Or, you could do what I did and tear it all down to find a broken piston, go buy a new piston, then discover that some PO had slipped in a 230 in place of the 250
(Different pistons, of course)
But it got worse. After getting the correct piston, I decided to do the bearings while it was apart. Since there were no oversize markings on the old bearings, I assumed they were standard and bought same. Got it all put back together and back in my Panel. The dang thing started up on the first crank and life was good-but-5 pounds of oil pressure! Sure enough, the crank had been ground 10 under.
On the bright side-I have a whole set of standard size bearings with 5 minutes on them, and a brand new 250 piston
Moral to the story: (and it's been said over and over) Never assume anything!!!