Any suggestions?
Ok, I understand the leakage is serious. First a remark. Check you haven't overfilled with oil. Level should not be higher than the upper mark. Actually quite a few CB
550 owners have made it a habit to have the oil level halfway the marks to prevent problems with the blow-by gas fouling the airfilter element. But in your case I doubt it will be a remedy for your problem.
This is what I'd do. Run the bike till it is hot. When returned home, put bike on the main stand and select first gear. Kill engine. Remove the cover and clean the area. Then restart the engine with clutch engaged. Release clutch, kneel down and look closely where it leaks. Idle and rev a bit if necessary.
Personally I hate to undertake any action, unless I have a good diagnosis.
When you're 100% sure that difficult seal is the problem, I'd bring it to a professional workshop who can do it. In Holland we have quite a few who can do the repair and then it's their responsibility.
Unless others here can guide you how to do it yourself.
