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I have a 2007 DF175 and checked the plugs today. The tips are tan-almost white. They are BKR6E, is this the correct plug and if so, what gap should I use? My manual calls for 0.028-0.031, but I know with todays ethanol fuels, some mechanics are increasing the gap to get a hotter spark.
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That's the correct plug and the correct gap. I wouldn't bother gapping any wider than the high end of the range specified (i.e., .031"). I don't think you would see any benefit from a wider gap.Mike
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There is no such thing as a hot spark, there is hot and cold plugs. Having a wide gap will take more secondary voltage to jump the gap but then you have less burn time, it only has a normal ignition system, on the other hand high energy ignition systems are designed to jump gaps as wide as 1.5 mill and burn for 1.5 milli secondsOriginally posted by wellcraft34 View PostComment
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Thanks Red,
Maybe "hotter" was the wrong word, it seems a wider gap would have a longer burn time than shorter? I also have a 300XS Merc 2 stroke which runs Iridium plugs. In 2008 the standard was .032" gap which has been steadily increased from .036 to .040 to .042 until today we're at .044, which according to Mercury service bulletin, is to smooth out idle and low speed operation due to todays ethanol fuels.Comment
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When ever I am diagnosing an ignition problem I will put he engine on an oscilloscope and look at the spark plug burn time in the combustion chamber. Fuel is conductive the richer it is the less secondary voltage is needed to jump the gap and the leaner it is more is needed, why mercury is saying increase the gap is to get more ignition voltage to burn the oily mix better on the electrode at idle.Originally posted by wellcraft34 View PostComment
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