It depends on how much oil you are over by. It can cause pressure build up in the engine and blow seals or start to foam causing oil to blow back a foul the plugs. If you are over by more than 1/2 quart I would drain and refill and pull plugs and check them also.
The only thing I noticed was I think clutch slip doing an easy 50mph through the park. Happened once it was maybe 85 degrees out, have about 300 miles since last change. The oil was up all the way on the stick.
Changing oil this week, going back vic oil. This last one was 1 gallon rotella with a little castrol 4t and a little vic oil. Didn't have enough rotella lol
First thing you will notice is the seals will start to go ask me how I know. That was with a very small amount of oil over the recommended. No clutch slipping or anything else to indicate an issue until the left side engine gasket started peeing on my leg.
Too much oil will create excess crankcase pressure, which can cause seals to weaken and leak. Some bikes (Kawi Vulcan 2000s I know of specifically) will create their own siphon with the crankcase breather and douche your leg down with hot oil if they're overfull too much. Basically, no good comes of it. Something to be avoided. I think you're better off a half quart low than a half quart over any day.
I'm also curious as to what you mean by "clutch slip." 50 MPH in 5th is my worst spot for gear lash. I'll go 5 mph over just to avoid it.
You can call me Billy. Or Luci. But don't call me Shirley.
2011 Cross Roads, crimson red
Lloyd'z ATS, IAV, VFC-III. Vic "High Performance" air filter. Ness Big Honkers. Funsies.