Cylinder ring buying and fitting advice

Discussion in 'Scooter Tuning' started by Buzz, Feb 2, 2017.

  1. Buzz

    Buzz Active Member

    Messages:
    446
    hi i bought a new cylinder head and piston set for 50cc scooter. Despite watching a few youtube videos i managed to snap both piston rings when trying to fit them. I now need to buy new rings but will any 50cc rings fit or do i need to buy a whole piston and ring set ? Plus any advice for fitting, it took no effort to snap these ones. Will warming up the rings help make them more forgiving?
     
  2. scubabiker

    scubabiker NITROJUNKIE

    Messages:
    7,321
    They need to be for that piston/bore.
    You can buy just rings
     
  3. Stevep

    Stevep Well-Known Member

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    5,895
    Did you snap them putting them on the piston or putting it into the bore?
     
  4. Buzz

    Buzz Active Member

    Messages:
    446
    I snapped one fitting it onto the piston, tried holding one e nd in the groove with my thumb and rolling my other thumb round to push the ring but it snapped. The other I snapped when I checked that it fitted in the cylinder head. Squeezed the ends together , slipped it into the cylinder and .ping.. clearly these are not flexible in the least!!
     
  5. scubabiker

    scubabiker NITROJUNKIE

    Messages:
    7,321
    Hmmmm....
     
  6. Buzz

    Buzz Active Member

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    446
    My thought exactly. Ordered new rings so ill try again.
     
  7. MiNoR cOnFuSiOn

    MiNoR cOnFuSiOn Administrator Staff Member

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    Rides:
    et2 monster
    i use my thumbs on the ends and spread just enough to clear the piston, never snapped one, you must be using a lot of force. go easy, make sure you get them round the right way, and you didnt mention ring end gap whatsoever, it will seize almost instantly if the ring end gap is too tight
     
    scubabiker likes this.
  8. Buzz

    Buzz Active Member

    Messages:
    446
    All sorted, I realised my technique was wrong as I was pulling the ends apart and not twisting, lesson learned. New rings needed a fair bit of filing to get the gap right but should be okay hopefully. I filed the ring to give a .25mm gap. I couldn't find the spec for my gilera dna50 but a piaggio site said between .24 - .26 unless anyone knows better before I fit the new head?
     
  9. MiNoR cOnFuSiOn

    MiNoR cOnFuSiOn Administrator Staff Member

    Messages:
    14,276
    Rides:
    et2 monster
    yup, over .2 replace ring at .8mm
     
  10. MiNoR cOnFuSiOn

    MiNoR cOnFuSiOn Administrator Staff Member

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    14,276
    Rides:
    et2 monster
    or just wait till it doesnt like to start or you can hear a little piston slap and just change it then, no point really ripping it apart to CHECK parts... if it aint broke and all that
     

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