Small Engines (Lawn Mowers, etc.): engine backfire, air fuel mixture, air leaks

Question
what causes backfires in engines or motors that seem to run good otherwise? (Riding lawn mower)  

Answer
Backfiring is generally caused by a lean air/fuel mixture condition.  You should also notice a decrease in power as it takes extra fuel (as opposed to less fuel) to make extra power.  This condition is generally caused by one of three things:  carb adjusmtent, blockage in carb and air leaks in the intake between the carb and the cylinder.  Hope this helps.