Bore measurements
 

Hello
I'm taking a measurement of the piston bore of my 1650. According to the manual the bore is 3.75 and my digital micrometer says the bore is 3.720 and I would like to know why my micrometer reads differently. Also How do you calculate the measurement into .10 over, .20 over & .30 over. I'm embarrassed to even ask this but I normally take it to be machined if damaged and let the set me up with what is needed so I haven't done the measurements.

Never Mind I found out what I was looking for