Compression check

You can typically expect around 150 pounds but what's more important is all cylinders are roughly the same within about 10 - 15 percent. It's also important that all cylinders be tested under the same conditions. That means the engine should be warmed up, the throttle should be blocked open, a battery charger should be connected so the battery doesn't become run down by the last cylinder, and each cylinder is cranked the same number of revolutions.

If any cylinder is found to be low a cylinder leakage test will identify the cause of the low compression.