We hashed this out several months ago but i have had lots of enquiries about it.
I have never done it but I've seen it done. You pressurise a cylinder through
the spark pluig hole with a known or measured pressure of compressed air. Then
time how long the cylinder holds the pressure, ie how long it takes to drop to
zero (OK not zero, but local atmospheric pressure for those of you who are
smarty pants). Listen down the dip stick hole of leakage past the rings into
the crankcase. Down the carbs for leakage past the ionlet valves, down the
exhaust for leakage past the exhaust valves, in the neighbouring cylinder for
leakage
in the head gasget to the neighbouring cylinder.
With home copression testers you MUST control for a fadding battery on the last
cylinders tested by repeating the test and reversing the order of the test
but with a rechaged battery. Or hook up a booster charger whilst cranking.
As the battery fades (even a good large battery will fade some which may or may
not affect the test) it turns the motor alittle more slowly and reduces the
maximun reading.
Sorry aboot awl de tipos
Cheers DW
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