* Hold the throttle to full open position to ensure the engine gets adequate air intake. * Crank the engine continually for at least five to 10 full revolutions to obtain an accurate reading on the compression tester. * Record the reading for each cylinder. If any of them vary 10 percent or more from each other a problem may exist in one or more cylinders. If the variance is greater than 10 percent, specialized testing equipment may be required to fully diagnose the problem. * If all cylinder readings are within 10 percent of each other, no further testing is required and compression is considered optimal.
