I'd finance everything.. at 0%. Usually only applies to new accounts. Why give away all the whole amount when you can keep most of it for now?

On the other hand, paying more than the bike is worth because of interest is pretty dumb.

Edit: Also, on the things I finance, I could pay for in cash, but I don't. As someone said earlier the only exceptions to financing things you can't afford now should be things like mortgages, health expenses, and other things that are essentials... like a car that gets you to and from that place where you make money.