Am having the same trouble as a lot of others with my 18 hp B&S Intek rider. The motor turns over 1 revolution and stops.Installed new battery and have reset the valve clearance to (.004 intake, 006 exhaust)I remember something about a gummed-up compression release causing this problem . Any ideas ? Pictures available ? Thanks!

Is the battery charged correctly? It could be in the starting system rather than valve issue. A bad starter can cause the same symptom. There is a compression release located internally. When the comp release has a failure it usually takes other parts with it. As for valve clearence I personally have not experienced a clearance no crank issue before so not able to answer. Almost all no crank issues I have seen where related to fluid in the cylinder or electrical.
Don