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99 1100 zxi cv carb adjustments

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  • 99 1100 zxi cv carb adjustments

    Hello, I recently rebuilt the top end on my 99 1100 zxi, I had my cylinders bored over 1mm, and did a complete top end kit. I put it back together and everything seems to be working fine, while doing this I converted to premix and installed a primer kit. I took it out on the water yesterday and it seemed slow, topped out at about 40mph and was slow to accelerate. The engine seems to be running fine, compression is good, full throttle on the water was at about 6000 rpm. I have read that after installing the primer kit, and boring the cylinders over that the carbs should be re-jetted to allow for more fuel since the engine will be sucking more air in. It has the CV carbs which have no adjustment screws, I am in the process of finding a set of the older non-cv carbs. Can anyone recommend what size jets would help this problem? I have rebuilt the carbs and fuel pump, new fuel lines and filter. The impeller and jet pump also seem fine, no chips or anything. If anyone has any ideas on what could be causing this please let me know. Thanks!

  • #2
    Re: 99 1100 zxi cv carb adjustments

    You should not have to jet up. Those carbs are hard to tune and make work well, like you said hunt down the cdk2s and go from there.
    SBT Tech Support is here to help with your problems.
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    • #3
      Re: 99 1100 zxi cv carb adjustments

      I am doing the same thing with the same carbs, but have yet to finish the job and test it out. I have read quite a bit about these carbs and do not understand why they are so difficult. I can see that there is very little adjustment at all that can be done, but if you rebuild them correctly, why would you need to make adjustments? Boring out the cylinders should not require an adjustment like you said. 80mm pistons with a 1mm overbore is like a 2% change in volume in the cylinder, that should not require a carb adjustment. I was only worried about the viscosity of the gasoline with the premix causing a flow issue in the main jet, but at 40:1 I was not sure if this will be true, after that the gas and oil are mixed anyway.

      My repair manual does not have ANYTHING on these carbs as it assumes the carbs on the ski are the CDKIIs. However, I found that the repair manual for the Ultra 150 does an excellent job explaining the function and pieces of the CDCV carbs even though the fuel pump is designed slightly differently. You can find the manual online.
      Last edited by dlofgreen; 08-08-2012, 07:18 PM.

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      • #4
        Re: 99 1100 zxi cv carb adjustments

        I am running 32:1 premix right now, the shop that bored my cylinders recommended it for the first hour for break in. Could the thicker mixture be what's causing my lack of power? The pto side cylinder seems to be running lean, which is the cylinder that failed previously. I rebuilt all three carbs, fuel pump, and cleaned out the entire fuel system. The ski had sat for about 2 years before I got it, it had a hole burned in the back piston. I was hoping the carb cleaning, rebuild, and premix would fix this. I've had it on the water once after the rebuild to test it, it just doesn't seem to have the pickup it should when I hit the throttle, and tops out at about 40 mph. My stock 96 seadoo xp blows the zxi away, I thought it would be the other way around. In my service manual there's a section in the appendix with diagrams of the cv carbs, but it has no info on adjusting anything. Maybe I'll try running it with 40:1 and see if that makes a difference. Thanks for the replies.

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        • #5
          Re: 99 1100 zxi cv carb adjustments

          SBT has a pretty thorough break in proceedure documented in the forum under Technical Articles. If you followed a procedure similar to this, you should be fine, if you took the engine to full throttle too quickly the rings might have sustained damage. Also, I have not looked into the primer kit over the choke, is it possible this affects the air flow through the venturi?

          They also have an article on gas:oil ratios and for the Kawasaki they say 50:1 after the break in period.

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          • #6
            Re: 99 1100 zxi cv carb adjustments

            The break in procedure I did was almost exactly like what sbt recommends. I never went over half throttle on the water, I wasn't out very long, just wanted to see if it would run with resistance. The compression is well within spec, and even on all cylinders. I tinkered around with it a little today, I noticed the front two cylinders had carbon build up on the spark plugs, while the rear was perfectly clean, looked new. I'm sure the carbon is from the rich premix, but it concerns me that the rear cylinder was so clean. I pulled the carbs apart again and made sure everything was clean and working how it is supposed to. In my gut I still think it is an issue with them, just not sure what it could be. This thing is going to drive me crazy.

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            • #7
              Re: 99 1100 zxi cv carb adjustments

              Just received my CDCV Carb rebuild kits from SBT so I have a better idea of the rebuild.
              1. Did you check the fuel filter screens on the valve seat that must be reused?
              2. Do you think your carbs are synchronized correctly? There is a procedure in the Ultra 150 manual.
              3. Have you done a pop off pressure test? The specs for the 40mm CV carbs are in the manual too but I believe the 1100zxi has 38mm carbs. At least make sure they are the same.
              4. Did you use an SBT fuel filter? I have heard bad things about auto shop fuel filters for jet skis.
              5. I did some research last night and there is a nice video on YouTube where a guy is testing flow rates of different gas and oil mixes. He found no viscosity issues for mixes under 10% I might check your fuel screens on the seats again after break in.
              6. Lastly there is an article online about CV carbs and primer kits. The guy who wrote it says he won't install primer kits on them as they don't work well together. I assume it disrupts the venturi. Any real reason for the primer? I never have issues starting my ski

              Questions
              With the kit where did you put the gasket for the Carb diaphram? My original did not have one.
              Did you use the lock washer? Again my carb had no lock washers.
              Last edited by dlofgreen; 08-09-2012, 10:52 AM.

