I'm not sure whether it was the base gasket or the o rings in the head but that's where I've narrowed it down to, I'm leaning towards the base gasket as I haven't had the bike running for very long since the rebuild, maybe 5-10min, and there was a fair amount of sludge in the crank, was also a light coating on the top of the piston, I'll flush it out with diesel at some point, right now I'm taking a break from it so I don't get upset and break something, I hate to admit it but I'm starting to think I should've just gone to a mechanic to start with, ahh well lesson learned I guess