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  1. #1

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    Keihn CV to CDKII swap

    I need help with what jets should be insatalled on a converson frm CDCV to CDKII. I have a 1998 STX1100 and am putting on a CDKII from a 1996 ZXI 1100. Lwhat ets would you reccomend for this conversion on high and low? Shoul I leave the high low set to stock settings? The only thing I have done is a TDK water box.


  2. #2
    steve45's Avatar
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    Does your CDKII carb rack have the accelerator pump? I've heard that you can't get replacements anymore.

  3. #3

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    No accelerator pump. Just the stock fuel pumps

  4. #4
    TexasZ's Avatar
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    As far as I know the stock 96ZXI 1100 settings should work with your 98 STX1100.
    You will want to run the OEM factory set of flame arrestors or else they will run way lean and cook pistons with the aftermarket set-up.

    I would definitely open those carbs up for a thorough cleaning, especially the little screen that sits under the needle and seat. Also to check out the needle ends to make sure they aren't deformed or have a ridge worn around the end...along with the arm height. Arm height can be checked out by putting a straight edge across the top of the carb body right there and the clearance between the straight edge and the little plastic button on the end of the arm should be .060 I use a feeler gauge by putting a couple of the blades together to get to .060

    Let us know how it turns out.

  5. #5

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    I ran this set up and it did run on trailer with stock flame arrestor. When I put it in the water with CDK-II for a test it bogged the whole way with a top speed of 32 MPH. I put old CDCV back on to ride this past weeked. They bogged out as always but it ran the same and hit 52 MPH. I was wondering if jets need to be increase dto 135 on high and about 98 on low. The CDCV carbs have bigger jets 165 High and 35 Low.

  6. #6
    TexasZ's Avatar
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    The constant velocity carbs are going to have larger jet sizes than the CDK's so any comparison there won't be useful.

    When you say bogging, define that a bit so we know we're both on the same page. Will it idle decently....when you throttle up, does it fall on it's face or die (lean)...or does it bog down (rich) and then a few seconds later take off even if it sputters a bit first?
    Did you try the adjustment needles already? You need to open them some (1/4 turn at a time) before jetting up. You know it's time to go up a jet size when you have turned the adjustment screw out to it's capacity and you still need more.
    Plug chops will give you some info to go on too.

    Before trying to tune the CDK carb set, did you go through and clean the CDK carb set out and look everything over? Check the height of the needle arm? Did you do a popoff test on the carbs.

    Carbs, even moreso a triple set can drive ya nuts if you don't do the basics so you know you're starting off with everything in good working order, and in synch with each other, that's why popoff being equal among the three is important. Trying to tune them is time consuming most times and requires patience.
    Since they came off a 1100 and going onto another carbed 1100, I would have thought that they would be pretty close on the settings the way they were.

    Work on the low end and get that right first, before even thinking about the highs...forget the highs until the low is right on.
    There is a set of steps to follow on tuning carbs. If my memory serves me correctly, there is a good set of instructions on carb tuning in the sticky's over in the Polaris section. Search feature will turn it up most likely...and or Google. Read several so you get a feel and balance and a better understanding of the process.

    Read the tuning article/s, try some stuff and come back and tell us where you're at and what's going on.

    We need some really specific info from you to help you more and to me it all starts with a known clean set of carbs with the popoff in synch.

    I am about to do a very similar swap myself on my son's ski. A triple set of CDK's off a 97 stx900 onto a 99 stx900 that had a set of CV carbs on it. I have already went through the set of CDK's that are going on it. I'll be putting it together tomorrow and test run it in the afternoon...I hope..LOL..things don't always go as planned...heck, they rarely go as planned around here. Fresh motor too, hope we did everything right so we don't get any kabooms, meltdowns, holes in bottom of case, etc...gulp!

    Just dawned on me...You did change the intake manifold right? The CDK intake manifold does not have that outer balance tube or the tubes that are made into the intake that open the space between the carbs like the CV carbs do.
    If you're using the CV intake for the CDK setup, then that's a big problem right there, the CDK intake is way different in it's design and function compared to the intake for the CV carbs.

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  8. #7

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    I did not change the manifold my STX has the balance tube between 1 and 3 cylinder. I was looking at a service manual from Kawasaki and it showed CDKII with this manifold? I did receive the manifold from the ZXI when I got these carbs. Let me try that and see if this works. I need to buy new gaskets to remove old manifold and replace. I am going to clean and buy a rebuild kit for the 3CDKII's and see how it runs .

    Thanks for the info. I will check back after I receive rebuild kits,new gaskets and take a ride.

  9. #8

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    Where can I buy a pop off pressure fro Keihn. What is a good pop off # for the carbs?

  10. #9
    TexasZ's Avatar
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    Quote Originally Posted by njskidemon View Post
    I did not change the manifold my STX has the balance tube between 1 and 3 cylinder. I was looking at a service manual from Kawasaki and it showed CDKII with this manifold? I did receive the manifold from the ZXI when I got these carbs. Let me try that and see if this works. I need to buy new gaskets to remove old manifold and replace. I am going to clean and buy a rebuild kit for the 3CDKII's and see how it runs .

    Thanks for the info. I will check back after I receive rebuild kits,new gaskets and take a ride.
    I'm certainly not the end all expert on Keihin carbs, far from it...but I'm almost certain that the CDK's did not ever use the same manifold as the CV carbs. Maybe some of the carb guru's will see this and chime in.
    Change the manifold to the correct one for the CDK carbs and that should make a world of difference.

    As far as the kits, I would highly suggest buying "Genuine Keihin" kits, NOT aftermarket. But first ckeck the carbs out when you are cleaning them, you may not need kits. The "Genuine Keihin" kits are expensive...they were right at 60 bucks each at jet-world.net the last time I looked.

    Intake manifold gaskets, yes...carb to manifold definitely along with the reed gaskets since you are changing the manifold. One tiny pinhole leak anywhere in there will cause it to run lean and cook a piston/s.

    The same pop off pressure gauge works with all the different carbs, it's not Keihin specific. There are a bunch of different ones for sale out there. I have a new one here from SBT that pumps up by hand. PM me and I'll make you a deal on it if you want a hand pump one. I made my own to work off my air compressor, faster and easier "if" you have a air compressor.

    Pop off number...check the popoff on all three carbs and write down the number on each carb. They tell you to do the popoff test three times on each carb to get a consistent number.

    If that is the factory set-up, they will most likely be the same or really close to it right now. If the numbers are off between them, then to synch them you make the carb with the highest number the same as the lowest. You bring down the number of the higher one by clipping a 1/4 of one ring off the end of one of the needle arm springs. Do a tiny bit at a time and re-check it.
    Look at some of the carb articles (sticky's) in the Yamaha section here (they are on Mikuni's)...that will help you understand pop off and how to do that.

    I have a feeling that 99% of your problems will go away as soon as you change the intake manifold. The carbs are simple to clean, take your time and have a good clean area to work. If new to this you probably just want to do one carb at a time until you get the hang of it.

    PM me if need be and I'll give ya my cell number so I can walk ya through a cleaning as you do it.

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