Forum bmwbike.com

My 1960 R50 has a 5 ring pistons (68 mm) , never rebored and originals:
this fact matches with what says the workshop manual of the r50 1955-1960.
Roland Slabon's book does not speak of those pistons and talks about 4 or 3 ring pistons.
I must rebore my cylinders to the first time (68,5mm) ; what MUST I looking for ?
3, 4 or 5 rings pistons ?
are they exchangeble or not ?
why Slabon says they are not (at page 92) ?

thanks
Michele

Hi Michele

The very old production pistons from the 1950s used 5 rings due to the primitive piston ring technology that they had in those days. The biggest problem was the oil ring, and that is why they required two of these. The modern pistons all use new ring technology where only 3 rings are required. These naturally offer less resistance, friction etc.

If you order new pistons from us, you will automatically receive new 3 ring pistons.

Best regards,

Mark
Mark Huggett GmbH