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Reading plugs

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Just installed a Lectron on an uptite 167. The carb is Fantastic. I may still be slightly rich, but my question is what causes a plug to have a straight line difference in colors. I know Ive heard it mentioned but cant recall the reason.

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Thanks for the link.

To clarify my question, when looking at the plug one half is grey and the other is chocolate.

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First, you cannot 'read' a plug with todays additve filled pump fuels. You can somewhat determine engine condition though it would be more apparent just from the drop in performance.

Plug shades can very depending on which side is next to an intake valve and wheich is close to the xahust valve. Intake side will be cleaner looking. Read about 'indexing' a plug. However, with modern high output ignition systems, it is no longer so much in favor.

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First, you cannot 'read' a plug with todays additve filled pump fuels. You can somewhat determine engine condition though it would be more apparent just from the drop in performance.

Plug shades can very depending on which side is next to an intake valve and wheich is close to the xahust valve. Intake side will be cleaner looking. Read about 'indexing' a plug. However, with modern high output ignition systems, it is no longer so much in favor.

I'm running 4:1 avgas to Sunoco 110 leaded race fuel mixed at 40:1 with Maxima. With a Lectron installed, I am extremely lean compared to the Mukini Tmx but I think I'm still rich. I am looking for a grey color on my plug but when I saw two distinct colors halving my plug I thought I had heard it being a tell tale of condition.

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The bike must not have a real good mixing "swirl" for even combustion. If your reading the plug you should do a throttle chop. Run a mile or more at what rpm your checking, then pull in the clutch and immediately shut the motor off, then look at the plug. Letting it idle for a couple minutes even could cause that color line due to leaner /richer mixture than what it was running at. It's best to get an exhaust sniffer to look at emissions to see how it is jetted, just not easy for many to do.

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Thanks, I'll keep trying.

This Lectron atomizes the fuel so well that it's scary how much you can lean out. Ez starts and no spooge even when runnin very rich.

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