Quote Originally Posted by Dave Severson
Test it with the cylinder at TDC, then at BDC and compare the readings.....If it's 4% at TDC and 10% at BDC it would indicate bad rings... If it's equal at the top and bottom, then listen at the headers and at the carb to determine which is leaking.

Might not be what the book sez, just what works for me.......