H problem

Possibilites other than a burned or sticky valve are: valve set too tight, bent or damaged push rod, push rod out of place, broken rocker arm, bad cam lobe, blown head gasket, and probably a few more. Also, check for a carbon-tracked or cracked mag or distributor cap.

If you narrow it down to a likely burned valve, you can verify this buy buying an adapter to screw into the spark plug hole that hooks to an air hose. You rotate the engine to a possition where both valves are closed, and apply air pressure. It will leak out the offending valve into the intake or exhaust manifold.

If you do not want to buy the air-to-sparkplug hole adapter, you can make your own by breaking the porcelain out of an old spark plug, and welding or brazing in a pipe fitting that will connect to your air hose.

Here is a couple of simple things that I would do though if I didn't have access to a compress tester. You can roll the engine over with the coil unhooked and see if the engine sounds like it is rolling over unevenly. That is a sign that one cylinder does have compression.

You can also roll it over using the crank and hear it blowing back through the exhaust if a valve is leaking.

The third thing that you can do is pull the rocker arm cover and see if all the valves are returning. You could have a valve that is sticking and not closing all the way. Got lucky with one tractor by using some penetrating oil and lightly taping the top of the valve with a hammer until it came loose.

Not the most scientific approaches, but they have worked for me in the past.