With a fully charged battery and good fuel, the engine should at least start, run, and idle, so check the oil and coolant levels, (assuming your bike is water-cooled) and fire it up. If everything goes according to plan, the engine should crank quickly and start easily, though it may take a moment or two for the fresh gas to work its way into the combustion chamber. After a short warm up, it should settle down to an even idle and respond smoothly to the throttle. Finish up by changing the engine oil and filter, especially if you can’t recall when you last did it. As a footnote, liquid-cooled bikes should have their coolant tested and changed on a regular basis. Even if the stuff looks fine, change it if it’s two or more years old. Like oil, coolant contains additives that are depleted in use. As the coolant degrades, so does its ability to protect your engine. If nothing else, a periodic coolant change is cheap insurance.