Common spark plug conditions.
https://diqn32j8nouaz.cloudfront.net...e_fullsize.jpg
Previously:
https://www.homemadetools.net/forum/...072#post157268
https://www.homemadetools.net/forum/...487#post189364
https://www.homemadetools.net/forum/...756#post190390
https://www.homemadetools.net/forum/...498#post154920
