At the heart of OTC’s pressure tester is a 2.5-inch gauge that reads from 0 to 300 PSI and 0 to 2,100 kPa, allowing you to check your engine’s compression in whichever unit you’re more ...

"This two-stroke engine could solve these practical difficulties and simultaneously permits a much larger range of compression ratio adjustment," added the official.

Once you've built an engine, the compression ratio cannot be changed without replacing the heads, head gaskets, or pistons, or changing the stroke, which are all factors that affect it.