Join Date: Sep 2007
Location: Anaheim, CA, USA
Re: Opinions on a first bike.
I suggest you buy something used and inexpensive, in reasonably reliable condition. Something with a small to medium displacement, but is sized comfortably for your son. Despite being 5' 10" and weighing 180 pounds, your son still needs experience controlling a motorcycle. I have watched too many big strong inexperienced new riders lose control of their motorcycles. How many times did you say, "Watch this!" when you were sixteen?
Consider it a "rental". In a year's time, with practice, he can sell it for nearly what he paid for it. By then, he will have acquired experience and maturity, and will have a much better idea of what kind of motorcycle should be his next one.
1970s vintage bikes are nostalgic for you, but may require too much maintenance and hunting for parts. Your son wants to ride, not tinker. Think about buying a mid-1990s 250-500cc standard or cruiser to start. If you go for a sport bike, I would find something on the small displacement side. 600cc is too fast, powerful, and tempting for a young rider.