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  1. #1

    Unhappy Higher RPMs Needed. 1997 750 ZXi. HELP!

    Hi All,

    I'm hoping you can help me with some suggestions. I took out my 1997 750 ZXi this weekend for the first time this season. I de-winterized it and it started right up. I also put in fresh plugs and fresh gas before I hit the lake.

    On the lake the ZXi felt very weak and its top speed was lower than normal. At wide-open throttle the RPMs sounded like they would at half-throttle. There is no tachometer on the ski, but I'm definitely missing some high-end revs. I was thinking the engine might just be getting worn out, but I checked the compression as soon as I got back. The gauge showed about 148PSI on both cylinders.

    Where do you think I should start to try and troubleshoot to and get it running back at full strength and higher RPM?

    Thanks,

    Barky


  2. #2
    steve45's Avatar
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    What do the spark plugs look like? Could be trash in the carbs causing it to run lean. The ethanol in modern 'gasoline' absorbs water and wreaks havoc on carbs.

  3. #3
    Thanks, Steve. I changed the spark plugs, but I will try to find the old ones and snap a picture of them.

    I was thinking a carb rebuild might be in order, but I wanted to pick the brains of the experts here first.

    Also, is 148PSI good compression? I think it is, but I don't know what the factory specs should be.

  4. #4
    steve45's Avatar
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    Actually, it sounds high to me. I think 120 is typical.

  5. #5
    I've looked online and I think for the three-cylinder 900cc and 1100cc that would be a high compression, but for the 750cc two-cylinder that compression is OK, maybe a little low. Not 100% sure, though.

  6. #6
    I found and fixed the major issue. One of the water hoses had a leak that I couldn't see until I trailer-tested the ski under a load at the lake. Added water weight in the engine compartment was definitely hurting performance.

    That said, the ski still only runs about 35mph tops (GPS verified). With compression near 150psi, the ski should be faster than that. I'm not sure what's going on. I guess I could try a carb rebuild, but I hate to just do trial and error work. Anyone have any suggestions?

  7. #7
    OzarkYamMonster's Avatar
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    If all is well the ski should run around 42 to 46 mph. My 2 cents.

  8. #8
    42 to 46 mph seems reasonable to me. 35 mph isn't cutting it. Now, if I only knew why 35 is the top speed...

  9. #9

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    you could try pulling off the spark plug caps off the plug wires and clip the plug wire untill you have a clean connection and reinstall the plug cap. it seems somewhat common on kawas

  10. #10
    Good idea, phatkewitz. I have not tried that yet. I am trying to narrow down the potential issues. I took a good look at the impeller today, and it still looks almost new. The grate and water intake side look good, too. Nothing wrapped up in the shaft or impeller.

    I'll try the spark plug wires next. Then, I think my next step will be to rebuild the carbs, though I'm not really looking forward to doing that.

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