Chiltons says that if the crank journal is undersized by 0.01" then the crank will have 0.254 stamped on the #4 counter weight which applies to all 4 bearings. Actual measurements of the # 1 & # 4 journal [standard size 2.0050-2.0060" dia] came out to be 50.2 - 50.4. This is about 0.5 - 0.7 mm less than 50.9 mm

Chilton's never says anything about the journal being under sized by 0.02", however, the driver side of the # 4 counter weight had "FE 50" stamped on it. I could not see a decimal point. If this is the correct marking for bearing size -- and sourcing bearings -- then it would explain a lot.

Does Mazda ever install cranks with journals that are undersized by .50mm?

Bret