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28442
I just got back from Silver Lake sand dunes. Before the trip I replaced the factory intake with an Fci, retuned, and installed new spark plug. I did a lot of drag racing, pretty much all day yesterday. After getting home a few hours ago, I removed the spark plug, and cut the threads off to get a better view of what's going on with my tune. I think it looks pretty good, if anything a touch rich, which I'd prefer over lean. Looks a little strange as half of the plug looks really good, the other half shows more of a rich tune. I thought it ran great, seemed to have really strong power everywhere these machines normally do, didn't bog at all and didn't get any backfiring. The closest races I had were against a stock Raptor 700, a modded Polaris Outlaw 525, and a Yfz450, that was supposedly stock, but was much faster than the other 2 Yfz450's I ran against. Here's some pics of the plug I just pulled out.
28443
 

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The black sooty side faces the exhaust valves during the exhaust stroke is all, you notice the tan/ coffee color all around the insulator showing a proper burn...

Is your ignition coil stock or upgraded...?
 
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