first of all I bought this bike used bout 8 months ago. Haven't done as much riding as I would like too. I've done all the usual tune up stuff. Good oil. Done my research. Noticed my oil was pouring out the swing arm when unscrewed the cap. Drained and refilled. Went one little ride to gas station for fresh fuel. It was a few months old cause I fish for a living 2 months at a time. Drained oil again cause it smelled of fuel. Filled back up, cleaned out PVC valve cause they were plugged. Ran it for few days constantly checking oil. Seemed ok so I went for hour and half ride. Rode it kinda hard. She sputters a tiny tiny bit. Cause I haven't been able to connect for a tune. Cable or computer problem. However that's another post. I figured maybe injectors. Seen diesels do this from faulty over filling inector. This engines seems same way. Or rings or is there maybe mech fuel pump leaking internally. Anyone's guess
I don't think he's still on here from 8 years ago. But good to check all the same things already stated in this thread. Theres no reason his solution would be the same as yours.
FYI, leaky injectors can make the oil smell like fuel, but not overflow it. IMO, he had a problem with the oil check valve and it was improperly filled by the PO. The checking/ filling procedure should be followed closely.