Carbon on No. 3 plug

[Roy.honda]

I've checked all the spark plugs. They are all ok. But the No. 3 plug has carboned up dark brown colour. It's not wet. Any ideas?

[Johnwebley]

sounds over rich,check float height,needle position,is the main jet in place,are all the other jets corrected and fitted correctly,


 swop the plug to another pot,and see what happens,