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Dave
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So after 11k I decided it was time to change spark plugs, went with the NGK's, pulled out the the stock Harley champions. I shut down the bike after riding for a while at 3100 RPM and shut it down right at 3100 RPM. My bike like many mildly stumbles around that RPM so I decided to check the plugs at that rpm. Looks like the front cylinder runs leaner than the back. I don't remember seeing this last time I checked the plugs at 5k but than I shut it down normally at idle. What do you think? My bike is a 03A with K&N, V&H powershots, and the old HD flash.
 

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Thats actually how my plugs look too. I don't get any stumble. I went into the tuner after I seen the plugs and asked what the Hell and he said that is normal on your bike, he showed me the A/F chart and it was in a good range. He said any darker and your O2's are not doing there job right. I still think it's lean a bit but they wanted another $250 to richen it up so I run 91. (No ethanol) and Mix 100+ when I can till I make a few more mods and its worth the extra cost to have it Re tuned

Edit... I have a K & N filter, SE tuner, V & H 2-1 Competition pipe.
 

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I don't think plug chops work on a 4 strokes,its really only effective with 2 strokes.The color seems ok to me for this bike,i dont like to see soot.The rear should be the leaner running cylinder.3 to 4 g is where these bikes run leanest,the dyno tunner guy told me to hang out in the 4500 plus range as thats where the A/F gets better on a stock V

reading plugs
http://www.ngksparkplugs.com/tech_support/spark_plugs/faqs/faqread.asp

http://www.bikerenews.com/Stories_Archives/Sparkplugs/Spark_Plugs.htm
 

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She f...in Hates me!
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800 Posts
Shutting it down once or all the time at any speed other than idle wont change the color of the spark plugs. Both plugs don't really look bad. The one on the right looks like the metal has a darker thicker carbon build up but you are not running lean nor to rich. Many things can effect spark plug carbon build up, like is the engine normally operated till it's fully warmed up. Is the engine lugged often. Is the engine run at high speed often. I just pulled my rear plug and it was bright white. The next day I had it dyno tuned and it was lean from 3500 rpm and down it was rich from 4200 to 5600 rpm and perfect from 5600 to 6400 and really rich from 6400 to 9000. So color is not the best way to diagnose an open loop fuel control system! Unless they are heavily carbon built up or very white just keep riding!
 
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