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K100 piston & rings


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When searching for a piston or piston ring the catalog indicates the brand (KS) and BR1, BR2 or BR3. What is the meaning of the BR% classification?

Best regards


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Dennis Andress

Well, I don't know....


But, BMW used to sell airhead pistons and cylinders with a grade of A, B, or C which referred to where they fit within the tolerance range.

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The best way to figure out exactly what piston/ring set you need is to look on the top of the old piston. You will have to clean off the carbon residue to find a small stamp on the head of the piston. At least that is how Mahle marked their pistons for the K100's. KS is just another vendor that BMW uses. Is that a four valver you are working on?

There are production tolerances and piston/ring fit is critical for long life. The Mahle I am familiar with were marked either A or B. Since the cylinder bore of these engines really doesn't wear, you can go back with the original sizes and be good.



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