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Thread: Small hole in piston

  1. #1
    Join Date
    Oct 2013
    Location
    Kawasaki
    Posts
    238

    Default Small hole in piston

    Any opinions about what to do about this and what may have caused it?

    It's from my 50cc scooter. You can see a small hole forming in the top of the piston. I don't know how long it's been there.
    The plug seems fine and not overheating, but some days the motor seems to get very hot. It's also just a very small area, not like I imagine overheating to be like.

    I ride it a lot, and quite hard. Could it just be wear and tear?

    I'm thinking to leave it for now and check in another 1,000 km or so, but if it's a 'change it now' situation, I have to do that.

    Could be an excuse for a future 'hop up'.

    Click image for larger version. 

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  2. #2
    Join Date
    Jun 2013
    Location
    Sagamihara-shi
    Posts
    717

    Default

    It's gotta be arcing and melting from the plug. Wrong plug installed? not gapped correctly?
    Bit of advice, Never create a forum account and screen name after drinking heavily and imagining stupid shit you would like to do before you die.

  3. #3
    Join Date
    Oct 2013
    Location
    Kawasaki
    Posts
    238

    Default

    Plug is correct.
    Looking at some new ones, they seem to have a hole / dimple too. I don't know why.
    I'll keep watching it.
    Click image for larger version. 

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  4. #4
    Join Date
    Oct 2006
    Location
    Kiryu, Gunma
    Posts
    2,449

    Default

    Are they manufactured on a lathe? Could be to accommodate an end support during turning.

  5. #5
    Join Date
    Mar 2016
    Location
    San Francisco
    Posts
    283

    Default

    Yeah that's fine, they come that way. ;)

  6. #6
    Join Date
    Oct 2013
    Location
    Kawasaki
    Posts
    238

    Default

    Quote Originally Posted by Mike Cash View Post
    Are they manufactured on a lathe? Could be to accommodate an end support during turning.
    That sounds like a good possibility. The cheaper pistons have production marks still on them.

  7. #7
    Join Date
    Oct 2013
    Location
    Kawasaki
    Posts
    238

    Default

    Thanks for people's help. I was a bit worried when I first saw it.

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