Join Date: Apr 2018
Location: Aiken, SC
Thanked 36 Times in 31 Posts
Feedback Score: 1 reviews
Oil doesn't degrade in any meaningful way by sitting in your motor. It doesn't care if it's in a plastic bottle or the bottom of your crankcase.
Only way to get rust on intake valves is for water to have gotten on them. Probably very high humidity does it, I'm not sure. If it's minor hazing, which is what it looks like, it will disappear in seconds when the motor runs.
I'd spray a little light oil, Marvel Mystery oil if you got it, down there and crank her up. Unless you're partial to tearing your motor down to check and clean everything.
You should always include year of bike and mileage when posting questions.