Posted by Peter the blacksmith on May 15, 2003 at 16:56:47:
In Reply to: Sportster Pipe posted by Ed on May 13, 2003 at 01:20:16:
..so you will know if the engine runs too lean (the rim of the plug is white, and your valves will burn!) or too rich (the rim of the plug is black, your exhaust will gradually get clogged with soot, no harm to engine). The best is the colour of light brown. I strongly recommend you check your plug after a 10 mile trip on straight roads, no citydriving. After all, tearing the tank off is a smaller job than fixing the burnt valves, you know... And the feeling to be sure the bike is ok is great.
Good luck ! Peter.