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Info Jetting up a MC22 for improved performance

Discussion in 'Honda 250cc In-line 4's' started by Damus, Jun 26, 2015.

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  1. Mclaren

    Mclaren Well-Known Member Contributing Member

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    I was wrong about my dyno hp
    Bit better than factory 25 years ago come down to clevenland show grounds motorcycle mad is he image.jpg
     
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    Mclaren, Jul 19, 2015
    #41
  2. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    This has popped back up in McIn7's thread again. :headbang:

    First of all there are two types of carb that interest us. One is the slide type that is opened by mechanical means, a cable. The other one uses a rubber diaphragm that responds to vacuum to lift the slide. This is the one being discussed.

    The pilot circuits are quite different on the two types. With CV carbs there is an incoming air jet, a pilot jet, 2 fixed openings into the throat and the adjustable idle circuit.
    [​IMG]

    [​IMG]

    So the internet is awash with advice about this. For example
    http://www.mychinamoto.com/forums/showthread.php?344-CV-carburettors-They-re-different
    and
    http://totalruckus.com/phpBB3/viewtopic.php?f=28&t=82639

    Now some of this seems quite reasonable but without quantitative evidence it is basically conjecture. There is some useful information though.

    The pilot mixture screw is for the idle mixture. It is adjustable so that you can fine tune the idle mixture not just rely on "turns out". It is not adjustable so that you can change the air/fuel ratio for the rest of the operating range @Damus.
    If you want to experiment with how the pilot circuit affects the jetting above idle then you will need to change the pilot and air jet. The limit is how much air/fuel mixture can pass through what is referred to as the transfer ports in the top diagram. Note that you will still be able to set your idle mixture correctly with the screw.
     
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    Last edited: Jul 19, 2015
    maelstrom, Jul 19, 2015
    #42
  3. Damus

    Damus She is a BEAST and riding it is comparable to sex Dirty Wheel Club

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    Okay my bad, i understand a bit better now. It can be a little difficult to get your head around but I am doing my best.
    That is very helpful information and am happy to learn and accept when I am wrong.
     
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    Damus, Jul 19, 2015
    #43
  4. Damus

    Damus She is a BEAST and riding it is comparable to sex Dirty Wheel Club

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    What type of slow jets do mc22's take?
    Are slow jets for mc22 purchasable from motorcyclespareswareouse.com.au??? Thank you!
     
    Damus, Aug 3, 2015
    #44
  5. Damus

    Damus She is a BEAST and riding it is comparable to sex Dirty Wheel Club

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    Damus, Aug 4, 2015
    #45
  6. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    heres all the mods u need Damus .....

    11836655_1679605032270552_5620700622555116659_n.jpg
     
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    GreyImport, Aug 4, 2015
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  7. Phil

    Phil Senior Member Contributing Member

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    Phil, Aug 4, 2015
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  8. Damus

    Damus She is a BEAST and riding it is comparable to sex Dirty Wheel Club

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    Its not for a mod, just you know new clean ones would be nice ^_^ (secretly is getting 1 size bigger).
     
    Damus, Aug 5, 2015
    #48
  9. Willrcr15

    Willrcr15 Well-Known Member

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    I'll bet they're not CV's
     
    Willrcr15, Aug 5, 2015
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  10. Damus

    Damus She is a BEAST and riding it is comparable to sex Dirty Wheel Club

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    for future people that need to know its "Keihin Type N424-21 Pilot Jet 28mm" from motorcyclespareswarehouse.com.au
     
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    Damus, Aug 7, 2015
    #50
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