There can be nothing more startling as when your riding mower backfires.  My worry always turns to “great how much is this going to cost me to fix”.    There are a bunch of reasons why your riding lawn mower may backfire.   In my case, the mower was backfiring when I shut it off.   You will find a bunch of different possibilities why this happens, but you will want to try this first as it is simply a matter of changing what you do before you shut down the mower.

Try this little trick before you spend any money trying different gas, re-gapping your spark plug or messing around with adjusting your valves or changing your carb mixture.   Before you turn off your riding mower, throttle down to idle for about 30 seconds or so.  This simple little trick may just solve your backfire problem.  I can’t take credit for this little bit of information.  I have a family friend who can fix just about anything.  He is always busy rebuilding and repairing small engines and he gave me that simple little trick.  Just on a side note, one other little trick he gave me was to always add Sta-Bil to my gas can.  Those two little tricks have made my life so much easier when it come so my lawn mowers!

So why will throttling down your riding mower before you shut it done help with back fires?  When you turn the key off on your riding mower, the spark plug stops immediately but inertia may keep the motor spinning just a bit.  This will suck more fuel into the cylinder and the send the unspent fuel into the exhaust which is hot and ignites the fuel.  Throttle down before shut off does reduces not only the fuel pulled in but the spin of the motor.  Both will reduce the instance of backfire.

So there you have it.  I am not saying this little trick will work for every issue but it is easy to try and it costs you nothing to try.