Posted by Hemimech [96.42.180.7] on Sunday, June 07, 2015 at 23:05:04 :
In Reply to: O/t cub cadet back fire posted by Perry [96.242.125.237] on Sunday, June 07, 2015 at 20:50:00 :
I have a B&S that would do the same thing on shut down for many years. Eventually when it would no longer start without ether I finally took the time to look at it. In this engine there was no longer any lash between the camshaft and the Intake valve. This meant that even on base circle the valve was being held open ever so little. Apparently the valve seat had worn or sunken into the cylinder head, letting the valve move closer to the camshaft. Compression was way down & accordingly intake manifold vacuum would have been more of a wave of pressure spikes. Carburetors don't seem to function very well when the air flows backwards;) I pulled both valves out & ground material off the tip of the valve stem until recommended lash was achieved. Never backfired after that & still runs to this day.