What is a "Rule Of Thumbs On Spark Plug Gaps In Small Engines"?

loger_gwOctober 6, 2012

What is a "Rule Of Thumbs On Spark Plug Gaps In Small Engines"? Or! Please share links to good charts related to various brand plugs and gaps in basic small engines. Otherwise, would you agree that .030 is the basic gap and largest? Would .020 or .025 be the smallest gap used? Would a smaller gap only reduce the life of a plug or create more heat and cause misfire problems?

My recent experience was to a Champion RJ19LM in my 6 HP Briggs Mower bad after about 5 yrs. It has always started 1st or 2nd pull and continued with the new plug. The new plug appeared to be factory set at .025 and is where I left it. I have not used it to ck performance vs just starting.

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Typically most gaps are .030" and if a person didn't know- you could probably get away with that. On common exceptions- most Kohler CV singles are .040" and Briggs 12" Inteks have a desire to want to be set at .020" on those w/ hot restart problems. If there is reason to suspect otherwise- best look in the owner's or service manual.

    Bookmark   October 6, 2012 at 4:35PM
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IMO depends on how strong ignition system. older breaker points system I say .015 to.017. New systems .025 about normal. I would say .030 maybe too big IMO due to wear, the gap should get bigger over time. Not big fan of Champions but in small engine world about all you can get most of the time.

    Bookmark   October 6, 2012 at 4:40PM
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I think the best rule of thumb is to follow the manufacturers recommendation. All major tractor manufacturers have their manuals on line.

    Bookmark   October 7, 2012 at 7:51PM
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