Small Engines (Lawn Mowers, etc.): 18 hp b &s vanguard v twin backfire, argo 6x6, briggs and stratton

Question
Hey Michael, I just purchased an argo, 6x6 with the briggs and stratton vanguard v twin 18 hp motor. The problem is when the engine is warm and I restart it, it backfires and scares the begesus out of my daughter, dog, cats and every other living creature within a mile. My manual does not cover this section. I have rebuilt many carbs for motorcycles, and jetted  and built a mean 68 camaro, but I do need a starting point. I have never worked on b&s this large, and the last one, an 8 horse burnt to the ground after I played with the carb. So you can see my dilema. From exp I beleive it may be a timming issue, but dont know where to start. This is supposed to be a dealer model with about 10 hrs on it, but when I just changed the oil It tells another story. Any help will be greatly appreciated. Thanks

Answer
Hi Brian,

Yes I agree, the timing may be off.
If the backfiring is from the muffler, the timing may be retarded, causing late ignition when trying to restart.  Another possible cause may be excess fuel leaking into the muffler after shut down.  Try idling the engine for 1/2 minute or more before turning off the ignition.

Let me know how you make out.
Michael