I have a 15.5hp Briggs & Stratton lawn tractor. It has an habit of backfiring when you shut it off after popwering down. It did this last Sunday while mowing and it will not start now. I looked at the valves, it has overhead valves & the exhaust valve is very loose. How do I adjust? Thanks! :confused:

Go to Home - Briggs & Stratton (http://www.briggsandstratton.com)
Click on maint. And repair .
On next page click on cust. Support and FAQ
On next page click on view more answers which is located under picture of engine.
On next page type in keyword such as VALVES in the search box.
Just about any info. On Briggs and Stratton engines can be found this way.

If you mean that the ex rocker clearance is very loose, more then can result from typical wear then the exhaust seat has problably fallen out as did on my 15.5hp. When seat falls out it holds valve down into cylinder and results in excessive rocker clearance. Mine ran good for 1-2 years and have had nothing but one problem after another since. Am now looking for replacement engine. Heard honda has a 13.3hp that will fit exact.