[rwhit57]

Black smoke is usually carbon. Another guess would be some settlement around the valves or on top of the pistons from sitting and it could have broke it loose once it got a little warm. The float and seat are a possibility but if you dont see any fuel leaking out of the carb I think I'd let it sit and run up to operating temp and then drive it around the block a time or two, staying close to home at first and if it improves venture out aways. My guess is it will clear up. if it does I'd probably throw some new spark plugs in it.