it looks like it running toooooo rich,or running on idle for way too long. how much winterising oil did you put down it? 40;1- 50;1 should clear it up and a damn good thrash to clear it all through!
If its a 2 stroke and you have squirted plenty of fogging oil into the bores, then I would say its ok as the fogging oil will go down the exhaust ports.
It was run in neutral for about 5 mins in a bucket, I then killed it removed the plastic cover from the carb air intake, restarted it and sprayed some fogging oil in to each carb until it stalled.