marcel, I was confused wondering if the slimmer one goes for the front carb to compensate for the bigger jet at the rear carb .. couldn’t find this info in any service manual as well … ,

      It’s running on the stalk main jets 92.5 front and 95 rear a, K&N air filter in the stalk air box … The bike does  a top speed of 150 kmph on the highway.. but it’s just that I feel it’s getting too hot … Should I lift both the slide needles to the third groove from top ..it’s in the middle groove now which I guess is the default settings

    • #3993
      ♠️ MARCEL
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      @mf448kxn6
      North UK
      GTR
      Points: 4,200

      On the needle , put it on the “lowest setting”  (which is closest to the pointy tip) , that will lift the needle 1 more step out of the carb , then you have some fuel much sooner around 4-7k , its good stuff.   {{No extra washers etc, don’t know why other places say this but never mind lol}}

      As you have a K&N, maybe consider 95 and 97.5 main jets as maximum.

      Though, you will ride the bike first with only the slide needle enriched, clean the spark plugs first.  If its dark brown everywhere , the fueling mix should be fine.   Last worry should be clearances on the valves, so that exhaust valves breath better once its up to temp  (it gets hotter if the ex-cams have less gapping)

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

    • #3998
      Alastair Pereira
      Member
      • Topics: 1
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      Joined:
      Mar 18, 2020
      @alastair
      Bangalore india
      Hyosung comet 250 2005
      Points: 51

      Cool , will have the jets replaced …. Hopefully I should be able to get 97.5 at a local parts dealer , will check that out today  and I am planning on installing new iridium spark plugs , and I haven’t checked the valve clearances the bike had done just 15,000 kms totally so I guess the clearance should be fine .

      And one more thing Marcel have you tuned the petrol mixture screw on a 250 ? The manual says not to tamper with these screws 😁, however I had to remove them cause my carbs were too stuck up after sitting for a couple of years ,

      The mixture screw for the rear carb was 4 1/2 turns out and the front was almost 2 .. is this the default tuning ?

      Any knowledge on this would be helpful .

      Cheers 🍻

    • #3999
      ♠️ MARCEL
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      @mf448kxn6
      North UK
      GTR
      Points: 4,200

      Unless you have the “numbers” of clearances per valve, you won’t know if that’s causing heat issues on the bike or premature cam wear. 15,000 is a lot of rides, so i’ll leave it there.   I usually do them at every 4-5,000 miles.

      Yes the manual is correct not to tamper with the mixture screws, as then you’re in the abyss. I know what they are but will try to keep this comment short so i’m not quoted incase the bike doesn’t like what i said (modding or stock bikes are not the same, too many variables, hence we leave the stock carb alone and just do jets).    Around 3 to 4 is normal on each pot, what the Koreans do factory wise.   Your new spark plugs will let you know when they leave a trail color. That’s my comments.

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

    • #4001
      Alastair Pereira
      Member
      • Topics: 1
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      Joined:
      Mar 18, 2020
      @alastair
      Bangalore india
      Hyosung comet 250 2005
      Points: 51

      Thanks a lot  for your help Marcel .

      Glad to be a part of this forum.

      Cheers 🍻

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