Compression test! A compression tester is one of the most useful tools you can have but you have to use them, I test my compression right after a rebuild and before I fire the engine for the first time, then check it during break in between heat cycles to monitor the engines performance and ring sealing, I also test and record my compression after every riding weekend. I have found in the past on my Pilot that the compression will not vary more than 5 psi between rebuilds, if your compression drops more than 5psi I suggest you take your engine apart for inspection, in my experience something is very worn or wrong when it drops 10 psi, even with my rings to the factory specified wear limits my compression never dropped more than 5psi.