A stuck or tight valve will cause very low, or no compression because the valve isn't seating. Always do a valve adjustment and check for stuck valves before doing a compression test. I like to pull all the spark plugs and block the carburetor wide open before testing compression- - - -it minimizes the load on the starter and assures that the cranking speed is the same for all the cylinders.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!