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  1. #1
    JohnCiccarelli's Avatar
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    Oct 2008
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    Bay Tree Lakes, NC
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    Question My First rebuild success and piston question

    I just completed my first engine rebuild on a 1997 SLT700. It seems to run fine. I wanted to thank all that answered my dumb questions. I have one more. The original piston and I believe a Wisco piston both had a machined hole on the side near the top. Does anyone know what this is for? The replacement pistons that I used were WSM and did not have this hole.

    Just Curious, John


  2. #2

    Join Date
    Sep 2006
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    topeka,ks
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    3,332
    its a hydro boost port there is a matching port in the cly ,

    im going to guess its for add lubercation to the wrist pin and bearings but it also might help charge the exhuast port better as well ,

    you will wanna veri its burning correctly by the piston wash i suggest takeing the domes off for a peak with in the next 3-10 hrs

    but make you can do that with plug chops right now


    did you face the arrow to the exhuast side ?

  3. #3
    Yup it's a boost port .. but I wouldn't call it Hydro boost

  4. #4
    Lake Mead Bum & BTLS Mark starflight's Avatar
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    May 2007
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    Boulder City, NV
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    From what I've read, it also helps cool the piston dome by circulating fuel/air mixture under the piston when when the hole aligns with the boost port.

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