It sounds like you're getting too much oil. Agreed?
Now here's where it becomes hard to detect.
I recently had to seal my tank because I had a leek between the oil and gas tanks.
I suspected this and found it by smelling gas in the oil when I drained the oils tank.
Run it out of gas. Pull the oil line to injector.
Once you have the oil tank empty, refill the gas tank. Let it sit over night. If you have a leek between them, it will fill the oil tank till they are at equal levels.
It's hard to tell with both tanks full because the liquid are at the same level and blend really slowly. You're best off using the gas to see if it goes into the oil tank because gas is much thinner.
Let me know.
The mix would be less obvious at low speeds because the injector supplies way less than at full throttle. Once you open it up and cross contamination would be made more obvious by the smoke.
Please let me know how you make out.