Why do motorcycles get such poor fuel mileage compared
to many cars, which are vastly bigger and heavier?
How much horsepower and/or torque increase does it take
to improve performance? What about RAM AIR?
What is the best cruising RPM?
Premium fuels versus mileage and combustion temperatures.

All objects …..cars, motorcycles, bicycles …..and you! …..when moving through air …..create friction and drag. On Earth, the weight of the atmosphere, held to the Earth by gravity, causes a higher pressure at sea level, than it does on a mountain top. The higher you go with your motorcycle, the faster you should be able to go, theoretically, due to less friction with the air ….or; conversely, the less power from your engine you would need for the same speed as at sea level; due to the reduced air drag. While friction and drag are not the same, you can regard them as the same for this particular bit of reasoning, which, other things not considered, is true about the speed, etc. If your motorcycle (and you!) are not moving, but if you are exposed to the wind, that creates friction and drag. Of course, if the wind is moving towards you while you are riding, that effectively also creates drag.

As you ride higher in altitude, the oxygen content of the air is less (by weight), and your engine will have less power as you go up in altitude, which will reduce performance increases from less air drag and less friction. In some instances, fuel mileage will increase with an altitude increase, especially so on fuel mixture compensating engines, such as those with fuel-injection. Mileage may decrease or increase, especially in hilly or mountainous riding. Sometimes supercharging or turbocharging can improve fuel mileage, particularly with small engines with smaller combustion areas (cylinders and heads). Mileage can also go down, if you use more and more throttle. Many factors enter into fuel mileage.