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2012 Honda Rebel 250
124 Posts
I have never been a believer in "plug chops". I check plugs after they have at least a couple hundred highway miles on them. Don't check them right after using the choke. In your picture, the top plug shows too lean, but if it is new it may change with some miles. The plug on the bottom shows too rich, but again, if it was removed right after running the engine with the choke on for several minutes, that will not be accurate. If the air fuel mixture is correct, the insulator should be a dark brown, but not black. Also, if an engine is burning oil, it will be impossible to get an accurate reading from the plug, because it will be oil fouled.

When you say new air filter, do you mean a new stock air filter in the stock airbox, or something like a pod filter? Getting rid of the airbox and installing a pod filter will seriously lean out the air/fuel mixture. Are both plugs the same number? Plugs with a different heat will also cause inaccurate readings.
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