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I opened a 2007 912ULS and found these strange rings on the pistons.

The top compression has a tapper inside, the middle is not tapered and has a step, and the oil scraper is different than the original ones.

Are there variations in rotax rings, or are all of them equal?
20170517_212439.jpg (You do not have access to download this file.)
20170517_213756.jpg (You do not have access to download this file.)
20170517_213823.jpg (You do not have access to download this file.)
20170517_224157.jpg (You do not have access to download this file.)
  • Re: Fake Piston Rings

    by » 6 weeks ago


    Ancient post, but I have the same question. I have the same beveled top ring as in your pic, but new part number for that “rectangular ring” 215590 is perfectly square with no bevel. Same dimensions otherwise. Seems they may have changed the design of the rings. My middle “compression” ring is same as yours and my oil ring is of newer design.


  • Re: Fake Piston Rings

    by » 5 weeks ago


    The original post is from 7 years ago.  The picture shows a oil ring that is not Rotax.  The compression rings do have a bevel however it is so small you can't see it with the eye.  You have to look at the ring marking and install it so the mark is facing the combustion chamber to get the bevel in the correct position.  (if it was square then there is no point in having a mark on the ring) 

    On the 100 HP engine the compression rings are different top and middle, the middle is indeed fitted with a notch.  

    Cheers

    39187_2_piston rings MMH .jpg (You do not have access to download this file.)

  • Re: Fake Piston Rings

    by » 5 weeks ago


    Great info, and thank you for circling the diagram. So, that would be same for 912s and 912ULS.

    In my case, oil rings are correct, middle ring correct, but the top ring looks different. Left one in photo is new, nearly square with the dot, right ring is old, square on top but with a bevel. I am wondering if maybe some older outer rings were beveled to show the direction instead of having the dot. They are dimensionally the same otherwise.

    39191_2_IMG_7593.jpeg (You do not have access to download this file.)

  • Re: Fake Piston Rings

    by » 5 weeks ago


    I will answer my own question. Left ring in my image is for 912UL. Right is for 912ULS. I ordered wrong replacement part.


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