Fuel in Oil

Either the cylinder was flooded and the bike sat, causing some gas to get through the ring, or the worse problem, but more likely, your piston rings are bad. Or it’s yknow, not broke in yet.

Usually the cause of fuel in your oil would be from a leaking fuel injector. When the bike is shut off, the fuel line is still pressurized and if the injector is leaking, it will dump fuel down into the cylinder.

An injector can be cleaned, however leaky injectors are hard to fix, recommend to replace and then reseal the unit.

To test to see if that's your issue, you will need to remove the throttle body or atleast the airbox but leave the fuel line and everything hooked up so you can observe it after you shut the bike off. You can also remove the injector and send it to get tested. I have an injector flow bench and tester where you can pressurize the injector to inspect for leaks and then pulse flow it. If you are going to try cleaning it, you need to pulse the injector open and closed while doing it, you can use a 9v battery to do that

Yamaha's rarely have bad rings and are very tolerant to a variety of break in procedure styles, so most likely the rings aren't bad if they were installed correctly and the previous posts are spot on, it's an injector issue. Ultrasonic cleaning probably isn't going to help you, as you need the injector to open when you push cleaner through it and clean it. Motion pro makes an injector cleaner tool but it's $160, the same price as a new injector for your bike, but many times shops will clean out an injector for $15-30 plus the cost of a can of carb cleaner if you ask, which is what I'd do before bagging it and throwing it in the tool box as a spare.