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              • #8
                Re: 99 1100 zxi cv carb adjustments

                1. Yes, I removed and cleaned them with carb cleaner, although they looked fine.
                2. They seem to be, the throttle butterflies open and close evenly at the same point. I'll look into this more.
                3. The pop off pressure test is about the only thing I have not done, I couldnt find any information on what the pressure is supposed to be for these carbs.
                4. I got the fuel filter from my local kawasaki dealer, it looks pretty much identical to the stock.
                6. Honestly, if I knew what I know now I probably wouldnt have done this. It was a suggestion from the previous owner, which I've learned didnt know much about anything. I got the kit from the kawasaki dealer as well, they said it should work fine and not require any adjustments. I wouldn't be too suprised if part of my issue was from removing the choke system. I think I've had to use the primer once since I've put everything back together, it seems to start up just fine without it. Perhaps the hole blown through the bottom of the case and the shattered piston was why it hard starting for the original owner LOL. (Thats not the engine I rebuilt, it came with two.)

                My original did have the gasket, I put it inbetween the diaphram and the fuel pump. My carbs do look like they have been rebuilt before, the screw heads were kind of torn up like someone didn't know what they were doing. Mine didnt have lock washers either, I did use them, I figured it cant really hurt anything.

                I read in a couple forums that the jets in the rear carb were slightly smaller that the jets in the front since the rear is the first to get fuel, when I pulled mine apart they were all the same though (Low speed #35, high speed #165). I'm ready to scrap these CV carbs and get a set of CDKIIs. There was a set on ebay I missed out on, they went for $51, I'm really kicking myself for that, all the others are around $300. I fould a set of CDKII carbs on craigslist near me, but they were from a 900, and I've read that the 900's didnt have the accellerator pump like the 1100s do. I wish I had a set of carbs from a good working ski to verify thats whay my problem is. I guess I'll keep watching ebay.

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                • #9
                  Re: 99 1100 zxi cv carb adjustments

                  Hope you get it figured out. Sounds like you did everything right, at this point I might suspect the primer kit or incorrect pop off pressure. My high and low jets are the same in all 3 carbs as well. What you read about them being different does not really make sense. Even though as you say the 3rd cylinder is closest to the fuel pump, it's a CV system that has return to the fuel tank. Therefore, the fuel line to all 3 carbs should be full of fuel at all times. What you are describing can't really happen unless there is air in the line. The fuel must make a continuous flow all the way back to the tank. When the cylinder needs more fuel (open throttle) the venturi pulls the needle out of the seat and a vacuum occurs in the carb. That pulls the diaphrm down onto the float arm and opens up the needle valve in the carb where fuel should be waiting. Fuel then flows through the high speed jet and down through both the bypass and the needle valve) If that does not happen, either: Your needle valve is not opening far enough (venturi problem perhaps due to the primer kit??) or the slide is sticky. Or the diaphram in the carb is not pressing on the float arm well (bent float arm or a poor diaphram action).

                  About the gasket... not the fuel pump one, but the diaphram for the actual carburetor. The oval looking diaphram (with metal) and gasket the one that presses on the float arm. My original carb did not have a gasket there. The diaphram was simply pressed between the carb body and the cover plate.

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                  • #10
                    Re: 99 1100 zxi cv carb adjustments

                    Oh I see, I have the gasket between the diaphram and cover. Thats how my carbs were assembled before. The old gaskets were really stuck on there, they looked like part of the cover, I had to use a razor blade to scrape them off.

                    Yea the theory about how the back carb would be getting more fuel didnt make much sense to me either. I am not sure what else I can do to these carbs, I wish I could put the choke plates back in, but I had to grind off the pressed in screws to remove them. At this point I am leaning towards getting another set of carbs, I'm not sure what else I can do to make these work. Something deffinately doesnt seem right with them. If I do get another set they sure wont be CV carbs. It troubles me that two different engines had the same cylinder fail, with the only link between the two being the carbs. The stock engine that I rebuilt was diagnosed as lack of oil, so the piston burned and scored the cylinder wall. It had a rebuilt engine in it when I bought it and the piston seized, bent the rod, and blew a hole through the bottom case. Good thing I bought this ski cheap.

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                    • #11
                      Re: 99 1100 zxi cv carb adjustments

                      At this point I would think that the installation of the primer kit by taking out the choke plates is the culprit. Likely changed the venturi action of the needle valve. Check these links:


                      Kawa Triple w/CV carb Primer Install with Pics
                      Ultra 150 issues... New owner
                      Diff between primer kit function & factory choke

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                      • #12
                        Re: 99 1100 zxi cv carb adjustments

                        Yea I'm leaning towards the same thing. Oh well.. Stupid mistake on my part. Looks like I'll be getting another set of carbs unless I can find choke plates and shafts by themselves. From what I've read it sounds like the CDKII carbs should bolt right up, just need to T off the pulse line to drive the accelerator pump as well as the fuel pump. I kinda would rather have those anyway, that way I can adjust things if I need to. Thanks for your replies by the way.

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                        • #13
                          Re: 99 1100 zxi cv carb adjustments

                          If you are going to scrap your carbs, you may want to check out this thread and see if there is one last hope for yours.

                          http://www.shopsbt.com/forum/t34974/

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                          • #14
                            Re: 99 1100 zxi cv carb adjustments

                            Well, I thought I had my problem solved. Picked up a set of CDKII carbs from my local craigslist from a 96 1100 zxi. They came with rebuild kits, I rebuilt all three of them, and reset the mixture screws to stock. Put them on the ski, fired it up, and the rpms kept climbing to the point that I had to shut it down. It seems to me like there is an air leak somwhere, however with the CV carbs on it idles fine. My intake gaskets are all new. I have no idea what the problem could be now.

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                            • #15
                              Re: 99 1100 zxi cv carb adjustments

                              I have never researched the CDKII carbs but I know some need two pulse lines from the crankcase and some cases have two ports. My case has one I assume yours does too. Does the CDKII carbs news two lines dis you split the pulse line?

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