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Thread: V Star carb rejetting?

  1. #1
    Join Date
    3rd January 2012 - 13:51
    Bike
    V Star 650
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    Auckland
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    3

    Cog V Star carb rejetting?

    Hi Guys,
    V Star 650 Classic 2009
    I have installed kuryakyn hypercharger on my bike, I have rejetted carb with Main FTC USA 120M plus Pilot 35, open pipes, set the needles on the 5th groove. I cannot find anywhere what should be PMS setting, Original manual states 1.5 turns, but says nothing about needles (if set as per original manual without needle mod it goes bad), so I had to glue it from everything I could find on the net. When bike is set on 2.5 PMS turns then it goes ok but I do not think that it is all it could do. Any one has any experience with that or knows any good mechanic who could help me. I have used this link as base to do the job but there are small differences with my setup - http://650ccnd.com/hc.htm
    Thnx Mark

  2. #2
    Join Date
    1st September 2007 - 21:01
    Bike
    1993 Yamaha FJ 1200
    Location
    Paradise
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    14,125
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    I did a bit of a search on Hyperchargers ...

    In theory, it makes the bike breath better...
    In reality it causes jetting issues, cost's a lot of money, and is covered with cheaply coated chrome that peels up....
    IMO they create a lean spot at highway speeds in a narrow range which makes it difficult to compensate for by jetting...
    ...but the K&N filter is nice...


    Seems to be the common view ...

    "modest" improvement in performance gained is the norm. I hope you weren't expecting an 1100 cc performance from a 650 cc bike ... or that of a 750 cc for that matter ...
    When life throws you a curve ... Lean into it ...

  3. #3
    Join Date
    3rd January 2012 - 13:51
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    V Star 650
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    Auckland
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    3
    thnx, however it didn't answer the question.
    If chrome will get lost then there is always black paint available , 650 is 650 and will not be 1100 but will be a bit more responsive and that is what I want. I would expect someone to let me know if my needle on 5th grove is ok or should it be 4th, 120 is it ok or should I put 122.5 in. From all I could read I understand that 5th grove gets me more fuel in mid range however is it going to kill the engine or not? Should I set it to 4th? How big is the difference between 4th and 5th? As far I understood 120 is just right size and going up may not help too much and do any good. Then when we agree on something above then any good advise how to set up PMS? I found that the best way is to close it and then count rotates while opening until bike starts being unhappy. Then put the pms in the middle based on the count. The other way is to close it and open until bikes works smoth. Then repeat steps on first cilinder.

    Thnx for help.

  4. #4
    Join Date
    1st September 2007 - 21:01
    Bike
    1993 Yamaha FJ 1200
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    Paradise
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    Experimentation would probably be the only way to find the best results FOR YOU. Dyno testing in a workshop would be the desired method ... but cost may deter you on this method ...
    When life throws you a curve ... Lean into it ...

  5. #5
    Join Date
    2nd February 2008 - 15:59
    Bike
    Roadstar 1600 & Royal Star Venture
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    Wellington
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    Quote Originally Posted by monolith View Post
    thnx, however it didn't answer the question.
    If chrome will get lost then there is always black paint available , 650 is 650 and will not be 1100 but will be a bit more responsive and that is what I want. I would expect someone to let me know if my needle on 5th grove is ok or should it be 4th, 120 is it ok or should I put 122.5 in. From all I could read I understand that 5th grove gets me more fuel in mid range however is it going to kill the engine or not? Should I set it to 4th? How big is the difference between 4th and 5th? As far I understood 120 is just right size and going up may not help too much and do any good. Then when we agree on something above then any good advise how to set up PMS? I found that the best way is to close it and then count rotates while opening until bike starts being unhappy. Then put the pms in the middle based on the count. The other way is to close it and open until bikes works smoth. Then repeat steps on first cilinder.

    Thnx for help.
    Actualy he did answer you, that there seems to be a concensus of a small flat spot with a hypercharger....
    What I would suggest is possibly reading up on how Kawasaki have made the 'ram air' system work, as it has somewhat the same effect as your hypercharger by increasing 'airbox pressure' From memory I think that kwaka used some kind of 'air balancing' system.......it may be described and useable for your bike?
    If the road to hell is paved with good intentions; and a man is judged by his deeds and his actions, why say it's the thought that counts? -GrayWolf

  6. #6
    Join Date
    2nd February 2008 - 15:59
    Bike
    Roadstar 1600 & Royal Star Venture
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    Wellington
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    Quote Originally Posted by FJRider View Post
    Experimentation would probably be the only way to find the best results FOR YOU. Dyno testing in a workshop would be the desired method ... but cost may deter you on this method ...
    Dyno testing may not work either...
    if you dyno a ZZR they produce about 12bhp less than quoted, a dyno tester put an industrial fan at about 80mph wind speed to see if the 'ram air' actualy worked... it immediately produced another 8+ bhp on the dyno. So the jetting needs to be adjusted to allow for the increased airbox pressure
    If the road to hell is paved with good intentions; and a man is judged by his deeds and his actions, why say it's the thought that counts? -GrayWolf

  7. #7
    Join Date
    3rd January 2012 - 13:51
    Bike
    V Star 650
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    Auckland
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    3
    Thnx,

    At this stage the bike does not keep rpms on idle, after short ride if is loosing it or keeps going another time (I suspect lose PMS screw), etc. on 3rd gair in half thrtl open if is dieing for a moment until I pass this point. Today I have got automotive multimeter which can test rpms, etc so I will be able to do something.

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