Reading Spark Plug Help

cr_bobcat

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So when I did my rocker install, I snapped some pictures of the spark plugs after I pulled them out. I don't really know how to read them. These have been in for about 2 years now. I think they look fine but like I said, I'm not an expert. The plug closest to the vice grips is from #1 and they are in order from #1 to #6.

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Get a magnifying glass and look at the porcelain back inside the metal casing. If it is white that is an indication of lean mixture or too hot of a spark plug, Reading a spark plug on the tip tends to be inaccurate. Assuming the engine is in good condition, (not burning oil) the color of the exhaust valve is a great indicator of rich/lean mixture. If open it can be seen through the spark plug hole.
 
This is sort of helpful...

http://beakysmotorcycles.com/flv_portfolio/spark-plugs/

Back in my biking days, before I broke my foot and screwed it up, I used to do a thing called a "plug chop". Basically you just kill the ignition and coast to a stop, remove the plug and then check it out. It's supposed to give you the most accurate idea of how your plug is doing in use under normal driving conditions.

I did it for tinker sake mostly but it was educational. If the electrode wasn't eaten away and the plugs weren't black or wet I ran 'em!
 
"… If the electrode wasn't eaten away and the plugs weren't black or wet I ran 'em!…"
2 stroke?
 
Really hard to get good readings with unleaded gas. I think I used Octane104plus to attain different shades of red. I stagger jetted a 4bl 289 intake that way. Plug chop is the best way for that.
 
Hi, my feeling is the whitest plugs are a little lean, probably # 1+6. The tan ones look fine. If you want to "play with it" you could go to a colder plug or a richer jet.
 
As previously mentioned, use a lighted magnifying glass to look at the center porcelain from tip to base & look for round silver speckles. If you see this that is from your piston from detonation.
Make sure your total advance is 36-38 degrees at WOT.
From what i see you could drop down one heat range, but otherwise they look pretty good.
Autolite plugs seem to run one heat range hotter than other plugs.
I like Denso or NGK plugs.
If you have 46's in there go to a 45. :beer: :beer:
 
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