There's several examples here for how bullet proof they are not. Granted, in many cases abuse and neglect are the cause. I know the full history of my 79, and I by no means think I should be out there strumming the thing to 7 grand. Old metal is old metal, no matter how well it's maintained. Even sitting dormant, aluminum and steel age, and aging has different effects on different metals.
It might surprise you to know that some parts of really big fucking aircraft are cut from a block of metal, then just sat on a shelf for 6 months to a year to see if they crack from internal stresses that cannot be detected, much less measured. That's crazy sounding stuff, but still the "state of the art" with some high strength alloys. I've seen progressive sections from a scanning electron microscope that show the crystalline structure of aluminum changing over the course of 10 years by nothing more than existing! Controlled environment storage, and the stuff changes, and the grain structure mutates over time, altering the properties of the metal. Although many times it's only altered on a finite level on the edge of the envelope, it's happening, regardless, and that kind of thing is in the back of my mind when working with naturally aged metal. Some of the metals in out 60 year old aircraft have naturally aged out of their standard properties. Age is a form of fatigue on an alloy. It may take longer to have it's effect, but it's coming, and can be compounded by conditions of storage and use.
It's for wind resistance.
Not without doubling or more the stock output of the engine or installing a "dust bin" fairing. A stock SV650S (404 pounds WET) with a fairing on it will barely kiss 130 (GPS), and that's with over 65 horsepower and nearly 50 ft-lb of torque and the rider in a full tuck. Put a GPS or accelerometer on the bike and you will be less than thrilled with what you see. Mechanical driven speedometers are notoriously inaccurate. 
