I have a 2015 FZ-09 with 1000 miles on it.This next part makes me sick. This weekend the bike fell over in driveway and was down for several minutes. I stood the bike up and off I went to ride with my son. In my haste I didn't check to see if fuel entered crankcase, anyhow after a 75 mile ride we parked the bikes and yes this is were it gets ugly. The sight glass is full of gas ,and after talking to dealership were I bought bike, I still can't get a straight answer if I need to rebuild motor. I do have full insurance to cover cosmetic damage from the drop, but not sure they will pay for engine rebuild. The bike seems to run ok, can someone tell me what I'm dealing with?
Obviously, first line of business is to change out the fuel laden oil with fresh oil change. With a 1000 miles on it, it was probably due for a change anyway. With the gas in the fuel, it will probably run out very nicely, as well as leaving the crankcase very clean. After you've filled the crankcase with fresh oil and changed out the filter, you'll want to do a compression check to see if there was any damage to the rings. I found this video showing them testing (a well used, I might add) FZ-09 engine which was posting compression in the 190-200psi range. Seems about right. If yours is in the range or higher (may be higher due to it being a newer engine), no issues.
From what I'm reading, the manufacturer's recommendation is to be easy on the bike for the first 1000 miles (I've seen some which are much more complicated than that, but we'll leave it there for now). Considering your last 75 is with the weakened oil, I'd suspect you've had very little effect on the engine itself. Is it good for the engine to run it with gas thinned oil? Absolutely not, but it doesn't mean you've killed it. Do the compression check. If it comes out good and you aren't hearing any real noises, you've dodged a bullet. I doubt the engine will require a rebuild.