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Discussion Starter · #1 ·
I've talked to a few people who say this is what they have gapped their Irridium plugs at and everything was fine.
Any one else tried this on their Thunderstroke?
 

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I bought a set of Iridium plugs, gaped them at .40 per RACNRAY recommendations, have not installed them yet, will put them in this Spring when I get the Chieftain out of Winter storage.
 

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When the standard gap is supposed to be at .034
Why then gap to .040?
The doesnt make sense to me.
I just put mine in at .034 but havent ran bike yet (still on the lift) but if someone could explain.
 

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Spark plug gap is dependent on ignition system energy and cylinder compression. I prefer a slightly larger gap but not too large as to cause misfiring.
A slightly larger gap may increase spark intensity. It takes more of a voltage build up in the secondary windings of the ignition coil to produce a higher voltage strong enuff to jump the larger gap, but the spark duration is shorter(kinda the same as a CDI system), and the larger gap exposes more of the a/f molecules to that spark creating a larger kernel of flame thus better combustion.
.006" in plug gap is nothing on a stock engine and I have found over the years no consequences.I installed a DynaTek CDI system on my Vaquero and gapped the plugs at .050", and when that spark jumped the gap with the plug grounded on the engine...IT SANG!!! Same sound the MSD ignitions on the 4 cylinder skoots I have werked with.

a .006" increase in plug gap may not produce any measurable or noticeable benefit, but it goes in a positive direction in how all this stuff werks together.

RACNRAY
 

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Bought Iridium plugs, gaped them to .040 with RACNRAY recommendation, going to install them when I get the Chieftain out of warm Winter storage.
 
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