I just purchased the bike a week ago, it's an 08' but been non-op since 11'. What should I do? I just pumped 91 octane almost a week ago and the owner kept it garaged. I don't have any problems riding the bike around the neighborhood.
Take the tank off, and drain it. You don't want to fire the bike up with a crap filled tank. Take the fuel pump out, clean the strainer, as that may be clogged.
Once off, get a gallon of CLR, and some stainless nuts and bolts. Pour a good amount of CLR into the tank, with the bolts. Shake the tank around, using the bolts to knock any loose rust of. Let it sit for a while. Pour everything out once you think it's clean. Pressure wash the inside, and let it dry. Once completely dry, grab some Por-15 or equivalent gas tank liner, and apply per directions.
If the top of the tank is like that, the rest of the tank is likely to need some attention.
Honestly I wouldn't waste my money, most of them products are not great. Id invest in a new tank be done with it. Atleast you'll know what you have and it'll be garaunteed problem free. Just my two centsI checked the inside of the tank and it's also semi rusted but I plan to use evapo-rust since it doesn't require any seal or any other products!? What do u think about that?