Thanks to everyone who has responded. You have given me some good ideas and much to think about. Let me address some things in particular.
>>Those crotch rockets scare the beegeezers out of me and thats what my son wants!!! <<
My nephew has one and I have ridden it several times. It is incredibly fast. You can pull the front wheel off the ground, just by goosing it, in second gear. Yeah, just what your 18 year old kid needs. I assume you are on your way to the bike shop with him now? [

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To your point though, yes, at least he is looking at a Harley and not a crotch rocket. Everything is relative, I guess.
>>sounds like he might be growing up before your eyes<<
Every now and then, there is a glimmer of hope from him. He is a good boy, he really is. But he is just a boy. I don't give a *hit what the law says. Not only did he graduate 3rd in his class, but he got the grades while working 20 hours a week at Subway. I am proud of him, but sometimes he can make the stupidest decisions. I don't know where he gets that. I certainly didn't make any stupid decisions when I was 19. I couldn't. I was married and had a baby at 19, so clearly, he didn't get his stupid decision making ability from me. [

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>>He is 19 and now an adult<<
He is 19 going on 15, if you know what I mean. For a smart kid, you never saw someone so immature.
>>He joined the UK air force and I didn't see him for a couple of months. When he came back, he was totally changed. He's courteous, a gentleman, responsible with his money and his life. I admire him and am much prouder to call him my friend. This may not happen with your son, but it is a possibility. <<
It will probably happen. It worked that way for me too. You might be a smart a$$ed kid, but you don't get very many opportunities to tell a drill sergeant to kiss your butt. They don't like it very well. [

] The military does have a way of making men out of boys and they do it very well.
>>if he doesn't have a car, a bike is really not a practical vehicle <<
He has a car, which I helped him to buy.
>>Is every girl going to want to get on a bike for a date? <<
Not EVERY girl, for sure, but those who do, put out, and there is NOTHING more important than that to a 19 year old boy. [

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>>I'm not father to a 19 year old so this may be useless advice. <<
Your advice was excellent.
>>If he's getting ready to join the Air Force, he most likely doesn't know where he'll be stationed following basic and tech school, right? <<
He will be stationed in Texas.
>>I wouldnt cosign though, he may be the most responsible boy/man on earth but your credit is sacred, and I wouldnt loan it to ANYONE, you never know what may happen <<
I thought about that too, but it is only an $8,000 bike. It isn't like I can't afford to pay for it, in the unlikely event that he can't, and he knows that. That being said, I did consider telling him that I wouldn't co-sign because I couldn't afford to make the payment, but I know he knows better.
>>I don't know a whole lot about bikes, but I do believe that a Sportster is a crotch rocket, no? Why not refuse to sign for the Sportster and let him buy a bike that is a step or two below in power and speed?<<
Harleys are not especially powerful motorcycles. A Harley is NOT what I would classify as a "crotch rocket." There are far faster motorcycles available for a lot less money.