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  1. #1

    300 ultra lost compression

    First I have to admit I am an extreme amateur back yard mechanic. I need advise with my 2011 Kawasaki 300x Ultra. I purchased the ski last spring with only 68 hours on it. This is my first ski. It ran great at first, 68 mph. I have only put about 6 hours on it. The ski started loosing top end speed. I was letting the ski sit in the water at the dock (fresh water). Not knowing any better, I thought a drop in speed could be from crud build up from sitting in the water. Then while on a short ride, and at low speed, the ski started missing and smoking. immediately shut off the ski and got a tow back to the dock.
    I don't know much about PWC at all. Took the ski to a shop and after a couple of months they told me I have no compression in one cylinder. There was oil in the hull as well, but I think this is from a valve cover gasket that has partially came out. (smoke comes out from around the gasket on top of the motor). The ski will start but with a miss. I trusted the guy I bought the ski from but could kick myself for not having someone check it out for me.

    I was told engine needs complete overhaul or replaced with a new one at around 4 grand.

    Thoughts?

  2. #2
    steve45's Avatar
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    Welcome aboard, nitro1!

    Sorry to hear about your problem. The Ultra 310s had problems with the pistons cracking, but in many cases they are installing the 300 pistons.

    I doubt that the seller could have known about the problem 6 hours before it happened, and I doubt that having it checked out would have found the problem.

  3. #3
    Hi nitro1, your issue sounds just like what i experienced this summer on my 2016 310R. I had a blown piston as well. I decided to rebuild my engine with forged pistons from Wossner for piece of mind even though I have a stock setup.

  4. #4
    thanks for your response. Would fixing a cracked piston require a complete motor rebuild? How expensive?

  5. #5
    Thanks for your response. I am not sure if I should fix the ski or sell as is. We had bought the ski as transportation to and from a houseboat that we are selling so it looks like I will no be needing a ski.

  6. #6
    steve45's Avatar
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    Quote Originally Posted by nitro1 View Post
    thanks for your response. Would fixing a cracked piston require a complete motor rebuild? How expensive?
    Depends upon how much damage there is. Is the cylinder damaged? Did metal circulate throughout the engine? You really can't tell until you tear into it.

  7. #7
    Ok, I appreciate your help.


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