Starting My New MotorBike Gonna Need Some Advice

Ok. I'm new to this scene. I've been looking for a way to get back and forth between classes besides driving. I live between 5 and 10 miles from campus, so I could bike it, but I'm lazy. I looked at the electric kits for a while and decided they weren't cost effective. It would take me about 2 years to make up the cost for what I would pay in gas. Anyway, I found a guy that doesn't need his weed eater anymore so I'm gonna give this motorized bike stuff a try.

I have an old 10 speed bike that i've been using for about a year. I think the motor I'm getting is a 25cc. I've got a few ideas in my head about how to mount the motor and hook everything up. As long as the motor has a clutch, which I'm pretty sure it does, I want to keep the pedal assembly in place. That way if anything goes wrong with the engine or anything, I can at least pedal to where ever I'm going.

So my question is, Any suggestions for attaching the motor, with a chain drive, and keeping the pedal functionality intact? Thanks.

Thanks. I know the friction drive is like 100 times easier, but I really want a chain drive for a couple of reasons. I live in Cincinnati, Ohio, where it basically rains constantly, which would cause all kinds of problems with slippage. The other thing is, I've read a lot about the friction drives tearing up peoples tires and stuff. I think a chain drive would be more efficient too, as far as mpg's and stuff.