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  1. #1

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    Apr 2013
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    03 Ultra 150 Bogging

    Recently bought an 03 150 that had a fresh top-end rebuild. Long story short the motor lasted about 7 hours before cylinder 1 thrust washer disintegrated. Running out of summer I purchased a used motor instead of sending crank and cylinder out to be repaired. New motor was installed and compression is 116-110-118. I had the carbs rebuilt by my local marine shop They wrecked my fuel pump during the rebuild so I purchased a "carbpro" brand from amazon. Ski fired up with the new pump and will idle fine, but keeps cutting out over 4k rpms. At first it would hit WOT and then drop ~200 rpms for a second and pick back up. Now it just seems to be bogging any time I give it more than 1/4 throttle. I've ordered a Kehin pump that will be here on Monday to see if it's the cheap china pump causing issues.

    I had zero fuel issues before swapping motors. Stock reeds and cages from old motor are being used in new one. I've pulled the tank and cleaned it, (tried to order a new sending unit but it's on backorder with no eta), checked the lines, filter shows 1/2" full, checked the vent. I've tested all the slides on the carbs with compressed air and they appear to be functioning correctly. I just discovered today that the PO had 4 of the 5 oil lines hooked up incorrectly, thankfully I'm running pre-mix otherwise it probably would have blown up my new motor.

    At this point I'm debating on whether I should pull the carbs off and check everything or wait for the fuel pump and see if that makes any difference. I did see a post about calibrating the TPS; I swapped mine to the new fuel pump but that was it. I'm running out of ideas and patience here as our season is pretty much over with as of today, and with the amount of money I've sunk into this thing in the last month I could have almost bought two good running ones.

    I'm not sure if this is related or not but when running on the hose today the PTO cylinder was very hot, like almost uncomfortable to touch whereas 1 and 2 were luke warm. All 3 pissers were flowing at an even rate but the water coming out of 3 was much warmer. Put it in the water on the trailer and cylinder 1 was hot but I think it was due to not fully being in the water as the pisser wasn't flowing as much as the other 2. Fully in the water all 3 pisser water-temps felt the same and all 3 cylinders were warm but not super-hot. The exhaust was hot (almost uncomfortable) though after running for about 2 minutes. I'm not familiar enough with jet skis to know if that's normal.

    Any help is greatly appreciated!


  2. #2
    steve45's Avatar
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    What thrust washer???

    That fuel pump looks like the right one. It's not the right one for the other models listed. The fuel filter should only be half full.

    Do you know what they actually did to the carbs? Did they give you a list of parts they installed? Did they clean the internal filters? Clean the fuel rails and replace the O-rings? Replace the O-rings on the needle valve seats? Don't use compressed air on the slides.

  3. #3

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    Apr 2013
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    Hey Steve, this is what failed on the previous motor and bent the rod, chipped the piston, and scored cylinder 1. It was caught early so thankfully didn't destroy the cases.


    It's my understanding that they used SBT kits to rebuild the carbs.

    I doubt anything was done above and beyond what is in this kit. They did say they were put in their ultrasonic cleaner I believe. I'm thinking I need to order some OEM parts and tear these carbs apart again. Unless the genuine fuel pump fixes the problem, which I don't think it will, I can't see anything other than the carbs causing this bogging issue.

    The gasket kit I ordered for the new motor had paper gaskets for the intake to carb surface, whereas the ones that came off my old motor were metal. Are they supposed to be metal or does it not matter? Thanks
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  4. #4
    steve45's Avatar
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    Aha! Thrust washers on the big rod bearings. I don't remember if they come that way from the factory or not. I was thinking of thrust washers on the pistons, which Yamaha uses, but Kawasaki does not.

    The metal carb gaskets are best, they can be removed for adjustment many times. If you go with the paper gaskets, put some grease on the so they don't stick so badly.

    I've had several engines with CV carbs and I've spent very little money fixing them. I always take them apart and see what's needed before I order parts because the parts are so expensive. I normally don't change the diaphragms, in fact, I don't even remove them. I very gently blow into the air side and watch them move and if they don't appear to have a pinhole in them, I re-use them. I don't think you can remove the diaphragm without damage (perhaps some solvent would help). One thing I DO replace is the O-rings under the needle valve seats, as well as the fuel rails. Look at the carbs where the fuel rails seat, that's where dirt collects. The O-rings are all the same, even though Kawasaki doesn't list them for the needle valve seats. Their price is outrageous! I bought some elsewhere, but the size is a little smaller. They are an odd size. Somebody else here was able to find some that fit better about a year ago. Do a search. You really want Viton O-rings. Check that the little metal orifice on the vacuum slide is clear. If you lose it, you can cut a little piece off of plastic tube from a spray can and it will work.

    Make sure that the rings on top of the carbs are aligned correctly!

    It's a good idea to make the oil lines extra long so that you can remove the carbs without having to unhook the in the future.

  5. #5

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    I found the post you were referring to and the correct o-ring size. For the fuel rail and needle valve seats I’m counting 19 needed. That posts also refers to o-rings for the mixture screws. I am not very familiar with carbs and the diagrams from partzilla don’t seem to list them. Should I pick these up as well and if so is it one per carb? Thanks.

  6. #6
    steve45's Avatar
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    I haven't replaced the O-rings on the mixture screws, but it sounds like a good idea. Yes, 19 O-rings is correct.

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  8. #7
    I don't know if the the throttle position sensor could cause this issue or not. Calibrating it isn't difficult but you will need a multimeter. If you don't have a service manual let me know and I will post the pages that describe how to do it.

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  10. #8
    Myself's Avatar
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    Just an FYI on the CV carbs.....I have yet to see any version of aftermarket diaphragm that is correct. The metal 'button' that presses the lever arm to the needle is about TWICE the thickness it should be and they won't work correctly. I carefully shave that down with a die grinder.

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  12. #9
    SplishSplash's Avatar
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    You mention the oil pump and your running premix? Which is it?

  13. #10

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    First, I would go get three brand new spark plugs and swap them out.

    Then I would obtain a pressure tester and a vacuum tester and do diagnostics as follows:
    Make sure the pulse line to the fuel pump fits tight and doesn't leak. Then pressure test the pulse line nipple on the fuel pump (max 5 psi test pressure for 5 minutes). If the pressure bleeds down then you have a problem. Then I would vacuum test and pressure test the fuel system (especially the fuel selector)(max 5 psi test pressure for 5 minutes) to make sure there are no air leaks allowing bubbles to get into the fuel supply. Then pressure test the fuel pump and carbs to see if there are any air or fuel leaks. Then take apart the carbs to pressure test the needle seat o-ring, the needle valve, and to do a standard pop-off test. Then check the lever arms for proper adjustment. Check the diaphragms to make sure they are not aftermarket (like Myself said). Check your carb base gaskets.

    This can be a start to the diagnostics.

    Before starting on the carb, obtain the manual and/or read some threads on carb rebuilding so you can get familiar with the methods and techniques to test everything inside the carb.

    Good luck.

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