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  1. #1

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    96 SL 780 Piston wash

    Hi, as you can see from the title, i have a question about piston wash. I have do search and read alot about piston wash and know how it is suppose to look like, the question I have is about how long it take to build up the piston wash?

    I just finish rebulit the top end of the engine with new pistons. now, some people said that it took about 2 hours of using the ski to get the wash build up inorder to check it. I have ride my ski for more then 2 hours since the rebuild. I remove the spark plug and look into the hole, and the piston look clean with a layer of oil on it and some tiny black dots of carbon build up on it.

    Now I am worry maybe I am running to rich that is when the wash cannot build up. or it just take more time for the wash to build up?

    Thanks for any suggestion.


  2. #2
    seaobin's Avatar
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    Are you running 32:1 right now? That will effect the wash as well. You are better running rich until you are sure everything is good. How does the ski perform? Hole shot, Top end, Max RPM's etc. How do the plugs look on plug chops.

  3. #3

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    yes, I am running 32:1 right now. the ski is doing well, but since this is my first ski I can't compare it with others. It is strong and can run to 50mph. the max rpm i ever see is 6450. the plug look like it is cover with black color oil but can wipe clean easy.

  4. #4
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    It does sound rich, but your max RPM is right near the peak RPM it should have (6500 RPM)

    Ride it a while longer and see what develops.

    If the pistons are clean, you are safe. If they are all black, then you need to be concerned.

  5. #5
    thester71's Avatar
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    Buy a set of head gaskets and pull the heads, I never understood trying to look down the spark plug hole? What you render as clean might be a well oiled version of a lean piston top. Don't even bother with plug chops they are way too hard to interpret, too many variables to consider.

  6. #6

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    Quote Originally Posted by thester71 View Post
    Buy a set of head gaskets and pull the heads, I never understood trying to look down the spark plug hole? What you render as clean might be a well oiled version of a lean piston top. Don't even bother with plug chops they are way too hard to interpret, too many variables to consider.
    i just rebuilt my top end. so the head gasket it new. I don't want to keep open then cover to check the piston wash. that is why i look into the plug hole, i will open it and check the wash once the wash is built up.

  7. #7

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    Theres nice borescopes on ebay for 90.00 much easier to check the wash

  8. #8

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