Kohler Backfire

[23 Reo 229]

After four years of sitting I brought out my 81 C-125 Hydro. The motor runs great but backfires when I shut it off. I alway throttle down slowly to idle before I turn it off. What are the causes of this and how do I fix this?

[can whlvr 993]

sometimes its a bad muffler,it has carbon inside that gets red hot and starts any un burned fuel in the muffler,or its running with a little too much gas in the fuel air mixture,not sure if thats too lean or rich,but a small adjustment on the main jet might help

[Hydro 131]

Both my 14 and 16 do it. The 16 more so. My 12 did it as well. I do the same, throttle down and let it idle before I shut it off. I have wondered about carbon given the head is to be de carboned every 200 hours. :confusion-shrug:

[bowtiebutler956 650]

My K301 does this as well, and I just rebiult it, so there is no carbon. I have the carb adjusted where it runs best. I don,t know, it could be a little rich. I find that if I let it idle at least 30 seconds, it doesn't usually do it. Stress on the usually! It sure will startle you!

Matt :flags-texas:

[Tap53 57]

Run engine at 1/2 to 3/4 throttle, with spray bottle squirt water in to carb, but not so fast to kill engine, us 8-10 oz of water..

If engine is new and still muffler explosion, timing is off, retard 1 degree.

[bowtiebutler956 650]

Thanks Tap53, I'll close the gap on the points a little, and see if this cures it.

Matt :flags-texas:

[312Hydro 474]

My 312H has done this since it was new. I always have to let it idle at least 30 seconds or it will backfire when I shut it off.

[smoreau 658]

I would think that a lean condition would make the exhaust a little hotter and make the unburnt fuel ignite after shutting the engine down after running it at full throttle for a long period of time. I would try to rich en up the main needle a little and try that. I have had this issue on some of the newer brigs engines with the plastic anti turn thing's on the needles adjustment. pop them off with a flat blade and adjust them a little fatter on the the fuel and the issue went away.

[stevasaurus 22,767]

Good advice above. I'll just add that if it is not a carb/muffler problem, it is probably the timing. If your Kohler points should be set at .020, try setting them at .018. You may find that it will start easier also. :)

[wallfish 17,020]

Try just shutting them down at 3/4 to full throttle with out any idle time at all.

[118lfd 8]

1/2 throttle shutdown as per the manual for my magnum 16 has cured this for me otherwise watchout.

[MaineDad 85]

Good advice above. I'll just add that if it is not a carb/muffler problem, it is probably the timing. If your Kohler points should be set at .020, try setting them at .018. You may find that it will start easier also.

That's what I do too!

[boovuc 1,090]

This topic comes up once in a while. If you have a magnum, the Wheelhorse manual tells you to idle down and when you kill the engine while ramping the throttle up to half. You won't get a backfire doing this.

For the single K series, I would go the way the others suggested. That being looking at fuel mix too lean, (running hotter), carbon in the heads or muffler, a "thin" spot on your muffler or most likely, a combination.

On Magnums, K and KT series engines, Kohler suggests the cool down before shutdown but that doesn't do you any good if your idle is set too high also. (Something I noticed on a few tractors I bought or looked at).

Before selling my C-120 years ago, it would backfire every once in a while on shutdown. Couldn't figure it out until I picked a very warm night to drive around the block twice then parked it under some trees and looked at the muffler and exhaust port. It had a faint glow close to the engine. I dialed up the fuel mix ever so slightly and the backfire never came back. You would have never seen that glow unless observing it in pitch darkness.

[varosd 1,185]

my neighbor down the street has a 312 and last year we were walking our Corgi as they were shutting down the engine, when Bam! the backfire made us all jump. has never happened since!

[SousaKerry 501]

Heck the backfire is the best part of running these machines, it announces to the world that the Wheel Horse is done. I make sure my puller gives a few good pops before I shut her down