Cb550f oil leak

[peterengland]

it's the long continuous rubber 'O' ring seal under the head cover, weird shaped thing

[philgresty]

Philgresty mentioned a blocked breather pipe. Not expecting much I removed the breather hose from the bottom of the airbox and just left it open to air, still connected at the other end to the top of the head. Took bike for a run, about half an hour, and guess what......no leaks. I don't know why as I have put all new parts in the airbox ie filter. The "element" is not available anymore so I made in as someone suggested out of scotchbrite, the green scouring pad stuff. Incidentally, when I bought the bike, thus hose was unattached to the airbox so I'm wondering if the previous owner had the same issue.
Anyway, any thoughts would be most welcome but as for now at least I come home with dry trousers and boots

glad my suggestion has seemed to do the trick for you, hopefully thats all it was, too much crankcase pressure.

[Chris400F]

If the excess pressure problem went away when the breather pipe was disconnected from the airbox but still connected to the engine then it sounds as if the problem was (is) not with the pipe at all but the filter arrangement at the bottom of the airbox. Either the air cleaner joint pipe has a blockage or the breather element at the bottom of the airbox is clogged up solidly. As you say you have replaced the element with scotchbrite this shouldn't be the problem so it sounds more as if there is a blockage somewhere. Might be worth having a look at to see if there is a blockage anywhere before condemning the system