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Pinned ZXR250 A model Keihin CVK30 Carb Jetting and Settings

Discussion in 'Kawasaki 250cc In-line 4's' started by GreyImport, Apr 18, 2018.

  1. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    Idle speed : 1500 +/- 50 RPM
    Pilot Screw base setting : 2¾ full turns out +/- ¼
    Fuel Height : 9.5mm
    Float Height : 13mm

    ..................... Cylinders 1-4 ......................
    Main Jets : #125 #128 #128 #125
    Needle Jets :
    Jet Needles : N76a N52x N52x N76a
    Pilot Jet : #35
    Starter Jet : #57
    Air bleed Jet : #35


    a model carb.png
     
    Last edited: Apr 19, 2018
  2. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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  3. Frankster

    Frankster See the World before you leave it Staff Member Premium Member Ride and Events Crew

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    ZXR250A carb main jets are 125;128;128;125
    ZXR250C carb main jets are 122;125;125;122

    Slow jet is #35 as you have stated.

    Air bleed jet should be #35 too. Adrian can confirm.
     
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  4. Linkin

    Linkin The Apprentice Premium Member Dirty Wheel Club Contributing Member

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    Will have to look at my carbs again
     
  5. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    A model info is wats needed ... C model stuff is in the manual

    Theres no carb details in the A model parts list that we have and the manual we have is only for the C model


    c model.png
     
  6. TonyZXR

    TonyZXR Active Member Premium Member

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    ok so after doing a bit of research it seems the following are the correct jet needles per bike year and model .
    1989-1990 A1-A2-B1-B2 Jet needle:outside cylinders: n76a
    :inside cylinder :n52x

    1991 1992 1993 c1,c2,c3 :either 4 jet needles are: n76u
    :either 4 jet needles are: n76v

    1994-1995-1997 c4 c5 c7: All 4 jet needles are : n1qw
     
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  7. Frankster

    Frankster See the World before you leave it Staff Member Premium Member Ride and Events Crew

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    That's very enlightening and would explain quite a few issues I've experienced over recent times. I will pull the carbs off the drag bike when I get back to Melbourne and have a look at the needles. I put a new (totally rebuilt) set of carbs on the bike sometime back and it it ran .30 of a second slower on the 1/4 mile. Same jet sizes, float height and all new internals/o-rings etc. I didn't check the needles. Could explain some of the drop off.
     
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  8. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    Can you please also check for markings on the needle jets /tubes :thumb_ups:
     
    Last edited: Apr 19, 2018
  9. sharky

    sharky Well-Known Member Premium Member

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    A model pilot screw base setting 2.75 turns out +/- .25
     
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  10. Frankster

    Frankster See the World before you leave it Staff Member Premium Member Ride and Events Crew

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    Tony, where did you get that information from? I've pulled apart 2 sets of ZXR250 carbs and they all have N76B needles! I'm trying to figure out were these needles (N76B) fit into the scheme of things.
     
  11. TonyZXR

    TonyZXR Active Member Premium Member

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    N76b is also right . I forgot to add it . My latest zxr A has n76bs in it. A models either had all 4 n76b, or 2 n76a and 2 n52x. info came from the zxr parts diagram
    jets.png
     
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  12. Frankster

    Frankster See the World before you leave it Staff Member Premium Member Ride and Events Crew

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    Thanks Tony.
     
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  13. TonyZXR

    TonyZXR Active Member Premium Member

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    Good useful info posted on the resources section for the A model:
    Pilot jet is 2 1/4 out instead of 2 3/4
    Only the zxr250r is supposed to have the n76a and n52x needle jets to offset the 4 130 mains
    The normal zxr250 has 4 n76b offset by the 125 and 128 mains
    Explains why my mates bike ran like poopoo with n76a and n52x installed with 125 and 128 mains

    I translated the page to english
    zxr250 carbs.png
     
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  14. RyanZXR

    RyanZXR Member Premium Member

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    Very useful!

    Anyone know where to buy these parts from? Mine may be damaged.
     
  15. Frankster

    Frankster See the World before you leave it Staff Member Premium Member Ride and Events Crew

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    Which parts are you referring to?
     
  16. RyanZXR

    RyanZXR Member Premium Member

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    After a bit of searching, I saw that you can get some from IMPEX. But they don't have the jet needles.

    upload_2020-3-25_11-16-5.png

    I am after a set of jets, and jet needles. I can buy the main jets from IMPEX.
    But haven't been able to find where to buy the pilot jet or starter jet.
    Thanks for the reply.

    Link to the page by the way.

    https://en.impex-jp.com/catalogs/mo...ony-pearl-cosmic-gray-japan-10647/661493.html
     
    Last edited by a moderator: Mar 25, 2020
  17. Frankster

    Frankster See the World before you leave it Staff Member Premium Member Ride and Events Crew

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    Try looking at other Kawasaki inline fours like the Balius. They may have similar needles. Main jets you can get from many places, but make sure you get some emulsion tubes too.
     
  18. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    Jets dont need replacing .. they dont 'wear out' .... only if they are the wrong size , damaged from being removed/replaced (pilot jets are usually very soft brass) , hacked inside from being poked with wire to clear them or some boofhead has drilled them out to make the bike go 100kmh faster

    Carbs and parts for them arnt Kawasaki parts so to speak .... on a ZXR they are Keihin (which is actually owned by Honda)

    https://nrp-carbs.co.uk/shop/index.php?route=common/home

    https://www.motorcyclespareswarehouse.com.au/search?page=3&q=zxr250
     
  19. Frankster

    Frankster See the World before you leave it Staff Member Premium Member Ride and Events Crew

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  20. RyanZXR

    RyanZXR Member Premium Member

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    You guys are awesome...!
    Having an answer the day I ask is so helpful.

    That's great, I will do my diligence and find a solution.

    Sounds like something I can be a part of.
     

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