I have a new wrist pin bearing that I put in my parts box about a year ago. I want to put it in my winter Zen project but it could be a RCMK bearing. The cage OD is .870mm and the needles are .560mm (hard to measure needles while in cage). I am using Zen piston,pin,and washers. Is this a Zen or RCMK bearing?

Measuring CAGES total width ....

A Zenoah WPB is @ .344" or 8.74mm

A RCMK WPB is @ .380" or 9.65mm

BOTH bearings are same O.D. and I.D. spec fitting the same rod I.D and piston pin O.D. Individual needle length and cage length is only difference.

Thanks Scott. The bearing I have is 8.74mm long. Went to work this morning and got my good calipers. The ones I used last night are now in the scrap box. Nothing worse than a tool that does not work correctly!