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Thread: Kawasaki zxiís

  1. #1

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    Kawasaki zxiís

    Iím sorry I meant to post this in the Kawasaki help section and I donít know how to change it


    I just got 2 Kawasaki zxiís in a trade. One of them is a 900 and the other is a 750. The guy claims to have rebuilt the carbs before they sat and that does look true.

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    The 900 only starts with starter fluid the first time then once it gets started it runs amazing and starts first try after warming up for 30 sec. is this a carb issue? I also see white smoke coming out of the 900 inside the hull, any common leaks?

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    900 plugs ^^

    The 750 seems like itís only running off of one cylinder, Boggs down a lot. I will be checking the compression on it tomorrow but Iím pretty sure that one of the carbs on it is just bad.

    Mostly need help with the 900, could the symptoms be an air leak on the intake side of things? Or does it just need a carb clean?
    Last edited by Jad951; 07-10-2021 at 09:18 PM.


  2. #2
    steve45's Avatar
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    Storing with gasoline containing ethanol can screw up the carbs. It wouldn't hurt to go through the carbs. Some people install primers to help with cold starting.

    Smoke inside the hull indicates and exhaust leak, probably a loose hose or a hole burned in a hose due to a water leak in the exhaust.

  3. #3

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    Quote Originally Posted by steve45 View Post
    Storing with gasoline containing ethanol can screw up the carbs. It wouldn't hurt to go through the carbs. Some people install primers to help with cold starting.

    Smoke inside the hull indicates and exhaust leak, probably a loose hose or a hole burned in a hose due to a water leak in the exhaust.
    The last owner told me about the primers but is it common that the ski wonít even come close to starting without starter fluid? It also idles around 3000 out of water which I know is normal on my bigger skis because the drag of the prop in the water lowers the rpmís down, but is that normal on these smaller skis? The jet pumps donít look too big in diameter. Should I adjust the idle screw?

    I also donít exactly trust the oil pump system, Iíve never had a pre mix ski but Iím thinking of changing over to it.

  4. #4
    steve45's Avatar
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    3000 sounds high to me. I'd still check for a leak.

    Yamaha has the best oil injection system because it squirts oil directly into the carb throat. Oil does not go through the internal parts of the carb that get plugged up with gum and corrosion. I've converted my 2-strokes to this design by using the Yamaha inline pop-off valves. The oil pumps don't fail, the hoses come off.

    Is pre-mix foolproof? Ha! What happens when a carb gets plugged up (which happens all the time with ethanol fuel)? What happens when you forget to take oil to the gas station? Or you mis-calculate how much oil it needs? Or when the oil settles out of the gasoline (I've got a picture of it)? Plus with pre-mix you use way too much oil at idle and foul spark plugs.

    Your choice.

  5. #5
    This is how I run a jetski shop in the desert nmpeter's Avatar
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    stop using ether. Nothing good has every come from that except the guy trying to start a snowplow in sub zero weather

    get a squirt bottle and put a little premix int here for your experimental engine starts before you end up blowing the engine up. You can drill a couple of 1/8 holes over each carb throat in the flame arrestor for squirtage, but the carbs will need some attention for sure.

    funny I need a govt authorization certificate to buy refrigerants, yet anybody can walk into an auto parts store and by highly explosive spray, no problem

  6. #6

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    Pretty upset, carbs looked brand new so I stuck my compression tester on the 900. The left 2 cylinders are at 90 psi and the one on the right is around 50 psi. Tested the 750 and both cylinders sat at 120 psi. I called the guy today because he said he did ďtop end rebuildsĒ on them last summer which I took as ďpistons, rings, and everything above was rebuiltĒ. Maybe Iím wrong but what he told me he meant by top end rebuild is he took off the heads and wiped them down and checked if they looked good. I donít know if Iím wrong about the top end rebuild including pistons and rings replacement or heís wrong but Iím really hoping that the rings are just stuck and if I let some 2 stroke oil sit in the cylinders the rings will free up and Iíll magically get 120 psi in each cylinder. So thatís why itís having trouble starting. Iím never trading or buying anything again without my compression gauge on me Iíve learned a good lesson here.

    For the 750 I just replaced the vacuum hose that goes to the fuel pump on the carbs had a hole in it. Just replaced almost all of the fuel lines on it and gave it a crank and it fired right up. It bogs down a little but Iím just going to say that thatís due to the engine being cold.

  7. #7
    This is how I run a jetski shop in the desert nmpeter's Avatar
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    my go to for dealing with stuck rings is marvel mystery oil. 120+ is expected, 90 is at the serviceable line ( going to be hard starting ) and 50 means trouble

    pick up a cheap inspection cameras ( amazon under $50) and have a look down the bores you might see something. pulling the heads is more work but you get a far better look

    a hole in the fuel pump vac line will make starting nearly impossible, good catch.

    In the big picture this won't be the last motor vehicle you buy, you actually are getting off pretty cheap as far as I'm concerned, i've seen far far worse and sometimes not before they were paid for with hard earned cash

    my guess is that you have at least one broken ring in the 900, its not tragic to refresh a top end, the question is how much value you have in these skis and how much further do you want to go.

    since there isn't a really easy way to determine engine hours the ski could have several hundred, which means the crankshaft may be due for a replacement, but one thing at a time now.

    fill the jugs with marvel mystery oil and let them site for a few days, that should free up any stuck rings. You may want to get an oil suction pump to remove the oil after, as it can get messy.

    in contrast, you can pour a few oz down the 50 psi jug after moving the piston close to TDC ( otherwise the oil could drain into the exhaust port and see if that one comes up). use a teaspoon or two of injector oil in the other jugs and report back on what they show.

    you _might_ get by with a ring job and a quick hone to fresh up the bores

    if you want to get right to it, pull the heads or go for the inspection camera. Too handy of a bit not to have one in your toolbox

    let me tell you about the guy that came to me with a seadoo that :

    1-had the pistons installed backwards by the "bmw car shop" he entrusted with his engine rebuild
    2-same shop didn't install the timing wheel correctly
    3-same shop blew the ecu by jumpstarting the ski on a fast charger attempting to start it

    he was into the ski for about $3k over the book value by the time I was done, and all I really did was replace the ECU with a used one, pulled the engine to fix the timing wheel and aligned the engine after replacing the driveshaft seal

    by the way, given the condition of the trailer, I'd grease the wheel bearings immediately

  8. #8

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    Here are some pictures of the top end, pulling the head off after I write this post to look at the rings, on the middle cylinder I can physically see a small gap between the piston and the walls, is that normal? The middle one is one of the ones with 90 psi.
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  9. #9

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    Update
    Iíve got the head off, i am sending these pictures in order of left to right, the left two pistons had 90psi and the right one had around 40 or 50. The only one that has a stuck ring that I can feel is the far right one that had 40 or 50 psi. Does that mean I need new pistons and rings and I need to get the cylinders bored out? Thanks for the help!


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  10. #10
    steve45's Avatar
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    The top ring land of the front piston is eroded by the exhaust port. It looks like one of the pistons has shed some metal onto the cylinder, but I would imagine that you can get by with just honing the cylinders. Looks like you caught it just in time.

    Yes, new pistons & rings, etc. are in order.

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