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Help Holes in the ZXR 250 head

Discussion in 'Kawasaki 250cc In-line 4's' started by Tonino, Oct 13, 2021.

  1. Tonino

    Tonino Active Member Premium Member

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    Hi I have just discovered after acrebore of my ZXR250A that oil is dripping from 4 holes above each exhaust . Can anybody tell me what is the purpose of these holes and is the head toast?
     
  2. jmw76

    jmw76 Well-Known Member Premium Member

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    I am not familiar with the zxr head, but typically the little holes above the exhaust are drain holes to allow water trapped in the spark plug holes (after washing) to drain away.
     
  3. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    Correct. If they are leaking oil, then the spark plug seals on the cam cover have gone old/hard and need to be replaced.

    On this topic... can people stop using silicone RTV/silastic on cam covers... with or without they always eventually leak - the difference is that the silastic always ends up everywhere and difficult to clean/remove from the head and cover, it will get into oil passageways and cause havoc if enough of it builds up on the oil strainer.

    Two clean, dry surfaces and a clean, dry rubber gasket should seal perfectly if fitted properly and the cover tightened correctly.
     
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  4. Tonino

    Tonino Active Member Premium Member

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    Thanks guys that solves the mystery for me.
     
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  5. jmw76

    jmw76 Well-Known Member Premium Member

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    A quick note on Silastic use. The Honda manual for the cbrs calls for the use of a sealant to be used on the half moon sections on the cam cover joint. Use it sparingly. Linkin is correct. Over zealous use of silicone cause other problems.
     
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