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A/C 912H Backfire


richp

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Sorry, inexperience spoken here: What makes my 912H with Kohler 12hp backfire? Didn't do it during first two mowings, now filled it up with new regular gas and it backfires when I turn engine off. Know this is a basic, but I don't know.
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I've had tractors in the past that if you didn't idle them down before shutdown, they would build up so much heat in the combustion chamber that they would ignight excess fuel built up after ignition stops.Don't know if thats your prob. but it is good to idle down before shutting off. Just A thought.
Rich
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Brett, I second Rich's recommendation. I don't know Kohlers but some engines don't like certain brands of gas, I normally use Exxon. Also carbon build up in the combustion chamber can cause backfire as it stays hot enough to ingnite the gas. If it only happened after putting in new gas I'd try another brand. Tim
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Thanks guys, idling down for a minute or two seems to stop the backfire. Does backfiring have any adverse affect on an engine or is it just a loud nuisance?
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Hi Brett, will you stop cutting your self short on experience as we all have to learn somehow and if you didn't ask questions none of us would have anything to do. I totally agree with Rich & my goodest friend Tim about the back fire and if you don't idle the engine down when hot raw gas empty's into the muffler and the heat from it inites the raw gas and thus a back fire. Or it can do the same in the cylinder. Alot of twin cylinders are prone to this also. Just keep asking your questions please.->jackl-happyjack<-
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Hi Brett,
Yup, we're back from our trip, so I can bug you again!
ALL "air-cooled" (in reality air AND oil cooled) engines must be idled for a few minutes before shutdown after being worked. This will greatly reduce top-end temperatures and contributes more than a little to engine life. The backfire will usually do no harm, but can't do any good.
If this gets to be an ongoing problem, you may need to de-carbon the top of the engine. Don't worry, we can walk you through that.
Fred
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