I get a lot of customers asking about the orientation of the piston when installing new cylinders. There is an old wives tale that there is a “top position” marked on the piston and these customers can not find it. The fact is that when you are installing a new piston it has no bias. Therefore there is no “upside down”. It is true that if you are working on cylinders that have been in service and you remove the piston you should mark the 12 o’clock position on the piston so that when it is re-installed in the cylinder it have the same orientation as before.