Re: Going back to motorized bikes...
I went through something similar. Built two bikes in the spring of 2008. One lasted about a year and a half. The other made it about two years. When that one died I didn't really feel like bothering with another.
Then in the spring of 2012 the 'itch' came back. So I bought a kit and built a bike that I'm still riding.
And I've noticed that I'm starting to ride it more than I ride my pedal bike. Partly it's because it is fun. I also wonder if I'm not just getting older.