Well the new carb didn't get much use today what so ever. Wasn't long before it started to play up with no apparent reason. Did notice a black gunge but nothing clicked. Got it home and started taking everything off. Soon found an answer though. Right by my thumb in the picture what looked like a gasket. Confirmed when I took the head off. I have now decided to strip off all the bits and change the crank gasket whilst I'm at it.