Thanks for you replies, I've had the bike around 2 month and haven't really had it out properly just round my garden due to lock down. To be honest everything I seem to tutch goes wrong. Changing coolant ( drain bolt was cross threaded) changing gear box oil ,( leaks every time the bike warms up slightly) ect lol. Back to the black fluid, I've just has a look at the bike around the exhaust and all seals/joints seem to be ok ( no black fluid) . There seems to be a couple of pipes in the area would they have anything to do with it ?