Where is the compression release on briggs and stratton 16.5hp and should it be cleaned and adjusted?

Unless it's a 2 stroke. Which I doubt. There is no compression release.

Its on the camshaft inside the motor.

Hi,
It is built into the camshaft and goes "out of play" by the running of the engine. If you are asking because you feel you have a bad cam(improperly heat=treated-many existed) it is easy to see by removing the valve cover and watching the movement of the rocker arms. They move the same, problem is somewhere else; bottom one barley moves wold indicate a bad cam(they made about 120,000) and they do still turn up.
Peace,
Clarke

If this is just a starting problem, the valves are probably out of adjustment. The engine will hit the compression stroke and stop turning over. Adjusting the valves will take care of this most of the time.