72 ct70 K1 piston replacement

Discussion in 'General' started by Sooner80, Mar 14, 2019.

  1. Sooner80

    Sooner80 New Member

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    I'm in the process of replacing my piston and rings , the problem I'm having is the bottom oil rings will not fit in the groove. The original doesn't look like it had the serrated ring in between the skinny rings , also the cheap generic piston is shorter and doesn't have the same shape on the dome .. are my $10 piston and ring usable?
     

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  3. OLD CT

    OLD CT Well-Known Member

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    HONE.jpg In a word, no. 10 bucks pissed away. The original is a ''old dome'' piston. You have a new dome piston. SO you will be down on compression. Very important, you will need to de glaze the cylinder also with a 46-48MM hone. Buy the correct OEM piston/rings and be sure to hone the cylinder.
     
    #2 OLD CT, Mar 14, 2019
    Last edited: Mar 14, 2019
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  4. Sooner80

    Sooner80 New Member

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    Well I got the rings to fit once I did it in the proper sequence. Will I be able to find a hone that small at the auto part store ?
     
  5. OLD CT

    OLD CT Well-Known Member

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    Good practice. Now I doubt that a auto parts store would have something that small.
    You could buy it on ebay with everything else. Type in 46-48 mm hone along with a set of 13010-087-023 standard bore rings. I'm guessing it's still standard... Measure the bore with a set of calipers would also be a good idea to know for sure. Search ART std ct70 piston. It is gonna be a little more $ than you expected to pay, but it will last a long time done right.
     
  6. Sooner80

    Sooner80 New Member

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    Looking through the gasket set ,I came across a seal that I'm not sure where it goes , any help would be appreciated
     

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  7. wanrep

    wanrep Active Member

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    It looks like the seal on the right side of the front wheel hub. I just bought one. I'm not that good.
     
  8. kirrbby

    kirrbby Well-Known Member

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    If that thing is tiny, and kinda hard...not rubber, it's the exhaust valve seal.
     
  9. Sooner80

    Sooner80 New Member

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    The gasket set is for a top end rebuild only , no wheel seals . This one is only about 1/4 inch
     
  10. racerx

    racerx Administrator
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    Most aftermarket gasket & seal kits are generic, meaning that they do include extra pieces. That looks like an early type valve seal...those come in two flavors, hard fiber and polymer, which is softer. This appears to be polymer.

    FYI some kits include the umbrella type seals, used on both valves...incompatible with 6v heads.
     
  11. Sooner80

    Sooner80 New Member

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    It does look like a valve seal , but there was only one .. is there any seal that slides over one of the head studs ?
     
  12. racerx

    racerx Administrator
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    I'm viewing this on a real monitor screen, now. It's a valve seal, end of story. The 6v heads only used one valve seal. No idea why that is but, the setup works.

    There are oil passage seals, as you asked. They are all O-rings and easily identified.
     
  13. Sooner80

    Sooner80 New Member

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    Thanks racerx, I did place the 2 o-rings
     
  14. Tripod

    Tripod Active Member

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    That's your exhaust valve seal. It goes under the top hat.
     

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