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Old 02-21-2010, 11:07 AM
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2door 2door is offline
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Join Date: Sep 2008
Location: Littleton, Colorado
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Default Re: Spark plug gap...Myth? Fact?

I totally agree with Duane here but I'm going to muddy his waters a bit. He explains the CDI system accurately and he is correct when he says that the ignition timing can be altered slightly by increasing/decreasing the gap. What he didn't add was that it has been our experience that these engines are not consistant in magneto rotor (magnet) position on the crankshaft. Comparing different engines we have found them with as much as four degrees difference as to where the keyway is indexed on the crankshaft in relation to piston TDC and magneto coil position. This advanced/retarded condition significantly impacts how an engine performs. In other words what works for some may have the opposite effect with another engine. I typically experiment with my engines and out of four, I have found four different plug gaps that work for me. Each engine is different in some respects. .024 to .035 is the range I work with and one engine, my doggiest, likes the smaller gap to run its best. The rotor position on this engine is 3 degrees retarded when compared with my best running engine which performs well with a wide gap, .035. Did I confuse things?
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