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Piston rings

Piston rings

Matching to a new or rebored cylinder


1. Push the piston rings down into the cylinder one by one, using a piston to position them correctly.


2. Measure the ring gap with a feeler gauge. If necessary, the gap can be enlarged by means of a special file. For ring gap clearance, see .


Matching in worn cylinder bore

Matching is carried out in the same way as with a new or rebored cylinder, but when matching in a worn cylinder bore the rings must be tested in the bottom dead centre position because the cylinder bores there have the smallest diameter.

Fitting piston rings on piston


Use a piston ring clamp when fitting the rings in the piston. The lower compression ring should be turned so that the side marked “top” is uppermost. Test the piston rings by rotating them in their grooves. Also check the clearance at several places.

I = Front marking on piston crown, arrow points to timing end.

1 = Upper compression ring

2 = Lower compression ring

3 = Steel strip ring (upper oil scraper ring)

4 = Middle ring (oil scraper ring)

5 = Steel strip ring (lower scraper ring)

Oil the piston and rings before fitting. Turn the compression rings so that their gaps are staggered 180°, placing them in line with the ends of the gudgeon pins. Ensure also that the spring gaps in the top and bottom rings of the three-piece oil scraper ring are placed opposite each other.