When to bore out cylinders?

[drake1]

I have a 787 that has never been rebuild I had to remove the jugs to fix a water leak so I decided to replace the piston and rings while I had them off. I had a 150 psi on both cylinders and only one piston had some small scoring with none on the cylinder walls, total hours on engine is 200. I have been told that I should go with the larger pistons and bore .25. I don't really see a need if I still had 150 psi. I wasn't even going to replace the pistons but I noticed some scoring so I figure I might as well. When do you determine when to bore and when not to?

 

[Dr Honda]

If you didn't have a melt-down... then just measure the bores. If they are out of round... have taper... or are warn past acceptable limits... then you go one size bigger. If they are in spec... put in the new STD sized pistons, and continue to run it as is.