HOME and how to join Forum Open Area General Scott topics Cleaning oiled up spark plugs Re: plug oiling

#6428
Richard Moss
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Your plug isnt hot enough..

According to NGK:

Fouling Range

Lower than the self-cleaning temperature of 400°c-450°c (750°f-850°f). Air-fuel mixture richer than 8:1 to 10:1.

A Simple but interesting read is this NGK site..

https://www.ngk.de/Heat_rating_and_heat_rating_nu.657.0.html

If you are running 18mm plugs you can always get 14mm conversion inserts and have access to a wider range of modern replacements.

good luck!