My B&S 17 1/2 HP Lawn tractor was cutting heavy grass. It started to backfire then stalled and would not start. I replaced the Head Gasket since it had been smoking, but it still will not start. It spins over fine and has 75 PSI Compression. It seems that some gas comes out of the carburetor when cranking over, but the spark is good and I checked the flywheel keyway, it is fine also.
Mousemang2

Hi,
That sounds like the valves are adjusted too tight at 75 psi. Should be 0.006"
Peace,
Clarke