> Cylinder 1: 135 psi dry / 155 psi with oil
> Cylinder 2: 40 psi dry / 60 psi with oil
> Cylinder 3: 75 psi dry / 90 psi with oil
> Cylinder 4: 135 psi dry / 170 psi with oil
Bill,
Cylinders #1 and #3 are normal. 40 psi would cause a miss on #2. 75 psi
would not cause a miss, but that cylinder would be low on power in
comparison to #1 and #4.
Compression should be checked with the plugs out so cranking speed is higher.
Sounds like burnt exhaust valves to me. If you want a definitive
diagnostic, remove the rocker shaft so all the valves are closed and
pressurize each cylinder (in turn) with shop air through an adaptor (use
the fitting from your compression guage and the hardware store to build
this). Listen at the tail pipe - if you hear a hiss and air is coming out
it is a bad exhaust valve. Listen at the carburetor - if you hear a hiss
and air is coming out it is a bad intake valve. If both of these are OK,
it is the rings.
Les Myer
PDLJMPR
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