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  1. #1

    Unhappy 750 ZXi bogging, now wont start...

    I just bought a '97 750 ZXi. I noticed that upon starting the ski for the first time it took about a minute of steady starting to get the engine running. Once it got going it ran fine and would restart with no hesitation. I took the ski out on the water for the first time and had no problems until I ran it at WOT for approx 10 sec where it would lose power and eventually cut off. No temp or oil warning lights came on. It was very difficult to get started again and once started gave hesitation with throttling up. It seemed to work itself out and would run normally again until WOT where the same problem showed up again. I took the ski out again a secong day and was experiencing the same problem. But the ski would not restart like it had done before. It seemed like the engine was just on the brink of cranking up but never would. Now the engine will crank but shows no signs of wanting to turn over. I have tried starting without the seat. The plugs have spark. The battery has a charge. After a little investigating it seems like this ski doesnt have a fuel pump? I pulled the fuel line at the carb and fuel comes out until I remove the gas cap(I'm guessing the fuel is provided by pressure in the tank/carb vaccuum?). Sorry, my knowledge is limited to your average auto engine with a fuel pump. One note: I was able to start the engine with starter fluid but it quickly dies out after the fluid has been used up. Does anyone have any ideas???


  2. #2
    Sounds like you might have a lean seize which isn't bad enough to lock up completely. You need to do a compression test to see what condition your pistons and rings are in.

  3. #3
    Thanks Shogun. I will get on that. In the mean time, would the lack of fuel be a problem in the carb or is it possible that the lines were not supplying enough fuel at WOT? What is the most likely cause of this?

  4. #4
    So I checked the compression and I came up with 155 psi on the first cylinder and absolutely 0 on the second. Any ideas?

  5. #5
    Yeah, time to replace atleast a piston. I would tear down the motor which is easy cause its a 750 twin and see if the cylinder is good. Hopefully all you need is a piston and rings and gaskets but you'll need to figure out why before you try to run it again.

    Let us know what you find and maybe we can walk you thru it.

  6. #6
    I was wondering how the second cylinder had no compression at all - I would expect to have some kind of pressure if the engine was turning. Is it possible that the connecting rod broke? I don't hear anything abnormal like half of a rod being slung around in the case, but it's the only thing that makes sense?

  7. #7
    axgrider73's Avatar
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    Yes, it is very common for a seized 2 stroke piston to have zero compression.

    Like mentioned above, sounds like a seizure from either being lean or overheat. Possibly an air leak?

  8. #8

    750ZXi engine probs w/pics...

    Ok, so I pulled the head off of the block. No broken connecting rod, but THIS is what I found. A large chunk of the piston has broken off and the cylinder sleeve looks like it has taken some damage too? Thoughts?

    <a href="http://s90.photobucket.com/albums/k2...t=DSCF0163.jpg" target="_blank"><img src="http://i90.photobucket.com/albums/k2...3/DSCF0163.jpg" border="0" alt="Photobucket"></a>
    <a href="http://s90.photobucket.com/albums/k2...t=DSCF0164.jpg" target="_blank"><img src="http://i90.photobucket.com/albums/k2...3/DSCF0164.jpg" border="0" alt="Photobucket"></a>
    <a href="http://s90.photobucket.com/albums/k2...t=DSCF0165.jpg" target="_blank"><img src="http://i90.photobucket.com/albums/k2...3/DSCF0165.jpg" border="0" alt="Photobucket"></a>
    <a href="http://s90.photobucket.com/albums/k2...t=DSCF0166.jpg" target="_blank"><img src="http://i90.photobucket.com/albums/k2...3/DSCF0166.jpg" border="0" alt="Photobucket"></a>
    <a href="http://s90.photobucket.com/albums/k2...t=DSCF0167.jpg" target="_blank"><img src="http://i90.photobucket.com/albums/k2...3/DSCF0167.jpg" border="0" alt="Photobucket"></a>
    <a href="http://s90.photobucket.com/albums/k2...t=DSCF0168.jpg" target="_blank"><img src="http://i90.photobucket.com/albums/k2...3/DSCF0168.jpg" border="0" alt="Photobucket"></a>
    <a href="http://s90.photobucket.com/albums/k2...t=DSCF0169.jpg" target="_blank"><img src="http://i90.photobucket.com/albums/k2...3/DSCF0169.jpg" border="0" alt="Photobucket"></a>
    <a href="http://s90.photobucket.com/albums/k2...t=DSCF0170.jpg" target="_blank"><img src="http://i90.photobucket.com/albums/k2...3/DSCF0170.jpg" border="0" alt="Photobucket"></a>
    <a href="http://s90.photobucket.com/albums/k2...t=DSCF0171.jpg" target="_blank"><img src="http://i90.photobucket.com/albums/k2...3/DSCF0171.jpg" border="0" alt="Photobucket"></a>

    I hope I took enough pictures

  9. #9
    Again, I only know the basics about engines, but I noticed that this damage is right where the piston opens up to what I believe is the exhaust port? Could this be a hint to the cause of the damage?
    Thanks again for everyone's help!

  10. #10
    Its hard to tell from the photos but its not unusual for the damage to be at the exhaust port. You probably overheated the cylinder and the rings hung up in the port.

    Either way it's time for atleast a new top end, and you'll need to tear it down enough to remove the pistons. If you cylinders clean up then I would imagine you could be back and running for few hundred dollars.

    You can probably find a Kawasaki manual on ebay or here on the internet. I would pull the motor out completely, its easier to work on that way.

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