Compression Check

Turn the ignition to the ON position.
Depress the accelerator pedal to position the throttle plate wide open.
Start with the compression gauge at zero and crank the engine through 4 compression strokes, 4 puffs.
Measure the compression for each cylinder. Record the readings.


The minimum compression in any 1 cylinder should not be less than 70 percent of the highest cylinder. No cylinder should read less than 690 kPa (100 psi). For example, if the highest pressure in any 1 cylinder is 1 035 kPa (150 psi), the lowest allowable pressure for any other cylinder would be 725 kPa (105 psi). (1 035 x 70% = 725) (150 x 70% = 105).