I just happened across your site the other day and have been reading frantically ever since. I am now hooked on the motorized bicycle and soon will be starting a project of my own. I am not much of a kit builder, I prefer to be a fabricator so here's what I have in mind. I picked up a Mongoose Bedlam at the dump the other day and decided that to be my ride. There will be some non traditional hurdles to jump, but I ain't skeered!
1) Aluminum frame, I don't have the skills to weld aluminum so cutting the frame isn't going to happen.
2) The mountain bike frame is 2 piece with an incorporated shock for a smooth ride...which means no room inside the frame for mounting of the motor.
3) I definitely am going chain drive as friction drive doesn't fit my style.
My motor will be a vintage Homelite brush cutter. Being thrifty as I am, I also found this at the dump (missing pull cord) but was told that it did run, but the PO needed a cord for his lawnmower and removed it from this heavy beast. When I acquired this trimmer, I didn't know what I would used it for because it is extremely heavy, must be Paul Bunyan used this back when men were men. The good with this trimmer is that it does in fact have a clutch so hopefully that will work out for me.
My plan is to mount the engine over the rear tire, much like the friction drive machines, but keep it as a chain drive machine as I desire the positive hook-up and lack of slipping.
I will start a thread with pictures, probably this evening of my bastard creation. Today I need to make sure my engine will in fact run and the remove the bits that are of no use. If time permits, I will begin working out the geometry and perhaps get started on the motor mounts.
Thanks for providing so much great information on your site, I plan on learning alot here as I get started on my first creation.