Crazy Rev's on Honda Rebel?

So I'm a little concerned, when I have a full tank of gas my bike (2006 honda rebel 250) seems to idle crazy fast. But after about 10 or so miles she seems to calm down a little. But she still seems to idle faster than my friends bike, (his is bigger 650cc, and a different make-yamaha) so I don't know if there is a problem, or if that is just part of having a 250cc. I have no clue how to adjust an idle even if I wanted to, and I dont' want to pay a shop to do it.
Is this a normal thing for these bikes?
Also, does the fuel grade make any difference? I think she sounds different now that I am using mid-grade, but I can't tell if it's all in my head, or not.
:(

Thanks!

Different bikes will sound and idle differently.

The level of gas in the tank shouldn't make any difference in the idle speed of the bike.

The fuel grade has nothing to do with idle. It has everything to do with knock-resistance.

What is knock-resistance?

If the octane is too low for your engine, it will "knock" or "ping". What's happening is the fuel is igniting at the wrong time when this happens. (On the compression stroke)

Lower octane fuel burns easier than higher octane fuel. If your engine doesn't knock using 87 octane, go ahead and use it so you can save some cash.

Check out CaptCrash's video on the subject. Just don't drink gas, it will rust your pipes!

http://www.youtube.com/watch?v=ZZx5w1jVUDA&feature=related

If you look on your carb you should see what looks like a small plastic knob. That's your idle adjustment. Get the bike up to operating temp, set it on a level surface, and use that knob to adjust the idle.