Hi - When I start the engine, it starts rough and I have to accelerate very carefully until the engine warms up a little. After start, I run it at high rpm's
to normalize the gas/air flow. If the slow acceleration didn't go well, the engine lurches rhythmically and black smoke comes out. But once I run it at high rps'm, this clears up.

The engine has always had that slight pause in acceleration - but it worked fine. Now all of a sudden - since yesterday - it's doing this black smoke thing.

I'm going to put a timing light on it and see if it's timed right. But it may be a fuel flow problem - either too much or not enough - making me feed it more to keep it going during that initial stage of getting it up to high rpm's.

Any clues anyone? Thanks, Dagaan