You use a compression tester.
Remove the spark plugs and screw in the appropriate fitting on the end of the hose. Crank the engine over and look at the reading on the pressure gauge. A new engine should read 150 -160 PSI. A motor with bad or worn out cylinders/rings would be 100 PSI or lower. It's also important that the readings from the cylinder with the highest pressure be no more that 10% difference from the cylinder with the lowest pressure reading. You can also look on Youtube for videos on how to check compression.
Remove the spark plugs and screw in the appropriate fitting on the end of the hose. Crank the engine over and look at the reading on the pressure gauge. A new engine should read 150 -160 PSI. A motor with bad or worn out cylinders/rings would be 100 PSI or lower. It's also important that the readings from the cylinder with the highest pressure be no more that 10% difference from the cylinder with the lowest pressure reading. You can also look on Youtube for videos on how to check compression.
