I have a 16hp B&S vanguard engine, no compression in left cylender. Would this be rings or Valves and can I find out withouy breaking the engine down ?

<moved>

Absolutely no compression could be a stuck valve. To test rings pour a table spoon of 30W oil into the spark plug hole and take another test. If the compression comes back up it could be the rings, if no change at all you have valve troubles. Have you ever adjusted your valves and do you know the clearances?

I would suspect the valves.

Sounds like the Valves to me