Engine compression read out

You'll need an air compressor to use the leak down tester. Rotate the engine to TDC on the compression stroke on the bad cylinder. The tester will have two gauges. Regulate the air pressure on the first gauge to 100 psi. The readout on the second gauge is the amount of leakdown. For example, if the second gauge shows 60 psi, you have 40% leakdown, if the second gauge shows 85 psi, you have 15% leakdown.

Listen at the tailpipe, carb and valve cover breather. Where there is noise, there is leakdown. I'm betting that you'll hear air whooshing through the tailpipe.