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  1. #1

    Switching to Wiseco Forged Pistons and Break In Help

    I just finished doing a rebuild on my 900 zxi. It has an SBT engine in it. I replaced the cylinder and put Wiseco forged pistons in instead of cast pistons.

    Are there any changes I should expect to make from switching over (i.e. carb adjustments)? The bore size is the same as it was before the rebuild.

    Also, what kind of oil do you use as a premix for the break in period, and what ratio do you mix it at? If you have any other advise on break in that would be helpful and appreciated. I know sometimes there are better methods than what the manual says.


  2. #2
    Since no one seemed to have an answer for me, I figured I would post what I found.

    So far the only difference carb wise i found was I had to turn down the idle screw. It was over revving when I first fired her up.

    As far as break in for anyone who is wondering, I called and talked with a marine engine specialist at wiseco. He gave me a general procedure for breaking in their jet ski pistons. This applies to all jet skis, not just kawi. Although, it may not apply to some of the special pistons. It is always better to ask.

    1. Start the engine out of the water, and run it at idle and consistently blip the throttle 1/4 of the way. Let it return to idle before blipping it again. Do this until you reach operating temp, shut it off, and let it cool completely. Do this 3 times min. (I have heard 5 times recommended through the grape vine pretty consistently).

    2. Start the engine out on the water and let it warm up to operating temp. Then, ride around at up to 1/2 throttle max and don't keep the throttle at the same position all the time. He said to go ahead and ride it 'hard' at up to 1/2 throttle for about 25-30 minutes. Don't go wide open. Shut it off after and let it cool completely again.

    3. He said after that you can ride it however you like. I have also heard/read about doing step 2 either 2 or 3 times and working your way up the throttle as you go. First 1/2, second 3/4, and finally WOT, still not holding it at the consistent spot as you go.

    I also read a post a jet ski mechanic put up on a site. He said he had rebuilt over 500 jet ski motors, and he said the ones with the longest lasting performance between rebuilds were the ones with the most conscientious and disciplined break in periods.

    That's what I found. Hope it helps someone.


  3. #3

    Join Date
    Oct 2011
    thanks stang it helped

  4. #4
    I've always taken the more cautious approach like you mentioned in step 3, ride 1/4 throttle varing throttle posiiton - let cool, ride 1/2 throttle- let cool, ride 3/4 throttle, let cool. Then good to go. I think I also did less of the 1/4 throttle out of water. Did that a little, but then got wet at idle to 1/4 throttle for a bit. Then I moved on to the higher throttle settings.

  5. #5
    steve45's Avatar
    Join Date
    Feb 2008
    The rings won't seat if you baby it too much.

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