I have a briggs and stratton 16 hp motor that will free spin with the spark plug out. With the spark plug in it comes to a complete stop on the compression stroke after a single revolution. By hand I can turn it past the compression stroke and when I hit the key it will spin until it reaches the compression stroke once again. Where would be a good place to start to track the problem.

John deer sabre model 28q777 type 0662-e1 code 9712122d

Valve adjustment.

What your probably seeing is the "compression release" system working.

Hi,
That ubiquitous YouTube video is helpful.
YouTube - Lawn Mower Repair Valve Adjustment (http://www.youtube.com/watch?v=NjzX-PUjKmo)
Peace,
Clarke