My little John deere L110 Lawn tractor Shoots a LOUD BANG almost everytime I shut it down! What cuses this and what can I do? It only has about 60 hours of runtime
thanks

 

Can you tell if it's backfiring through the exhaust or through the intake/carburetor?

Running lean would be my first suspect but it could also be timing or valves that need adjusting.

 

On the bottom of the carburetor, you'll find a small cylindrical device that is screwed in with wires coming from it. This is the anti-backfire solenoid. Take it off and clean it, make sure the plunger moves freely in and out and that when you push it in and release it, that it pops back out instantly. If it moves out slowly, it needs more cleaning or replacement. Carburetor cleaner in a spray can works well to clean it. Work the plunger in and out while letting the spray cleaner work it's way down into the insides of the solenoid.

 

OOh, I wish I had one on my 1955 Ford 640. I'll take Dane's advice and check mixture, too.

 

Larry, you might want to check the timing too. Years ago my NAA would backfire sometimes when I shut her down and if I remember correctly - I adjusted both the timing and the carb to fix it.

 

Do you throttle it down for a few seconds before shutting it off?

 

Timing and high speed mixture are not adjustable on this. What happens when the engine backfires is this: You shut the key off which kills the ignition. When you do this, the engine is still turning and slowing down. With every cycle, the engine is still pumping gas through it, but it's not getting burned since you turned off the ignition. This unburned fuel just goes out the the exhaust. That would be okay, except the muffler is now really hot from being used. As soon as the fuel-air ratio gets high enough to combust in the hot muffler, it does. That's your backfire.

The anti-backfire solenoid closes the main jet in the carburetor, keeping any fuel from being drawn in after you turn the key off. That's how it stops the engine from backfiring, and if it is working properly, it won't backfire.

 

Will get to it ASAP and update you!