Well That’s a Fine Start

[max]

Thanks for all these checks, regarding the oil level check; to evaluate how much over the top mark it is place a 6 to 10 mm thick board on the ground on the place where the center stand is used, put the bike on the center stand with the board under the leg under the sight glass, this is the safest way to place the bike on the center stand at an angle without dropping it.
if the level is still too high with the bike on a lean the oil level needs to be lowered, take your time, think it through.

To do this the bike has to sit level without the extra board and a cold engine ( as you have done before ).

Best way to do this is to loosen the drain bolt, place a container with some newspaper under it and loosen the drain plug until the oil starts to run out, watch the sight glass while draining the oil and stop when the top level is reached, take your time and practice to screw the drain plug back in, re-tighten the drainplug and clean up any spills, done properly this should not be a messy job, slow flowing oil does not run along the ridges of the thread of the drainplug very well.

Do not re-use the drained oil, you don't want any contaminants in the new engine, simply not worth it.

If it was me i would clean the area to your satisfaction and go for a ride, if more oil presents itself let us know. and if all stays dry enjoy the bike as we all do, cheers.

[GoldOxide_imp]

Although quite unlikely, it is possible:

I picked up a motorcycle from dealership and by the time I got home I had significant fresh oil dripping out of the gear shifter seal. The seal failed.

The dealership picked up the machine and dealt with the issue.

[Lord Popgun]

I thought Max would mention this as he is pretty sharp

The clutch cover does not have a gasket. It has a sealant (Three Bond 1207B or equiv.)

[Obleo]

To me sounds like it was overfilled.

[The Flying 1100_imp]

Found the leak…

It’s coming from this bolt it the photo. Should I tighten?

[max]

That's the main oil galley plug,( supplies the pressured oil to the crankshaft ) we need popgun's help here, good find mate.

[Lord Popgun]

Max, although it is shown on the parts fiche there appears to be no mention of it in the service manual.

Nothing in the torque spec section or the crankcase section. If it were mine I’d probably take it out, put some thread sealer on it and tighten it “securely”.

Maybe a better mechanic will chime in.

[max]

Google turned up this post from 2016 which had it seems a similar issue that did not have the repair documented so we don't know what happened ;

[url=http://cb1100forum.com/forum/showthread.php?tid=8487&page=2]http://cb1100forum.com/forum/showthread....487&page=2

Other than that a few plugs have o-rings, they have a groove close to the flange to hold the o-ring, another ( sideways view ) picture of the plug would help to find out if this is the case and if sealer has been applied and how much unless someone knows the answer.

However the dynamic balancer shaft ( just to the right with the clamping bolt) is very close by and it has a seal that weeps very slightly sometimes, worth a second look before taking the galley plug out.