View Full Version : snapper backfire

05-01-2010, 01:45 AM
I'm running a snapper 21 with the wisconsin robin 5hp engine. Sometimes when I stop the mower to empty the bag, it will backfire when I restart the mower.

It only backfires once, on the first pull, after i've re-started it. The mower has been maintained impeccably, and runs really well. No smoke, runs smoothly, plenty of power, etc...

Anyone know why I get that backfire after a quick break to empty bag?

05-01-2010, 11:04 PM
Can you leave it idling while you empty the bag?

05-02-2010, 11:07 AM
With this model, there's now way to safely unload bag with engine idling.

05-02-2010, 10:30 PM
try to slow down the RPMs and let it cool down a bit before turning it off. dont go from full RPMs to stop

Shasta Lake Landscaping
05-07-2010, 07:24 PM
I just got one of these mowers today out of a pile of junk that was to be hauled away at a clients house. After I change the oil and do regular maintenance I'll run it and see if mine does the same.

05-12-2010, 12:05 AM
The back fire is the fuel mix hitting a hot spot someplace, could be a piece of carbon in the head or exhaust.
I agree try to let it cool down a bit before shut down.
Fix may involve cleaning piston top, cylinder head and muffler.


05-12-2010, 12:41 AM
I've been trying to let it idle down for a few seconds before i shut it off to empty the bag. I haven't had a backfire since I started doing this.

Tony O
05-13-2010, 01:53 AM
I have the same mower set-up you do and the same identical problem you just described. I purchased mine used from CL, hadn't been used commercially. I had this problem since day one but other then that it's been
a great mower smooth and plenty of power. I just acquired a Tru-cut rotary mower and I'm thinking of swapping out the Honda 5hp for the Wisconsin Robins.

Shasta Lake Landscaping
05-13-2010, 02:33 AM
Mine does not backfire, although I did decarbonize the cylinder head when I did the other maintenance things. Where can I get a manual for the engine? I found the snapper manual online but couldn't find the Wisconsin manuals.

05-13-2010, 02:46 AM
I got these from Subaru Robin...

Shasta Lake Landscaping
05-13-2010, 02:56 AM
Thank you!