Running rich - black soot & water out exhaust
 

Recently bought 2008 Suzuki Boulevard with Lehman Trike. It is a US model brought to Canada, has 21800 miles on dial. Changed the spark plugs - old ones were a nice light brown on the tip. When started from cold, exhaust spits out water and black soot as if running rich. Compared to the Honda Shadow I had (a v-twin with 2 spark plugs per cylinder- Boulevard has single plug per cylinder), my trike seems to run somewhat rougher. Haven't checked valve for gap, etc. Any thoughts or tips would be appreciated.