Ariens Snowblower Backfires

[bill18163]

I have an old Ariens snow blower that has an 8hp HMSK80 Tecumseh engine. It's about 25 yrs old. I've kept it in good shape by keeping up on replacing parts as needed but it backfires a lot. Mostly when you are stopping it and it will put out a pretty loud bang at times. But it will do it also when starting but not as bad as when stopping. Once it it running it is mostly OK with a hiccup now and then. If I knew what was wrong I would do some work on it since it would be something to keep me busy during this virus problem. I'm retired and at home most of the time. Could someone offer up an idea on what might be causing this?

[RoyM]

Idle it down for a minute before shutting it off. If the spark is killed at full speed raw fuel will be sucked in as the engine is spooling down and ignited by the hot exhaust (afterfire) IIf it backfires through the carburetor which is not a good thing the ignition timing is off or the intake valve is leaking.